17,823 research outputs found
A new North American species of Microrhagus Dejean, 1833 (Coleoptera: Eucnemidae) : with a key to the Nearctic species
Microrhagus brunneus, new species (Coleoptera: Eucnemidae: Melasinae: Dirhagini) is described from Arkansas, Indiana, Kentucky, Louisiana, North Carolina, Oklahoma and Wisconsin. Dorsal, ventral and lateral habitus, along with male aedeagus are illustrated and a new key is provided to distinguish the new species from the four other Microrhagus species in the region
Description of a new species of Adelorhagus Horn, 1890 (Coleoptera: Eucnemidae) from Honduras with a key to the species
Adelorhagus bicoloratus, new species (Coleoptera: Eucnemidae: Melasinae: Dirhagini) is described from Honduras. Dorsal, ventral and lateral habitus, along with male aedeagus are illustrated and a key is provided to distinguish the new species from that of Adelorhagus lateralis Horn, 1890
Plasmonic nanoantennas as integrated coherent perfect absorbers on SOI waveguides for modulators and all-optical switches
The performance of plasmonic nanoantenna structures on top of SOI wire
waveguides as coherent perfect absorbers for modulators and all-optical
switches is explored. The absorption, scattering, reflection and transmission
spectra of gold and aluminum nanoantenna-loaded waveguides were calculated by
means of 3D finite-difference time-domain simulations for single waves
propagating along the waveguide, as well as for standing wave scenarios
composed from two counterpropagating waves. The investigated configurations
showed losses of roughly 1% and extinction ratios greater than 25 dB for
modulator and switching applications, as well as plasmon effects such as strong
field enhancement and localization in the nanoantenna region. The proposed
plasmonic coherent perfect absorbers can be utilized for ultracompact
all-optical switches in coherent networks as well as modulators and can find
applications in sensing or in increasing nonlinear effects.Comment: 10 pages, 6 figure
Diel and seasonal courses of ambient carbon dioxide concentration and their effect on productivity of the epilithic lichen Lecanora muralis in a temperate, suburban habitat
Ambient CO₂ concentration (together with CO₂ exchange and microclimate) was recorded every 30 min for 15 months for Lecanora muralis growing in the Botanical Garden Würzburg (Germany, northern Bavaria), a habitat on the outskirts of the city. Annual mean CO₂ was around 17 ppm higher than the global average reported for the time of measurement (361 ppm; 1995/96), and daily values ranged from 317 to 490 ppm. Diel courses of CO₂ could be classified into three different types. Type A, when CO₂ levels rose overnight and then fell strongly to below global levels during the day, which predominated in the summer (about 75 of days); Type B, irregular diel courses occurred during all seasons with often very rapid changes apparently due to advective CO₂ transport; Type C, CO₂ concentration was typically almost stable at generally between c. 330 and 430 ppm which predominated in the winter (63 of days).
Under controlled conditions, CO₂ saturation of net photosynthesis (NP) of L. muralis at optimal hydration and light occurred at around 1000 ppm. NP was also affected by low CO₂ at limiting light and thallus water contents. Based upon these data, we estimated the improvement of NP of L. muralis due to transient increase of ambient CO₂ (as compared with the global average) for one selected combination of environmental factors (nocturnal dew or frost). This combination is an important source of water for the lichen, resulting in 40 of its annual production and, especially in these situations, photosynthesis was increased by high ambient CO₂ in the early morning under prevailing Type A conditions. After dew activation, light compensation point of NP occurred at an average concentration of 413 ppm and diel maxima of NP at 402 ppm. This allows a rough estimate that the transiently elevated CO₂ increased the photosynthetic gain of the lichen after dew of 7, or an improvement to its annual carbon balance of about 3. Conditions, especially interrelationships between lichen hydration, light and CO₂ are so complex that we are not yet able to extend our estimates to other environmental situations of photosynthetic activity of L. muralis
Ecophysiological adaptations of the lichen genera pseudocyphellaria and sticta to south temperate rainforests
Temperate rainforests are a poorly researched habitat with respect to lichen ecophysiology in comparison to desert and polar regions. The evergreen, broadleaf forests provide a dim, moist environment that is relatively stable throughout the year. Lichens are abundant in both quantity and species diversity with the large foliose genera Sticta and Pseudocyphellaria normally being dominant, visually and in terms of biomass. These lichens exhibit a great diversity of both form and habitat range. Physiological and morphological adaptation has also been demonstrated. Pseudocyphellaria dissimilis shows changes in thallus water storage capacity with evaporative demand and is also highly shade-adapted. The species has the lowest light saturation and compensation values for photosynthesis yet known for lichens (20 and 1-μmol m−2s−1, PAR, respectively). Unexpectedly it is also highly desiccation-sensitive with some thalli being killed after only 20 h exposure to 15% relative humidity. Photobiont versatility is also a feature of these genera. Photosymbiodemes occur, i.e. a single thallus containing both green algal and cyanobacterial sectors. Because the different sectors have the same fungal partner and grow in the same habitat, it is possible to investigate whether particular physiological traits are photobiont determined. The ability to recover photosynthetic activity in humid air is confined to thalli with green algal photobionts whilst the inability of thalli containing cyanobacterial photobionts to tolerate high light stress may be related to their lack of a protective xanthophyll cycle
New Species Records for Wisconsin False Click Beetles (Coleoptera: Eucnemidae),
In Wisconsin, Microrhagus opacus, Euryptychus ulkei and Fornax bicolor are recorded for the first time. Records for these three species are based on nine specimens, most of which were taken since 2008. Two specimens of M. opacus taken from a Grant County Malaise trap in the late 1970’s as part of a statewide gypsy moth parasitoid recovery project, were previously identified as Microrhagus audax. Most of the specimens reported herein were taken late in the collecting season, primarily during August. A checklist of the 20 genera and 41 species of Wisconsin Eucnemidae is also included
An unusual growth form of Cladonia furcata: The trampling-resistant primary thallus colonizing a paved pathway
Lichens are well known to be susceptible to damage by trampling. Fruticose species, with their
highly branched structure, are particularly sensitive and Bayfield et al. (1981)
described substantial damage to Cladonia uncialis, C. arbuscula, C. rangiferina,
and C. impexa on paths in lichen-rich heath communities in north-east
Scotland. Less visible communities, biotic soil crusts in arid and semi-arid
areas with their cover of crustose lichens, are also easily disturbed by walking,
car driving, or grazing and recovery can take decades.
We report here an interesting situation where a lichen (Cladonia furcata) is apparently being
maintained and even spread in a habitat because trampling prevents it from
completing its monocarpic life cycle
An ultrafast reconfigurable nanophotonic switch using wavefront shaping of light in a nonlinear nanomaterial
We demonstrate a new concept for reconfigurable nanophotonic devices
exploiting ultrafast nonlinear control of shaped wavefronts in a multimode
nanomaterial consisting of semiconductor nanowires. Femtosecond pulsed laser
excitation of the nanowire mat is shown to provide an efficient nonlinear
mechanism to control both destructive and constructive interference in a shaped
wavefront. Modulations of up to 63% are induced by optical pumping, due to a
combination of multimode dephasing and induced transient absorption. We show
that part of the nonlinear phase dynamics can be inverted to provide a
dynamical revival of the wavefront into an optimized spot with up to 18%
increase of the peak to background ratio caused by pulsed laser excitation. The
concepts of multimode nonlinear switching demonstrated here are generally
extendable to other photonic and plasmonic systems and enable new avenues for
ultrafast and reconfigurable nanophotonic devices.Comment: 18 pages, 6 figure
The Functions of the Multiproduct and Rapidly Evolving \u3cem\u3edec-1\u3c/em\u3e Eggshell Gene Are Conserved Between Evolutionarily Distant Species of Drosophila
The Drosophila dec-1 gene encodes multiple proteins that are required for female fertility and proper eggshell morphogenesis. Genetic and immunolocalization data suggest that the different DEC-1 proteins are functionally distinct. To identify regions within the proteins with potential biological significance, we cloned and sequenced the D. yakuba and D. virilis dec-1 homologs. Interspecies comparisons of the predicted translation products revealed rapidly evolving sequences punctuated by blocks of conserved amino acids. Despite extensive amino acid variability, the proteins produced by the different dec-1 homologs were functionally interchangeable. The introduction of transgenes containing either the D. yakuba or the D. virilis dec-1 open reading frames into a D. melanogaster DEC-1 protein null mutant was sufficient to restore female fertility and wild-type eggshell morphology. Normal expression and extracellular processing of the DEC-1 proteins was correlated with the phenotypic rescue. The nature of the conserved features highlighted by the evolutionary comparison and the molecular resemblance of some of these features to those found in other extracellular proteins suggests functional correlates for some of the multiple DEC-1 derivatives
The Evolution of the Rationale for Government Involvement in Agriculture
Agricultural and Food Policy, Q18, Q10,
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