Electron temperature and electron density in the F-region of the ionosphere. I. Observed relationship

Ionospheric data from three incoherent scatter stations over the height range 225–450 km were studied for all daylight hours over a wide range of solar conditions. The relationship between electron temperature T_e, electron density Nand solar flux at 10.7 cm wavelength S_10.7 was expressed as T_e = A−B·(N−5 × 10¹¹) + C·(S_10.7−750), where N is in units of m⁻³ and S_10.7 in kJy.This provided a very satisfactory expression for all data taken at Malvern and St. Santin between 0800 and 1600 LT. For data taken at Arecibo, however, the linearity broke down at low electron densities. The data from all three stations were therefore divided into two sets according to electron density and reexamined.ForN < 5 × 10¹¹ m⁻³ B increased steadily with height and decreased steadily with latitude.For N > 5 × 10¹¹ m⁻³ B did not appear to vary with height, with season or with latitude. C was approximately constant for all sets of data.The different mechanisms involved in the heat balance of the electron population are discussed and a qualitative explanation for the relationship is proposed.     

A new approach for geomagnetic archaeointensity research: insights on ancient metallurgy in the Southern Levant

We present results from an archaeointensity investigation based on a relatively unexploited recording medium, copper slag deposits. Together with a recently improved experimental design for the archaeointensity experiment, we demonstrate the applicability of this medium, as well as other archaeometallurgical artifacts, for the study of the ancient geomagnetic field intensity. In addition to archaeointensity data from well-dated archaeological contexts, we obtained reliable archaeointensity results from poorly dated or contentious archaeometallurgical sites in the Southern Levant. These results shed new light on the dating of these sites, among them the copper smelting installation of Timna 39b – a site that has important implications for the beginning of metallurgy during the fifth millennium BCE. The paper also aims to introduce archaeointensity research to the archaeologist scholar, and to encourage further collaboration between the disciplines in future research.     

Explaining prehistoric variation in the abundance of large prey: A zooarchaeological analysis of deer and rabbit hunting along the Pecho Coast of Central California

Three main hypotheses are commonly employed to explain diachronic variation in the relative abundance of remains of large terrestrial herbivores: (1) large prey populations decline as a function of anthropogenic overexploitation; (2) large prey tends to increase as a result of increasing social payoffs; and (3) proportions of large terrestrial prey are dependent on stochastic fluctuations in climate. This paper tests predictions derived from these three hypotheses through a zooarchaeological analysis of eleven temporal components from three sites on central California’s Pecho Coast. Specifically, we examine the trade-offs between hunting rabbits (Sylvilagus spp.) and deer (Odocoileus hemionus) using models derived from human behavioral ecology. The results show that foragers exploited a robust population of deer throughout most of the Holocene, only doing otherwise during periods associated with climatic trends unfavorable to larger herbivores. The most recent component (Late Prehistoric/Contact era) shows modest evidence of localized resource depression and perhaps greater social benefits from hunting larger prey; we suggest that these final changes resulted from the introduction of bow and arrow technology. Overall, results suggest that along central California’s Pecho Coast, density independent factors described as climatically-mediated prey choice best predict changes in the relative abundance of large terrestrial herbivores through the Holocene.     

Effects of composition and fountain effect on the annual variation of the day-time F-layer at low latitudes

The annual variation of the daytime F2-layer peak electron density (NmF2) is studied at two low latitude stations, Okinawa and Tahiti (geomagnetic latitudes ± 15°) for the sunspot maximum years 1979–1981. Observed values are compared with those calculated using the MSIS model and a simplified version of the continuity equation for day-time equilibrium conditions. Summer-winter differences imply an intensification of the fountain effect on the winter side of the equator at the expense of the summer side. This could be explained by a summer to winter neutral wind. Semi-annual variations, however, appear to be mainly due to changes in neutral composition.     

The volcanic eruption of Thera and its effect on the Mycenaean and Minoan civilizations

Since Professor Sp. Marinatos linked the eruption of Thera with the destruction of Cretan sites, difficulties have been met in reconciling the dates of the two incidents which, based on pottery, were c. 1520 BC and 1450 BC, respectively, giving a “time gap” of 70 years. None of the mechanisms proposed for the Cretan site destructions-tsunamis, ash fallout, earthquakes, civil disturbances or invasion can be reconciled with the magnitude of the simultaneous site destructions. Therefore, an alternative theory is proposed that the Cretan holocaust was caused by “nuées ardentes” emanating from Thera. It is postulated that these were released through a “split” in the cone wall, of limited area, generating a high velocity jet of tephra fluidized in a red hot gas stream. Such a jet is immensely destructive and lethal, causing death by pulmonary oedema. The shape (like a blowtorch) and course of the ash fallout, as measured by deep sea cores, shows that these nuées ardentes passed over the eastern part of Crete, causing severe destruction and depopulation. The geological record confirms that tephra deposits from such Peléan eruptions have travelled for 160km, or more, and that normally the main eruption is preceded by a preliminary one of lesser intensity, with a time gap ranging from 51 to 203 years. Settlements on or at the base of the volcano would have been abandoned at the time of the preliminary eruption/earthquakes (c. 1520 BC). A time gap of 70 years would be reasonable, fitting with the Cretan catastrophe around 1450 BC. In the meantime, reoccupation had commenced, but was terminated by the final eruption. Apparently, Knossos on the periphery of the blast was severely damaged by fire (possibly again in LM II) and rebuilt, being finally destroyed in late LM IIIB. During this time span some “blurring” of pottery dating may be attributed to recovery and use of pottery “heirlooms”. The nuée ardente theory explains the simultaneous destruction of sites by fire and blast, the Cretan depopulation, as well as the time gap. In general ¹⁴C results confirm the dates proposed. So far tephra deposits have not been identified on Crete itself, but grains of it have been found at Pyrgos. It is suggested that cores from lake bottoms should be examined for the area, and that Cretan soil samples should be checked for tephra particles by employing the flotation technique, used in mining, for separating them.     

历史的追寻--2004年丝绸之路佛教艺术与历史文化学术考察活动侧记

2004年8月14日至28日兰州大学敦煌学研究所成功举办了“2004年丝绸之路佛教艺术与历史化学术考察活动”,共有台湾地区师生59人参加了这次考察活动。这次考察活动在学术指导小组的带领下,参观了丝绸古道上的物古迹和名景点,增强了台湾师生对祖国大陆的认同感和自豪感,因此这次活动不但具有学术价值,还有更重要的现实意义。     

浅谈马家窑彩陶及其鉴别

马家窑文化是黄河上游新石器时代晚期文化,甘肃新石器时代文化以丰富的彩陶为特征,特别是马家窑文化的彩陶,达到了彩陶艺术的巅峰,代表了中国彩陶艺术灿烂辉煌的成就。马家窑彩陶具有非凡的文化价值、欣赏价值及收藏价值。其真伪的鉴别方法多样,既有普遍性、常识性的鉴别方法,又有特殊性、科学性的鉴别手段。     

敦煌写本《籯金》系类书叙录及研究回顾

本文在诸家著录《籯金》写卷的基础上,通过比对原卷,对敦煌写本《籯金》系类书的9个写卷进行了较为详尽的叙录,并对关于《籯金》系类书近百年来的研究成果进行系统性的梳理和回顾,以期推动本课题研究的深入。     

The effect of a top predator on kangaroo abundance in arid Australia and its implications for archaeological faunal assemblages

The dingo has received considerable attention in the Australian archaeological literature as an agent of bone fragmentation and accumulation. Dingoes have also been studied with respect to their commensal relationship with Aboriginal people. Study has not been directed, however, to the meta-role of dingoes as prey regulators that suppress kangaroo abundance, and the subsequent impact on human subsistence that direct competition between dingoes and humans over the same animal resources could have produced. This study presents data gathered in two adjacent cultural landscapes defined by human land use, one with dingoes and one without dingoes – to illustrate the archaeological effect that dingoes may have had on human economic systems by suppressing kangaroo abundance. Live kangaroos and kangaroo skeletal remains were on average 14-fold and 32-fold more abundant in the absence of dingoes, and contemporary commercial kangaroo harvesting and sheep grazing were restricted to areas where dingoes were absent. Given the marked effects that dingoes have on contemporary kangaroo abundance and the human economy, we argue that dingoes likely shaped the human economy in the past through human–dingo competition for the same limited resources. Evidence for competition between humans and dingoes could be investigated in the archaeological record by comparing the relative frequency of prey of different body sizes, as well as the degree of fragmentation of kangaroo skeletal elements, before and after the arrival of dingoes.     

浅谈石窟讲解中的技巧与实际操作

云冈石窟是世界三大石窟艺术宝库之一,国家为此专门成立保护研究机构。现就自己工作十余年来石窟讲解工作的经验与几点肤浅看法提出来与同行们探讨。 一、讲解工作的重要性文物讲解是有效地将文物价值及其研究成果与社会公众联系起来的重要承担者和信息传递使者。宣教工作是文物与观众之间联系的桥梁和纽带,随着国家经济实力的增强,文化教育程度的提高和旅游事业的发展,观众的求知欲望、审美情趣都随着社会经济发展发生明显的变化,观众的需求决定了这项工作存在的必要性和重要性。大多数观众都希望在参观中能听到讲解员的讲解,…     

Quantifying the effects of erosion on the archaeology of intertidal environments: A new approach and its implications for their management

Abstract

While the high archaeological and palaeoecological value of intertidal deposits has become well known, approaches to their management remain extremely restricted. Despite the often high levels of erosion experienced by some sites there has been very little development in methods aimed at understanding or quantifying the threats. This paper presents an approach aimed at monitoring erosion within the Humber estuary, UK, where previous finds including Bronze Age boat remains and trackways have made it an area of international importance. Two sites have been investigated and the results from these demonstrate both the high rate of sediment removal and also the highly variable nature of intertidal erosion. It is argued that global figures relating to rates of erosion are wholly inappropriate when attempting to manage archaeological deposits that have survived in intertidal environments. Rather, management of such archaeologically rich but threatened landscapes is only possible through regular quantitative monitoring. Such an approach offers coastal protection authorities a valuable opportunity to assess the long-term progress of erosion and coastal change. This methodology could be employed alongside management agreements within those particular coastal cells or process units that have been identified in a Shoreline Management Plan.     

淮军研究及其历史文化资源利用

淮军是晚清时期一支重要的武装力量,也是清代军事体制从传统向近代转化过程中承先启后的一种重要组织形式。本文从六个方面简要介绍了淮军的研究状况,指出了既有研究中存在的问题及今后应该关注的方向,并就如何利用好淮军历史文化资源提出了建议。     

祈雨习俗及其地域差异——以传统社会后期的江南地区为中心

江南地区虽属平原水乡泽国 ,但是由于季风气候的缘故 ,降水变率大 ,往往旱涝不常。所以旱期祈雨 ,在江南水乡也很普遍。江南地区的祈雨一般选择在龙王庙、观音庙、城隍庙以及其他神灵和已故乡贤名宦的祠庙中进行。本文研究表明 ,江南有共同的祈雨对象 ,但区域内部这种祈雨却呈现了多样化 ,有其各自的特色和主要的侧重对象 ,并且在地域分布上也有明显的差异。可以认为 ,江南地区祈雨神灵的分布特点和地区差异完全是受地理环境影响的结果。     

1931年淮河流域水灾及其影响研究——以皖北地区为对象

1931年水灾是淮河流域百年罕见的洪涝灾害.此次水灾之兴,与连续的大强度、大范围的降水和残破的水利设施有关.水灾发生时,水利工程被毁,大片的土地被淹,房屋倒塌,人口死亡甚巨;水灾发生后,由于皖北地区自宋元以来形成的脆弱的社会生态环境的影响,以及国民政府的救济不力,灾区出现了土地荒芜、粮食短缺、物价飞涨、灾民无以聊生而四处流徙、疾疠和匪患猖獗等严重社会后果,极大地掣肘了皖北地区的社会经济发展.     

西方孙中山研究的历史考察及其学术流变探析

孙中山是现代中国民族和民主革命的先驱,青年时期求学于檀香山,后在香港专攻医学,在海外先后建立兴中会、同盟会等革命团体,与外国人多有联系。百余年来,从外国友人、在华游历家、传教士到现当代的历史学研究者,在不同学术层面对孙中山进行个案研究,并受政治、社会与学术变迁的影响而呈现不同的发展阶段。从研究主体来看,其研究者经历了从情感自发到学术自觉的身份转变;就研究内容而言,其成果彰显出从描述历史到研究社会科学化的学术流变。重视史料的挖掘与整理、注重西方各国学术成果的推介、关注学术动态并强调域外学术交流,是呈现这一学术流变的根本原因。     

Rehydroxylation dating of fired clays: an improved time-offset model to account for the effect of cooling on post-reheating mass gain

Dating of fired clay ceramics can be critical in building chronologies of archaeological sites. However, direct dating techniques such as luminescence, archaeomagnetism and radiocarbon dating are not always suitable or even possible. Rehydroxylation dating of fired clays is a developing method that has the potential to provide an alternative/complementary approach. Determination of a second stage, Stage II, mass gain rate in fired/reheated clay ceramics using a time^1/4-based model is central to this method. Experiments on modern brick samples demonstrate that the Stage II mass gain is not linear with t^1/4 as expected. The non-linearity observed can be taken account of through the introduction of a time-offset that represents the additional time required for mass gain at a specific aging temperature to equate to the additional mass gained above this aging temperature during cooling of the sample post-firing/reheating. Simulations of the mass gain curves expected during post-firing/reheating cooling highlight the significant effect of this mass gained during cooling and provide excellent agreement with experiment. Simulations also suggest that the two-stage structure in the mass gain curves observed might be better explained as largely the result of a single t^1/4-based process (Arrhenius in temperature dependence) across both stages; Stage I results from mass gained during cooling with Stage II resulting from mass gained during static temperature conditions. The overall implications for the dating method are that a non-linear Stage II mass gain (as a function of time^1/4) is expected and that an improved time-offset model provides a solution while removing issues of subjectivity in isolating the Stage II mass gain rate. This should lead to an improvement in the accuracy of RHX dates produced on archaeological material and further its development as a viable dating technique.     

近代中国大同思想的比较研究及其启示

大同思想是中国传统文化中的瑰宝.中国近代以洪秀全、康有为和孙中山为代表的不同阶级、阶层的先进人士,围绕"中国向何处去"的时代主题,在探索救国救民的征途中,设计了三种各具特色的大同理想方案.它们之间既有联系又有区别,是多种因素综合作用的结果.洪秀全、康有为和孙中山三人大同思想的演进更替过程,具有很强的历史继承性和内在的逻辑性,体现了近代中国乐观主义的时代气质.     

试论蓬莱水城的历史地位与价值

一、蓬莱水城是我国古代著名的军事港口 ,具有重要的军事战略意义 ;二、蓬莱水城是具有独特建筑风格的军事要塞 ;三、蓬莱水城是我国古代北方主要的对外贸易口岸 ,对促进中外经贸往来发挥了积极的作用 ;四、蓬莱水城作为我国古代北方的重要门户 ,对加强中外文化交流起到了桥梁作用。