Reflection of electromagnetic waves by density gradients in a magnetised plasma

The reflection of electromagnetic waves by density gradients in a plasma with a magnetic field derived from a scalar potential is studied. Conditions are found for reflection at grazing incidence at a surface S containing field lines. No restriction is placed on the angle between the wave-normal and the field, and account is taken of the curvature of the surface and the anisotropy of the medium. Particular reference is made to whistler-mode waves in the magnetosphere. The minimum electron density enhancement needed for reflection is calculated. Guidance by small-scale irregularities and ‘super whistlers’ (whistlers with upper cut-off above one-half the equatorial electron cyclotron frequency) are briefly discussed.     

An empirical study on the modification of China's current urban social security system

This study challenges the conventional correlation between economic performance and the level of the development of social security systems. By focusing on China's urban areas, we provide an overview of the components and benefits, from a comparative perspective, of China's current social security system. We also create a comprehensive and generally applicable method using factors such as economics and population, among others, as standards to evaluate the efficacy of China's system. In order to demonstrate our primary hypothesis – that the Chinese Communist Party government has to modify its social security system to adapt to or bring about changes in the basis of its legitimacy – we analyse Chinese social security records and other related data after 1949 by statistical methods. The formula we provide in this study can be used to forecast China's expenditure on its urban social security system, and other scholars can apply our methods to countries in which conditions are broadly similar.     

The effects of ionospheric horizontal electron density gradients on whistler mode signals

Whistler mode group delays observed at Faraday, Antarctica (65° S, 64° W) and Dunedin, New Zealand (46° S, 171° E) show sudden increases of the order of hundreds of milliseconds within 15 minutes. These events (‘discontinuities’) are observed during sunrise or sunset at the duct entry regions, close to the receiver's conjugate point. The sudden increase in group delay can be explained as a tilting of the up-going wave towards the sun by horizontal electron density gradients associated with the passage of the dawn/dusk terminator. The waves become trapped into higher L-shell ducts. The majority of the events are seen during June-August and can be understood in terms of the orientation of the terminator with respect to the field aligned ducts. The position of the source VLF transmitter relative to the duct entry region is found to be important in determining the contribution of ionospheric electron density gradients to the L-shell distribution of the whistler mode signals.     

An empirical examination of shift-share instruments

Bartik's (1991, 1993) approach to identifying shocks in demand to regional economies has been used extensively for nearly 30 years. We chronicle the development of Bartik-type shift-share instruments and examine the empirical performance of alternative versions that use different combinations of national shift and local share variables in their construction. We offer three main findings. First, instruments constructed from shares that omit employment in nontraded sectors empirically dominate versions that include total employment. Second, industrial sectors with high average shares and low variation across areas are more likely to be nontraded and endogenous. This suggests placing large weights on nontraded sector shares worsens both relevance and potential endogeneity. Finally, we demonstrate national shifters other than employment, such as prices and wages, can be used to construct instruments with unique and relevant explanatory power.     

Out of the crisis: an empirical investigation of place-specific determinants of economic resilience

This article attempts to isolate the structural characteristics that affect the resilience of a regional economy. It focuses on the role played by related/unrelated variety and differentiated knowledge bases as drivers for regional resilience and originally explores their interdependences. Italy is the empirical setting, and Italian local labour systems the unit of analysis. Regional resilience is measured as growth of the employment rate after the Great Recession that began in 2008. Results confirm the importance of related variety and of differentiated knowledge bases as drivers for regional resilience. We found support of the creative capacity of culture argument, providing evidence that a moderate concentration in symbolic knowledge-based economic activities contributes to resilience. Synthetic and analytical knowledge-based activities provide positive and no support to regional resilience, respectively. Finally, the relatedness of the symbolic knowledge-based activities increases regional economic resilience. Some policy implications are then derived from these findings.     

Decreasing house prices and household mobility: An empirical study on loss aversion and negative equity

This paper examines the effects of loss aversion and negative equity on household mobility. We stress the importance of studying these mechanisms simultaneously. By making use of a unique administrative data set of Statistics Netherlands, covering the period 2006–2011, we estimate the effects of loss aversion and negative equity. The results provide strong evidence for loss aversion, while less evidence is found for a lock‐in effect of negative equity. The results indicate that moderately underwater households do have a lower mobility, but heavily underwater households do not. Additional results indicate that the particularly high mobility of heavily underwater households is not default‐driven.     

Innovation and cooperation during the emergence of local industrial clusters: An empirical study in Germany

This paper studies the dynamics that cause the emergence of local industrial clusters at a general level. Predictions about these dynamics are deduced from theoretical modelling. The predictions are tested with the help of empirical data from Germany. Three-digit manufacturing industries are classified according to their dynamics. It is examined whether certain industrial characteristics are able to predict the type of dynamics occurring. It is shown that a high number of process innovations and a high share of regional cooperation with suppliers and public research institutes characterize those industries in which local clusters emerge.     

The population ecology of hunter-gatherers and their prey

In this paper we combine foraging theory and population biology models to simulate dynamic relationships between hunter-gatherers and their prey resources. Hunter-gatherer population growth responds to the net marginal rate of foraging; prey population growth responds logistically to exploitation. Thus conceived, the relationship between forager and prey biomass is time-dependent and nonlinear. It changes from stable equilibrium to damped and stable cycles with modest adjustments of input parameters. And, it produces the largest sustainable human population at intermediate levels of individual work effort. At equilibrium the forager takes all prey types with a pursuit and handling rate greater than or equal to its maintenance foraging rate. The structural properties of the model compel us to reject standard anthropological interpretations of the carrying capacity concept; they provide new insights on old issues such as original affluence and intensification. Analysis of the interaction of human population, diet selection, and resource depletion requires microecological models in part because the relevant processes occur on time scales largely invisible to both ethnography and archaeology.     

Alternative explanations of the dependence of the density of centers on the density of population

ABSTRACT. The paper is devoted to modeling the relationship between the density of service centers and the density of population (or on the density of demand). Several models lead to an exponential function with the exponent equal to ⅔. For a number of real systems of centers, the power is considerably different from ⅔ (more often it is nearer to 1). I describe a series of models that explain this difference.     

秦俑陶质彩绘原始工艺和剥落过程的探索性研究

为了制作陶俑彩绘的仿真样品,探索失传两千年的秦人制作陶质彩绘的原始工艺,根据已知的各种信息,探讨了秦俑彩绘制作的传统工艺,包括生漆添加猪血的作用、生漆层的配方、颜料层的配方、生漆层和颜料层的制作方法、基底陶块的选择等。制作了陶俑彩绘的仿真样品:生漆层厚度为35~68μm;颜料层厚度:红色20~50μm,白色55~70μm、绿色50~70μm、蓝色55~65μm,与秦俑生漆层和彩绘层的真实厚度相近。生漆层中猪血的最适应比例为4%,颜料层中所用粘合剂适宜浓度:明胶:水为1:32,蛋清:水为1:2。仿真样品经过加速老化破坏循环后,可以大体重现彩绘从陶块上起翘脱落的过程。研究结果为进一步研究病害机理,开展彩绘加固或回贴实验等研究提供了基础方法。     

Local and territorial determinants in the realization of public–private–partnerships: an empirical analysis for Italian provinces

ABSTRACT

Relational networks and intangible factors are crucial elements for the competitiveness of a territory. Public–Private–Partnerships (PPPs), in particular, allow for the provision of goods and services that favour the exploitation of complementarities between public and private resources. They aim at promoting an increase in the overall efficiency of investment projects through a complex mechanism that distributes risk and revenues among stakeholders. This paper examines the local and territorial determinants of PPPs through an econometric analysis based upon Italian municipal data, grouped at the provincial level. Using a tobit model, we analyse the relationship between the realization of successful PPP initiatives and different sets of factors, including less analysed local and territorial determinants. We stress the role of the local management of infrastructure assets, the administrative efficiency of local authorities and the diffusion of previous local development initiatives. Local management and territorial context factors explain most of the occurrence of successful PPP initiatives in the pre-crisis period while usual determinants (infrastructure endowment and financial distress) display a weaker effect.     

An empirical analysis of the effects of consanguineous marriages on economic development

In this study, development experiences toward economic development are investigated to provide an alternative analysis of economic development, human capital, and genetic inheritance in the light of consanguineous marriages. The countries analyzed in the study are discussed in accordance with consanguineous marriage practices and classified by their per capita gross domestic product (GDP) growth. A broad range of countries are analyzed in the study. Arab countries that experienced high rates of growth in their gross national income during the twentieth century but failed to fulfill adequate development measures as reflected in the growth in national income, countries undergoing transition from tight government regulation to free market democracy, and African nations that have experienced complications in the process of development show important differences in the process of economic development. It is shown that the countries that have reached high average development within the context of per capita GDP have overcome problems integral to consanguineous marriage.     

New perspectives on instrumentalism: an empirical study of cultural diplomacy

Museums are increasingly recognised as having a role to play within international relations, to facilitate cultural exchange, assert national identity and foster mutual understanding. Whilst international work is perceived to be politically motivated and diplomatically advantageous, it can be highly beneficial to cultural institutions. In this paper, ‘cultural diplomacy' is shown to be a strategy used by museums to enable organisational development and economic growth. This paper demonstrates how national museums adopted a political rhetoric and used strategic lobbying to formulate a new cultural policy, which expanded the scale and scope of their international work. By defining the parameters and principles of this policy, the institutions wield power, thus challenging the conventional perceptions of policy-making and contradicting commentators who accuse museums of political subservience. Throwing the notion of instrumentalism into disarray, this paper calls for a theoretical and conceptual rethinking, to revamp understanding and bring it in line with practice.     

Nation and reproduction: immigrants and their children in population discourse in Italy

Italian society is undergoing significant demographic changes: on one hand, the widespread decrease in birth rates and extended life expectancies lead to a substantial aging of the population; on the other hand, rising immigration rates constitute an important factor behind the renewal and growth of young population segments. According to conventional disciplinary divisions, such changes are the established domain of demography; however, it mainly draws on ethno‐national categories to investigate them. In reference to the Italian context, this article specifically highlights the way national demography employs forecasts and value judgments derived from a qualitative and selective definition of population to address the marked increase in children born to foreign parents. By examining the reproductive behaviours of migrants in Italy, the article thus offers a wide‐ranging reflection on the social boundaries that shape the formation of an ‘other’ generation.     

The process of international mediation: An analysis of the determinants of successful and unsuccessful outcomes

This article examines the relevance and importance of mediation in the management of international disputes. It utilises an original data set on disputes and mediation events to analyse systematically the factors and conditions associated with successful mediation. Four clusters of factors, and their relative impact on mediation, are explored. These are: (a) factors concerning the dispute itself, (b) factors concerning the parties in dispute, (c) factors pertaining to the mediator, and (d) factors pertaining to mediation behaviour. Multiple regression analysis reveals that the level of hostility, as measured by fatalities, has the greatest (negative) impact on the chances of successful mediation. Other variables that significantly affect mediation success include a history of friendly relations, socio‐cultural similarity, neutral grounds, and an active mediation strategy.     

An empirical evaluation of copper procurement and distribution: elemental analysis of Scioto Valley Hopewell copper

In prehistoric North America, artifacts of copper occupy a position of prominence in the Hopewell societies of Ohio’s Scioto Valley. These artifacts also represent the social contacts and long-distance interactions that brought copper to the Scioto Valley. Yet, our understanding of Hopewell copper acquisition, and the movement of copper artifacts within the social networks of the Scioto Valley and beyond, has been limited due to the limited availability of geochemical data concerning provenance and variability. We begin to develop the foundation for understanding these important social issues by analyzing the elemental variability of Hopewell copper through the use of laser ablation inductively coupled plasma mass spectrometry. We analyze 24 samples from four known copper source regions and 52 samples from 6 prominent sites in the Scioto Valley. Results suggest that a majority of the artifacts are consistent with sources in the Great Lakes, with a plurality classified as Isle Royale. However, 21% of Scioto Hopewell copper artifacts were most consistent with southern Appalachian sources. High elemental variability argues against simple models of copper acquisition and suggests that different social groups had access to a variety of copper sources through varying social networks. Native copper regardless of source seems to have been channeled along similar social and symbolic pathways. Our results suggest that instead of being derived from the struggle to access a specific source, value is derived from the social relationships represented by the copper and the connotation of exotic connection embodied in both style and material.     

The relationship of bone mineral density and other growth parameters to stress indicators in a medieval juvenile population

In this study the radii of 34 juveniles from Wharram Percy, a British medieval site, were measured for bone mineral density (BMD) using dual energy X‐ray absorptiometry (DXA) in order to investigate evidence of stress including Harris lines, cribra orbitalia and deficient cortical index, which is usually attributed to poor nutrition. BMD measurements are used in modern children to assess growth and development and generally correlate with linear growth. Only rare chronic illnesses affect bone mineral accrual in children. Radiographs of the radii were examined to assess cortical index and of the femora and radii for Harris lines. The results indicate that BMD is well correlated with dental age and linear growth, but is poorly correlated with cortical index. The variability in cortical index indicates the influence of environmental factors. There is no relationship between BMD and the presence or absence of Harris lines or cribra orbitalia. Thus, despite obvious evidence of skeletal stress in this juvenile population, bone was not under‐mineralised and bone mineral accrual proceeded normally with growth. This reinforces the conclusion that cortical index is a more sensitive indicator of environmental stress than either Harris lines or cribra orbitalia, and may be compared with BMD measurements to assess the effect of stress on growth. Copyright © 2005 John Wiley & Sons, Ltd.     

Imagining the social impact of museums and galleries: interrogating cultural policy through an empirical study

This paper aims to contribute to an understanding of how museums and galleries are regulated through an examination of the production and implementation of policy. It concentrates on those aspects that view them as vehicles through which social policy, such as that dealing with social inequality, can be implemented. To do this, it identifies the ways that motivations, behaviours and social outcomes of engagement are imagined by New Public Management-derived policy, and audit and evaluation tools. This is then examined using the results of a study of how visitors consume contemporary visual art galleries in north-east England, UK. The study concludes that the complex nature of engagement cannot be accommodated by policy in its present form and cannot be captured by existing audit and evaluation tools. It suggests that new approaches that acknowledge the roles visitors play in the construction of meanings need to be developed.     

中国古代砖石建筑及其保护修复概述

砖石建筑是指利用砖石材料以一定的结构形式砌筑的建筑物或构筑物,这是中国传统建筑营造的一大类型,在中国建筑史上具有悠久历史和重要地位。我国现存砖石建筑分布地域广、数量多,本文从保护角度出发,介绍了砖石建筑历史及类型,并结合具体案例,对砖石建筑的保护与修复过程中的病害类型、原因、治理方法等进行了概述。