How friends share urban space: An exploratory spatiotemporal analysis using mobile phone data

This study proposes a framework to investigate the roles of urban spaces in connecting social contacts (i.e., “friends”). The framework is applied to a Call Detail Record (CDR) dataset collected in Singapore. First, a comparative analysis is performed to understand how friends share urban space differently from random people. Then, we derive two metrics to quantify the “bonding” and “bridging” capabilities of places in the city. The two metrics reflect the potential of a place in connecting friends and random people (e.g., chance encounters), respectively. Finally, we examine the temporal signature of the places’ bonding capabilities, and associate the results with various types of Points of Interest (POIs). We find that: (1) friends are more likely to share urban space than random people, and they also share more locations; (2) a place could play different roles in connecting friends vs. random people, and the relationship (between bonding and bridging) varies depending on the time and type of a day (weekdays vs. weekends); (3) the temporal signature of bonding capability is strongly related to the semantics of a place; (4) certain POI types (e.g., shopping malls) tend to have a much higher impact on bonding capability than others (e.g., sports centers).     

圣彼得堡土地利用格局现状特征及形成机制

以圣彼得堡市为例,依据1948、1987和2016年土地利用数据计算居住、工业和商业用地的区位熵值并分析其变化,基于统计小区、圈层式及扇形分布3个视角,运用GIS分析计划与市场经济影响下的城市用地空间分布特征。研究结果表明,居住、工业和商业用地的空间分布规律不同：① 3类用地在城市整体空间分布中均表现出一定的分散特征,其中,居住用地空间分布表现最为分散,工业用地呈现出分区域性布局特征,相比而言商业用地空间聚集程度最高;② 商业用地在核心圈层处于主导地位,工业用地在老城区圈层为主导地位,居住用地在近郊区圈层为主导地位,远郊区圈层仍处于初步发展阶段,城市景观发展尚未成熟;③ 对比圈层式和象限式结构各类用地区位熵值分布结果,提出圣彼得堡市3类用地空间分布扇形结构特征明显,说明沿主要交通线路是现代城市用地空间扩展主要方式,其中工业用地在城市空间分布中占据更为有利的交通区位优势,居住用地次之,商业用地在城市中心区域中分布不足。圣彼得堡城市用地空间分布形成主要机制总结为以下5个方面：前苏联时期城市用地空间结构主要框架的保持;行政区划调整为城市用地结构改善提供了路径;市场经济下住房体制改革推进了城市居住郊区化;土地市场对土地功能置换进程作用较弱;产业转型缓慢导致老城区仍主要为生产中心。     

Making Decisions About Forestland Succession: Perspectives from Pennsylvania's Private Forest Landowners

Decision-making processes that private forest landowners (PFLs) engage when planning for their forestland’s future are not well understood. The forest ecosystem and the people who depend on its services face several critical challenges, including how to sustainably manage an increasingly parcelized forest. The Theory of Planned Behavior has been used to illuminate connections among constructs informing PFL behavior, but fails to adequately capture the complexities of forest owners’ lived experiences and how those inform behaviors. In-depth interviews provide a deeper understanding of how Pennsylvania PFLs make decisions concerning ownership succession. We approached those who recently subdivided, sold/donated conservation easements, or had not committed to any plan and asked them to tell us about their planning experiences. Relationships among family members and the quality of their communication about the land and succession emerged as important factors in the planning process. Implications for theory, forest planning, education and outreach, and further study are advanced.     

A model of diffusion produced by a cellular surface flow

A model of diffusion induced by the joint action of random cells of two different sizes (granulation and supergranulation) is developed. The basic properties of the model are defined by the dimensionless ratio = (the life time)/(characteristic size/velocity) constructed for these two types of cells. An analytical expression for the diffusivity as a function of is derived. It is estimated that for the standard parameters used the contribution of granulation to the joint diffusion is small. A comparison between the model and numerical simulations of the kinematic diffusion of magnetic fields on the solar surface is made.     

Genetic structure and recent population expansion in the commercially harvested deep-sea decapod,Metanephrops challengeri (Crustacea: Decapoda)

ABSTRACT

Determining the genetic structure and population dynamics of harvested species are key aspects of effective fisheries management. New Zealand scampi (Metanephrops challengeri) is a species of nethropid lobster that supports a commercial fishery on the continental shelf and slope around New Zealand. To determine the genetic structure and historical population demography of New Zealand scampi, we sequenced a 623 base-pair fragment of the mitochondrial gene cytochrome c oxidase subunit one (CO1) from 321 individuals across six widely separated sites off the coast of mainland New Zealand and the subantarctic Auckland Islands, representing much of the species’ distribution. The Auckland Islands population was found to be genetically distinct from all other sampled populations, potentially resulting from an absence of continuous suitable habitat between the central-eastern South Island and the Auckland Islands. An isolation-by-distance pattern of genetic structure was also detected. With the exception of the Mercury Islands, all sampled populations showed signs of recent population expansion, potentially linked to changes in habitat availability during the glacial-interglacial cycles of the Pleistocene. We recommend that the current NZ scampi management areas and harvesting rates for each remain unchanged.     

Winter-to-winter recurrence of sea surface temperature, salinity and mixed layer depth anomalies

The mean seasonal cycle of mixed layer depth (MLD) in the extratropical oceans has the potential to influence temperature, salinity and mixed layer depth anomalies from one winter to the next. Temperature and salinity anomalies that form at the surface and spread throughout the deep winter mixed layer are sequestered beneath the mixed layer when it shoals in spring, and are then re-entrained into the surface layer in the subsequent fall and winter. Here we document this ‘re-emergence mechanism’ in the North Pacific Ocean using observed SSTs, subsurface temperature fields from a data assimilation system, and coupled atmosphere–ocean model simulations. Observations indicate that the dominant large-scale SST anomaly pattern that forms in the North Pacific during winter recurs in the following winter. The model simulation with mixed layer ocean physics reproduced the winter-to-winter recurrence, while model simulations with observed SSTs specified in the tropical Pacific and a 50 m slab in the North Pacific did not. This difference between the model results indicates that the winter-to-winter SST correlations are the result of the re-emergence mechanism, and not of similar atmospheric forcing of the ocean in consecutive winters. The model experiments also indicate that SST anomalies in the tropical Pacific associated with El Niño are not essential for re-emergence to occur.The recurrence of observed SST and simulated SST and SSS anomalies are found in several regions in the central North Pacific, and are quite strong in the northern (>50°N) part of the basin. The winter-to-winter autocorrelation of SSS anomalies exceed those of SST, since only the latter are strongly damped by surface fluxes. The re-emergence mechanism also has a modest influence on MLD through changes in the vertical stratification in the seasonal thermocline.     

The sedimentary record of the Issyk Kul basin,Kyrgyzstan: climatic and tectonic inferences

A broad array of new provenance and stable isotope data are presented from two magnetostratigraphically dated sections in the south‐eastern Issyk Kul basin of the Central Kyrgyz Tien Shan. The results presented here are discussed and interpreted for two plausible magnetostratigraphic age models. A combination of zircon U‐Pb provenance, paleocurrent and conglomerate clast count analyses is used to determine sediment provenance. This analysis reveals that the first coarse‐grained, syn‐tectonic sediments (Dzhety Oguz formation) were sourced from the nearby Terskey Range, supporting previous thermochronology‐based estimates of a ca. 25–20 Ma onset of deformation in the range. Climate variations are inferred using carbonate stable isotope (δ¹⁸O and δ¹³C) data from 53 samples collected in the two sections and are compared with the oxygen isotope compositions of modern water from 128 samples. Two key features are identified in the stable isotope data set derived from the sediments: (1) isotope values, in particular δ¹³C, decrease between ca. 26.0 and 23.6 or 25.6 and 21.0 Ma, and (2) the scatter of δ¹⁸O values increased significantly after ca. 22.6 or 16.9 Ma. The first feature is interpreted to reflect progressively wetter conditions. Because this feature slightly post‐dates the onset of deformation in the Terskey Range, we suggest that it has been caused by orographically enhanced precipitation, implying that surface uplift accompanied late Cenozoic deformation and rock uplift in the Terskey Range. The increased scatter could reflect variable moisture source or availability caused by global climate change following the onset of Miocene glaciations at ca. 22.6 Ma, or enhanced evaporation during the Mid‐Miocene climatic optimum at ca. 17–15 Ma.     

Exploring food choices within the context of nutritional security in Gaborone,Botswana

Food consumption experiences remain largely unexplored in urban Africa, despite mounting concerns regarding both over‐ and undernutrition of city dwellers and the potential impact on overall human health and development. This paper seeks to explore the foodstuffs people consume and the factors that shape consumer choice in Gaborone, Botswana. Empirical data were drawn from food diaries and observations of 40 households and discussions with them, plus key informants interviews in Gaborone. Analysis reveals the range of foodstuff people consume, highlighting the prevalence of diets comprised of energy dense, processed and animal‐sourced foods, which are major nutritional security concerns. However these diets were not summarily western or westernizing as per the nutritional transition thesis, as our analysis suggests subtleties of dietary patterns, including the fact that meat‐based diets are traditionally rooted rather than imported and meals tend to comprise both local and western components. The paper also identifies multiple interacting factors influencing consumer food choices, illustrating how food decisions embody context‐specific personal and social circumstances. Understanding how these factors shape what people eat in Gaborone may enable policy makers to facilitate the conditions within which healthy food choices can be made and to address emerging public health and nutrition challenges in African cities.     

An easy approach to assess the susceptibility of a landslide by utilizing simple raster overlay methods: A case study on Huangtupo landslide (P.R. China)

Semi qualitative index based methods using rankings and ratings are commonly used in susceptibility estimations over a wide area. However, generalized ranking and ratings are not applicable for one single landslide. This paper gives an easy and transferable approach to a susceptibility assessment of Huangtupo landslide (P.R. China), using raster addition without taking account for ranking and ratings. Slope, aspect, curvature, location and drainage buffer distance raster data sets have been obtained out of open source digital elevation models using ESRI’s ArcGIS. These conditioning factor raster data sets have been translated into raster data sets including simple yes or no criteria, referring to triggering or not. Subsequently they have been added by raster math to acquire a simple raster overlay map. After that this map is compared to initial displacement measurements, obtained by using a ground based synthetic aperture radar device. Acquired data is recalculated to a raster data set using the same spatial extent, to provide the possibility of comparison of the two raster data sets. The results reveal, that 76.35% of all measured movements occur in areas where raster cells include three or more conditioning factors, indicating that easy raster math operations can lead to satisfying results in local scale.