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Greg BG Moorhead Laura Trinkle-Mulcahy Mhairi Nimick Veerle De Wever David G Campbell Robert Gourlay Yun Wah Lam Angus I Lamond 《BMC biochemistry》2008,9(1):28
Background
Protein phosphatase one (PP1) is a ubiquitously expressed, highly conserved protein phosphatase that dephosphorylates target protein serine and threonine residues. PP1 is localized to its site of action by interacting with targeting or regulatory proteins, a majority of which contains a primary docking site referred to as the RVXF/W motif. 相似文献2.
alpha-Keto alkynes react with CO and H(2) in the presence of catalytic quantities of the zwitterionic rhodium complex (eta(6)-C(6)H(5)BPh(3))(-)Rh(+)(1,5-COD) and triphenyl phosphite affording either the 2-, 2(3H)-, or 2(5H)-furanones in 61-93% yields. The cyclohydrocarbonylation is readily accomplished using substrates containing alkyl, aryl, vinyl, and alkoxy groups at the acetylenic terminal, as well as a variety of primary, secondary, and tertiary alkyl, aryl, and heteroaryl groups connected to the ketone functionality. Structural and electronic properties present in the starting materials mediate the chemo- and regioselectivity of the reaction. 相似文献
3.
G. Labeyrie T. Ackemann B. Klappauf M. Pesch G.L. Lippi R. Kaiser 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):473-483
First experimental investigations are reported on nonlinear beam shaping due to the interaction between an intense laser beam
and a cloud of laser cooled rubidium atoms. Resonant excitation of the F = 3 ↔ F
′ = 4 hyperfine transition is considered. The single-pass interaction through the cold vapor causes an increase in the laser
beam intensity in the forward direction (zero transverse wavevector component) when observed in Fourier space, for sufficiently
high values of saturation. A qualitative explanation of the observations based on a two-level model for a resonantly excited
transition proves acceptable. The observations are compatible with an interpretation based on nonlinear index-induced focusing
of an incident beam with curved wavefront, as is used in z-scan measurements. Simple physical considerations allow us to deduce the conditions for the observability of optical patterns
in the beam transmitted by a cold atomic cloud. 相似文献
4.
Birefringent Fresnel zone plates in silica fabricated by femtosecond laser machining 总被引:4,自引:0,他引:4
We demonstrate maskless, single-step fabrication of strongly birefringent Fresnel zone plates by focusing of femtosecond laser pulses deep within silica substrates. The process allows us to produce alternate zone rings directly by inducing a local refractive-index modification of the order of n~10(-2) . The embedded zone plates shown in this Letter exhibit efficiencies that vary by as much as a factor of ~6 for orthogonal polarizations. Focal lengths of primary and secondary foci are shown to compare well with theory. 相似文献
5.
Bidel Y Klappauf B Bernard JC Delande D Labeyrie G Miniatura C Wilkowski D Kaiser R 《Physical review letters》2002,88(20):203902
We study light coherent transport in the weak localization regime using magneto-optically cooled strontium atoms. The coherent backscattering cone is measured in the four polarization channels using light resonant with a J(g) = 0-->J(e) = 1 transition of the strontium atom. We find an enhancement factor close to 2 in the helicity preserving channel, in agreement with theoretical predictions. This observation confirms the effect of internal structure as the key mechanism for the contrast reduction observed with a rubidium cold cloud [G. Labeyrie et al., Phys. Rev. Lett. 83, 5266 (1999)]. Experimental results are in good agreement with Monte Carlo simulations taking into account geometry effects. 相似文献
6.
Form birefringence and negative index change created by femtosecond direct writing in transparent materials 总被引:1,自引:0,他引:1
Although femtosecond lasers have proved to be of great utility for micromachining within bulk transparent materials, little is known about the fundamental physics that drive the process. Depending on the laser intensity delivered to the sample, any of three types of feature can be written into the glass. We observed that in the intermediate regime there is a correlation among the negative sign of the effective index change, the presence of anisotropic reflection, and birefringence. We propose a model that can explain all three principal characteristics. Results show that the local index change can be as high as 10(-1). 相似文献
7.
Doppler cooling on a narrow transition is limited by the noise of single scattering events. It shows novel features, which are in sharp contrast with cooling on a broad transition, such as a non-gaussian momentum distribution, and divergence of its mean square value close to the resonance. We have observed those features using 1D cooling on an intercombination transition in strontium, and compared the measurements with theoretical predictions and Monte Carlo simulations. We also find that for very a narrow transition, cooling can be improved using a dipole trap, where the clock shift is canceled. 相似文献
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