Current carrier lifetime in doping superlattice crystals

It is shown, that the lifetime of nonequilibrium current carriers in the luminescence process in doping superlattice structures changes in a wide range with increasing the excitation level of the crystal. Two effects are important, i. e., (a) lowdimensional character of the carrier distribution and (b) change in the overlap of electron and hole wave functions. At low excitation, non-radiative recombination can play principal cause in the stabilization of the effective lifetime of current carriers. At high excitation, the effective lifetime of current carriers approaches the value in the bulk crystal. The major attention was given to the compensated GaAs doping superlattices with i-layers (n-i-p-i crystals) and to the structures with no i-layers (n-p-n-p structures). The layer thickness of n-, p-, and i-type were 20, 40, or 60 nm and the concentrations of the dopants Te and Zn made up to 1018 cm3. Photoluminescence spectra and the decay time of the spontaneous emission intensity in the superlattices were measured at the temperature interval from 1 1 to 300 K. The influence of u-particle irradiation and thermal annealing on the luminescence spectra and the carrier lifetime was also investigate

Realization of a classical counterpart of a scalable design for adiabatic quantum computation

We implement a classical counterpart of a scalable design for adiabatic quantum computation. The key element of this design is a coupler providing controllable coupling between two bistable elements (in our case superconducting rings with a single Josephson junction playing the role of a classical counterpart of superconducting flux qubits) The coupler is also a superconducting ring with a single Josephson junction that operates in the non-hysteretic mode. The flux coupling between two bistable rings can be controlled by changing the magnetic flux through the coupler. Thereby, the coupling can be tuned from ferromagnetic trough zero to to anti-ferromagnetic.Comment: 3 pages, 3 figures v2: extended discussion experimental result

Tunable photoluminescence spectra of doped semiconductor superlattices

Taking into account the density state tails appearing due to fluctuations of impurity concentrations, the spontaneous emission spectra of doped semiconductor superlattices are calculated. In the framework of the model developed, the explanation of the experimentally observed longwave edge and the shift of the photoluminescence spectra with increase in the excitation level and temperature is given. The role of the defects formed on α-irradiation is discussed, and the lifetime of current carriers is evaluated depending on the design parameters and excitation conditions of the GaAs doped superlattices

Enhancing faba bean (Vicia faba L.) genome resources

Grain legume improvement is currently impeded by a lack of genomic resources. The paucity of genome information for faba bean can be attributed to the intrinsic difficulties of assembling/annotating its giant (~13Gb) genome. In order to address this challenge, RNA-seq analysis was performed on faba bean (cv Wizard) leaves. Read alignment to the faba bean reference transcriptome identified 16,300 high quality unigenes. In addition, Illumina paired-end sequencing was used to establish a baseline for genomic information assembly. Genomic reads were assembled de novo into contigs with a size range of 50-5000 bp. Over 85% of sequences did not align to known genes, of which ~10 % could be aligned to known repetitive genetic elements. Over 26,000 of the reference transcriptome unigenes could be aligned to DNA-seq reads with high confidence. Moreover, this comparison identified 56,668 potential splice points in all identified unigenes. Sequence length data was extended at 461 putative loci through alignment of DNA-seq contigs to full length, publically available linkage marker sequences. Reads also yielded coverages of 3466x and 650x for the chloroplast and mitochondrial genomes respectively. Inter- and intra-species organelle genome comparisons established core legume organelle gene sets, and revealed polymorphic regions of faba bean organelle genomes

SpitWorm, an herbivorous robot: Mechanical leaf wounding with simultaneous application of salivary components

Induction of plant defense against insect herbivory is initiated by a combination of both, mechanical wounding and chemical factors. In order to study both effects independently on plant defense induction, SpitWorm, a computer controlled device which mimics the damage pattern of feeding insect larvae on leaves and can additionally apply oral secretions (OS) or other solutions to the ‘biting site’ during ‘feeding’, was developed and evaluated. The amount of OS left by a Spodoptera littoralis larva during feeding on Phaseolus lunatus (lima bean) leaves was estimated by combining larval foregut volume, biting rate, and quantification of a fluorescent dye injected into the larvae’s foregut prior to feeding. For providing OS amounts by SpitWorm equivalent to larval feeding, dilution and delivery rate were optimized. The effectiveness of SpitWorm was tested by comparing volatile organic compounds (VOC) emissions of P. lunatus leaves treated with either SpitWorm, MecWorm or S. littoralis larvae. Identification and quantification of emitted VOCs revealed that SpitWorm induced a volatile bouquet that is qualitatively and quantitatively similar to herbivory. Additionally, RT-qPCR of four jasmonic acid responsive genes showed that SpitWorm, in contrast to MecWorm, induces the same regulation pattern as insect feeding. Thus, SpitWorm mimics insect herbivory almost identical to real larvae feeding