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.     

切支丹时代欧洲人从日本运出白银分析

16世纪40年代,欧洲人(葡萄牙人)首次登陆日本.其后,他们在日本进行长达100年的传教和经商,日本和欧洲史学界称这一时期为"切支丹时代"或"切支丹世纪"①.在双方的贸易中,欧洲人从日本运走大量白银,白银成为日本最主要的输出品,这足以引起学者们的重视.本文从分析日本白银的开采冶炼着手,继而论述日本白银被大量运出的原因,然后统计了日欧白银交易的具体数据,并以此作为研究分析的基础.经研究发现,日本白银不但是日欧贸易中重要而特殊的商品,还是16-17世纪东西方交流交往的集中体现.欧洲人从日本运出白银不但促进了欧亚的经济交流,还推动了世界交通和贸易的发展.     

The coral Cothonion from the lower Cambrian of North Greenland

Originally described from the Coonigan Formation of New South Wales, Australia, a second occurrence of the operculate coral Cothonion sympomatum is here described from the Paralledal Formation of North Greenland. Both finds are of late early Cambrian age, Series 2, Stage 4 in the emerging fourfold classification of the Cambrian. The new find supports widespread distribution patterns seen in early Cambrian Small Shelly Fossils, although associated trilobites belong to traditional redlichiid (Australia) and olenellid (Greenland) realms, respectively.     

Developing a framework of Holocene climatic change and landscape archaeology for the lower Gulf region, southeastern Arabia

Geomorphological and geoarchaeological studies from the lower Gulf region of southeastern Arabia are increasing our knowledge of hydrological, ecological, and aeolian changes during the Holocene. Preliminary analyses of sediment records from two palaeolakes in the United Arab Emirates are presented, highlighting the potential of these sediment sources for providing high-resolution decadal studies of climate change and landscape evolution over the past 10,000 years. In order to study the society-environment relationship in this marginal region, a framework of environmental change is being developed against which the archaeology of the region can be set.     

铁路与淮河流域中下游地区社会变迁(1908-1937)

近代河、漕、盐三政的中心地位丧失导致淮河中下游区域的全面衰败,但铁路这一新型交通工具的引入却遏制了这一过程.随着通过本区域连接中国南北东西的干线铁路建成,本地域交通体系以铁路为中心得以重组,进而推动了农业商品化和工矿业的发展,并使少数城市迅速崛起,从而使城镇体系和商业网络也发生了显著变化,农村社会经济和结构也有所改变,整个地区的经济重心由运河沿线转往铁路沿线.     

王士琦墓出土金银器的样式与工艺

明代王士琦墓出土金银器百余件,为人熟知的金带銙一副二十枚、金镶玉带具一件是王士琦物,其余则以女子首饰为多。本文对王士琦墓出土的金银器,尤其是其中的女子首饰,作了大致的梳理,包括对这些器物予以重新命名,兼及对式样和工艺的讨论。     

The angular distribution of radio waves partially reflected from the lower ionosphere

Measurements of radio waves partially reflected from the D-region made using two antennae of very different beamwidth are reported. The arrays are composed of 40 and 4 dipoles respectively. It is shown that the gain of the larger array over the smaller is often variable—both in height and time. These results can be used to estimate the off-vertical angles from which significant energy is returned. For altitudes less than 80 km angles less than 10° seem to be usual but at higher altitudes the angles increase to values of the order of 15°–20°. Other important properties of the echoes, such as the probability distribution of the amplitude were also measured. The results are discussed with particular reference to the differential absorption method of measuring electron densities and also to the nature of the irregularities responsible for the partial reflections.     

Asteropygine trilobites from the Late Devonian of the Kerman region,Iran

The discovery of two new Frasnian species of the subfamily Asteropyginae, Bradocryphaeus kermanensis and Radiopyge hamedii, in the Haruz section north of Kerman, east-central Iran, demonstrates for the first time the presence of North Gondwanan trilobites in this region. The two new species provide a link between faunas from Afghanistan to the east and the Alborz Mountains in north Iran. The recognition of R. hamedii confirms the validity of Radiopyge Farsan, hitherto known only from Afghanistan, as well as the presence in some Frasnian Asteropyginae of six pairs of lateral pygidial spines.     

Atomic oxygen concentrations from rocket airglow observations in the equatorial region

A rocket payload designed to measure mesospheric sodium, hydroxyl and oxygen nightglow emissions, in addition to electron density and temperature, was launched from the Alcantara Launch Center (2°S, 44°W), Brazil, at 23:52 LST on 31 May 1992. The height profiles of the atomic oxygen OI557.7 nm and molecular oxygen Atmospheric (0-0) band emissions showed maxima at 100±3 km and 98±3 km, respectively. The emission data are used to calculate the atomic oxygen concentration profiles. The results show the validity for the equatorial region of the empirical parameters proposed by McDade et al. (1986).     

南越王墓出土秦代“西共”银洗及相关问题

在广州西汉南越王墓的后藏室中出土一件银洗,银洗口沿的正、背面刻有铭文,内有"西共"字样。作者认为,从其刻辞的内容和计量单位看,这件银洗当为秦器,是秦代沿用至西汉的器物,原本是西县共厨的器物,后来流散到各地。西县大约在今甘肃省天水市西南的礼县、西和县一带。共厨是秦代的一种职官,负责皇帝郊祀时所用的厨具和食物等。     

The characteristics of VHF echoes from the summer mesopause region at mid-latitudes

Radar observations have been carried out at Aberystwyth (52.4°N, 4.1°W) during the period May–August 1990 to search for echoes analogous to the Polar Mesosphere Summer Echoes commonly observed at high latitudes. Signal strength measurements in the vertical and at 12° from the vertical are used to examine the aspect sensitivity of echoes, and Doppler measurements at 6° from the vertical and in the vertical to estimate wind velocities. The observations show the presence of two types of moderately strong echoes from heights above 80 km. On most days a spectrally broad echo is observed with characteristics consistent with isotropic turbulence scatter. On certain days between mid-June and mid-July, stronger spectrally narrow echoes are observed with characteristics similar to Polar Mesosphere Summer Echoes.     

Atomic oxygen determination from a nitric oxide point release in the equatorial lower thermosphere

Atomic oxygen density values in the 80–105 km altitude equatorial region have been obtained by analyzing the chemiluminescence of nitric oxide point releases from three CENTAURE II-C rockets. The light emission produced by the NO—O chemiluminous recombination was sufficiently high to render the artificial clouds observable only by ground-based instruments. The difficulties associated with these kind of experiments have been greatly avoided by a new technique ejecting the NO gas into the backward direction of the flight. It has been found that below 90 km the derived atomic oxygen densities are in relatively good agreement with those reported by other workers. At approximately 105 km the measured value is about two times higher than the n(O) density obtained by averaging a set of data from a great number of other nights but coincides rather well with the measurements of Dickinsonal. (1980).     

Gravity wave detection in the lower thermosphere with the French incoherent scatter facility

Very few gravity-wave measurements are available in the 100 to 120 km altitude range of the atmosphere. This paper illustrates the capability of the French multistatic incoherent scatter facility to fill this altitude gap in medium scale gravity-wave studies. We have been able to detect a particular gravity-wave and to compute its horizontal characteristics: horizontal wave-length: 51km, azimuth: 294°, period: 15 min. Its associated vertical energy flux at 105 km was equal to 0.4 erg cm⁻² s⁻¹. This flux shows the importance of medium scale gravity-waves in the lower thermosphere equilibrium.     

A provenance study of archaeological obsidian from the Andahuaylas region of southern Peru

To date, most obsidian sourcing studies in the Andes have concentrated on the highlands and Titicaca Basin of far southern Peru and northern Bolivia. Toward achieving a more complete understanding of the region, this paper offers new data on the long-term prehistoric obsidian procurement and consumption patterns in the Andahuaylas region of the south-central Peruvian highlands. Obsidian sourcing data from Andahuaylas are particularly interesting since the area is centrally located among several important regional obsidian sources. A total of 94 obsidian samples from a range of sites of different temporal periods were chemically analyzed using portable X-ray fluorescence (PXRF), as well as laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results demonstrate a number of interesting trends, the first of which is the long-term importance of the Potreropampa obsidian source to populations of the Andahuaylas region from at least the early Formative period (∼2500 BCE). Secondly, the results indicate that procurement strategies by local populations in Andahuaylas were primarily reliant on nearby (<150 km) obsidian sources. Finally, the paucity of more distant, yet widely exchanged, high quality obsidian (i.e., Chivay, Alca) confirm that as a region, Andahuaylas was more heavily connected economically (and likely culturally) with local areas to the south (Apurímac) and to the west (Ayacucho).     

The oldest human remains from the Beagle Channel region,Tierra del Fuego

The biohistory of the human peopling of the Fuegian Archipelago and the processes of biocultural adaptation and microdifferentiation of the ethnohistorical ‘canoe’ (‘sea nomad’) and ‘foot’ natives are poorly known. Here we report the oldest human remains of a ‘sea nomad’ native discovered so far in the Beagle Channel region. The specimen consists of a deciduous molar from the site of Imiwaia I, dated to 5870 ± 145 years BP. The microwear pattern indicates the consumption of hard food processed by long chewing cycles. The histomorphometric analysis shows the presence of at least three episodes of stress between 8 and 10.5 months after birth, and an unusually thin neonatal line, suggesting a mechanically non‐stressing birth event. Copyright © 2006 John Wiley & Sons, Ltd.     

Irrigator relations with water in the Sunraysia region,northwestern Victoria

Irrigated agriculture faces significant challenges under climate change, and may not be feasible in parts of the Murray‐Darling Basin beyond 2050. Recent research into the cultural politics of water has paid limited attention to the water cultures and relations of irrigators in Minority World countries. We analyse the water relations of grape farm irrigators in the Sunraysia region of Victoria using interviews and farm tours undertaken between 2014 and 2016. Findings are summarised under five themes: (1) the sociality of irrigation water, (2) temporal and spatial relations, (3) the risk of rain, (4) the micro‐scale of water knowledge, and (5) environment as actor. These themes shed light on the diverse relations that constitute both environmental and irrigation water. Irrigators are embedded in these relations at multiple scales, local and distant, mediated by technology and infrastructure. The scale of our focus makes visible water and other forms of environmental knowledge that often go unnoticed in broader debates over irrigation. The concept of “the environment”, understood as an embodied actor in policy discourse and by irrigators, is an emergent trend that warrants ongoing research attention.     

战国中山国金银错工艺赏析

战国中山国是北方少数民族白狄族鲜虞部在今河北中西部建立的诸侯国,始建于春秋末年,鼎盛于战国中期,后为赵所灭。中山国是战国中期仅次于“战国七雄”的诸侯国,是当时的五个“千乘之国”之一。但由于历史短暂,史书上关于中山国的记载非常简略零散,所以两千多年来战国中山国一直被称为“神秘王国”。     

The characteristics of VHF radar echoes from the tropopause region near a jet stream

Measurements carried out with the SOUSY radar system to the south-east of a jet stream during a night in November 1981 are described. Particular attention is paid to the association between power and spectral width of echoes returned from the vicinity of the tropopause located near 12 km. A negative association is found between power and spectral width of echoes from 150 m height channels between 10.65 km and 11.70 km, both with the radar beam directed vertically and at 7° to the vertical in the northerly and easterly directions. Evidence for a positive association is only found for height channels centred at 11.85 and 12.15 km and then chiefly with the beam directed vertically. A partial correlation analysis suggests that the possible influences of the finite beamwidth of the radar system and of wind shear on the spectral width do not affect the associations found. The results are discussed in terms of the scattering and partial reflection mechanisms giving rise to the echoes.