Light flux modulation

Finally, it should be noted that a more general application of modulation spectroscopy can be used to obtain selective information on an excitable sample. Modulated excitation (ME) spectroscopy can always be applied with samples allowing periodic stimulation via a periodic variation of any external thermodynamic parameter, e.g. temperature, pressure, concentration, electric field, light flux. ME causes a... 

We detected the saturated fluorescence emitted by a beam of 23S metastable atoms as they cross at right angle the slave laser light. A 1015 atoms/s.sterad flux of metastable helium atoms was produced by electronic collisions in a DC discharge of a helium atomic beam, similar to that described in [15]. To improve the precision of the linecenter determination, we increased the signal-to-noise ratio S/N by means of standard frequency modulation the third harmonic demodulated lineshape is shown in Fig. 4. The function expected for a Lorentzian spectrum was fit and linecenters were calculated with an uncertainty ranging between 10 kHz and 20 kHz, that is consistent with the observed S/N, mainly limited by the stability of the reference frequency and of the metastable helium beam. The reproducibility was two or three times worse than the uncertainty,... 

Aside from the inordinately dominant light of molecular genetics, the new wave in biochemistry today is, what has come to be called, metabolic control analysis (MCA) (Comish-Bowden and Cardenas, 1990). The impetus behind this wave is the desire to achieve a holistic view of the control of metabolic systems, with emphasis on the notion of system. The classical, singular focus on individual, feedback-modulated (e.g., allosteric), rate-limiting enzymes entails a naive and myopic view of metabolic regulation. It has become increasingly evident that control of metabolic pathways is distributive, rather than localized to one reaction. MCA places a given enzyme reaction into the kinetic context of the network of substrate-product connections, effector relationships, etc., as supposedly exist in situ, it shows that control of fluxes, metabolite concentrations, inter alia, is a systemic function and not an inherent property of individual enzymes. Such... 

Most TTSs are cool stars. Therefore, their radiation is sensitive to temperature variations on their surface, especially at short wavelengths. The existence of surface inhomogeneities (cool and hot spots) of rotating stars leads to a periodic modulation of the flux illuminating the CS dust and, as a result, to the periodic modulation of the intrinsic polarization of stars. Its amplitude depends on the amplitude of the light modulation as well as on the CS disk parameters including its inclination to the line-of-sight and the optical parameters of CS dust. 

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