Characteristics of polar cap aurora

The characteristics of extremely high-latitude dayside auroras are examined by using auroral TV data obtained at Godhavn, Greenland, and simultaneous DMSP particle data. Two different kinds of aurora are found near the pre-noon sector, namely (1) the polar arc: this aurora is observed during quiet periods and originates from the dayside region. It is related to about 100 eV electron precipitation or less, and (2) the polar corona: this aurora is observed during disturbed periods and the appearence latitute of this aurora is confined within a certain region about 70–80° MLAT. It is related to a few hundred eV electrons. These results suggest that the origin of the polar arc seems to be the plasma mantle or low-latitude boundary layer, and the origin of the polar corona seems to be the low-latitude boundary layer or Boundary Plasma Sheet.     

Photometric observations of proton aurora at Sanae

Proton aurora was monitored at Sanae (invariant latitude 60°S) by recording Hβ emission with a tilting-filter photometer, and observed for K_p⩾ a 3_. Study of two nights of intense auroral activity during 1978 revealed that the times of onset of proton and electron auroral substorms and magnetic substorms agreed within 5 min. Further, electron aurora occurred poleward or equatorward of proton aurora for a location under the eastward or westward auroral electrojet respectively.     

The dynamics of the poleward edge of the trough deduced using data from a meridional chain of vertical-incidence sounding stations

Data from four ionospheric stations located along the 902E meridian in the range 55–702 of corrected geomagnetic latitude, were used to construct latitude-time electron density distributions in the F2-layer peak for 17 winter nights of 1982–1983. It is concluded that under stationary convection conditions the poleward edge of the trough during the nighttime displaces only 0.5-l°/h, that is, significantly less than obtained from existing analytical models of the ionospheric trough. When the stationarity is upset (due to the development of a substorm or abrupt changes of the north-south component of the IMF), the poleward edge of the trough is observed to displace abruptly equatorward. In the substorm expansion phase these displacements can amount to 4–5° in less than an hour. Such displacements of the poleward edge in the evening hours can characterize the dynamics of the inner edge of the plasma sheet.     

Preliminary results from a study of the F-region heating during an intense aurora observed by EISCAT

Observations of large time variations in the ionospheric F-region temperature derived from EISCAT are compared with simultaneous observations of the E- and F-region plasma densities. The observations suggest that the F-region may be heated by current driven instabilities generated during intense precipitation of auroral electrons.     

Notes on the diversity of the properties of radio bursts observed on the nightside of Venus

We report on further studies of radio wave bursts detected by the Orbiting Electric Field Detector (OEFD) on PVO in the nightside ionosphere of Venus. We have tested a total of 25 cases of wave burst activity for evidence of whistler-mode propagation to the spacecraft from impulsive subionospheric sources. As in a previous study of 11 of these cases (Sonwalkar et al., 1991), we find at least two distinct classes of events, one, mostly involving bursts at 100 Hz only, that passes certain tests for whistler-mode propagation, and another, mostly involving bursts in two or more of the four PVO narrowband channels (at 100 Hz, 730 Hz, 5.4 kHz, and 30 kHz), that fails to pass the tests. The subionospheric lightning hypothesis continues to be tenable as a candidate explanation for many of the 100 Hz-only events, but its plausibility could be better evaluated if mechanisms could be found to explain the existence of a significant number of 100 Hz-only cases that do not pass all the applicable whistler-mode tests, as well as the existence at a wide range of altitudes of multichannel cases that are clearly not propagating whistler-mode waves. The wideband bursts are often observed at altitudes above 1000 km and frequently occur in regions of locally reduced electron density. Those observed at high altitude (and possibly at low altitude as well) are believed to be generated near the spacecraft, possibly by an as yet unknown mechanism responsible for similar burst observations made near Earth and other planets.     

Calculations and ground-based observations of pulsed proton events in the dayside aurora

A procedure is established to evaluate the Balmer excitation rates of Hα and Hβ to produce the corresponding volume emission rates versus height, using semi-empirical range relations of protons in air. The calculations are carried out with identified ion-energy particle spectra of the dayside aurora obtained by low altitude satellites. The calculated emission intensities of Hα and Hβ indicate that they are indeed observable by ground-based optical detection. Measurements of the dayside aurora from Nordlysstasjonen in Adventdalen, Svalbard, are discussed in relation to these calculations. Periodic bursts of auroral Hα and Hβ emissions are observed in the dayside aurora by ground-based photometers and spectrometers. The mean period between proton events is found to be 10 min on average. Furthermore, it is found that when the time between successive bursts decreases, the emission ratio of Hα and Hβ fluctuates indicating a step-like behaviour in the primary initial proton energy.     

Instabilities in pitch angle diffusion and their possible relation to a 3 Hz modulation in pulsating aurora

The Coroniti-Kennel theory of electron precipitation pulsations has been reviewed, and an additional restriction of differential relaxation time has been introduced, making the model unstable under most conditions. The solution to the model was found to be nonlinear, and a very crude numerical solution has been attempted. Although suffering from several nonrealistic approximations, this model has confirmed the idea that a 3 Hz modulation in pulsating auroral forms is related to short bursts of Coroniti-Kennel type strong pitch angle diffusion. Strong pitch angle diffusion will fill the loss cone and is therefore not consistent with a self-excited steady state diffusion, i.e. it must be of a transient nature. The repetition frequency of such bursts depends on the size of the diffusion region along the magnetic field line combined with the parallel velocity of precipitating particles. Estimates based on reasonable diffusion region and velocity give a modulation frequency comparable to observations. The suggested mechanism is consistent with self-excited pitch angle diffusion only; it excludes the possibility that the diffusion is parasitic.The numerical model also indicated that the abnormal pitch angle distribution generated as a result of a magnetic disturbance might survive for hundreds of seconds and thus acts as a ‘memory’ on the fieldline, making it more susceptible for further disturbances.     

Innovation and convergence: expanding boundaries of chemical industry

Abstract

The chemical industry has been a major driver of industrialisation for the last hundred years, but during the past decade the pace of change has accelerated. This paper examines the major innovations in chemical industry and goes on to examine the important changes that diffusion of information technology, e-business, and new techniques of molecular design have brought about. Convergence inducing innovations are today a major driver of change, and the paper concludes by suggesting that chemical industry is at the beginning of a phase of megaconvergence, involving digital convergence, genetic convergence, and nanoconvergence.     

Differential Doppler measurements of the ionosphere during a solar eclipse

The effects of the solar eclipse of 26 February 1979 on the ionosphere were measured using differential Doppler techniques. Nayy navigation satellite passes were monitored at 12 sites located across the North American continent. These data yield a measurement of the vertical columnar electron content along a north-south line. Different sites monitoring the same pass provide simultaneous observations of ionospheric variations along different longitude lines. Two satellite passes occurred during or just after the eclipse. These data show a shoulderjust northward of the umbra region and a trough just behind the umbra containing large horizontal gradients. This sharp trough recovered quickly with a half-life of about 10 min.     

Optical dating of a Fimic Anthrosol in the southern Netherlands

Plaggen agriculture was the dominant land use system in the Pleistocene cover sand area of Northwest Europe before the introduction of chemical fertilisers. In today's landscape Fimic horizons and driftsand deposits are characteristic survivors of plaggen agriculture. The age and accumulation rate of these phenomena cannot be satisfactorily determined by conventional methods like pollen analysis and radiocarbon dating. The results of optical dating applied to a Fimic horizon of a plaggen soil near Weert (Netherlands) are compared with those from conventional methods.     

Analyses of measurements taken from adult femurs of a British population

The femur remains an important bone in palaeoanthropology and this paper reports various analyses of measurements taken from long-cassette radiographs of adult femurs of a reference population from the south of England (n=81, males 33, females 48). Discriminant analysis confirmed that the male femur is usually larger than the female femur, and that a femur may be sexed with some confidence. Discriminant scores have been derived to permit estimates to be made, from the whole or a part of a femur, of the probability of the male gender. Outcomes from a principal component analysis suggest: that the female proximal femur is a morphological unit; that neck length and shaft length are dissociated and there is no common factor representing linearity; and that the male bicondylar width is anomalous, a finding that is confirmed by other analyses. An estimate of the robusticity of the complete female, but not male, bone may sometimes be made from a proximal fragment. The robusticity of the complete bone may be made confidently from the shaft for both genders. The two width variables relating to a distal fragment cannot be used to predict the robusticity of the complete bone for either gender. A method of defining the position of the waist in terms of displacement in deciles down the shaft is described. The position of the waist seems to have a bimodal distribution. The positive association between age and distal displacement may be due to remoulding of the shaft with age or to a cohort (generational) effect. There is a weak correlation between a small neck–shaft angle and the distal displacement of the waist, two archaic phenotypic traits. Ten statements in the literature relating to the femur have been examined and tested; six are confirmed and four are unconfirmed, and it is suggested that there is a need for further studies relating to the morphology of the femur.     

Optical measurements of the quenching coefficient of the O(1D) state by collisions with ambient molecules utilizing the ionospheric heating experiment

Alterations of the 01 6300 Å nightglow during ionospheric heating experiments at Arecibo (Puerto Rico) are considered. The experimental results led to deexcitation rates of O(¹D) atoms by collisions with molecules of nitrogen and oxygen in the range (1–6) × 10⁻¹¹ cm³ s⁻¹. This range is in fair agreement with previous results, for such a quenching coefficient, which have employed different measurement techniques.     

1.7 GHz scintillation measurements at midlatitude using a geostationary satellite beacon

Preliminary results of 1.7 GHz scintillation measurements made in Japan using a geostationary satellite during May–August in 1977 are presented. Since the propagation path below about 100km altitude is nearly parallel to the geomagnetic field, it was possible to observe irregularities along the field direction. The scintillation activity was enhanced at night in June and the maximum peak-to-peak variation of scintillations observed was about 2.3 dB. Simultaneous measurements of the total electron conterrt show that irregular electron density structures play an important role in 1.7 GHz scintillations.     

COVID-19 is expanding global consciousness and the sustainability of travel and tourism

Abstract

The sustainable development model has largely failed to address the social and environmental challenges of the 21^st century. True sustainability will only occur when it is valued as a part of the taken-for-granted daily life of individuals and cultures across the globe. This has not yet happened because humanity has not evolved a global consciousness quickly enough to match the global advances in telecommunications and transportation technologies that have created a socially and economically ever-shrinking planet. Travel and tourism contributes to the expansion of global consciousness, although only in a haphazard and unintentional manner. The COVID-19 pandemic is a result of planetary time-space compression and is forcing an expansion in human consciousness that will make humankind better able to address global problems. There will still be considerable diversity on the planet, as now, but the pandemic will stimulate growing numbers of people, businesses and governments to adopt new ways of thinking, behaving and operating that are more closely aligned with the goals of sustainable development. This could be further enhanced if travel and tourism were to adopt the expansion and awakening of global conscious as a fundamental and transformational value in the products and experiences that it offers.     

Tolerant exclusion: expanding constricted narratives of wartime ethnic and civic nationalism1

ABSTRACT. During war, the demarcation ‘enemy alien’– whether on ethnic or civic grounds – can lead to loss of political, social or economic rights. Yet not all minorities are excluded even though they pose problems for civic and ethnic national categories of belonging. This article explores the experiences of an ethno‐religious minority who posed an intriguing dilemma for ethnic and civic categorisation in North America during World War II. The Mennonite experience enables a close examination of the relationship between a minority ethnic (and religious) group and majority concepts of wartime civic and ethnic nationalism. The article supports arguments that both ethnic and civic nationalism produce markers for the exclusion of minority groups during wartime. It reveals that minority groups can unintentionally become part of majority ‘nationalisms’ as the content of what defines the national ideal shifts over time. The experiences also suggest that a minority group can help mobilise symbolic resources that participate in transforming what defines the national ideal.     

Development of Optical Fiber Communication

TheTibetAutonomousRegionhasmademuchgroundinthedevelopmentanduseofopticalfibercommunicationline.August28,1995:TheLhasa-XigazeandLhasaShannanopticalfibercommunicationlinesopened.Afterfivemonthsoftrialservice,theywereputintoofficialoperation.TheLhasa-Xigazeopticalfibercommunicationline,thefirstofitskindinTibet,extends340km.ItcrossestheGangdeseMountain(whichisnotoriousastheforbiddenareaforlife)withanelevationaveraging4,000meters.Itwaslaidin38daysandnights.1996:TheXigaze-Gyangze(viaBainan…     

An alternative interpretation of auroral precipitation and luminosity observations from the DE,DMSP, AUREOL,and Viking satellites in terms of their mapping to the nightside magnetosphere

We present an interpretation, which differs from that commonly accepted, of several published case studies of the patterns of auroral electron precipitation into the high-latitude upper atmosphere in the near-midnight sector based on their mapping to the nightside magnetosphere. In our scheme bright discrete auroral structures of the oval and respective precipitation are considered to be on the field lines of the Central, or Main, Plasma Sheet at distances from 5–10 to 30–50 R_E, depending on activity. This auroral electron precipitation pattern was discussed in detail by Feldstein and Galperin [(1985) Rev. Geophys.23, 217] and Galperin and Feldstein [(1991) Auroral Physics, p. 207. Cambridge University Press. It is applied and shown to be consistent with the results of case studies based on selected transpolar passes of the DE, DMSP, AUREOL-3 and Viking satellites.A diagram summarising the polar precipitation regions and their mapping from the magnetospheric plasma domains is presented. It can be considered as a modification of the Lyons and Nishida (1988) scheme which characterizes the relationship between the gross magnetospheric structure and regions of nightside auroral precipitation. The modification takes into account non-adiabatic ion motions in the tail neutral sheet, so that the ion beams characteristic of the Boundary Plasma Sheet (BPS) originate on closed field lines of the distant Central Plasma Sheet (say, at distances more than ~30 R_E).     

Optical characterization of tropospheric aerosols

Complex calculations of optical scattering using high-speed electronic computers have become so commonplace that the technology has evolved into several specialty fields, e.g., extinction spectroscopy, angular scattering measurements and nephelometry. As a consequence, the overall technology and our ability to remotely characterize or quantitatively analyze atmospheric aerosols might be further advanced than is realized by workers in the individual disciplines who do not have the time to keep up with advances in other disciplines. This paper examines techniques of transmission (extinction) and turbidity spectroscopy, polarization and angular scattering measurements and related developments and concludes that computer programs can be written to optimize desired parameters in interdisciplinary investigations.