Weak modulation function

Figure 3 shows the transmittance function for molecular chains with various lengths using the same parameters as in Fig. 2. The functions are shifted for better visibility. For n — 2, it is a Lorentzian as suggested by the exact result (equation (40)). With growing chain length, the transmittance function shows weak modulations within the band, and drops sharply outside of the band. We also show the exact result obtained in the limit of infinite chain length (equation (41)).

Fig. 2. (A) Fluorescence yield (in arbitrary units) for isolated, dark-adapted chloroplasts as a function of time in the absence (a) and presence (b) of DCMU. (B) Light-induced fluorescence-yield change in lyophilized chloroplasts (control), in hexane-methanol extracted chloroplasts, and in extracted chloroplasts reconstituted with PQ-9. Small upward arrows indicate weak, modulated green monitoring light turned on larger arrows for intense actinic light on (upward arrow) and off (downward arrow). (A) adapted from Zankel and Kok (1972) Estimation of pool size and kinetic constants. In A San Pietro (ed) Methods in Enzymology 24 222 (B) from Liu, Hoff, Gu, Li and Zhou (1991) The relationship between the structure of plastoquinone derivatives and their biological activity in photosystem II of spinach. Photosynthesis Res 30 100.

Mass spectrometers that use electrospray ionization (ESI) do not function well if the eluent contains low volatility salts. This is a major concern when an ion-exchange column is used as a first-dimension column and the salt concentration is used to modulate the retention in this column. In this case, another valve can be connected between the second-dimension column and the detector so that any salt from the second-dimension elution process that is either unretained or weakly retained can be diverted prior to feeding zones to the mass spectrometer. 

Tacrine has been found to be somewhat effective in patients with mild-to-moderate symptoms of this disease for improvement of cognitive functions. The drug is primarily a reversible cholinesterase inhibitor that increases the concentration of functional ACh in the brain. However, the pharmacology of tacrine is complex the drug also acts as a muscarinic receptor modulator in that it has partial agonistic activity, as well as weak antagonistic activity on muscarinic receptors in the CNS. In addition, tacrine appears to enhance the release of ACh from cholinergic nerves, and it may alter the concentrations of other neurotransmitters such as dopamine and NE. 

The phenol molecule is another illustration of modulation. Its name ending with the suffix -ol and its hydroxyl function (-OH) define it as an alcohol. But, it is a weak... 

Another unique feature of the betatron X-ray beam is its intensity as a function of the electron density of the plasma. It is found to be sharply peaked at ne = 1.1 x 1019cm-3, as shown in Fig. 11.10. Below this critical density, the X-ray signal rapidly vanishes, mainly because the number of trapped electrons is too low. This was confirmed by experiment no electrons were detected by the spectrometer. At larger densities the X-ray signal drops and a plateau is reached. For these experimental conditions, the resulting amplitude of the plasma wave becomes too weak. The pulse must first be modulated and additional laser energy would be needed. As a result, the temperature of the electron beam decreases and its divergence increases. The PIC... 

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