Mid-latitude range spread and travelling ionospheric disturbances

This paper first discusses some early results (most hitherto unpublished) on off-vertical reflections which result from tilted isoionic contours associated with the passage of travelling ionospheric disturbances (TIDs). Azimuth of arrival and zenith angle information on these returning signals is discussed together with the role of these signals in producing both resolved and unresolved range spread on ionograms. Some ray tracing through a model ionosphere which incorporates wavelike structures is shown to predict fixed-frequency patterns (on recordings of virtual height vs. time) of converging and diverging satellite traces similar to those observed in practice. New experimental evidence is then presented to suggest (from the N(h) analyses performed) that TID wavetrains of several cycles are effective in producing spread traces on ionograms by specular reflections from the tilted surfaces of each cycle of these wavetrains. Ionograms from a modern ionosonde show that range spread consists primarily of discrete satellite traces even though at times these traces overlap and vary in intensity as a function of frequency thus creating a diffuse range spread ionogram.     

Mid-latitude ionospheric scintillations of VHF radio signals associated with peculiar fluctuations of Faraday rotation

Simultaneous measurements of the scintillation and Faraday rotation of 136 MHz radio waves radiated by the Japanese geostationary satellite ETS-2 have been studied at Kokubunji Japan during April to May, 1977.These preliminary results show that there is a close association between scintillations and the peculiar fluctuations of the Faraday rotation due to ionospheric spread F, and an empirical formula relating them is presented.Furthermore, the successive daily values of the two parameters show a close correspondence with a cross correlation coefficient of about 0.8. An unexpected result is that cross-correlation between the incidence of Es and the Faraday fluctuations on a daily bases is found to be about 0.65.     

Tropospheric gravity waves and their possible association with medium-scale travelling ionospheric disturbances

Analysis of pressure fluctuations observed over a period of several days using an array of microbarographs has shown the existence of long trains of gravity waves with two or more waves often present simultaneously. Meteorological data from radiosonde ascents indicates that many of the waves have a velocity which matches that of the background wind at some level within the troposphere. Generally this height corresponds to that of a frontal zone marking the transition between air masses and it is suggested that the waves may have been generated by shear flow instability within the frontal layer. Theoretical considerations, based on a three-layer model troposphere, show that some of the observed waves could have been ducted in or near the frontal zone. Some evidence is found to indicate that a non-linear wave-wave interaction between pairs of waves occurring simultaneously in the frontal zone could yield secondary waves with the characteristics of the gravity waves which had been observed in the thermosphere at appropriate times and whose group paths were traced to source regions in the troposphere in the general vicinity of the microbarograph array.     

Small scale ionospheric irregularities near regions of soft particle precipitation: scintillation and EISCAT observations

Results are presented from a coordinated experiment involving scintillation observations using transmissions from NNSS satellites and simultaneous measurements with the EISCAT ionospheric radar facility. The scintillation was used to indicate the presence of sub-kilometre scale irregularities while the radar yielded information on the larger structures in the background ionosphere. Two examples are discussed in which localised patches of scintillation were observed at L-shells near ‘blob’ like enhancements in F-region ionisation density. Elevated electron temperatures indicated that the enhancements may have had their origins in soft particle precipitation. While structuring of the precipitation on the 100 m scale cannot be completely ruled out as a source of the irregularities, in one case the blob gradient can be shown to be stable to the E λ B mechanism. The most likely cause of the irregularities appears to be shearing of the high velocity plasma flow in a region adjacent to the density enhancement. This region is characterised by a high ion temperature while the resulting scintillation has a shallow spectral slope.     

试析中国青瓷制瓷技艺影响下高丽青瓷的发展与传播

一直以来,高丽青瓷的研究备受中国学界关注。在中韩陶瓷交流史的研究中,文献是非常重要的参考资料。本研究将以朝鲜官方史料《高丽史》、《朝鲜王朝实录》及李奎报《东国李相国集》等朝鲜文人文集及科学实验数据为中心,辅以《宣和奉使高丽图经》、《大元圣政国朝典章》、《入唐求法巡礼行记》等中、日方文献,探讨中国青瓷制瓷技艺对高丽青瓷的影响及高丽青瓷的发展与传播。     

Spectral characteristics of high frequency waves backscattered by small scale F-region irregularities: evidence of strong sub-auroral ion flow

The spectra of high frequency waves backscattered at night by small scale (10–20 m) sub-auroral F-region irregularities often exhibit large Doppler shifts and widths in the local time sector 2000–2400. After local midnight the Doppler shifts and the widths of the spectra decrease rapidly. We present examples of experimental data, obtained with the two coherent backscatter radars of the EDIA¹ experiment, showing the spectral characteristics just mentioned. From the Doppler shift measured at the two sites we deduced the perpendicular velocity of the irregularities, which can reach values as high as 2000 ms ⁻¹. These observations are interpreted using results of theoretical models which predict strong sub-auroral ion flow in the trough region.     

EDIA-EISCAT comparison between small scale F-region irregularities and large scale electron density structures at sub-auroral latitudes

Small scale sub-auroral F-region irregularities were observed on 6–7 February 1984 by the two HF radars of the EDIA experiment while the EISCAT UHF system was scanning the ionosphere between 57° and 66° invariant latitude at a slightly different longitude. The bistatic EDIA system was mainly designed to detect the F-region irregularities at sub-auroral latitudes and to measure their perpendicular velocities. This paper is devoted to an examination of the morphology of the irregularity regions detected by the HF radars and of their production mechanisms, by comparison with the horizontal and vertical electron density profiles measured by EISCAT. It is shown that decametric irregularities observed at about 360–430 km height are not associated with any large scale horizontal density gradients in the F-region (350km). However, a strong north-south gradient observed at lower altitudes (150–200km), which is likely to indicate the southern boundary of the high energy particle precipitation zone, is well correlated with the strong scattering regions observed by the HF radars. The EISCAT electron temperature measurements at 350km height also show horizontal gradients which are well correlated with the small scale F-region irregularities. We discuss implications of these observations on the mechanisms of production of irregularities in the sub-auroral F-region.     

The classification of distorted-mirror reflections and its ionospheric modification due to the underlying ionization

A systematic classification of reflections from a sinusoidally distorted-mirror has led to the identification of three classes of rays: direct simple rays which hit the mirror once on reflection; direct complex rays which hit the mirror several times before reflection; indirect rays which leave from and return to the source at different angles. The conditions on the distortion amplitude, wavelength and height for the different classes to exist are obtained. A comparison of results is made with those from a Chapman layer with a sinusoidally varying height of peak density, in the absence of any magnetic field. The broad classification of solutions is preserved, but direct and indirect rays are no longer independent and at large scale heights the presence of underlying ionization removes some solutions. The construction of ionograms of these profiles shows that indirect and complex direct rays contribute significantly to the traces observed.     

The evolution of rice: molecular vignettes on its origins and spread

The domesticated species Oryza sativa or Asian rice evolved starting approximately 9,000 years ago and from its centers of origin in China and India has subsequently spread throughout the Old World (and in historical times in the New World as well). This species is one of the key domesticated crop plants in the world and has emerged as a model for studying the origins and spread of domesticated taxa as well as in investigating the genetic basis for plant variation under domestication. Archaeological data has been critical in dissecting the origins and spread of rice throughout Asia, but molecular information has also provided a complementary approach to examining the evolutionary dynamics of this species. The evolutionary history of a species can leave its footprints within its genome. Moreover, genetic studies allow us to study the history of traits that do not leave an archaeological record—for example, grain stickiness or flowering time—which can provide insights into how crop species are adopted by different cultures. In this review, several molecular studies into the origin and spread of Asian rice are discussed and we explore the advances these genetic studies offer in our understanding of the evolution of domesticated species. We also explore how archaeological data can provide critical insights that can help refine genetic models of the origin and spread of domesticated species.     

Environmental injustice in America and its politics of scale

Environmental burdens, such as proximity to hazardous sites, tend to be inequitably borne by poor Americans in general, and by Americans of color in particular. So argues a loose coalition of grassroots organizations and public-interest groups known as the Environmental Justice (EJ) movement. Prompted by that movement, the national government and some state legislatures have established policies to address future inequity. Those policies assume that the scope of environmental injustice spans the country, with many hazardous facilities dotting the landscape in communities of color and/or of the poor. However, various industries and also some social scientists call into question the argument that inequities occur on a national, or even state-wide, scale. Their counter-arguments typically espouse a market-based explanation that localizes the problem: any inequitable risks result from the impersonal forces of the marketplace functioning within individual communities. The politics of EJ pivot around defining the scales of inequity and its resolution. This paper examines the debates over environmental justice in terms of the tension between the scale(s) of the problem itself and the scale(s) at which the problem is to be resolved (or at least ameliorated) via government policy. The paper also sketches several theoretical and political implications of the debates. Theoretically speaking, market-based explanations tend to privilege the local scale, thereby ignoring vital factors that help us to understand environmental inequity as a phenomenon operating at a multitude of scales from the local to the national and international scales. Politically speaking, if the inequities were particular to discrete locales, then extensive governmental involvement would be unnecessary.     

Design and realization of a goniopolarimeter with application to the study of ionospheric tilts

The purpose of the paper is to describe a high frequency goniopolarimeter operating in the range of 3–30 MHz. The system uses four sensors, each of them is composed of two cross polarization active loop antennas oriented east-west and north-south. By “goniopolarimeter” we mean a system which determines both arrival angles (goniometer function), the type of the mode (O or X), the magnitude of this mode and the corresponding Doppler shift. It works with known broadcast transmitters and permits measurements over a large geographic area. The signal process deals with narrowband signals, polarization filtering, nonlinear frequency analysis and interferometry technique. We present some experimental results and discuss the application of this system to the study of ionospheric tilts.     

Plasma convection and auroral precipitation processes associated with the main ionospheric trough at high latitudes

Intervals of F-region electron density depletions associated with the main (mid-latitude) ionospheric trough have been studied using latitude scanning experiments with the EISCAT UHF radar. From 450 h of measurements over a one year period at solar minimum (April 1986–April 1987) the local time of appearance of the trough at a given latitude is observed to vary by up to about 8 h. No seasonal dependence of location is apparent, but troughs are absent in the data from summertime experiments. A weak dependence of trough location on K_p is found, and an empirical model predicting the latitude of the trough is proposed. The model is shown to be more appropriate than other available quantitative models for the latitudes covered by EISCAT. Detailed studies of four individual days show no relationship between local magnetic activity and time of observation of the trough. On all four of these days, however, the edge of the auroral oval, evidenced by enhanced electron densities in the E-region, is found to be approximately co-located with, or up to 1° poleward of, the F-region density minimum. Simultaneous ion drift velocity measurements show that the main trough is a region of strong (> several hundred metres per second) westward flow, with its boundary located approximately 1°–2° equatorward of the density minimum. Within the accuracy of the observations this relationship between the convection boundary, the trough minimum and the precipitation boundary is independent of local time and latitude. The relevance of these results is discussed in relation to theoretical models of the F-reregion at high latitudes.     

日本农协金融的早期发展概况及启示

日本农协金融作为合作金融的典型代表,是比较成功的农村金融服务体系．章简要地介绍了战后恢复时期日本农协金融的发展概况,介绍了日本政府为解决农民资金短缺而采取的支持和辅助农协金融发展的措施．日本农协金融对我国发展农村合作金融的启示：一是要加强农村金融立法,尽快出台《合作金融法》：二是要加大对农村金融的扶持力度,建议通过立法将农信社定位为国家扶植农业的工具,将农业发展银行的县级支行合并列农信社;三是祛除农信社的官办色彩,把农信社真正办成农民自己的合作金融组织,农民才是农信社的“主人”,信用社是为农民服务的“仆人”．     

The importance of location and scale in rural and small town tourism product development: The case of the Canadian Fossil Discovery Centre,Manitoba, Canada

This paper begins with a review of the literature on tourism in rural economies, to establish a framework for analyzing large‐scale tourism products in rural and small town regions. The review is followed by the development of a typology of large‐scale attractions in rural and small town regions, including parks, casinos, events, heritage, and cultural products. The typology leads into the example of the Canadian Fossil Discovery Centre (CFDC) in Manitoba, Canada. Located in an agricultural region of south‐central Manitoba, the community of Morden is located 125 km from the provincial capital city, Winnipeg, which had a population of 811,900 in 2016. Morden is also located 35 km north of the border with North Dakota. Thus, while a small town in a traditionally rural region still dependent upon an agricultural economic base, Morden has been recently successful in diversifying its economy, including through manufacturing, services, hospitality, and tourism. In part, this success is due to a south‐central Manitoba location; however, it is also the result of innovative local leadership, including the prioritization of hospitality and tourism related to the CFDC. This paper describes the case study as an example of successful tourism development within an already economically and socially diversifying region.     

Stylistic variability of stemmed obsidian tools (mata’a), frequency seriation,and the scale of social interaction on Rapa Nui (Easter Island)

Easter Island, or Rapa Nui, has been the focus of much research and speculation, particularly with reference to the island’s hundreds of giant, enigmatic statues and the set of conditions that supported their construction and transportation. In this paper, we analyze an abundant class of lithic artifacts, mata’a, to study of patterns of cultural transmission with implications for the evolution of groups, competition, and scale of socio-political organization among this island population. While these kinds of studies often draw upon assemblages of decorated ceramics, here we show how analysis of variability unconstrained by performance allows us to measure aspects of inheritance related to the manufacture of these artifacts. In the case of mata’a from Rapa Nui, we demonstrate that it is possible to reach falsifiable conclusions about the evolutionary dynamics that shaped the remarkable archaeological record on Rapa Nui.     

Small scale irregularities associated with a high latitude electron density gradient: scintillation and EISCAT observations

A coordinated experiment involving scintillation observations using NNSS satellites and special program measurements with the EISCAT ionospheric radar facility is described. The results reveal the presence of sub-kilometre scale irregularities in the vicinity of a long lived steep equatorwards gradient in electron density. Evidence is presented of a southwards plasma flow which would cause the gradient to be unstable to the E Λ B gradient-drift mechanism. An instability growth time of about 4 min has been estimated from the observations. Cooler electron temperatures associated with enhanced densities rules out soft particle precipitation as an irregularity source in this case.     

方志发展应顺应时代突出新特点

21世纪是信息化、经济全球化的时代。地情顺应这一发展在变化,方志的内容和形式也应与时俱进,思想上要突破旧定式,根据时代特点创造新的形式。继承方志已有的优良传统,真实、系统、全面反映地情的同时,要突出精、特、新、快,以使志书更全面真实、客观公正地反映地情。