Applicability of palaeomagnetism of pyrrhotite to ore-genetic studies

Pyrrhotite has never before been used in palaeomagnetic investigations, being highly anisotropic magnetically. The aim of this paper is to show that fine-grained pyrrhotite aggregates of hydrothermal origin can be used for palaeomagnetic purposes. This has been proved with polymetallic Turkak veins from Kutná Hora in Central Bohemia as an example. It can be assumed that other localities with occurrence of hydrothermal pyrrhotite aggregates which contain directionless, uniformly scattered pyrrhotite grains and therefore forming a magnetically isotropic medium may be suitable for palaeomagnetic studies.

---

Zusammenfassung Pyrrhotin, mit einem hohen Grad magnetischer Anisotropie, ist bisher für die paläomagnetische Datierung unbeachtet geblieben. Diese Arbeit will zeigen, daß feinkörnige Pyrrhotinaggregate hydrothermalen Ursprungs für paläomagnetische Untersuchungen geeignet sind, was am Beispiel polymetallischer Gänge von Turkak in Kutná Hora in Zentralböhmen dargestellt wird. Es ist anzunehmen, daß auch andere Vorkommen hydrothermaler Pyrrhotinaggregate in denen regelmäßig verteilte Körner richtungslos orientiert vorliegen und so ein magnetisch isotropes Medium bilden, sich für paläomagnetische Untersuchungen eignen.

     

Coronal mass ejection associated with the stationary post-flare arch of 21–22 May 1980

By using a combination of X-ray (HXIS), H (Haleakala), white-light corona (Solwind), and zodiacal light (Helios) images on 21–22 May, 1980 we demonstrate, and try to explain, the co-existence of a coronal mass ejection with a stationary post-flare coronal arch. The mass ejection was seen, both by Solwind and Helios, in prolongation of the path of a powerful spray, whereas the active region filament did not erupt. A tentative comparison is made with other occurrences of stationary, or quasi-stationary post-flare coronal arches.     

Results from several persistent train spectra intercompared

Some results following from two contemporary photographical programs (Slovakia and Japan) for persistent meteor train spectra are compared. It shows that even though both programs are not too different according to their lenses and films used, the spectral interval detected is very different. In this respect prism as a dispersion element is more favourable than the grating with blaze wavelength near 610 nm. However, some results previously assumed as typicai for presented persistent trains-e.g. the forbidden Herzberg O₂ emission, the NO₂ continuum and OH red emissions-seem to be substanciated especially due to higher and linear dispersion of those grating spectra.     

Effect of cofactors of adjusted and unadjusted quantities on their functions

aamuam uu am a (m u naamuu n) u u (a) uu a uu mu uu. mam (19), (28) naam, m amua am mau u m ¶rt; am amu: a) na ¶rt;um am, n n a uu am u uu a uu; ) ma ¶rt;um am, m aam uu a uu.     

Tidal deformations of viscoelastic body

Summary The tidal deformations of a viscoelastic body are studied using the simple Kelvin-Voigt model. Expressions for the phase lag and amplitude change of the displacement vector are derived. The energy dissipation rate is calculated for the main disturbing bodies and for diurnal and semidiurnal tidal waves.

---

am nuu ¶rt;auu n ma ua-ma. ¶rt; au ¶rt; ana¶rt;au a u uu anum¶rt; ma u. aumaa m ¶rt;uunauu uu ¶rt; u a a m u nm .

     

Sustainable landscape management in Slovenia: Environmental improvements for the Velenje coal mining community 1991–2000

The Velenje area (almost 200 km² with over 31,000 inhabitants) is based on the Šalek Valley, which became a leading area of industrialisation and urbanisation after the Second World War, with consequent pollution problems. Various industrial plants polluted the river Paka while more serious hazards arose through the coal mine which is a still causing landscape subsidence and the thermal power station in the neighbourhood of Šoštanj which is a major source of sulphur dioxide and nitrogen oxide pollution. In 1987 there was an ecological protest which marked the beginning of a sustainable development strategy for the community. During the past decade programmes have dealt with the degradation of air, soil and water to achieve cleaner air, a transformation in landuse and enhancement the river's formerly weak self-purifying capabilities. This article examines the changes in the valley since the attention of the authorities was drawn to the deterioration of living conditions. Despite the pressures of transition which have seen unemployment rising to over ten percent, significant environmental improvements have been made and the area stands as a model for the rest of the country. This revised version was published online in July 2006 with corrections to the Cover Date.     

Displacement of points determined by spatial intersection

Summary A procprocedure is presented for the direct determination of the components of the vector of spatial displacement of a point by spatial intersection. The horizontal, vertical and slope distances are determined by integrated surveying systems (electronic tacheometers), and the first survey is adjusted using conditional observations. The vector of displacement on the individual intervals of observation is determined by means of the matrix equation (33) into which it is only necessary to substitute the appropriate vectors of the observational differences.     

Analytical computation of atmospheric drag effects

An analytical interpretation of the satellite orbital element perturbations under influence of a drag has been developed. Some useful formulae for the perturbations of the semi-major axis are given. The agreement with observed values is very good.     

Rr CrB and Algol – The First and Last Star in Zdeněk Kopal’s Life with Binaries

Several important turning points appeared in the personal life and scientific career of Zdeněk Kopal, every time, when he entered a new field of research. Four particular periods of his life will be commented in the present paper: the studies in Prague and early observations in the variable star programme of the Czech Astronomical Society; the first lectures on close binaries at Harvard; the intermezzo of lunar research; and the last period after 1989, when Zdeněk Kopal returned several times to Prague University.