THE AGGREGATED SPATIAL CHOICE MODEL VS. THE MULTINOMIAL LOGIT: AN EMPIRICAL COMPARISON USING MIGRATION MICRODATA

Frequently, in spatial interaction analysis, researchers are forced to use destinations that are zonal aggregates of the ‘real’ destinations perceived by the participants in the interaction process. Previous simulation studies demonstrated that, under certain circumstances, the aggregated spatial choice model can outperform the popular ordinary multinomial logit model, both in explanatory power and predictive ability. In this paper, the two models are compared with interprovincial migration microdata for the time period 1990-91, obtained from the 1991 Canadian census. Since this is not meant to be a migration study, the analysis is limited to out-migrants from Ontario. The results indicate that, at least with the data used, the multinomial logit model performed reasonably well. The paper, however, highlights some practical advantages that can accrue from the use of the aggregated model. Dans l'analyse de l'interaction à référence spatiale, il arrive fréquemment que les chercheurs soient contraints de se servir de destinations qui regroupent les?vraies?destinations perçues par les participants dans le processus d'interaction. Les études en simulations antérieures ont démontré que, dans certaines circonstances, le modèle groupé des choix à référence spatiale peut donner de meilleurs résultats que le modèle ordinaire commun du logit multinomial, sur le plan de la capacité d'explication comma sur celui de la valeur de prévision. Dans la présente étude, on fait la comparaison entre les deux modèles en utilisant les microdonnées sur l'émigration interprovinciale en 1990-91 obtenues par le recensement de 1991. L'analyse ne porte que sur les émigrants de l'Ontario puisqu'elle ne vise pas particulièrement l'étude de l'émigration. D'après les résultats, le modèle employant le logit multinomial fonctionne relativement bien, au moins avec les données utilisées. Toutefois, l'étude souligne certains avantages pratiques pouvant inciter à se servir davantage du modèle groupé.     

GEOGRAPHIC SEPARATION AND PATTERNS OF SOCIAL INTERACTION BETWEEN RESIDENTS OF SENIOR CITIZEN APARTMENT BUILDINGS AND THEIR ADULT CHILDREN

In this study, research questions are formulated to investigate the determinants and consequences of the physical distances separating residents of government-assisted senior citizen apartment (SCA) projects and their adult children. Interview survey data were obtained from residents (n= 97) of three SCAS in suburban Winnipeg, Canada, and geographically matching baseline samples of community residents (n= 105). The analysis involves the use of bivariate statistical inferential tests and multiple regression frameworks. The results disclose that (1) greater parent-child separation distances are registered by SCA residents compared to the community elderly; (2) ‘distance of the most recent residential move’ is the most significant predictor of the intergenerational separation distances recorded by SCA residents; (3) spatial proximity is the most significant predictor of social interaction between SCA residents and their children. It is concluded that the results have important implications for (1) developmental models of elderly migration and (2) policies governing the provision of seniors' housing. Dans cette étude, on s'interroge sur les déterminants et les conséquences des distances physiques qui séparent les reéidents des programmes d'habitation pour personnes âgées (SCA) subventionnés par le gouvernement, et leurs enfants adultes. On a recueilli des données d'enquête en faisant des entrevues avec les résidents (n= 97) de trois SCA dans la banlieue de Winnipeg, Canada, et avec des résidents dans la communauté (n= 105) qui font partie des échantillons de référence appariés géographiquement. Pour analyser les données, on a utilisé des tests d'inférence statistique bivariés et des analyses de régression multiple. Les résultats démontrent les faits suivants: (1) les enfants des résidents des SCA sont séparés de leurs parents par une plus grande distance que les enfants des personnes âgées dans la communauté; (2) ? la distance du plus récent déménagement?est le prédicteur le plus important des distances de séparation intergénérationnelle; (3) la proximité spatiale est le prédicteur le plus significatif de l'interaction sociale entre les résidents des SCA et leurs enfants. Ces résultats comportent des conséquences importantes pour le développement des modèles de migration des personnes âgées, aussi bien que pour les politiques qui régissent le logement pour personnes âgées.     

清末地方督抚在师日举措上的互动--以张之洞为中心

甲午战后,中国朝野上下逐渐以日本为榜样学习西方,地方督抚在师日举措上有着诸多互动,包括互相商议以应对新局势、已与日本建立联系的督抚积极劝说同僚或为之牵线、后进者主动效仿先进等。这种互动从点、线、面上呈现出时段集中于清末中日关系交好的早期、南方督抚互动更为频繁、内容广泛且循序渐进的特征。督抚群体的互动为各自辖区乃至清廷仿照日本提供了便捷和经验;但也正是督抚的这种自主性对清末的师日活动造成阻碍,限制各地人才、技术等资源的流动。     

‘Nuclear Sword of the Moslem World’?: the United States,Britain, Pakistan,and the ‘Islamic Bomb’, 1977–80

There exists today considerable fear of nuclear proliferation across the ‘Islamic world.’ Despite this, an issue that - in part - set the tone for contemporary debates has largely gone under-examined in the scholarly literature. The emergence of the ‘Islamic bomb’ idea in the late 1970s created a meme that remains with us today. Analysing the roots of this meme allows us to examine its creation and the attitudes of governments towards this alleged emergent nuclear-proliferation threat. This analysis demonstrates that while the media portrayed the ‘Islamic world’ as violent, undifferentiated, and determined to gain nuclear capability, the US and British governments assessed matters evidentially and came to the conclusion that the ‘Islamic bomb’ represented a propaganda problem rather than an imminent nuclear-proliferation concern. Attitudes towards the ‘Islamic bomb’ highlight media and governmental attitudes towards the changing power balances in the Middle East and South Asia during a turbulent and troubled period.     

Symbionts in a stromatoporoid-chaetetid association from the Middle Devonian Burdekin Basin,north Queensland

A spectacular association between a chaetetid, a stromatoporoid (Salairella sp.), and straight, vertical tubes interpreted to have housed symbiotic worms is reported from the Givetian Burdekin Formation, Burdekin Basin, north Queensland. The final growth surface of Salairella sp. shows skeletal distortion characterised by long, rather continuous coenosteles and coenostroms with upturned edges. This distorted interface was probably the result of spatial competitive interaction between the encrusting chaetetid and the underlying stromatoporoid. Neither sediment infilling, erosion or surface breakage occurs on the final growth surface of the stromatoporoid skeleton. As such, the growth of the Salairella sp. specimen appears to have been supressed by the encrusting chaetetid. Worm tubes are continuous through the distorted interface without interruption. The skeletal association also suggests that the round, straight, vertical tubes had a symbiotic intergrowth relationship initially with the stromatoporoid and, subsequently, the chaetetid.     

港澳与珠江三角洲文化特色及其关系比较

港澳文化与珠江三角洲文化都以岭南文化为本根,由于历史原因,形成不同文化特色;港澳文化与珠江三角洲文化之间是互动关系,这种互动性在时空分布上是一个动态过程;港澳与珠江三角洲文化的交流与融合,最终将导致文化的趋同。     

Mechanisms of fluid flow and fluid–rock interaction in fossil metamorphic hydrothermal systems inferred from vein–wallrock patterns, geometry and microstructure

Comparison of mass transfer patterns, geometry and microstructures developed within and around veins allows the interpretation of processes of fluid flow during deformation, metamorphism and mineralization. A classification of vein types based on the degree of interaction with wallrock (using petrological, geochemical or isotopic indicators) can be used to identify a range of processes, from closed system behaviour in which the vein mass is derived from local wallrock, through to open system behaviour in which the vein mass is derived externally. Microstructural characteristics, such as wallrock selvages, multiple growth events recorded by vein seams and vein crystal morphology, also help to constrain mass transfer patterns during vein formation. We present a range of processes for vein formation, including: (i) the formation of closed system fibrous veins by dissolution–precipitation creep, including varieties in which tensile failure is not required; (ii) pressure‐ or kinetically dependent closed system segregation veins in which transfer of soluble components from wallrock to vein leaves behind a residual selvage; (iii) similar vein–selvage patterning, but with mass imbalances between vein and wallrock requiring fluid advection through both interconnected fracture networks and in the surrounding permeable rock; and (iv) the proposed formation of veins by fluid ascent in mobile hydrofractures, in which isotopic or chemical disequilibrium within and around the vein suggests that the crack and fluid within it moved essentially as one. The postulate of rapid fluid and mass transfer via such mobile hydrofractures has implications for the release of volatiles from metamorphic terrains. Also, consideration of a broad range of possible vein‐forming mechanisms is highly desirable when dealing with mineral deposits found in deformed, metamorphosed rocks, because closed system veining may produce patterns that, if erroneously recognized as being open systems, could lead to false interpretations of the role of tectonic fracturing in ore genesis.     

旅游吸引物空间结构分析——以中国首批国家4A级旅游区(点)为例

本文利用地理数学方法中的空间分析手段,通过对首批国家4A级旅游区(点)在不同地域范围的空间分布规律进行研究,以及对各旅游区(点)与非农业人口在20万以上的城市之间的空间关系分析,揭示了国家首批4A级旅游区(点)的空间结构整体特征,以及与不同规模客源市场之间的距离分异特征,为旅游目的地空间结构理论研究提供了基础方法。     

我国城市化与产业结构演变的互动变化趋势研究

城市化与区域产业结构演变的互动,是我国城市发展与产业结构有序演变的重要路径。本文从理论与实践相结合的角度,对我国城市化与区域产业结构演变相互作用的地域进行了类型划分,研究了不同地域类型城市化与区域产业结构有序演变相互作用的特点、模式及变化趋势。为我国产业结构调整与优化,城市化的有序推进提供一种新的思路。     

Hydrogeochemical dynamics affecting steam‐heated pools at El Chichón Crater (Chiapas – Mexico)

El Chichón is an active volcano located in the north‐western Chiapas, southern Mexico. The crater hosts a lake, a spring, named Soap Pool, emerging from the underlying volcanic aquifer and several mud pools/hot springs on the internal flanks of the crater which strongly interact with the current fumarolic system (steam‐heated pools). Some of these pools, the crater lake and a cold spring emerging from the 1982 pumice deposits, have been sampled and analysed. Water–volcanic gas interactions determine the heating (43–99°C) and acidification (pH 2–4) of the springs, mainly by H₂S oxidation. Significantly, in the study area, a significant NH₃ partial pressure has been also detected. Such a geochemically aggressive environment enhances alteration of the rock in situ and strongly increases the mineralization of the waters (and therefore their electrical conductivity). Two different mineralization systems were detected for the crater waters: the soap pool‐lake (Na⁺/Cl^? = 0.4, Na/Mg>10) and the crater mud pools (Na⁺/Cl^? > 10, Na/Mg < 4). A deep boiling, Na⁺‐K⁺‐Cl^?‐rich water reservoir generally influences the Soap Pool‐lake, while the mud pool is mainly dominated by water‐gas–rock interactions. In the latter case, conductivity of sampled water is directly proportional to the presence of reactive gases in solution. Therefore, chemical evolution proceeds through neutralization due to both rock alteration and bacterial oxidation of ammonium to nitrate. The chemical compositions show that El Chichón aqueous fluids, within the crater, interact with gases fed by a geothermal reservoir, without clear additions of deep magmatic fluids. This new geochemical dataset, together with previously published data, can be used as a base line with which to follow‐up the activity of this deadly volcano.