The unique emission properties of single-walled carbon nanotubes are attractive for achieving increased functionality in integrated photonics. In addition to being room-temperature telecom-band ...emitters that can be directly grown on silicon, they are ideal for coupling to nanoscale photonic structures. Here we report on high-efficiency coupling of individual air-suspended carbon nanotubes to silicon photonic crystal nanobeam cavities. Photoluminescence images of dielectric- and air-mode cavities reflect their distinctly different mode profiles and show that fields in the air are important for coupling. We find that the air-mode cavities couple more efficiently, and estimated spontaneous emission coupling factors reach a value as high as 0.85. Our results demonstrate advantages of ultralow mode-volumes in air-mode cavities for coupling to low-dimensional nanoscale emitters.
A search for solar axions has been performed using an axion helioscope which is equipped with a 2.3-m long 4 T superconducting magnet, a gas container to hold dispersion-matching gas, PIN-photodiode ...X-ray detectors, and a telescope mount mechanism to track the sun. A mass region around ma=1 eV was newly explored. From the absence of any evidence, analysis sets a limit on axion–photon coupling constant to be gaγγ<5.6–13.4×10−10 GeV−1 for the axion mass of 0.84<ma<1.00 eV at 95% confidence level. It is the first result to search for the axion in the gaγγ–ma parameter region of the preferred axion models with a magnetic helioscope.
The Tokyo axion helioscope Ohta, R.; Akimoto, Y.; Inoue, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2012, Letnik:
670
Journal Article
Recenzirano
Odprti dostop
The Tokyo Axion Helioscope experiment aims to detect axions which are produced in the solar core. The helioscope uses a strong magnetic field in order to convert axions into X-ray photons and has a ...mounting to follow the sun very accurately. The photons are detected by an X-ray detector which is made of 16 PIN-photodiodes. In addition, a gas container and a gas regulation system are adopted for recovering the coherence between axions and photons in the conversion region giving sensitivity to axions with masses up to 2eV. In this paper, we report on the technical detail of the Tokyo Axion Helioscope.
We searched the genomes of eight rice cultivars (Oryza sativa L. ssp. japonica and ssp. indica) and a wild rice accession (Oryza rufipogon Griffith) for nucleotide polymorphisms, and identified 7805 ...polymorphic loci, including single-nucleotide polymorphisms (SNPs) and insertions/deletions (InDels), in predicted intergenic regions. Polymorphisms are useful as DNA markers for genetic analysis or positional cloning with segregating populations of crosses. Pairwise comparison between cultivars and a neighbor-joining tree calculated from SNPs agreed very well with relationships between rice strains predicted from pedigree data or calculated with other DNA markers such as p-SINE1 and simple sequence repeats (SSRs), suggesting that whole-genome SNP information can be used for analysis of evolutionary relationships. Using multiple SNPs to identify alleles, we drew a map to illustrate the alleles shared among the eight cultivars and the accession. The map revealed that most of the genome is mono- or di-allelic among japonica cultivars, whereas alleles well conserved among modern japonica paddy rice cultivars were often shared with indica cultivars or wild rice, suggesting that the genome structure of modern cultivars is composed of chromosomal segments from various genetic backgrounds. Use of allele-sharing analysis and association analysis were also tested and are discussed.
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