Current results of an arachnological survey of some sandstone rock sites in Bohemia (so-called "rock cities")

Current results of an arachnological survey of some sandstone rock sites in Bohemia (so called 'rock cities'). The spider fauna of the Adrspach·Tepllce rocks was investigated. Some records on spider fauna of other nine sandstone rock areas are included. The phenomenon of 'rock cities' manifests itself in three aspects: (1) In the bottom parts are microclimatically cold spaces, frequently hosting northern or mountain species of invertebrates, which here have an azonal occurrence. (2) The sun exposed tops of rocks can host thermophilous species. (3) Some species are limited to the surface of rocks and boulders. These are referred to as lithophilous or lithobiont species

Numerical simulation of mold filling and casting solidification

Cílem této diplomové práce je, na základě numerické simulace stávající technologie výroby hliníkového odlitku držáku kladky V9X, analyzovat příčiny vzniku vad typu zavaleniny a studené spoje. Následným cílem je vypracovat návrh variantního řešení tvaru odlitku tak, aby došlo k odstranění zmíněných vad. Toto variantní řešení bude rovněž ověřeno numerickou simulací. Úspěšnost navržených změn, pak posoudí zkušební odlití odlitku. V rámci řešení problému bude provedena simulace cyklování formy a následně plnění odlitku. Během analýzy plnění dutiny formy bude rovněž rozebrána první fáze plnění, tedy pohyb pístu v tlakové komoře. S ohledem na typ vznikajících vad nebude provedena analýza tuhnutí odlitku.The object of this diploma thesis is to analyze, persuant to numerical simulation of current technology of production aluminous casting roller-reck V9X, causes of the rise of cold lap and laminations defects. Consequently, to work up a project of variant solution of the shape of casting so, as to come to elimination mentioned defects. This variant solving will be tested with numerical simulation as well. Fruitfulness of these designed changes will be verified by testing molten of the casting. In terms of solve the problem the simulation of cycling of the mold and subsequently the filling of the casting will be effected. During the analyse of filling of the die the first phase of filling will be effected too.It means the movement of the piston throught the chambre. Simulation of solidification of the casting wont be effected because of the type of the defect.

In memoriam RNDr. Ing. Ludek J. Dobroruka, 1933 - 2004

Obituar

New records of spiders from pond littorals in the Czech Republic

Tmeticus affinis (BLACKWALL, 1855), Tetragnatha shoshone LEVI, 1981, Clubiona juvenis SIMON, 1878, Marpissa Canestrinii NINNI, 1868, and Theridiosoma gemmosum (L. KOCH, 1877) are new records for the Czech Republic. New data about Enoplognatha caricis (FICKERT, 1876), Theridion hemerobium SIMON, 1914, Rugathodes instabilis (O. P. CAMBRIDGE, 1871), Tetragnatha striata L. KOCH, 1862, and Dolomedes plantarius (CLERCK, 1757) are given. The validity of the name Enoplognatha caricis (FICKERT, 1876) is supported

Migration Dynamics for the Ideal Free Distribution

This article verifies that the ideal free distribution (IFD) is evolutionarily stable, provided the payoff in each patch decreases with an increasing number of individuals. General frequency-dependent models of migratory dynamics that differ in the degree of animal omniscience are then developed. These models do not exclude migration at the IFD where balanced dispersal emerges. It is shown that the population distribution converges to the IFD even when animals are nonideal (i.e., they do not know the quality of all patches). In particular, the IFD emerges when animals never migrate from patches with a higher payoff to patches with a lower payoff and when some animals always migrate to the best patch. It is shown that some random migration does not necessarily lead to undermatching, provided migration occurs at the IFD. The effect of population dynamics on the IFD (and vice versa) is analyzed. Without any migration, it is shown that population dynamics alone drive the population distribution to the IFD. If animal migration tends (for each fixed population size) to the IFD, then the combined migrationpopulation dynamics evolve to the population IFD independent of the two timescales (i.e., behavioral vs. population)

Spiders (Araneae) of stony debris in North Bohemia

The arachnofauna was studied at five stony debris sites in northern Bohemia. In Central Europe, the northern and montane species inhabiting cold places live not only on mountain tops and peat bogs but also on the lower edges of boulder debris, where air streaming through the system of inner compartments gives rise to an exceedingly cold microclimate. At such cold sites, spiders can live either on bare stones (Bathyphantes simillimus, Wubanoides ura/ensis), or in the rich layers of moss and lichen (Dip/oeentria bidentata). Kratoehviliella bieapitata exhibits a diplostenoecious occurrence in stony debris and on tree bark. Latithorax faustus and Theonoe minutissima display diplostenoecious occurrence in stony debris and on peat bogs. The occurrence of the species Seotina eelans in the Czech Republic was documented for the first time

Disproportionation and Metallization at Low-Spin to High-Spin Transition in Multiorbital Mott Systems

We study the thermally driven spin state transition in a two-orbital Hubbard model with crystal field splitting, which provides a minimal description of the physics of LaCoO3. We employ the dynamical mean-field theory with quantum Monte-Carlo impurity solver. At intermediate temperatures we find a spin disproportionated phase characterized by checkerboard order of sites with small and large spin moments. The high temperature transition from the disproportionated to a homogeneous phase is accompanied by vanishing of the charge gap. With the increasing crystal-field splitting the temperature range of the disproportionated phase shrinks and eventually disappears completely.Comment: 4+ pages, 4 figure