An earthquake of Mw 7.1 occurred on January 14, 2018 in the southern coast of Peru. In this study, public available Global Ionospheric Maps (GIMs) provided by the Center for Orbit Determination in Europe (CODE) were used to look for ionospheric disturbances pre- and post-earthquake. Twelve days before the seismic event, a positive anomaly was detected at low latitudes in the northern hemisphere in differential vertical total electron content maps. Moreover, given the low-latitude nature of this incident, changes in the shape of the Equatorial Ionization Anomaly (EIA) were analyzed as well. A significant amplification of the northern crest in the EIA of 33.3% was also observed 12 days before the earthquake. Because the geomagnetic and solar conditions for January 2, 2018 were very quiet and also knowing that natural ground radioactivity produced by the earthquake's preparation can increase the total electron density in the EIA, it is considered that this ionospheric disturbance is product of the earthquake's preparation. Additionally, the detection of a negative ionospheric anomaly 2 days after the incident is reported. An association to the earthquake of this negative disturbance is hinted at, due to the also the rather quiet geomagnetic and solar 0conditions after the seismic occurrence.
In the paper, a design, implementation and optical parameters of a system transforming Gaussian laser beam into a nondiffracting bessel beam are described. The construction of the proposed laser beam convertor enables a phase modulation of the spatial spectrum of the created beam. It is used for the transversal adjustment of the beam spot into the desired position by a maintainance of propagation direction. In the contribution, the possible usage of the laser convertor in optical micromanipulation is discussed and the achieved experimental results are demonstrated. and V článku je popsán návrh, realizace a optické parametry systému, který umožňuje transformaci laserového svazku s gaussovským profilem na nedifrakční svazek besselovského typu. Konstrukce navrženého laserového konvertoru je řešena tak, aby umožnila fázovou modulaci prostorového spektra vytvářeného svazku. Ta je využita k příčnému nastavení stopy svazku do požadované polohy při zachování směru šíření. V příspěvku je rovněž diskutována možnost využití laserového konvertoru v optických manipulacích a demonstrovány dosažené experimentální výsledky.
The desire to explore distant lands and exotic civilisations is a
defining attribute of one of our most famous travellers, Enrique Stanko Vráz (b. 1860 - d. 1932). Besides being a traveller, he was also a photographer, writer and collector. We learn most about his journeys from his books, in which his travel experiences were transmuted into literature, and from the countless photographs taken while staying in exotic countries. Vráz understood
photography to be the perfect means of documenting facts and events; he always preferred an informative to an emotional style. His captions written on glass negatives are of exceptional value.
Vráz would always try to describe and, more importantly, understand
the culture of any country he visited. He himself was a very
charismatic personality with an ability to make friends easily - which is why he was able to find out things that for other travellers and explorers would remain secret. His approach to people from other cultures was open-minded and friendly, but also carried a dose of healthy scepticism.