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In this work, the radiation from electrons in multi-periodic undulator fields with symmetric and asymmetric harmonics was analyzed using generalized Bessel functions formalism. The asymmetric, symmetric, and anti-symmetric periodic magnetic fields with harmonics were studied in order to get the enhanced radiation of the high harmonics of undulator radiation (UR). The effect on the spontaneous and stimulated UR was explored. The exact integral forms for the Bessel coefficients were obtained for undulators with general symmetric and asymmetric field harmonics. Spectral properties of the radiation from several configurations of the undulator fields with harmonics were compared with each other. The resulting spontaneous UR spectrum and harmonic intensities were obtained analytically in the form of integrals and compared with the respective results that were obtained numerically with SPECTRA program. The dimensionless scaling parameter of a free electron laser (FEL)—the Pierce parameter (ρ)—was computed and compared for the different considered undulators. We studied the differences in the behavior of the high-gain single pass FEL harmonics and the spontaneous UR harmonics in the same undulators. The undulators with variable deflection parameter (k) were considered. The effect of the k parameter (deflection parameter for a common planar undulator) on the spontaneous UR and on the high-gain FEL radiation was explored. In this context, an experiment with variable strength undulators at FLASH 2 FEL was analyzed; the shorter saturated length in high harmonic self-seeding (HHSS) regime vs. self-amplified spontaneous emission (SASE) is explained.

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An increase in glucose concentration in the medium rapidly decreases respiration rate in many cell types, including tumor cells. The molecular mechanism of this phenomenon, the Crabtree effect, is still unclear. It was shown earlier that adding the intermediate product of glycolysis fructose-1,6-bisphosphate to isolated mitochondria suppresses their respiration. To study possible roles of glycolytic intermediates in the Crabtree effect, we used a model organism, the yeast Saccharomyces cerevisiae. To have the option to rapidly increase intracellular concentrations of certain glycolytic intermediates, we used mutant cells with glycolysis blocked at different stages. We studied fast effects of glucose addition on the respiration rate in such cells. We found that addition of glucose affected cells with deleted phosphoglycerate mutase (strain gpm1-delta) more strongly than ones with inactivated aldolase or phosphofructokinase. In the case of preincubation of gpm1-delta cells with 2-deoxyglucose, which blocks glycolysis at the stage of 2-deoxyglucosephosphate formation, the effect of glucose addition was absent. This suggests that triosephosphates are intermediates of the Crabtree effect. Apart from this, the incubation of gpm1-delta cells in galactose-containing medium appeared to cause a large increase in their size. It was previously shown that galactose addition did not have any short-term effect on respiration rate of gpm1-delta cells and, at the same time, strongly suppressed their growth rate. Apparently, the influence of increasing triosephosphate concentration on yeast physiology is not limited to the activation of the Crabtree effect.

The theoretical study of the effect of electron beam parameters, in particular, the emittance and its asymmetry on the radiation from relativistic electrons in undulators is conducted both analytically and numerically. The reasons for the odd and even harmonic generation and radiation are explored. The difference in the underlying physical reasons for the spontaneous and stimulated radiation of harmonics in free electron lasers (FELs) is elucidated. The generalized forms of the special functions of the Bessel and Airy type are employed to account analytically for the off-axis and angular effects together with the effect of the beam energy spread. A comparative analysis of the radiation spectra for undulators with different beams is performed. The examples of the radiation at SPARC and LEUTL are given. The effect of the asymmetry of the beam on the radiation properties is analyzed. The alternative theoretical approaches of other authors are also employed for the analytical calculation of the harmonic powers in FELs. The results are compared with existing experimental data.