Mapping family connectedness across space and time     

Caglar Koylu  Diansheng Guo  Alice Kasakoff  John W. Adams 《制图学和地理信息科学》2013,40(1):14-26

Understanding the structure and evolution of family networks embedded in space and time is crucial for various fields such as disaster evacuation planning and provision of care to the elderly. Computation and visualization can potentially play a key role in analyzing and understanding such networks. Graph visualization methods are effective in discovering network patterns; however, they have inadequate capability in discovering spatial and temporal patterns of connections in a network especially when the network exists and changes across space and time. We introduce a measure of family connectedness that summarizes the dynamic relationships in a family network by taking into account the distance (how far individuals live apart), time (the duration of individuals’ coexistence within a neighborhood), and the relationship (kinship or kin proximity) between each pair of individuals. By mapping the family connectedness over a series of time intervals, the method facilitates the discovery of hot spots (hubs) where family connectedness is strong and the changing patterns of such spots across space and time. We demonstrate our approach using a data set of nine families from the US North. Our results highlight that family connectedness reflects changing demographic processes such as migration and population growth.  相似文献   

Dynamo action in flows with cat's eyes     

Alice Courvoisier  Yannick Ponty 《地球物理与天体物理流体动力学》2013,107(5):413-429

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Sedimentation rates on embanked floodplains determined through quartz optical dating     

Jakob Wallinga  Noortje Hobo  Alastair C. Cunningham  Alice J. Versendaal  Bart Makaske  Hans Middelkoop 《Quaternary Geochronology》2010,5(2-3):170-175

We investigate the use of quartz optically stimulated luminescence (OSL) dating for determining fluvial overbank sedimentation rates over decades to centuries. For the study we took 11 samples from three cores from an embanked floodplain along the River Waal (Rhine) near Neerijnen (The Netherlands). We propose a measurement protocol for young fluvial quartz based on the single-aliquot regenerative dose procedure. Parameters for the protocol are chosen to isolate the fast OSL component, eliminate an ultrafast OSL component and avoid thermal transfer. The protocol shows excellent dose recovery and recycling ratios. For each sample, a Gaussian is fitted to the lower part of the equivalent dose distribution to obtain an estimate of the burial dose. We discuss the validity of the OSL ages using internal and external controls, and conclude that there is no evidence for large systematic offsets in the OSL ages. OSL based sedimentation rates are between ～3 and 8 mm/a, in line with previous estimates.  相似文献   

Direct observation of cosmic strings via their strong gravitational lensing effect – I. Predictions for high-resolution imaging surveys     

M. Alice Gasparini  Phil Marshall  Tommaso Treu  Eric Morganson  Florian Dubath 《Monthly notices of the Royal Astronomical Society》2008,385(4):1959-1964

We use present theoretical estimates for the density of long cosmic strings to predict the number of strong gravitational lensing events in astronomical imaging surveys as a function of the angular resolution and survey area. We show that angular resolution is the single most important factor, and that interesting limits on the dimensionless string tension   G μ/ c ²  can be obtained by existing and planned surveys. At the resolution of the Hubble Space Telescope ( HST ) (0.14 arcsec), it is sufficient to survey of the order of a few square degrees – well within reach of the current HST archive – to probe the regime   G μ/ c ²∼ 10⁻⁷  . If lensing by cosmic strings is not detected, such a survey would improve the limit on the string tension by a factor of two over that available from the cosmic microwave background. Future high resolution imaging surveys, covering a few hundred square degrees or more, either from space in the optical or from large-format radio telescopes on the ground, would be able to further lower this limit to   G μ/ c ²∼ 10⁻⁸  . These limits will not be improved significantly by increasing the solid angle of the survey.  相似文献   

Interactive effects of hypoxia and PBDE on larval settlement of a marine benthic polychaete     

Paul K.S. Shin  Singaram Gopalakrishnan  Alice K.Y. Chan  P.Y. Qian  Rudolf S.S. Wu 《Marine pollution bulletin》2014

Marine benthic polychaete Capitella sp. I is widely known to adapt to polluted habitats; however, its response to xenobiotics under hypoxic conditions has been rarely studied. This research aimed to test the hypothesis that interactive effects of hypoxia and congener BDE-47 of polybrominated diphenyl ethers (PBDE), which is ubiquitous in marine sediments, may alter the settlement of Capitella sp. I. Our results revealed that under hypoxic condition, settlement success and growth in body length of Capitella larvae were significantly reduced compared to those under normoxia of similar BDE-47 concentration. While no significant changes in morphology of settled larvae were noted in both exposure conditions, the presence of BDE-47 could enhance polychaete growth. The present findings demonstrated that the interactive effects of hypoxia and environmentally realistic concentrations of BDE-47 in sediments could affect polychaete settlement, which, in turn, reduce its recruitment and subsequent population size in the marine benthic ecosystem.  相似文献   

Topographic locations and size of earthquake‐ and typhoon‐generated landslides,Tachia River,Taiwan          下载免费PDF全文

Alice Y.‐L. Huang  David R. Montgomery 《地球表面变化过程与地形》2014,39(3):414-418

Analysis of mapped landslide locations using a high‐resolution (5‐m grid) digital elevation model (DEM) in the Tachia River basin, Taiwan, finds distinct differences in the topographic locations and size of landslides during the 1999 Chi‐Chi earthquake and the 2001 Toraji typhoon. Our analysis supports Densmore and Hovius' hypothesis that earthquake‐induced landslides cluster near ridgetops due to topographic amplification of ground shaking, and that typhoon‐induced landslides occur with greater frequency lower on slopes. In addition, the differing topographic locations of seismically‐induced and subsequent typhoon‐induced landslides shows no evidence of residual post‐earthquake influences on landslides during typhoon Toraji previously hypothesized for drainage basins closer to the earthquake epicenter. Our results support the interpretation that in this tectonically active landscape, seismically‐induced landslides help shatter and erode ridgetops but typhoon‐triggered landslides concentrate erosion farther downslope, with the combination acting to more uniformly lower upland terrain than either process does individually. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

The ultraviolet spectrum of the gravitationally lensed galaxy 'the Cosmic Horseshoe': a close-up of a star-forming galaxy at z∼ 2     

Anna M. Quider  Max Pettini  Alice E. Shapley  Charles C. Steidel 《Monthly notices of the Royal Astronomical Society》2009,398(3):1263-1278

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Relationships between cut-off lows and the semiannual and southern oscillations     

Alice Favre  Bruce Hewitson  Mark Tadross  Christopher Lennard  Ruth Cerezo-Mota 《Climate Dynamics》2012,38(7-8):1473-1487

The characteristics of Southern Cut-off Lows (CoLs) are studied for the period 1979–2008. The systematic identification of CoLs is realized by applying an original automated scheme using mean daily geopotential height and air temperature at 500?hPa NCEP-DOE II Reanalysis data. From closed lows’ trajectories established from the Equator to the polar jet stream, extratropical lows are analyzed and the stage of cut-off is defined as a secluded low presenting a cold core. From 4,843 cases the general CoL features are presented and confirm several previous results such as the geographic distribution which shows that they are more frequent in the latitudinal band contained between 20°S and 45°S and in close proximity to the continents. On a seasonal time scale, CoLs are more numerous from late summer to autumn, with a maximum of frequency in March/April. In winter (June–July–August), they are fewer but deeper than during the rest of the year. In the median domain (~32.5°S), the annual cycle of the frequency is bimodal and present two peaks during transitional seasons. In this zone, the seasonal cycle varies in accordance with the Semiannual Oscillation. Thereby, when the meridional gradient of temperature/pressure is reinforced between mid and high latitudes, CoLs are more frequent in the median domain. Over the period 1979–2008, the annual CoLs’ frequency exhibits a positive trend of about 25%. This increase is associated with a widening of the latitudinal domain of occurrence equatorward as well as poleward. The trend is linked with an abrupt positive shift in the number of CoLs’ generation between 1998 and 1999. The geographical distribution of CoLs frequency varies significantly in accordance with El Ni?o Southern Oscillation with more CoL’s at lower (higher) latitudes during La Ni?a (El Ni?o) events, principally in the Southern Pacific.  相似文献   

Determinants of poverty: lessons from Kenya     

Alice Atieno Oluoko-Odingo 《GeoJournal》2009,74(4):311-331

Poverty and food security are twin concerns of Kenya in a manner similar to many affected developing countries. It is characterized by the inability of the affected households in the country to acquire and retain sustainable livelihoods. The picture in Kenya is bound to be complicated by the projected changes in climate, as well as by population increase and environmental degradation, all which will put pressure on the natural resource base and militate against the achievement of sustainable development. The poverty picture in Kenya has hardly changed since independence over four decades ago despite the enormous resources and efforts which have been directed at tackling it. The current national poverty level remains high at well over 70% in some pockets which remain particularly vulnerable. Following the recent post-election violence, there is now a fear that the situation could degenerate into famine conditions and further hopelessness for a sizeable proportion of the rural population. Government efforts to eradicate poverty and food insecurity spelled out in a thirty year development plan are unlikely to succeed unless underlying causes of inequality are properly addressed. The paper contains suggestions for new approaches to addressing the twin problems.  相似文献   

Prediction of future short-term stream chemistry — a modelling approach     

Colin Neal  Alice Robson  Brian Reynolds  Alan Jenkins 《Journal of Hydrology》1992,130(1-4):87-103

The problem of predicting future short-term chemical behaviour in acidic and acid-sensitive streams is addressed. A relatively simple method is presented which combines a chemical technique for splitting the hydrograph into ground water and soil water components, based on the conservative component acid neutralization capacity, with the long-term hydrochemical model (MAGIC) in a ‘two-box’ mode. This method, coupled with a chemical speciation program (ALCHEMI), is used to assess short-term variations in stream chemistry with change in atmospheric deposition chemistry. The method is applied for a semi-natural moorland catchment in mid-Wales (Afon Gwy). For both hydrogen ion and inorganic aluminium, the modelled stream mixing relationships are non-linear, particularly at low hydrogen ion concentrations. The results also show that the relationship between hydrogen ion and inorganic aluminium concentrations varies with time in the stream. This result has important implications as it implies that aluminium concentrations will not recover, with reduced anthropogenic sulphur deposition, as rapidly as has previously been thought. Two methods, for use with critical load evaluation of ecological stress, are presented for describing the changes occurring: the hydrogen ion and inorganic aluminium concentration duration curve; the hydrogen ion and inorganic aluminium incident frequenty diagram.  相似文献