Some characteristics of the quiet polar D-region and mesosphere obtained with the partial reflection method

It is shown that from a detailed analysis of the amplitude behaviour of electromagnetic waves partially reflected in the D-region valuable information about the reflection process and the dynamics of the mesosphere can be obtained. The results indicate that the process which is responsible for the partial reflections is different for different heights in the D-region and also changes with the season. From the temporal fluctuations of the amplitudes of the reflected waves, estimates of various turbulence parameters of the mesosphere have been deduced. Their mean values are in satisfactory agreement with results obtained by other methods.     

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.     

The quiet night ionosphere: comparison of calculated and measured decay rates

The slow decay of the total content of the quiet night ionosphere at a mid-latitude station is shown to be satisfactorily explained by the measured increase in the height of the layer after sunset together with a small flux (⪝10¹²m⁻²) of thermal plasma from the protonosphere deduced from experimentally measured quantities. The ionospheric recombination rate found here is in good agreement with the published laboratory rates of the two principal recombination reactions. For the four nights under study, use is made of the total content from Faraday rotation, sub-peak electron density versus height profiles from a ground based ionosonde, and protonospheric plasma densities and electric fields from whistler measurements. The simultaneous electric fields are used to show that they are not a very significant factor in maintaining the F2-layer during the quiet times reported here.     

The relationship between electron temperature and electron density under quiet conditions in the auroral zone

A theoretical model is described which predicts electron temperature in the day-time F-region above EISCAT on geomagnetically quiet days, given the observed values of electron concentration, ion temperature and heat conduction, the daily average of solar radiation at 10.7cm and the MSIS-86 model of the neutral atmosphere. The values predicted by the model agree very closely with the observed temperatures, both for average conditions and for individual days. On two occasions the onset of a geomagnetic disturbance after a period of quiet conditions was accompanied by a growing divergence between the predicted and observed values, which corresponds to an additional source of electron heating such as would be provided by low energy particle precipitation.     

A comparison of foF2 obtained from a time-dependent ionospheric model with Argentine Islands' data for quiet conditions

In this study a comparison is made of the Utah State University Time-Dependent Ionospheric Model (TDIM) and an ionosonde data set from Argentine Islands. This study is unique in that the Argentine Islands data set of foF2 spans complete diurnal, seasonal and solar cycle conditions for low geomagnetic activity. The TDIM reproduces these foF2 variations extremely well. Although the observed winter and summer solstice foF2 diurnal curves have opposite phases, they are readily modelled. At equinox where a sharp transition occurs from winter to summer, or vice versa, the monthly average is complicated by this feature and hence the TDIM does not reproduce the diurnal fine structure.The neutral wind induced vertical plasma drift is the only free parameter in this study. All the other inputs are fixed for the specific solar, seasonal and diurnal conditions. A vertical plasma drift variation is presented; although simplistic, it couples the geographic and geomagnetic frames. With additional information such as hmF2, it would be possible to deduce a unique vertically induced drift pattern.     

An experimental and modeling study of Na-rich hydrothermal alteration

Sodic alteration assemblages including clinoptilolite, mordenite, analcime and Na‐montmorillonite were locally observed in sediments in the eastern part of the Hachimantai geothermal region, northeast Japan. This study investigated the mechanisms of sodic enrichment in the sediments during alteration. Kinetic results for water/rock interaction experiments are reported here. Batch‐type experiments were conducted at 150–250°C under saturated vapor pressure. Pyroclastic rocks dissolved incongruently in these experiments, and the solubility and dissolution rates among elements varied as follows: the apparent steady‐state concentrations of major elements are Si > Na ? K > Ca > Al and the order of the dissolution rates is Si > Al > Na ? K > Ca. Na had the highest steady‐state concentration and fastest dissolution rate of the alkali and alkali earth metal ions. Based on surface analysis of plagioclase, dissolution was effected via a reaction layer of Na‐montmorillonite on the mineral surface. Additionally, a reaction model constructed based on the experimentally observed reaction mechanism quantitatively explains the dissolution behavior. These results show that Na‐montmorillonite can be precipitated by pyroclastic rock/meteoric water interactions without seawater involvement: the Na is derived from the host rocks.     

EISCAT results during the ROSE campaign and comparison with STARE measurements

EISCAT measurements were performed during the four ROSE rocket launches. The results are presented. It is shown that the upper altitude limit of instabilities observed by in-situ measurements agrees with calculations using EISCAT results of drift and ion sound speed and assuming the two-stream-instability mechanism. The EISCAT results together with the STARE observations were used to calculate the ion velocity and the ψ-values from the dispersion relation of two-stream-instabilities. A comparison of EISCAT, STARE and in-situ measurements is discussed.     

Asphaltum hafting and projectile point durability: an experimental comparison of three hafting methods

The design of a projectile delivery system often plays a critical role in the durability and breakage patterns associated with spent projectile points. This paper presents the results of an experimental project designed to examine projectile point durability and breakage patterns between three different hafting methods. Specifically, we compare two asphaltum hafting techniques drawn from archaeological and ethnohistoric accounts from the Central Valley of California with a more stereotypical cross-hatched sinew hafting system. Our results suggest a small yet statistically significant increase in durability among asphaltum hafted points, opening the door to future research on these ethnohistorically documented hafting techniques.     

The politics of being sorry: the Greensboro truth process and efforts at restorative justice

This paper examines the Greensboro Truth and Reconciliation Commission (GTRC) to better understand the way the truth process in Greensboro, North Carolina intersects with conceptions of restorative justice and geographic understandings of the ‘right to the city.’ The GTRC was a grassroots truth process focused on a shooting of labor organizers in 1979 by Ku Klux Klan and American Nazi Party Members and the complicity of local officials in the violence. In 2006, the GTRC released its report to the citizens of Greensboro and its recommendations for the city touched off a contentious debate. Using a multi-method qualitative approach—including open-ended interviews and archival research—I argue the GTRC process engages with notions of right to the city activism that challenges the right to the city literature to focus on broader discussions of racism, activism, and white privilege that emerges from critical race scholarship and contributes to the growth of robust, multiracial anticapitalist coalitions; an approach to scholarship on the right to the city that has broad academic purchase for social geography and urban political engagement in general.     

邓小平、陈云的改革思想比较

邓小平、陈云在中国改革开放的实践探索中,对为什么要改革、怎样改革、改革的任务与目的、改革的性质、改革成败的评判标准等重要问题,都有明确的观点和系统的论述。这些观点和论述有共性,也有差异,有区别,也有联系,对中国改革开放都产生了积极而深远的影响。邓、陈改革思想中的大同,主要是由二人的经历类似、信仰一致决定的。邓、陈改革思想中的小异,主要是由二人的性格特点、工作方法和所处的具体位置不同决定的。这种差异具有互补的作用。邓、陈的互相配合与互补,是中国新时期改革开放和现代化建设新局面得以开辟并取得巨大成就的重要因素之一。     

The role of equilibrium and disequilibrium in modeling regional growth and decline: a critical reassessment

ABSTRACT. The assumption of interregional equilibrium in migration research has recently been attacked. At issue is the motivation for on-going migration if rents and wags accurately compensate for spatial amenity variations; but if rents and wages fail to accurately compensate potential migrants, then amenity valuations must be flawed. We here show that arguments supporting substantial disequilibrium in the US. economy are unconvincing. The substantive issues are then clarified by a model which allows for both equilibrium and disequilibrium migration. We conclude that intertemporally systematic migration stems predominantly from equilibrium forces.     

An inter-site comparison of enamel hypoplasia in bison: implications for paleoecology and modeling Late Plains Archaic subsistence

Bison bison mandibular molars from the Late Plains Archaic kill/butchery sites of Buffalo Creek (Wyoming) and Kaplan-Hoover (Colorado) exhibit significant frequencies of dental enamel hypoplasia (DEH), a defect believed to reflect information about physiological status of individual animals. This study provides a methodology to estimate the ontogenetic and seasonal timing of DEH formation in bison dentition. Integration of these estimates with data from bison life history and grassland ecology allows inferences on age- and season-specific factors exacerbating periodic physiological declines that were recorded in the form of enamel hypoplasias. Differences between assemblages indicate regional variability in grassland conditions, with data from Buffalo Creek pointing to recurrent drought that reduced forage capacity and contributed to physiological stress in bison over two consecutive years. Seasons of physiological stress reflected in the DEH correspond to each of the three kill events at the locality, suggesting that predictability of bison behavior in this location was a critical factor in influencing the seasonal timing and location of repeated hunting episodes. Unlike Buffalo Creek, timings of stress episodes are not consistent with season of death in the Kaplan-Hoover bison assemblage, suggesting that favorable grassland conditions were the primary factor influencing timing of this large single-kill event in order to provision for the upcoming winter. DEH analysis represents a developing approach in the construction of models addressing key aspects of local grassland and bison ecology as well as offers unique insights into the hunting strategies and subsistence decisions of Late Plains Archaic foragers.     

On face transplantation: Ethical slippage and quiet death in experimental biomedicine (Respond to this article at http://www.therai.org.uk/at/debate)

More and more teams around the globe are gaining ethical clearance to perform face transplant surgery. The operation is a highly experimental medical treatment and patients who are otherwise healthy are dying as a consequence of submitting themselves to the operation. This article is concerned with the quiet deaths and ethical slippages that are emerging in this new medical terrain. It suggests that an examination of the relationship between nationalism and medical advancement is necessary to understand this slippage, because inter alia the surgery has been afforded national significance.     

Diet in medieval Denmark: a regional and temporal comparison

The aim of this research is to explore regional and temporal patterning in diet in medieval Danish populations. δ¹⁵N, δ¹³C_coll, δ¹³C_ap values were obtained from 154 human bone samples from three sites located in the Jutland peninsula of Denmark. These sites span the medieval period. The results suggest that the medieval Danish diet was composed of C₃ plants, terrestrial animals, and freshwater and marine fish in varying amounts. The data also suggest some regional patterning in diet, but little temporal differences in the composition of diet.     

Fluid effect on hydraulic fracture propagation behavior: a comparison between water and supercritical CO2‐like fluid

The initiation of hydraulic fractures during fluid injection in deep formations can be either engineered or induced unintentionally. Upon injection of CO₂, the pore fluids in deep formations can be changed from oil/saline water to CO₂ or CO₂ dominated. The type of fluid is important not only because the fluid must fracture the rock, but also because rocks saturated with different pore fluids behave differently. We investigated the influence of fluid properties on fracture propagation behavior by using the cohesive zone model in conjunction with a poroelasticity model. Simulation results indicate that the pore pressure fields are very different for different pore fluids even when the initial field conditions and injection schemes (rate and time) are kept the same. Low viscosity fluids with properties of supercritical CO₂ will create relatively thin and much shorter fractures in comparison with fluids exhibiting properties of water under similar injection schemes. Two significant times are recognized during fracture propagation: the time at which a crack ceases opening and the later time point at which a crack ceases propagating. These times are very different for different fluids. Both fluid compressibility and viscosity influence fracture propagation, with viscosity being the more important property. Viscosity can greatly affect hydraulic conductivity and the leak‐off coefficient. This analysis assumes the in‐situ pore fluid and injected fluid are the same and the pore space is 100% saturated by that fluid at the beginning of the simulation.     

Structural ways to embed a research laboratory into the company: A comparison between Philips and General Electric 1900-1940

This paper compares the Philips Research Department and the Research Laboratory of the American company General Electric (GE). 1 It argues that it is, above all, the issue of the organization of industrial research, appropriate leadership and the embeddedness of a research department in the company as a whole that is important for an historical analysis of an industrial research department. The complex structures that Gilles Holst (the first Philips research director) and Willis Whitney (the GE research director during the first decades of the twentieth century) set up in their organizations enabled scientists to keep in touch with the resources provided by the universities, and made it possible for them to come up with articles, patents and devices for their respective companies. It enabled them also to strengthen their contacts inside and outside the laboratory's walls. However, more than his colleague Whitney at GE, Holst at Philips intended to integrate the research laboratory into the company as a whole. Holst's policy as a research director will be illustrated using the case of Philips' radio research. A comparative discussion of industrial research in the 1930s within both companies shows that the "successful" integration of research activities is context-dependent.     

论1939-1940年中国建立遏制日本的远东国际联合阵线的努力

1939-1940年,中国为寻求国际援助,对英美开展一系列外交,试图建立遏制日本侵略扩张的远东国际联合阵线.由于英国必须将主要力量对付德国的进攻,美国尚未完全摆脱孤立主义的束缚,中国的这些努力并没有取得直接成果.但是,中国通过这些努力,加强了与英美为首的西方国家的联系,使它们对中国将抗日战争进行到底的决心有了更清楚的认识,从而为中国取得大规模国际援助创造了必要条件.随着国际社会对中国援助的全面加强,远东地区针对日本的国际联合阵线逐步形成.