ELF and VLF wave generation by modulated HF heating of the current carrying lower ionosphere

This paper presents further experimental results on ionospheric current modulation, using powerful amplitude modulated HF waves produced by the new heating facility at Ramfjordmoen near Tromsø, Norway. As a result of the current modulation, waves in the ULF, ELF and VLF range can be efficiently generated. The experiments discussed here cover the range from low ELF up to 7 kHz. The observed signal strengths are of the order 1 pT. Decomposition of the received ELF/VLF waves into R- and L-mode shows that both modes are usually of comparable strength. The signal strength as a function of modulation frequency shows pronounced maxima at multiples of approximately 2 kHz. The paper also presents a brief theoretical discussion of the processes involved in the generation of ELF/VLF waves by HF induced current modulation.     

Small-scale fluctuations of magnetic and electric components of the ELF and VLF wave fields in the sub-auroral topside ionosphere : stochastic characteristics of the wave field

When the Interkosmos-14 and Interkosmos-19 satellites crossed the region of spatially varying electron concentration in the topside ionosphere adjacent to the high-latitude boundary of the main ionospheric trough, it was discovered that there were simultaneous fluctuations of plasma density, temperature and the amplitudes (H_x and E_y) of the ELF and VLF radio/plasma emissions. The probability characteristics of the naturally perpendicular H_x and E_y fluctuations are analysed. The correlation coefficient R(_H, E_y) turned out to be less than 0.6 at frequencies of F ⩽ 4.65 kHz, while at higher frequencies R increases, up to 0.9 at 15 kHz. The following interpretations are proposed:

1. 1.1. While measuring noise emissions, as a rule a mixture of numerous elementary waves is recorded.
2. 2.2. At frequencies exceeding the local lower hybrid resonance frequency (in our case f_LHR ≈ 5 kHz), a mixture of electromagnetic waves experiencing the influence of the inhomogeneous electron concentration N_e is registered.
3. 3.3. At frequencies which are lower than the local value f_LHR the mixture mainly consists of ELF waves. The wave field has a complicated structure, and the dynamical coherence between electric and magnetic field components is not as simple as at VLF frequencies (f ≈ 15 kHz).
4. 4.4. It is shown that the wave components for a mixture of electromagnetic and electrostatic waves (for instance a mixture of VLF and lower hybrid frequency waves) have a lower correlation coefficient because the electrostatic waves are unrelated to the electromagnetic waves.
5. 5.5. The correlation analysis offers an opportunity to detect the presence of waves of various types in the wave mixture.

     

Shortcomings in our understanding of the lower ionosphere as revealed by an analysis of radiowave absorption measurements

Empirical relationships derived from an extensive series of equatorial ground-based radiowave absorption measurements are analysed in terms of our current understanding of the basic processes that control the formation and behaviour of the lower ionosphere. Multi-frequency absorption and virtual height measurements are combined with the results of a rocket borne experiment to construct an equatorial noontime reference electron density profile corresponding to the conditions of a non-flaring sun at solar cycle maximum. The enhancement in this electron density profile, and hence in the absorption of radio waves, as the solar 1–8 Å flux increases by moderate amounts is then calculated from our knowledge of the ion production and loss processes. In order to bring the calculated increase of absorption into agreement with the empirically established relationship (Gnanalingam, 1974), we find it necessary to reduce by a factor of about 5 the Meira (1971) nitric oxide densities below 90 km.Attention is drawn to the wide disparity between the effective recombination coefficient and the average dissociative recombination coefficient for the known ion composition in both the molecular and cluster ion regions of the lower ionosphere. The factor of 5 reduction in the nitric oxide profile required to explain the solar control of absorption, however, largely eliminates this disparity in the cluster ion region.Our analysis of the diurnal variation of radiowave absorption and virtual height also reveals a gross discrepancy between the calculated and measured variations. In order to resolve this discrepancy, a mechanism is needed which would cause the electron density in the 95–105 km region to decrease with increasing solar zenith angle faster than is predicted by the present theory of ion production and loss processes in this region.Also presented in this work is an ad hoc model of the diurnal variation of the electron density profile which is consistent with the measured diurnal variation of radiowave absorption and virtual height.     

Indirect phase height measurements of the lower ionosphere compared with rocket measurements of D-region electron density

A comparison between rocket-measured electron density profiles of the lower ionosphere and the results of ground-based indirect phase height measurements in the LF range, carried out near the Soviet rocket sounding station Volgograd over several years, confirms—to a first-order approximation—the height of the level of electron density which according to magnetoionic ray theory is necessary for reflection of the waves. In a second-order approximation, however, an additional phase path change has to be taken into account, which is caused by the ionization below the reflection level. This makes the observed phase height always slightly smaller than the real geometric height, on average by −1 km, but in extreme cases by up to −4 km, depending on the actual height gradient of electron density below the reflection level. Due to systematic diurnal and seasonal variations of this gradient, the amplitude of the diurnal variation of the observed phase height is found to be slightly larger than that of the real geometric height, whereas the reverse is true for the seasonal variation at constant solar zenith angle.     

Mean geopotential fields for the lower thermosphere of the southern hemisphere

Satellite radiance data are used to compile monthly mean contour maps for the 0.005 mb and 0.001 mb constant pressure surfaces. Aspects of the seasonal and spatial distribution of the geopotential height fields are discussed. Zonal geostrophic wind speeds are calculated from the zonal mean heights.     

Whistler-mode propagation: results of model calculations for an inhomogeneous plasma

Waveforms computed using the new whistler model derived from Maxwell's equations were analysed. In the calculations, realistic model values for magnetospheric parameters were used. The results accurately described whistler-mode propagation in the magnetosphere and provide explanations for some features exhibited by real observed whistlers when they are analysed. In particular, solutions of the exact full-wave whistler model can explain the whistler fine structure, and may be used to develop a more accurate (matched filtering) fine-structure analysis method.     

Night-time electron density of the lower ionosphere in the South Atlantic Geomagnetic Anomaly region obtained with a LF/VLF oblique ionosonde

Studies of the reflectivity of the night-time lower ionosphere in the region of the South Atlantic Geomagnetic Anomaly have been carried out for the period August 1980 to July 1981, using data collected by an oblique ionosonde at low/very low frequency, in the southern part of Brazil, near the centre of the Anomaly. From these studies monthly average behaviour of heights and reflection coefficients of the lower ionosphere between 15 and 60 kHz have been deduced. Assuming an exponential model of the electron density distribution in the lower ionosphere the appropriate numerical parameters were calculated using a trial-and-error approach with ‘full wave’ calculations and iterative computational techniques. For the period considered three sets of parameters could satisfactorily represent the lower ionosphere in the anomalous region and in the period analysed: one valid from August to November 1980, one valid from December 1980 to March 1981 and the other valid from May to July 1981. April 1981 seemed to present anomalous behaviour.     

Progressive localism for an ethics of care: Local Area Co-ordination with people with learning disabilities

In the UK devolution to ‘new’ nations and localities is generating differences in the tone and substance of social care. In Scotland there is an apparent rejection of the ‘personalisation’ model dominant in England and other neoliberal welfare states; in its place, there is an emphasis on locally based co-produced care provision, involving local organisations, practitioners and individuals. The paper argues that this is an outcome of the open and deliberative nature of policy-making, and the further devolution of social care provision to local authorities in Scotland. Local scale networks and spaces of provision are generating a ‘progressive localism’, contesting the association between the local scale and financial austerity, drawing on a relational understanding of place. Non-commodified and locally-based provision expands the discourse of care from ‘caring for’ individuals to ‘caring about’ people and places, in what is termed an ‘ethics of care’. The paper uses the example of people with learning disabilities to examine a more broadly conceived ‘caring’ within local communities, offering possibilities for inclusion and belonging. The paper draws on interviews with key policy makers and place-based care practitioners, known as ‘Local Area Co-ordinators’.     

Tools for identifying partisan gerrymandering with an application to congressional districting in Pennsylvania

In League of Women Voters v. Commonwealth of Pennsylvania (2018) the Pennsylvania Supreme Court struck down as a “severe and durable” partisan gerrymander the congressional map drawn by Republicans in 2011 and used in elections from 2012-2016. It did so entirely on state law grounds after a three-judge federal court had rejected issuing a preliminary injunction against the plan. After Pennsylvania failed to enact a lawful remedy plan of its own (due to total disagreement as to how to proceed between the newly elected Democratic governor and the still Republican-controlled legislature), the Court then ordered into place for the 2018 election a map of its own drawn for it by a court-appointed consultant. In a split court, the Court map was endorsed only by judges with Democratic affiliations. Here we compare the 2011 and 2018 congressional maps in terms of a variety of proposed metrics for detecting partisan gerrymandering. We also examine the remedy map proposed by a group of Republican legislators and that proposed by the Democratic governor. We conclude that the 2011 map was a blatant and undisguised pro-Republican gerrymander. Moreover, the remedy map proposed by Republican legislators was a covert pro-Republican gerrymander (what we refer to as a “stealth gerrymander”). The Democratic governor's proposed plan cannot be classified as a pro-Democratic gerrymander and indeed has, if anything, a slight pro-Republican tilt. The 2018 court-drawn remedial map, by all measures, was not a gerrymander.     

遵循康德：跨文化视野下欧洲人的世界史观

约恩·吕森以一名德国学者的视角 ,通过研究康德的短文《世界公民观点之下的普遍历史观念》 ,把康德关于世界史和理性的概念应用于当今世界跨文化交流中 ,试图通过构建全人类的共同历史 ,依靠理性的力量来解决文化差异及个性冲突等全球化进程中迫切需要解决的重要问题     

Combining New Awareness and Public Support for Archaeology with In Situ Preservation of an Archaeological Monument

Preserving archaeological remains in situ is one of the main objectives of the Valletta Treaty, which was signed by the Dutch government in 1992. Subsequently, preservation in situ has become one of the pillars of archaeological heritage management in the Netherlands. Another objective of the Treaty is the promotion of heritage education and raising of public awareness for the protection and investigation of archaeological heritage. Until recently, this goal has received too little attention. The design and building of an underground visitor centre, DOMunder, raised an important question: How can we transform an archaeological monument into an asset for the community and at the same time ensure long-lasting preservation? Not many parallels exist, as most archaeological sites in urban environments are seen as a burden for development. Sites are generally either excavated or left in situ; in both cases the archaeology remains invisible and inaccessible to the public. In the case of DOMunder, the location in a wet sedimentary environment provided even more challenges. This paper focuses on a few of the many questions and problems that were raised before and during the building process and the (preliminary) answers and solutions.     

A Multivariate Model for Spatio‐temporal Health Outcomes with an Application to Suicide Mortality

This article considers models for multivariate mortality outcomes (e.g., bivariate, trivariate, or higher dimensional) observed over a set of areas and through time. The model outlined here allows for spatially structured and white noise errors and for their intercorrelation. It also includes possible temporal continuity in such types of error via structured temporal effects. An extension to spatially varying regression effects is considered, as well as the option of nonparametric specification of priors for spatial residuals and regression effects. Allowing for spatially correlated intercepts or regression effects may alter inferences regarding the changing impact on mortality of socioeconomic or environmental predictors. The modeling framework is illustrated by an application to male and female suicide mortality in London, focusing on the impact on suicide of deprivation and social fragmentation (“anomie”) in the 33 London boroughs during three periods: 1979–83, 1984–88 and 1989–93. Suicide trends by age group are also considered and show considerable differences in the trends in impacts of deprivation and social fragmentation.