The objective of this study was to evaluate the effects of dietary zeolite clinoptilolite on re- productive performance, serum progesterone and insulin-like growth factor 1 (IGF-1) concentra- tions in 78 Holstein Friesian (HF) cows during pregnancy and lactation. The cows were divided into two groups comprising 40 (control group; CON) and 38 (CPL group) cows. To assess repro- ductive performance of HF cows the following variables were registered: the interval from calv- ing to first insemination (days open to first service, DFS), the interval from calving to pregnancy (days open to pregnancy, DOP), and the number of services per pregnancy (NSP). The average values of progesterone (5.64±0.59 ng/mL vs. 5.16±0.64 ng/mL) were not statistically different (p<0.05) and IGF-1 levels (400.17±17.72 ng/mL vs. 348.36±20.39 ng/mL) were higher in the CON than in the CPL group which received 50 g of clinoptilolite twice a day. However, in the CPL group ovarian cyclity resumed on days 40 and 60 postpartum. In addition, DFS (p<0.05) and DOP (p>0.05) were shorter in the CPL than in the CON group (115.1±19.9 and 137.5±36.3 days vs. 124.2±17.3 and 143.8±33.5 days, respectively). During 305 days of lactation, milk production was higher in the CPL vs. CON (8325.5±628.8 kg vs. 8050±586.8 kg). The NSP was lower in the CPL than in CON group (1.91 vs. 2.14). The dietary clinoptilolite supplement had a positive in- fluence on milk yield, exhibited modulating effects on endocrine status of dairy cows, and im- proved reproductive performance, with the decreased NSP, and fewer DFS and DOP.

The article concerns the opinion on stationary and remote examinations carried out during the COVID-19 pandemic, perceived from the perspective of the assessed students. The study aimed to find out about the students' perspective on remote final and midterm exams at The Maria Grzegorzewska University and to attempt to compare it with the traditional examination. The subject of the research was, among others, the forms of checking knowledge and skills, problems arising during the exams, as well as the way of taking into account the special needs of the examtakers. The students' opinions on the above-mentioned issues and their preferences regarding the examination situation were taken into account. The research used the method of diagnostic survey. The obtained results indicate that students during remote exams declare a higher level of stress related to potential technical problems, and in the case of stationary examinations the problem is chaos, noise and distraction. Regardless of the form of the exam, a similar percentage of students declare that they do not cheat - 73.53% during full-time exams, 68.49% pass fair during remote exams. The most common form of cheating during remote examinations is the use of previously prepared notes (21.85%), and 2.52% use the help of colleagues.

This work summarizes efficiency measurement results of a full bridge, 3 phase inverter composed of state-of-the-art Si IGBT transistors and Si or SiC diodes. Different (symmetrical and discontinuous) space vector modulation strategies were chosen in order to examine their influence (together with modulation frequency) on inverter losses. Induction machine was used as load, different load points were examined. Results clearly show, that proper modulation strategy, minimizing the switching losses of semiconductor switches, can increase the overall output efficiency at about 1% in case of both silicon and hybrid constructions. The drawback of DPWM approach is connected with the decreased quality of inverter output current. Hybrid technology can also improve the output efficiency at about 1% when compared to traditional constructions, but only in case of elevated switching frequencies. At low frequencies (below 10 kHz) modern semiconductor offer comparable results at much lower device costs.

The paper proposes a list of five „stylized facts”, regarded as the main trends with respect to the development of the global economy in the 20th c. The author’s main purpose is to answer the question whether, in the light of the contemporary growth theory and demographic forecasts, these trends are likely to continue unchanged also in the 21st c. Taking into account this theory and those forecasts, the paper offers forecasts of the average GDP per capita for both the countries of the Technology Frontier Area (TFA) and the catching-up countries. By these forecasts, the strong divergence trend of the last two centuries will be replaced by a strong convergence trend during the 21st c. Moreover, the global rate of growth of the per capita GDP will continue to be high in the first half of the current century, but strongly declining in the second half.