High power coherent beam combination from two fiber lasers

Phase locking of two fiber lasers is demonstrated experimentally by the use of a self-imaging resonator with a spatial filter. The high-contrast interference strips of the coherent beam profile are observed. The coherent output power of the fiber array exceeds 12W and the efficiency of coherent power combination is 88% with pump power of 60W. The whole system operates quite stably and, for the spatial filter, no thermal effects have been observed, which means that we can increase the coherent output power further by this method. (c) 2006 Optical Society of America

Phase-locking of two large-core fibre lasers with 60W of coherent output power

A phase-locking fibre laser array with up to 60 W of coherent output power based on two large-core fibre is reported. The slope efficiency of the in-phase mode is 37%. For two cases of spacings between the cores, steady high-contrast interference stripes are observed. When the whole system operates under a high pump power level, no thermal effects for the spatial filter have been observed, which means that we can increase the coherent output power further by increasing the individual fibre laser power.

Refined genome-wide comparative map of the domestic horse, donkey and human based on cross-species chromosome painting: insight into the occasional fertility of mules

We have made a complete set of painting probes for the domestic horse by degenerate oligonucleotide-primed PCR amplification of flow-sorted horse chromosomes. The horse probes, together with a full set of those available for human, were hybridized onto metaphase chromosomes of human, horse and mule. Based on the hybridization results, we have generated genome-wide comparative chromosome maps involving the domestic horse, donkey and human. These maps define the overall distribution and boundaries of evolutionarily conserved chromosomal segments in the three genomes. Our results shed further light on the karyotypic relationships among these species and, in particular, the chromosomal rearrangements that underlie hybrid sterility and the occasional fertility of mules.

Comparative map between the domestic pig and dog

Cross-species chromosome painting with probes derived from flow-sorted dog and human chromosomes was used to construct a high-resolution comparative map for the pig. In total 98 conserved autosomal segments between pig and dog were detected by probes specific for the 38 autosomes and X Chromosome of the dog. Further integration of our results with the published human-dog and cat-dog comparative maps, and with data from comparative gene mapping, increases the resolution of the current pig-human comparative map. It allows for the conserved syntenies detected in the pig, human, and cat to be aligned against the putative ancestral karyotype of eutherian mammals and for the history of karyotype evolution of the pig lineage to be reconstructed. Fifteen fusions, 17 fissions, and 23 inversions are required to convert the ancestral mammalian karyotype into the extant karyotype of the pig.

Single base-resolution methylome of the silkworm reveals a sparse epigenomic map

Epigenetic regulation in insects may have effects on diverse biological processes. Here we survey the methylome of a model insect, the silkworm Bombyx mori, at single-base resolution using Illumina high-throughput bisulfite sequencing (MethylC-Seq). We conservatively estimate that 0.11% of genomic cytosines are methylcytosines, all of which probably occur in CG dinucleotides. CG methylation is substantially enriched in gene bodies and is positively correlated with gene expression levels, suggesting it has a positive role in gene transcription. We find that transposable elements, promoters and ribosomal DNAs are hypomethylated, but in contrast, genomic loci matching small RNAs in gene bodies are densely methylated. This work contributes to our understanding of epigenetics in insects, and in contrast to previous studies of the highly methylated genomes of Arabidopsis(1) and human(2), demonstrates a strategy for sequencing the epigenomes of organisms such as insects that have low levels of methylation.

Heroin impairs map-picture-following and memory tasks dependent on gender and orientation of the tasks

Male and female heroin-dependent patients (HDPs) matched with "normal" people were tested on 4 topographical orientation tasks: schematic map-following, map-memory, schematic picture-following, and picture-memory tasks. The results showed that, in general

A genetic map of large yellow croaker Pseudosciaena crocea

Genetic linkage maps were constructed for large yellow croaker Pseudosciaena crocea (Richardson, 1846) using AFLP and microsatellite markers in an F-1 family. Five hundred and twenty-three AFLP markers and 36 microsatellites were genotyped in the parents and 94 F-1 progeny. Among these, 362 AFLP markers and 13 SSR markers followed the 1:1 Mendelian segregation ratio (P > 0.05). The female genetic map contained 181 AFLP and 7 microsatellite markers forming 24 linkage groups spanning 2959.1 cM, while the male map consisted of 153 AFLP and 8 microsatellite markers in 23 linkage groups covering 2205.7 cM. One sex linked marker was mapped to the male map and co-segregated with the AFLP marker agacta355, suggesting an XY-male determination mechanism and this may be useful in the breeding of monosex populations. (c) 2007 Elsevier B.V. All rights reserved.

Direct observation of coherent spin transfer processes in an InGaAs/GaAs quantum well via two-color time-resolved Kerr rotation measurements

A two-color time-resolved Kerr rotation spectroscopy system was built, with a femtosecond Ti:sapphire laser and a photonic crystal fiber, to study coherent spin transfer processes in an InGaAs/GaAs quantum well sample. The femtosecond Ti:sapphire laser plays two roles: besides providing a pump beam with a tunable wavelength, it also excites the photonic crystal fiber to generate supercontinuum light ranging from 500 nm to 1600 nm, from which a probe beam with a desirable wavelength is selected with a suitable interference filter. With such a system, we studied spin transfer processes between two semiconductors of different gaps in an InGaAs/GaAs quantum well sample. We found that electron spins generated in the GaAs barrier were transferred coherently into the InGaAs quantum well. A model based on rate equations and Bloch-Torrey equations is used to describe the coherent spin transfer processes quantitatively. With this model, we obtain an effective electron spin accumulation time of 21 ps in the InGaAs quantum well.

Enhanced infrared emission from colloidal HgTe nanocrystal quantum dots on silicon-on-insulator photonic crystals

A two dimensional silicon-on-insulator based photonic crystal structure is used to enhance the emission from colloidal HgTe nanocrystal quantum dots embedded in a thin polymer film. The enhancement is resonant to the leaky eigenmodes of the photonic crystals due to coherent scattering effects. Transmittance and photoluminescence experiments are presented to map the leaky mode dispersion and the angle dependence of the emission enhancement factor, which reaches values up to 80 (650) for vertical (oblique) emission in the telecommunication wavelength range.