We present the first extended-cavity diode laser in Littrow configuration operating in the cyan wavelength range around 497 nm. The gallium-nitride based diode laser features a free-space output with ...up to 60 mW, operates in a single frequency mode, is tunable over a range of more than 8 nm and has a Lorentzian linewidth of less than 90 kHz. A detailed characterization of the tuning capabilities of the diode laser and its emission spectrum is provided. This compact, simple and low cost laser source replaces more complex systems based on frequency doubling and therefore simplifies the development of future compact and mobile optical clocks based on neutral strontium. Applications include efficient repumping of strontium atoms from the \(5s5p\) \(^3P_2\) state and the 9.8 MHz broad \(5s5p\) \(^3P_2 \rightarrow 5s5d\) \(^3D_3 \) transition might be of interest for sub-Doppler cooling.
We present a concept for a high-precision optical atomic clock (OAC) operating on an Earth-orbiting space station. This pathfinder science mission will compare the space-based OAC with one or more ...ultra-stable terrestrial OACs to search for space-time-dependent signatures of dark scalar fields that manifest as anomalies in the relative frequencies of station-based and ground-based clocks. This opens the possibility of probing models of new physics that are inaccessible to purely ground-based OAC experiments where a dark scalar field may potentially be strongly screened near Earth's surface. This unique enhancement of sensitivity to potential dark matter candidates harnesses the potential of space-based OACs.
Within the OPUS collaboration, we develop optical frequency references based on spectroscopy of the ^1{S_0}\rightarrow ^3P_1 intercombination line of 88Sr at 689 nm in thermal and laser-cooled ...strontium beams for operation on sounding rockets. One main objective is to identify suitable experimental setups and core components for a compact and robust strontium beam clock, providing a stepping stone for future spaceborne devices. Recent results demonstrate successful laser stabilization to the inter-combination line in a thermal beam breadboard setup.
Zimdahl et al describe a map of more than 12,000 gene-based single nucleotide polymorphisms (SNPs) from transcribed regions, created by aligning cDNA sequence from three other strains to the recent ...rat BN/SsNHsd/Mcwi (henceforth BN) genome assembly. They conclude that the first generation cDNA-based SNP map for the rat provides a public resource for defining functional variation across the genome.
We have identified in the fission yeast Schizosaccharomyces pombe a MutS homolog that shows highest homology to the Msh2 subgroup. msh2 disruption gives rise to increased mitotic mutation rates and ...increased levels of postmeiotic segregation of genetic markers. In bandshift assays performed with msh2Δ cell extracts, a general mismatch-binding activity is absent. By complementation assays, we showed that S. pombe msh2 is allelic with the previously identified swi8 and mut3 genes, which are involved in mating-type switching. The swi8-137 mutant has a mutation in the msh2gene which causes a truncated Msh2 peptide lacking a putative DNA-binding domain. Cytological analysis revealed that during meiotic prophase of msh2-defective cells, chromosomal structures were frequently formed; such structures are rarely found in the wild type. Our data show that besides having a function in mismatch repair,S. pombe msh2 is required for correct termination of copy synthesis during mating-type switching as well as for proper organization of chromosomes during meiosis.
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