Youth Mobility and Territorial Disparities: An Analysis of Urban and Rural Barcelona     

Xavier Delcls‐Ali  Carme Miralles‐Guasch 《Geographical review》2019,109(3):399-415

Travel behavior of the present generation of youths is being increasingly explored due to their relevance in shaping future accessibility needs and mobility habits. The present study offers an original perspective on this topic by identifying territorial disparities that emerge in youth mobility patterns in rural and urban areas. Unlike most previous research, we propose taking a global view on mobility by analyzing all trip purposes and transportation modes. This is conducted by analyzing a comprehensive mobility survey in the Barcelona Metropolitan Region, which provides data on mobility engagement, trip purposes, modal split, travel times and territorial differences. In general, youngsters account for larger daily travel times than older adults, present a higher attachment to public transportation and walk less on a daily basis. These differences are enhanced in rural territories, where while older adults overcome accessibility issues with higher use of the private vehicle, youngsters are more likely to invest larger travel times on transit.  相似文献   

Industrial and geographical mobility of workers during industry decline: The Swedish and German shipbuilding industries 1970–2000     

《Geoforum》2016

This article follows the industry employment histories of all individuals who at some point have been affiliated with the declining German or the dismantling Swedish shipbuilding industry during 1970–2000. We analyse the situation of the individual workers leaving shipbuilding, investigating the extent to which they were employed at all, tended to move to related sectors within or outside the region, and whether such moves were beneficial for the individuals. Combining insights from labour geography and redundancy studies with evolutionary economic geography, we find remarkably similar results for the West German and Swedish cases. Our findings indicate a notable impact of the regional industry structure on the labour market outcomes for workers leaving shipbuilding. This suggests that more attention should be devoted to the specific structures of the absorptive capacity of regional labour markets. The findings are discussed within the context of a mature industry.  相似文献   

Estimating attendance from cellular network data     

Marco Mamei  Massimo Colonna 《International journal of geographical information science》2016,30(7):1281-1301

An automatic estimate of the number of attendees to events happening in the city can provide valuable information to geographic information systems and geo-located applications. We present a methodology to estimate the number of events’ attendees from cellular network data. In this work, we used anonymized Call Detail Records (CDRs) comprising data on where and when users access the cellular network. Our approach is based on two key ideas: (1) we identify the network cells associated with the event location. (2) We verify the attendance of each user, as a measure of whether (s)he generates CDRs during the event, but not during other times. We evaluate our approach to estimate the number of attendees to a number of events ranging from football matches in stadiums to concerts and festivals in open squares. Comparing our results with the best groundtruth data available, our estimates provide a median error of less than 15% of the actual number of attendees.  相似文献   

增强型AlGaN/GaN高电子迁移率晶体管高温退火研究     

王冲  全思  马晓华  郝跃  张进城  毛维 《海洋学报》2010,32(10):7333-7337

深入研究了两种增强型AlGaN/GaN高电子迁移率晶体管(HEMT)高温退火前后的直流特性变化.槽栅增强型AlGaN/GaN HEMT在500 ℃ N₂中退火5 min后,阈值电压由0.12 V正向移动到0.57 V,器件Schottky反向栅漏电流减小一个数量级.F注入增强型AlGaN/GaN HEMT在 400 ℃ N₂中退火2 min后,器件阈值电压由0.23 V负向移动到-0.69 V,栅泄漏电流明显增大.槽栅增强型器件退火过程中Schottky有效势垒  相似文献   

Open-system chemical behavior in deep Wilcox Group mudstones,Texas Gulf Coast,USA     

Ruarri J. Day-Stirrat  Kitty L. Milliken  Shirley P. Dutton  Robert G. Loucks  Stephen Hillier  Andrew C. Aplin  Anja M. Schleicher 《Marine and Petroleum Geology》2010

Wilcox Group mudstones have been mechanically and geochemically transformed over a temperature range of 20–200 °C. Our research controlled for provenance and age by sampling from five wells, parallel to the paleodepositional axis, all within the Houston delta system. Across the sampled depths, mudstone porosity has been reduced from ∼25 to <10% and bulk mineralogical change as documented by quantitative X-ray diffraction includes decreases in quartz, K-feldspar and kaolinite content whereas illite + illite − smectite, chlorite, and plagioclase increase. These mineral transformations transfer elements at a scale of less than 1 mm from one mineralogical form to another, however, X-ray fluorescence data suggest that among major elements only Al₂O₃ and TiO₂ are fully conserved within the system (trace-element ZrO₂ is also conserved). K₂O has been added to and SiO₂ released from the Wilcox Group mudstones. Cathodoluminescence and secondary electron imaging did not find this SiO₂ locally precipitated. We, therefore, document an open-system geochemical behavior.  相似文献   

Element mobility during continental collision: insights from polymineralic metamorphic vein within UHP eclogite in the Dabie orogen     

Y.‐M. SHENG  Y‐F. ZHENG  S‐N. LI  Z. HU 《Journal of Metamorphic Geology》2013,31(2):221-241

Metamorphic dehydration and partial melting are two important processes during continental collision. They have significant bearing on element transport at the slab interface under subduction‐zone P–T conditions. Petrological and geochemical insights into the two processes are provided by a comprehensive study of leucocratic veins in ultrahigh‐pressure (UHP) metamorphic rocks. This is exemplified by this study of a polymineralic vein within phengite‐bearing UHP eclogite in the Dabie orogen. The vein is primarily composed of quartz, kyanite, epidote and phengite, with minor accessory minerals such as garnet, rutile and zircon. Primary multiphase solid inclusions occur in garnet and epidote from the both vein and host eclogite. They are composed of quartz ± K‐feldspar ± plagioclase ± K‐bearing glass and exhibit irregular to negative crystal shapes that are surrounded by weak radial cracks. This suggests their precipitation from solute‐rich metamorphic fluid/melt that involved the reaction of phengite breakdown. Zircon U–Pb dating for the vein gave two groups of concordant ages at 217 ± 2 and 210 ± 2 Ma, indicating two episodes of zircon growth in the Late Triassic. The same minerals from the two rocks give consistent δ¹⁸O and δD values, suggesting that the vein‐forming fluid was directly derived from the host UHP eclogite. The vein is much richer in phengite and epidote than the host eclogite, suggesting that the fluid is associated with remarkable concentration of such water‐soluble elements as LILE and LREE migration. Garnet and rutile in the vein exhibit much higher contents of HREE (2.2–5.7 times) and Nb–Ta (1.8–2.0 times) than those in the eclogite, indicating that these normally water‐insoluble elements became mobile and then were sunken in the vein minerals. Thus, the vein‐forming agent would be primarily composed of the UHP aqueous fluid with minor amounts of the hydrous melt, which may even become a supercritical fluid to have a capacity to transport not only LILE and LREE but also HREE and HFSE at subduction‐zone metamorphic conditions. Taken together, significant amounts of trace elements were transported by the vein‐forming fluid due to the phengite breakdown inside the UHP eclogite during exhumation of the deeply subducted continental crust.  相似文献   

劳动力区际流动及其人力资本再分配效应——基于技能互补性假说的理论与实证分析     

敖荣军 《地理与地理信息科学》2007,23(1):59-63

由于劳动力的异质性,不同技能劳动力之间的合作和互补可以获得递增收益。客观存在的技能互补性导致技能劳动力迁入与迁入地技能劳动力需求之间的正反馈关系,从而引发了劳动力区际流动与人力资本地区集中之间的累积循环。该文基于Giannetti提出的技能互补性假说,从一个新的角度对劳动力区际流动的动因进行理论与实证分析,并揭示该假说的区域经济学含义。  相似文献   

Time, idealisation and international development: promoting Canadian co-management in northern Russia     

Elana Wilson 《Area》2007,39(3):323-330

In this article, I trace the efforts of a development team working to promote a Canadian approach to natural resources management in the Russian North. These development workers used two communication strategies related to time and history to render Canadian knowledge mobile and applicable to a new location: (1) imagining today's Russian North as equivalent to the Canadian northern past and (2) reframing and idealising the Canadian past and present to make the governance export less discursively 'messy' for an outside audience. The relative failure of these communicative strategies points to the need for richer dialogue in efforts to move knowledge cross-culturally.  相似文献   

GIS‐assisted modelling for debris flow hazard assessment based on the events of May 1998 in the area of Sarno,Southern Italy: Part I. Maximum run‐out     

G. Toyos  D. Oramas Dorta  C. Oppenheimer  M. T. Pareschi  R. Sulpizio  G. Zanchetta 《地球表面变化过程与地形》2007,32(10):1491-1502

Based on the debris flow events that occurred in May 1998 in the area of Sarno, Southern Italy, this paper presents an approach to simulate debris flow maximum run‐out. On the basis of the flow source areas and an average thickness of 1·2 m of the scarps, we estimated debris flow volumes of the order of 10⁴ and 10⁵ m³. Flow mobility ratios (ΔH/L) derived from the x, y, z coordinates of the lower‐most limit of the source areas (i.e. apex of the alluvial fan) and the distal limit of the flows ranged between 0·27 and 0·09. We performed regression analyses that showed a good correlation between the estimated flow volumes and mobility ratios. This paper presents a methodology for predicting maximum run‐out of future debris flow events, based on the developed empirical relationship. We implemented the equation that resulted from the calibration as a set of GIS macros written in Visual Basic for Applications (VBA) and running within ArcGIS. We carried out sensitivity analyses and observed that hazard mapping with this methodology should attempt to delineate hazard zones with a minimum horizontal resolution of 0·4 km. The developed procedure enables the rapid delineation of debris flow maximum extent within reasonable levels of uncertainty, it incorporates sensitivities and it facilitates hazard assessments via graphic user interfaces and with modest computing resources. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Interrogating the ten-year transport plan     

Iain Docherty 《Area》2001,33(3):321-328

This paper presents an analysis of Transport 2010, the government's ten-year plan for transport. It develops discussions held by members of the RGS-IBG's Transport Geography Research Group (TGRG) in September 2000. It is argued that the plan marks something of a return to previous policies designed to accommodate increasing mobility.  相似文献