Miocene molluscs and barnacles from Mont Rond,Kerguelen Islands

A sedimentary deposit discovered at Kerguelen Islands in 1988 is interbedded in the Cape MacLear cliffs, near Mont Rond (Ronarc'h Peninsula). The age of this oceanic deposit is considered to be lower to middle Miocene as indicated by isotopic dating of both the underlying and overlying basalts. This deposit yields a fauna essentially consisting of molluscs (bivalves, gastropods) and crustaceans (cirripedes). This fauna exhibits some similarities to Miocene to Recent austral faunas (New Zealand, Argentina) as a result of the establishment of the Antarctic Circumpolar Current. However, it has no species in common with the extant Kerguelen fauna. The Mont Rond fossil assemblage is best compared with either of two types of extant communities developed on a bare sandy sea floor where infaunal species are dominant, but most likely to an opportunistic one in depths from approximately 10 to 80 m.     

Some direct comparisons of mesospheric winds observed at Kyoto and Adelaide

Direct comparisons have been made of the prevailing and tidal wind fields observed in the 80–100 km height region using data obtained with a meteor radar at Kyoto (35°N, 136°E) and a partial reflection spaced antenna system at Adelaide (35°S, 138°E). Data taken with a partial reflection system at Townsville (19°S, 147°E) has also been included so that the latitudinal variations of the tidal structures could be taken into account. The comparisons extend over periods of up to one month duration centered on the equinoxes of 1979 and the January solstice of 1980. They show that there are often significant differences in the tidal amplitudes and phases observed at Kyoto and Adelaide, despite their near geographic conjugacy, probably indicating the presence of antisymmetrical tidal modes. The diurnal tide is appreciably stronger at Adelaide on the average, than at Kyoto, whereas the semi-diurnal amplitudes are on the average greater at Kyoto.     

Mechanisms for observed total electron content pulsations at mid latitudes

Total electron content variations in the Pc3–Pc4 range of frequencies of the order of 4 parts in 10⁴ have been reported in apparent correlation with simultaneous ground based magnetic pulsation observations. By means of a term-by-term analysis of the continuity equation for electrons, the plausibility of various mechanisms is investigated. The most likely explanation is in terms of localized increases in the electron density at F-region heights caused by the field-aligned (compressional) component of the pulsation magnetic field. The analysis predicts a tendency for the amplitude of the TEC pulsations to vary in antiphase with ground-based measurements of the north-south component of the pulsation field.     

Gravity-wave motions in the mesosphere and lower thermosphere observed at Mawson,Antarctica

We present the results of MF radar observations of mean winds and waves in the height range 78–108 km at Mawson (67°S, 63°E), Antarctica. The measurements were made in the period from 1984 to 1990. Climatologies of the prevailing zonal and meridional circulations made with a 12-day time resolution show that the mean circulation remained relatively stable over the 6 yr of observation. Climatologies of gravity-wave motions in the 1–24 h period range were also generated. These reveal that the r.m.s. amplitudes of horizontal wave motions near the mesopause (~90 km) are about 30 m s⁻¹, and that there is some anisotropy in the motions, especially at heights below 90 km. Meridional amplitudes are larger than zonal amplitudes, which suggests a preference for wave propagation in the north-south direction. Comparisons with MST radar wind observations made near the summer solstice at Poker Flat, Alaska (65°N) and at Andøya, Norway (69°N) show similarities with the Mawson observations, but the wave amplitudes and mean motions are larger in magnitude at the northern sites. This suggests hemispheric differences in wave activity that require further study.     

Source regions of medium scale travelling ionospheric disturbances observed at mid-latitudes

The characteristics of medium scale travelling ionospheric disturbances (MSTIDS) have been determined from observations carried out between 1972 and 1975 at Leicester U.K. (52°32′N, 1°8′W) using the HF Doppler technique. By reverse ray tracing through a model atmosphere an estimate of the source locations of these waves can be obtained. Auroral sources do not appear to represent an important generation mechanism for MSTIDs observed at mid-latitudes. The majority of waves originate at tropospheric altitudes at ground ranges of less than 1500 km from the observation point, and a moderate correlation is found between the occurrence frequency of MSTIDs and the intensity of the meteorological jet stream.     

Plasma drifts inferred from thermospheric neutral winds and temperature gradients observed at low latitudes

Low-latitude plasma drifts (zonal and meridional) in the F-region are inferred from the observed night-time thermospheric neutral wind velocities and temperature gradients, together with models for the neutral density (MSIS-86 model) and the electron density (IRI model). The thermospheric neutral winds and temperatures are derived from measurements of Doppler shifts and widths of the Oi 630.0 nm airglow emission line, respectively, using a Fabry-Perot interferometer at Cachoeira Paulista (23°S, 45°W), Brazil. The equations considered are the ideal gas law and the momentum equation for the thermosphere, which includes the time variation of the neutral wind, the pressure gradient which is related to the temperature and density gradients and the ion drag force. The present method to infer the night-time plasma drift using observed neutral parameters (time variation of neutral wind velocities and temperature gradients) showed results that are in reasonable agreement with our calculated plasma drifts and those observed in other low-latitude locations. On the other hand, it is surprising that sometimes the winds flow from the observed coldest sector to the hottest part of the thermosphere during many hours, suggesting that plasma drift can drive the neutral winds at low latitudes for a period of time.     

Phase velocity studies of 34-cm E-region irregularities observed at Millstone Hill

Phase velocity observations at E-region heights made with the Millstone Hill 440 MHz radar find no evidence of an ion acoustic limiting speed for phase speeds observed near 0° magnetic aspect angle. Under most circumstances the phase speed increases steadily with increasing backscattered power amplitude. For a 34cm volume backscatter cross-section, σ_v, less than ∼5 × 10⁻¹³ m⁻¹, the phase speed is at or below the usual ion acoustic speed in the E-region (350m/s), and increases only slowly with the observed backscattered power amplitude (∼50 m/s per 10dB). At higher power levels, the phase speed exceeds 350 m/s, reaching values in excess of 750 m/s at times, and increases more rapidly with backscattered power (∼200 m/s per 10dB). Phase velocity/time maps observed over a 3° span of latitude suggest that many features of the phase speeds observed are directly related to changes in the ambient convection electric field in the E-region due to changing activity conditions or the effects of superimposed magnetospheric pulsations.     

VLF transmissions observed at anomalously high latitude above the ionosphere in the conjugate hemisphere

Ariel 3 and 4 satellite observations of the GBR 16 kHz and NAA 17.8 kHz transmissions above the ionosphere in the conjugate hemisphere show that their wave-fields generally show a rapid reduction in signal strength for geomagnetic latitudes greater than 55°–60°. Sometimes, however, the signal strength has been observed to be high in the invariant latitude range > 60°. At certain times during these observations, the signal showed clear evidence of amplification, whilst at other times the pattern of signal strength was displaced to higher latitude with the signal strength integrated over latitude being unchanged from that normally observed.It is shown that the plasmapause can guide both the NAA and GBR signals but that the efficiency of this guiding depends on the plasmapause position. The important condition is found that the plasmapause must be situated sufficiently equatorwards that half the equatorial electron gyrofrequency at the plasmapause position is greater than (or approximately equal to) the transmitter signal frequency. Ray-tracing calculations in a realistic magnetosphere model indicate that for the 16 kHz GBR signal, the efficiency of guiding falls off for L_pp, (the L-value of the plasmapause) > 3.0 and guiding effectively ceases for L_pp > 3.5.Guidance by the plasmapause results in a wave-field at higher latitude than for non-guided propagation. This will only occur when, following geomagnetic storms, the plasmapause position is at a sufficiently low L-value. This is in agreement with the experimental observations of anomalously high latitude signal reception following strong magnetic storms (K_p ≥ 4+).     

Weathering the Storm: Social Policy and the Great Recession

This review discusses recent challenges to the welfare state arising from the Great Recession (GR). The GR was a significant event for social policy analysts, as it tested the responsiveness of welfare systems in the midst of a recent trend toward austerity politics in advanced economies. Social policy changes were part of the toolkit advanced democracies used to respond to the GR, and the welfare state mitigated the consequences of the GR. However, a stark limitation of the social safety net in the United States was the failure to assist immigrant households. The nexus of immigration and social policy is likely to be a significant controversy as we consider the meaning of social citizenship.     

The effect of induced currents in the sea on magnetic bays observed at a coastal observatory

It is widely accepted that return currents from the auroral electrojet are responsible for the magnetic bays in the D component. The different directions of the return currents, at either end of the electrojet, means that the sign of the D bay should change as the station moves from east to west of the central meridian of the electrojet. However, there is confusion as to whether this change occurs, giving rise to different models for the substorm current system. The possible effect of induced currents on magnetic bays is shown to be significant and should be examined for each observatory before using their magnetic bays to infer substorm current systems.An analysis of magnetic bays at Halley Bay (75°S, 27°W), a coastal site in Antarctica, shows that a change in the sign of D bays does not occur. It is shown that induced currents flowing in the sea, parallel to the coast, would have an effect that is consistent with the observations.     

A Storm of Changes Sweep over Tibetan Farmers and Herdsmen Led by the Qinghai-Tibetan Railway

From the opening traffic of the Qinghai-Tibet Railway,a major restriction on transportation to and from Tibet was finally removed. Such a change has had a massive impact on the economy of the Tibet Autonomous Region (TAR) as a whole and,in particular,on the rural Tibetans.In other words,the railway became a leading force in the re- structure and advancement of the Tibetan economy.     

A Storm of Changes Sweep over Tibetan Farmers and Herdsmen Led by the Qinghai-Tibetan Railway

From the opening traffic of the Qinghai-Tibet Railway,a major restriction on transportation to and from Tibet was finally removed. Such a change has had a massive impact on the economy of the Tibet Autonomous Region (TAR) as a whole and,in particular,on the rural Tibetans.In other words,the railway became a leading force in the re- structure and advancement of the Tibetan economy.