12,562 research outputs found

    A REVISION OF THE AFRICAN GENERA PAROPSIOPSIS AND SMEATHMANNIA (PASSIFLORACEAE - PAROPSIEAE), INCLUDING A NEW SPECIES OF PAROPSIOPSIS FROM CAMEROON

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    The African genera Paropsiopsis Engl. and Smeathmannia R.Br. (Passifloraceae - Paropsieae) are revised. The two genera are well separated based on the presence or absence of a second, annuliform, corona, as well as the number of stamens and curvature of their filaments. An overview of important characters and a key to all genera of Paropsieae is provided. In Paropsiopsis all previously recognised species are united under P. decandra (Baill.) Sleumer. In addition one species, Paropsiopsis atrichogyna J.M.de Vos & Breteler, is newly described and illustrated. In Smeathmannia both previously recognised species are maintained, but infraspecific taxa are rejected. Descriptions of both genera and their species, keys to species, illustrations and distribution maps are provide

    The Impact Of Tax Benefit Systems On Low Income Households In The Benelux Countries. A Simulation Approach Using Synthetic Datasets

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    Computing the tax-benefit position of similar typical households across countries is a method widely used in comparative fiscal- and social policy research. These calculations provide convenient summary pictures of certain aspects of tax-benefit systems. They can, however, be seriously misleading because they reduce very complex systems to single point estimates. Using an integrated European tax-benefit model (EUROMOD), we substitute the typical household by a synthetic dataset, which can be used across countries. By varying certain important household characteristics (notably income), this dataset captures a much larger range of household situations. The calculations performed on this range of households not only show the tax-benefit position of many individual households but also demonstrate which household characteristics determine taxes and benefits in each country. Hypothetical calculations such as those presented here do not exploit the ability of EUROMOD to determine the impact of social and fiscal policies on actual populations. Nevertheless, they can be a valuable contribution to understanding tax-benefit systems since they allow us to separate the effects of tax-benefit rules from those of the population structure. We compute and compare disposable incomes for a large range of pre-tax-and-benefit income (so called budget constraints) of households in the Benelux countries. Disposable incomes are then decomposed to separately show the effects of each simulated tax and transfer payment. Based on these results, we illustrate the performance of the three tax-benefit systems in terms of ensuring a minimum level of household income.European Union, Microsimulation, Poverty, Benelux, Average Production Worker

    Effects of changing travel patterns on travel satisfaction: A focus on recently relocated residents

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    Previous studies indicate that travel satisfaction is affected by elements such as travel mode choice and trip duration. However, how people’s satisfaction levels with travel adapt after changing their travel behaviour has not yet been analysed thoroughly. In this study we analyse travel satisfaction of 1650 respondents who recently relocated to selected neighbourhoods in the city of Ghent (Belgium), and therefore changed their daily travel patterns (i.e., commute and leisure trips). Based on a two-step approach, i.e., a factor analysis followed by a cluster analysis, respondents are segmented into four clusters based on their changes in travel behaviour after they moved. Results indicate that especially clusters with respondents that decreased travel distance and duration, and increased the use of car alternatives have high levels of travel satisfaction, for both commute trips and leisure trips. Respondents from these clusters also indicated the highest levels of travel satisfaction improvements. This study provides additional motivation for policy makers and urban planners to convince more people to relocate to urban areas, or for densification and land use mixing of existing neighbourhoods, as this will not only result in more sustainable travel patterns, but also in more satisfying travel patterns

    An eccentric companion at the edge of the brown dwarf desert orbiting the 2.4 Msun giant star HIP67537

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    We report the discovery of a substellar companion around the giant star HIP67537. Based on precision radial velocity measurements from CHIRON and FEROS high-resolution spectroscopic data, we derived the following orbital elements for HIP67537 b\,b: mb_bsinii = 11.1−1.1+0.4^{+0.4}_{-1.1} Mjup_{\rm {\tiny jup}}, aa = 4.9−0.13+0.14^{+0.14}_{-0.13} AU and ee = 0.59−0.02+0.05^{+0.05}_{-0.02}. Considering random inclination angles, this object has ≳\gtrsim 65% probability to be above the theoretical deuterium-burning limit, thus it is one of the few known objects in the planet to brown-dwarf transition region. In addition, we analyzed the Hipparcos astrometric data of this star, from which we derived a minimum inclination angle for the companion of ∌\sim 2 deg. This value corresponds to an upper mass limit of ∌\sim 0.3 M⊙_\odot, therefore the probability that HIP67537 b\,b is stellar in nature is â‰Č\lesssim 7%. The large mass of the host star and the high orbital eccentricity makes HIP67537 b\,b a very interesting and rare substellar object. This is the second candidate companion in the brown dwarf desert detected in the sample of intermediate-mass stars targeted by the EXPRESS radial velocity program, which corresponds to a detection fraction of ff = 1.6−0.5+2.0^{+2.0}_{-0.5}%. This value is larger than the fraction observed in solar-type stars, providing new observational evidence of an enhanced formation efficiency of massive substellar companions in massive disks. Finally, we speculate about different formation channels for this object.Comment: Accepted for publication to A&

    Ultrafast optical switching of three-dimensional Si inverse opal photonic band gap crystals

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    We present ultrafast optical switching experiments on 3D photonic band gap crystals. Switching the Si inverse opal is achieved by optically exciting free carriers by a two-photon process. We probe reflectivity in the frequency range of second order Bragg diffraction where the photonic band gap is predicted. We find good experimental switching conditions for free-carrier plasma frequencies between 0.3 and 0.7 times the optical frequency: we thus observe a large frequency shift of up to D omega/omega= 1.5% of all spectral features including the peak that corresponds to the photonic band gap. We deduce a corresponding large refractive index change of Dn'_Si/n'_Si= 2.0% and an induced absorption length that is longer than the sample thickness. We observe a fast decay time of 21 ps, which implies that switching could potentially be repeated at GHz rates. Such a high switching rate is relevant to future switching and modulation applications

    Examining the spatially heterogeneous effects of the built environment on walking among older adults

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    Understanding the relationship between the built environment and walking among older adults could offer important insights for land use and transport policies which seek to promote active ageing. However, most previous studies have explored global relationships, i.e. the effects are averaged or assumed to be constant over the region of interest. In this study, we focus on the local spatial variations in the relationship between the built environment and the daily time spent walking by older adults. We apply a geographically weighted regression (GWR) model, using data collected from 702 older adults in Nanjing, China. Our results show that spatial heterogeneity exists for built environment effects within the entire study area. It has an impact on all the relationships, with nuances in the significance level, parameter magnitude or sign reversals, depending on the location. Therefore, policy interventions would only be effective in certain areas for certain built environment attributes. By exploring the local contexts of relationships, we further suggest that the spatial heterogeneity stems from contextual effects, i.e. the specificities of places with a discriminative composition of individual and/or environmental characteristics. Our findings can help to enrich the understanding of associations between land use and travel behaviour, as well as offer local planning guidance for creating age-friendly neighbourhoods

    Do e-shopping attitudes mediate the effect of the built environment on online shopping frequency of e-shoppers?

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    It is widely acknowledged that e-shopping has considerable effects on e-shoppers’ travel behavior. Therefore, it is valuable to investigate the built environment effects on online shopping, which can help clarify whether land use policy is effective to manage online shopping and further moderate travel demand. However, this issue has not been fully investigated in prior research. In particular, some existing studies fail to identify a significant link between the built environment and online shopping. One of the possible reasons is that the indirect effects of the built environment on e-shopping through e-shopping attitudes are rarely considered. Against this backdrop, considering the mediating role of e-shopping attitudes, this paper aims to explore the influence of the built environment on the frequency of e-shopping for clothes and shoes, food and drinks, cosmetics, and electronics. Data used in this study are acquired from 675 face-to-face interviews with online buyers in Chengdu, China, and the Structural Equation Modeling method is employed. The outcomes show that higher residential density has a positive impact on online shopping frequency. Higher accessibility to metro stations has an indirect and negative influence on e-shopping frequency through pro-e-shopping attitudes. In contrast, mediated by e-shopping attitudes, higher accessibility to bus stations has an indirect and positive impact on online shopping frequency. The mediating role of attitudes provides a possible explanation for the influences of transportation accessibility on e-shopping frequency. Land use policies seem influential in online shopping attitudes and frequency, and thus moderate e-shoppers’ travel demand

    Understanding dyadic promoter-stakeholder relations in complex projects

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    In this study, we propose a Bilateral Double Motive framework of stakeholder cooperation in complex projects. The framework analyses and explains dyadic promoter-stakeholder relationships at a micro level by acknowledging both transactional and relational motives. We demonstrate the framework’s usefulness by illustrating its explanatory power in two instances of cooperation and two of non-cooperation within two health information technology projects. The study contributes to project management theory through its combined focus on transactional and relational motives. Further, the study contributes to practice by providing a tool for planning and evaluating cooperation in health Information Technology projects and similar complex multi-stakeholder environments
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