The evaluation procedure of a new laser-cooled caesium fountain primary frequency standard developed at the National Institute of Standards and Technology (NIST) is described. The new standard, NIST-F1, is described in some detail and typical operational parameters are discussed. Systematic frequency biases for which corrections are made – second-order Zeeman shift, black-body radiation shift, ...

Fluorescent proteins (FPs) emitting in the far-red region of the spectrum are highly advantageous for whole-body imaging applications because scattering and absorption of long-wavelength light is markedly reduced in tissue. We characterized variants of the red fluorescent protein eqFP611 with bright fluorescence emission shifted up to 639 nm. The additional red shift is caused by a trans-cis is...

Phytochrome A (phyA) is the only photoreceptor in plants, initiating responses in far-red light and, as such, essential for survival in canopy shade. Although the absorption and the ratio of active versus total phyA are maximal in red light, far-red light is the most efficient trigger of phyA-dependent responses. Using a joint experimental-theoretical approach, we unravel the mechanism underlyi...

Although the tremendous variability in floral colour among angiosperms is often attributed to divergent selection by pollinators, it is usually difficult to preclude the possibility that floral colour shifts were driven by non-pollinator processes. Here, we examine the adaptive significance of flower colour in Disa ferruginea, a non-rewarding orchid that is thought to attract its butterfly poll...

Although the importance of regulatory and functional sequence evolution in generating species differences has been studied to some extent, much less is known about the role of other types of genomic changes, such as fluctuation in gene copy number. Here, we apply analyses of gene function and expression of anthocyanin pigment pathway genes, as well as cosegregation analyses in backcross populat...

The characteristic photon energy for Gamma Ray Bursts, Epeak, has a remarkably narrow distribution for bursts of similar peak flux, with values between 150 and 600 keV for most faint bursts. This result is surprising within the framework of internal shock models, since spectral shifts associated with the jet’s blue shift (by a Lorentz factor of Γ) and the cosmological red shift (by a factor of ...

The position of the oxygen dissociation curve (ODC) is modulated by 2,3-diphosphoglycerate (2,3-DPG). Decreases in 2,3-DPG concentration within the red cell shift the curve to the left, whereas increases in concentration cause a shift to the right of the ODC. Some earlier studies on diabetic patients have reported that insulin treatment may reduce the red cell concentrations of 2,3-DPG, causing...

Taste 2 receptors (TAS2R) mediate bitterness perception in mammals, thus are called bitter taste receptors. It is believed that these genes evolved in response to species-specific diets. The giant panda (Ailuropoda melanoleuca) and red panda (Ailurus fulgens styani) in the order Carnivora are specialized herbivores with an almost exclusive bamboo diet (>90% bamboo). Because bamboo is full of bi...

Salmonids undergo a developmental transition from parr to smolt that involves a number of physiological and morphological changes. In recent years, my laboratory has studied shifts in red muscle function at this parr-smolt transformation (PST) in rainbow trout, Oncorhynchus mykiss. Parr red muscle has faster contraction kinetics than smolts, including faster rates of activation and relaxation a...