In this paper we present the results of our work concerning the long-distance fibre optic dissemination of time (1 PPS) and frequency (10 MHz) signals generated by atomic sources, such as caesium clocks, hydrogen masers or caesium fountains. For these purposes we developed dedicated hardware (a fibre optic system with active stabilization of the propagation delay and bidirectional fibre optic amplifiers) together with a procedure to enable calibration of the time transfer. Our laboratory measurements performed over fibre lengths of up to 480 km showed an Allan deviation of the order of 4 × 10 −17 , time deviation below 1 ps (both at one-day averaging) and the possibility of calibration with picosecond accuracy even for the longest from evaluated links. After successful laboratory evaluation the system was next installed on a 421.4 km long route between the Central Office of Measures (GUM) in Warsaw, Poland, and the Astrogeodynamic Observatory (AOS) in Borowiec near Poznań, Poland. Experiments comparing the UTC(PL) and UTC(AOS) atomic timescales using the fibre optic link and TTS-4 dual-frequency GNSS time transfer receivers showed that the consistency of the results is within the calibration accuracy of the GPS receivers and with much better noise performance. The field operation of the system proved its full functionality and confirmed our previous laboratory evaluation to the maximum extent possible using the methods for comparing distant clocks available at GUM and AOS.

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The prevalence of lower urinary tract symptoms (LUTS) and overactive bladder (OAB) has been measured by population-based investigations in many parts of the world. However, data are lacking for Eastern Europe, and there has not been any large population-representative study in any country of this region. Therefore, the aim of this study was to evaluate the prevalence and associated bother of LUTS and OAB in a population-representative sample of persons aged ≥ 40 years in Poland. This investigation was conducted as a computer-assisted telephone interview. The survey sample was stratified by age, sex, and place of residence to reflect the entire Polish population. LUTS and OAB were assessed by a standardized protocol based on the International Continence Society definitions and validated questionnaires. Of 6005 participants, 57% were women, and the mean age (range) was 60.7 (40–93) years. The prevalence of LUTS was 69.8% (men 66.2%; women 72.6%). There was no difference in prevalence between urban and rural areas. LUTS were often bothersome among men and women, but women were more likely to be bothered compared with men. There were also statistically significant correlations between the frequency and the bother intensity of each of the LUTS. The prevalence of OAB was higher in women (39.5%) than in men (26.8%), and OAB increased with age. Lastly, LUTS had detrimental effects on the quality of life because one third of the participants had concerns about their urinary-specific quality of life. This investigation was the first nationwide, population-representative epidemiological study of LUTS and OAB in an Eastern-European country. LUTS were highly prevalent, often bothersome, and had negative effects on the quality of life of men and women aged ≥ 40 years. Our findings are comparable with other epidemiologic studies of LUTS and OAB conducted in different regions of the world.Trial registration: NCT04121936.

In this paper, we present an overview of the electronically stabilized (thus named ELSTAB) fiber-optic time and frequency (T&F) distribution system based on our idea of using variable electronic delay lines as compensating elements. Various extensions of the basic system, allowing building a long-haul, multiuser network are described. The fundamental limitations of the method arising from fiber chromatic dispersion and system dynamics are discussed. We briefly characterize the main hardware challenge of the system, which is the design of a pair of low-noise, precisely matched delay lines. Finally, we present experimental results with T&F distribution over up to 615 km of fiber, where we demonstrate frequency stability in the range of 1-7 ×10(-17) for 10(5) s averaging and time calibration with accuracy well below 50 ps. Also, practical implementation of the ELSTAB in the Polish T&F distribution network is shown.

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