High-resolution Induan-Olenekian boundary sequence in Chaohu,Anhui Province

The Lower Triassic of Chaohu has been exten-sively studied owing to its classic stratigraphic se-quence formed in a unique paleogeography, very easyaccessibility and comfortable working conditions inthe area, and the Induan-Olenekian boundary stratareceived special attention in recent years to meet therequirements of defining the GSSP of the boundary.The best-studied boundary sequence in Chaohu is atthe West Pingdingshan Section, which was recom-mended as a GSSP candidate for the Induan-…     

Non-Equilibrium Distribution Functions in the Heliospheric Interface and Their Relaxation by Local Wave–Particle Interactions

The partially ionized local interstellar medium, before interacting with the heliospheric plasma on the upwind side, most probably undergoes an outer bow shock. After conversion into a sub-magnetosonic plasma flow, it then passes around the heliopause. While the ionized component at the bow shock undergoes abrupt changes of its dynamical properties, the neutral component first continues to flow downstream of the shock with its unperturbed properties. Consequently, the two fluids immediately after the bow shock passage are out of dynamical and thermodynamical equilibrium. Neutral atoms move with a higher bulk velocity and are cooler than the ions. Due to intensive local charge-exchange couplings between neutral atoms and protons these different properties tend to mix each other via momentum and energy exchanges. It turns out that the charge exchange period is shorter than the relaxation period. Hence the distribution functions cannot relax rapidly enough to their highest-entropy forms, i.e. shifted Maxwellians. Here we study the transport processes of newly injected ions in velocity space considering their quasi-linear and non-linear interactions with the ambient MHD turbulence in the plasma interface region. For that purpose we study the turbulence levels in the helio-sheath plasma region. We calculate the expected deviations from equilibrium distributions of ionic and atomic species in the outer heliospheric interface. It clearly turns out from these studies that non-relaxated non-equilibrium distribution functions have to be expected both for O-/H-ions and atoms in this region. This has inherent implications for the diagnostics of interstellar parameters, deduced from observations made further inwards from the interface region.     

Last interglacial and Holocene climatic development in the Norwegian Sea region: Ocean front movements and ice-core data

Planktonic foraminiferal evidence suggests that the ocean front systems between Polar and Atlantic surface waters in the Norwegian Sea generally were located closer to Greenland during Oxygen Isotope Substage 5e than in the Holocene. During both these periods oscillations have occurred in the position of the fronts. In the western Norwegian Sea region, the substage 5e influence of warm Atlantic waters was interrupted by a return to polar conditions. These findings support both ice-core data and evidence from Europe that the last interglacial was a period of rapid climatic shifts.     

THE RUHOBOBO,RWANDA METEORITE: A NEW L6 CHONDRITE

Ruhobobo is a new meteorite which fell in Rwanda, Africa, in 1976. We found and analyzed olivine (Fa 23.4), opx (Fs 19.7, Wo 1.4), cpx (Fs 7.5, Wo 44.0), plagioclase (An 11.7, Or 5.6), chromite, “whitlockite”, kamacite, taenite and troilite. Based on these analyses and on microscopic observation, Ruhobobo is an unshocked L6 chondrite.     

Asteroids in cometary orbits

Orbital integrations are presented for a total of 14 asteroids with perihelia inside 1.7 AU and with aphelion distances in excess of 4 AU, 10 of which were discovered in 1979–1984. The integrations were normally extended over approximately ±1000 years in a three-body model (Sun-Jupiter-asteroid). The effects of uncertainties of starting orbits are not treated in this work, and as far as the real asteroids are concerned, the results should be regarded mostly as preliminary indications. A wide variety of orbital evolutions is found, and some of them evidently belong to the cometary, chaotic type. Three such cases are identified with certainty (1983 SA, 1983 XF, and 1984 BC) and two or three more with various degrees of likelihood. An asteroidal motion is found for the well-observed object 1979 VA. A stable libration around the $\text{2}\text{1}$ resonance is found for 1981 FD, which obviously adds to the Griqua group. A long-lasting libration around the $\text{5}\text{3}$ resonance performed by 1982 YA is probably unstable. Temporary librations are also found for 1983 SA ($\text{4}\text{3}$ resonance) and 1983 XF ($\text{2}\text{1}$ resonance), but these objects appear to transit into irregular motions with close approaches to Jupiter (less than 0.01 AU for 1983 XF). A very rapid large-amplitude ω libration around 90° is found in the future motion of 1983 VA. If this will indeed occur for the real asteroid, the object will oscillate with a period of only 750 years between a main-belt orbit of very high inclination and a low-inclination Apollo-type orbit.     

Rockfalls into forests: Analysis and simulation of rockfall trajectories — considerations with respect to mountainous forests in Switzerland

Rockfalls are a major threat to settlements and transportation routes in many places. Although the general protective effect of forests against rockfalls is currently not questioned, little is known about the ideal properties of a forest stand that provides good protection. Therefore, in this study the question was assessed of how mountainous forests may influence rockfalls of single boulders. An actual rockfall trajectory was measured, recorded, analysed and simulated with a rockfall model. Rockfalls into different forest scenarios were also modelled for the site. Results showed that the actual rockfall event can be well simulated. Furthermore, a completely forested slope reduces velocity and energy of the falling blocks much better than a sparsely forested slope. For the profile discussed in this paper, the largest effect upon falling 3 m³ blocks was obtained with a high forest containing 350 trees per ha. The results confirmed common assumptions on ideal properties of a protective forest stand against rockfalls.