A simple experiment for the electron charge qe measurement is described. The experimental set-up contains standard electronic equipment only and can be built in every high-school lab all around the world with pocket money budget for several days. It is concluded that it is time such a practice to be included in the regular high-school education. The achieved 13% accuracy is comparable to the best student university labs. The measurement is based on Schottky noise generated by a photodiode. Using the criterion dollar per accuracy for the electron charge qe measurement, this definitely is the world's best educational experiment. An industrial replica can be easily sold across the globe. *

A new experimental set-up for Boltzmann constant measurement is described. Statistically averaged square of voltage U 2 is measured for different capacitances C. Boltzmann constant is determined by the equipartition theorem C U 2 = k B T . For fixed capacitance, voltages could be measured for different temperatures. The set-up consists of low-noise high frequency operational amplifiers ADA4898-2. An instrumental amplifier is followed by an inverting amplifier, square of the voltage is created by an analog multiplier AD633 and finally the averaged signal is measured by a multimeter. More than 10 high-school students were able to measure the Boltzmann constant with the experimental set-up in the 5 th Experimental Physics Olympiad with excellent accuracy compared to the price, conditions and available time for the experiment. A new derivation of the important for the statistical physics theorems by Nyquist and Callen-Welton is given in an appendix in the level of introductory courses in physics listened by teachers. For the understanding of the work of the experimental set-up, it is necessary to know only the equipartition theorem.

The present paper is dedicated to integrable models with Mikhailov reduction groups G R ≃ D h . Their Lax representation allows us to prove, that their solution is equivalent to solving Riemann-Hilbert problems, whose contours depend on the realization of the G R -action on the spectral parameter. Two new examples of Nonlinear Evolution Equations (NLEE) with D h symmetries are presented. 2010 Mathematics Subject Classification. Primary: 35K10, 35Q15; Secondary: 37K15, 35Q55.

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