On the R z -sunspot relative number variations

The Zürich sunspot relative number R _z series has been analysed by the cyclogram method. The amplitude and the frequency variations of the Fourier 11 yr component between 1700–1983 A.D., were determined in a continuous way.Four distinct time intervals with significantly different characteristics of the periodicities are observed and discussed.Their second harmonics are also considered. The periodicity changes are contemporary to those of the 11 yr cycles.Around the year 1903 it seems that an important event has happened in the Sun. In fact the 11.4 yr cycle periodicity, that was very stable since at least 1825 started to change gradually to smaller values and similarly it happened to the second harmonic which also stopped and abruptly changed of phase of 90°.     

Factors affecting the distribution and abundance of Macrobrachium petersi (Hilgendorf) in the Keiskamma River and estuary,South Africa

A dry (1979–1980) and a wet (1980–1981) season had a marked effect on the freshwater inflow into the Keiskamma estuary. Under low inflow conditions, which results in elevated salinities in the upper reaches, an upstream migration of adult Macrobrachium petersi (Hilgendorf) to freshwater takes place. During periods of increased river inflow adult M. petersi move downstream to the more saline reaches of the estuary. These two migratory responses have been interpreted as (a) a breeding migration under high inflow conditions which ensures that larvae are in close proximity to salinities that favour growth and development, and (b) an adult upstream migration back to freshwater to escape elevated estuarine salinities as a result of the low freshwater inflow.     

Volcanic style in the Strand Fiord Formation (Upper Cretaceous), Axel Heiberg Island, Canadian Arctic Archipelago

The Strand Fiord Formation is a volcanic unit of early Late Cretaceous age which outcrops on west-central and northwestern Axel Heiberg Island in the Canadian Arctic Archipelago. The formation is part of the thick Sverdrup Basin succession and immediately precedes the final basin foundering event. The Strand Fiord volcanics are encased in marine strata and thin southward from a maximum thickness of 789+ m on northwestern Axel Heiberg to a zero edge near the southern shore of the island. Tholeiitic icelandite flows are the main constituent of the formation with volcaniclastic conglomerates, sandstones, mudrocks and rare coal seams also being present. The lava flows range in thickness from 6 to 60 m and subaerial flows predominate. Both pahoehoe and aa lava types are common and the volcanic pile accumulated mostly by the quiet effusion of lavas. The volcaniclastic lithologies become more common near the southern and eastern edges of the formation and represent lahars and beach to shallow marine reworked deposits. The Strand Fiord volcanics are interpreted to represent the cratonward extension of the Alpha Ridge, a volcanic ridge that was active during the formation of the Amerasian Basin.     

The klein–nishina Effects in Blazar Jets

Blazars are the only (with one or two exceptions) extragalactic objects which were detected and identified at gamma-ray energies so far. It is suspected that most of the unidentified gamma-ray sources may be the blazars as well. Because the entire electromagnetic spectrum of these objects is dominated by non-thermal radiation from relativistically moving jets, the effects such as the Klein–Nishina regime in the Compton scattering may play a major role in shaping some parts of the blazar spectrum. Within the framework of external radiation Compton model, we present how these effect influence the spectra of blazars for which the production of gamma rays is dominated by Comptonization of external radiation.     

Stable isotope geochemistry and structural elements of the Sabina region (Central Apennines, Italy)

Various tectonic features are present in the Meso-Cenozoic basin units of the Sabina region (Central Apennines, Italy): Mio-Pliocene northeasterly verging thrusts are followed by Plio-Pleistocene, N-S oriented right-lateral strike-slip faults. Stable isotope geochemistry and examination of meso- and microstructures show that strain conditions differed through the course of tectonic history. Carbon and oxygen isotope analyses of the calate-filled extensional fractures, the sigmoidal veins present between stylolitic cleavage surfaces, and fault plane surfaces with differing motion, demonstrate those different geneses.
The "C/'" C of the older calcite-filling fractures (present both in the thrust and the strike-slip systems) suggests a deposition from shallow, fresh water circulation. Furthermore, the calcite fill of en echelon systems, that occur in the southernmost Plio-Pleistocene units, is clearly the result of a more recent, right-lateral strike-slip movement, connected with shallow water circulation within Mesozoic limestones.
The sigmoidal vein fills are derived from solid-state pressure solution processes which were the result of strike-slip movement. The deformation pattern related to the older thrust system is similar, but less intense; this also demonstrates general recrystallization processes in a closed system.
This suggests that the total shortening of the deformed sections is lower than that obtained on the basis of solution on stylolitic planes, because a sigruficant volume of dissolved carbonates remained in the system.
Stable isotope analysis also confirms that the deformational history of strongly cleaved rocks in the Sabina region took place in two phases and that extensional fractures formed before stylolithic planes, as suggested by structural and field observations.     

Astrometry from space: GAIA and planet detection

The proposed baseline GAIA mission will be able to detect the astrometric signature of Jupiter-size planets around of the order of a million stars, using either global or narrow-angle astrometry. If the mission can realize the higher astrometric accuracy that photon statistics allows for bright stars, lower-mass planets (from Earth size to ten times larger) can be found around ten to a few hundred stars.     

Influence of viscous dissipation on a hydromagnetic field

The effect of a transverse magnetic field and of the viscosity diffusion on the free-convection flow of an electrically-conducting incompressible fluid past a uniformally accelerated vertical plate is discussed. A finite difference method has been used to obtain a numerical solution. The influence of the various parameters on the flow field is discussed.     

Analytical and numerical analysis of the generalized Shkarofsky function

The main analytical properties of the generalized Shkarofsky function and a numerical code for its computation are discussed. The results of a numerical analysis are compared with the results of an asymptotic analysis for parameter values relevant to the problem of whistler-mode propagation in the Earth's magnetosphere. This comparison allows us to specify the range of applicability of different approximations to the generalized Shkarofsky function, which have been used for the analysis of relativistic effects on whistler-mode propagation and instability.