Mimicry and ultrastructural analogy between the semi-aquatic grasshopper Paulinia acuminata (Orthoptera: Pauliniidae) and its foodplant, the water-fern Salvinia auriculata (Filicatae: Salviniaceae)

The semi-aquatic grasshopper Paulinia acuminata is mimetically protected by a striking similarity to its foodplant, the floating fern Salvinia auriculata. A SEM study of the cuticula of young grasshopper nymphs and the Salvinia leaf surface reveals a similar ultrastructure of epicuticular waxes which makes both organisms extremely water repellent

Direct observation and evolution of electronic coupling between organic semiconductors

The electronic wavefunctions of an atom or molecule are affected by its interactions with its environment. These interactions dictate electronic and optical processes at interfaces, and is especially relevant in the case of thin film optoelectronic devices such as organic solar cells. In these devices, charge transport and interfaces between multiple layers occur along the thickness or vertical direction, and thus such electronic interactions are crucial in determining the device properties. Here, we introduce a new in-situ spectroscopic ellipsometry data analysis method called DART with the ability to directly probe electronic coupling due to intermolecular interactions along the thickness direction using vacuum-deposited organic semiconductor thin films as a model system. The analysis, which does not require any model fitting, reveals direct observations of electronic coupling between frontier orbitals under optical excitations leading to delocalization of the corresponding electronic wavefunctions with thickness or, equivalently, number of molecules away from the interface in C60 and MeO-TPD deposited on an insulating substrate (SiO2). Applying the same methodology for C60 deposited on phthalocyanine thin films, the analyses shows strong, anomalous features - in comparison to C60 deposited on SiO2 - of the electronic wavefunctions corresponding to specific excitation energies in C60 and phthalocyanines. Translation of such interactions in terms of dielectric constants reveals plasmonic type resonance absorptions resulting from oscillations of the excited state wavefunctions between the two materials across the interface. Finally, reproducibility, angstrom-level sensitivity and simplicity of the method are highlighted showcasing its applicability for studying electronic coupling between any vapor-deposited material systems where real-time measurements during deposition are possible.Comment: 12 pages, 6 figures, Supplementary informatio

Exciton diffusion length and charge extraction yield in organic bilayer solar cells

A method for resolving the diffusion length of excitons and the extraction yield of charge carriers is presented based on the performance of organic bilayer solar cells and careful modeling. The technique uses a simultaneous variation of the absorber thickness and the excitation wavelength. Rigorously differing solar cell structures as well as independent photoluminescence quenching measurements give consistent results

Campbell's Monkeys Use Affixation to Alter Call Meaning

Human language has evolved on a biological substrate with phylogenetic roots deep in the primate lineage. Here, we describe a functional analogy to a common morphological process in human speech, affixation, in the alarm calls of free-ranging adult Campbell's monkeys (Cercopithecus campbelli campbelli). We found that male alarm calls are composed of an acoustically variable stem, which can be followed by an acoustically invariable suffix. Using long-term observations and predator simulation experiments, we show that suffixation in this species functions to broaden the calls' meaning by transforming a highly specific eagle alarm to a general arboreal disturbance call or by transforming a highly specific leopard alarm call to a general alert call. We concluded that, when referring to specific external events, non-human primates can generate meaningful acoustic variation during call production that is functionally equivalent to suffixation in human language

The SASSCAL contribution to climate observation, climate data management and data rescue in Southern Africa

A major task of the newly established "Southern African Science Service Centre for Climate Change and Adaptive Land Management" (SASSCAL; www.sasscal.org) and its partners is to provide science-based environmental information and knowledge which includes the provision of consistent and reliable climate data for Southern Africa. Hence, SASSCAL, in close cooperation with the national weather authorities of Angola, Botswana, Germany and Zambia as well as partner institutions in Namibia and South Africa, supports the extension of the regional meteorological observation network and the improvement of the climate archives at national level. With the ongoing rehabilitation of existing weather stations and the new installation of fully automated weather stations (AWS), altogether 105 AWS currently provide a set of climate variables at 15, 30 and 60 min intervals respectively. These records are made available through the SASSCAL WeatherNet, an online platform providing near-real time data as well as various statistics and graphics, all in open access. This effort is complemented by the harmonization and improvement of climate data management concepts at the national weather authorities, capacity building activities and an extension of the data bases with historical climate data which are still available from different sources. These activities are performed through cooperation between regional and German institutions and will provide important information for climate service related activities

Preclinical safety and tolerability of a repeatedly administered human leishmaniasis DNA vaccine.

The leishmaniases are a complex of vector-borne diseases caused by protozoan parasites of the genus Leishmania. LEISHDNAVAX is a multi-antigen, T-cell epitope-enriched DNA vaccine candidate against human leishmaniasis. The vaccine candidate has been proven immunogenic and showed prophylactic efficacy in preclinical studies. Here, we describe the safety testing of LEISHDNAVAX in naive mice and rats, complemented by the demonstration of tolerability in Leishmania-infected mice. Biodistribution and persistence were examined following single and repeated intradermal (i.d.) administration to rats. DNA vectors were distributed systemically but did not accumulate upon repeated injections. Although vector DNA was cleared from most other tissues within 60 days after the last injection, it persisted in skin at the site of injection and in draining lymph nodes. Evaluation of single-dose and repeated-dose toxicity of the vaccine candidate after i.d. administration to naive, non-infected mice did not reveal any safety concerns. LEISHDNAVAX was also well tolerated in Leishmania-infected mice. Taken together, our results substantiate a favorable safety profile of LEISHDNAVAX in both naive and infected animals and thus, support the initiation of clinical trials for both preventive and therapeutic applications of the vaccine