1,203 research outputs found

    Shopping centre siting and modal choice in Belgium: a destination based analysis

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    Although modal split is only one of the elements considered in decision-making on new shopping malls, it remarkably often arises in arguments of both proponents and opponents. Today, this is also the case in the debate on the planned development of three major shopping malls in Belgium. Inspired by such debates, the present study focuses on the impact of the location of shopping centres on the travel mode choice of the customers. Our hypothesis is that destination-based variables such as embeddedness in the urban fabric, accessibility and mall size influence the travel mode choice of the visitors. Based on modal split data and location characteristics of seventeen existing shopping centres in Belgium, we develop a model for a more sustainable siting policy. The results show a major influence of the location of the shopping centre in relation to the urban form, and of the size of the mall. Shopping centres that are part of a dense urban fabric, measured through population density, are less car dependent. Smaller sites will attract more cyclists and pedestrians. Interestingly, our results deviate significantly from the figures that have been put forward in public debates on the shopping mall issue in Belgium

    Ecosystem decay of Amazonian forest fragments: a 22-year investigation

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    P E R M A N E N T G E N E T I C R E S O U R C E S N O T E 1265 Cell/Tissue Genomic DNA extraction kit (TianGen) and digested with MboI (Takara). Fragments of 400-1000bp were collected by TianGen Gel DNA Extraction Kit. Doublestranded MboI adapters, Linker A (5′-GATCGTCGACGG-TACCGAATTCT-3′) and Linker B (3′-CAGCTGCCAT-GGCTTAAGAACTG-5′) (250 pmol, excess) were ligated to DNA fragments with T4 DNA ligase (Takara) at 16°C overnight. Excess adapters were removed by washing on an Ultrafree column (Pall). DNA fragments were amplified 10 cycles with linker B and purified. The products were denatured and hybridized to biotin-labelled (CA) 12 , (GA) 12 , (ACA) 8 , (AGA) 8 , (GACA) 6 and (GATA) 6 oligo-nucleotides (mixed in advance at the ratio of 3:1:1:1:2:2) in 0.5X SSC at 68°C for 1 h. DNA fragments bound to these probes were captured with Promega Streptavidin MagneSphere® Paramagnetic Particles and eluted by DNase-free water after being washed four times in 0.1× SSC at room temperature, and then amplified for 10 cycles with Linker B. The enriched fragments were ligated to pGEM-T-easy vector (Promega) at 4°C overnight, and then transformed into Promega high-efficiency competent Escherichia coli cells (Dh5α), which were cultured on Luria-Bertani solid medium containing 100mg/mL ampicillin. One-hundred and ninety-nine white positive clones were picked and sequenced with the T7 primer on ABI 3730xl DNA analysers at the Shanghai Sangon Biological Engineering Technology & Services Co., Ltd. Sequences were screened for microsatellites containing at least six di-, five tri-, five tetra-, four penta-, three hexa-and three octa-nucleotide repeats using the software misa (http:/ /pgrc.ipk-gatersleben.de/misa/). One-hundred and twenty-six (excluding five duplicates) microsatellite-containing sequences were identified and consisted of 28.1% di-, 7.8% tri-, 22.7% tetra-, 6.3% penta-, 1.6% hexa-, 4.7% octa-nucleotide and 35.2% compound microsatellite repeats. Fifty-seven good sequences with sufficient flanking regions were selected for primer design with Primer 3 (http:/ /biotools.umassmed.edu/bioapps/ primer3_www.cgi). An M13 (-21) universal leading sequence (18bp) 5′-TGTAAAACGACGGCCAGT was added to the 5′ end of each forward primer listed in Observed (H O ) and expected (H E ) heterozygosities were calculated with arlequin 3.0 Three primer pairs RUSS33, RUSS47 and RUSS57 amplified more than two fragments per individual, suggesting that they belong to duplicated loci. RUSS33 amplified three to six fragments per individual with well-defined patterns. It can be explained by the amplification of a tandem mini-satellite repeat in a model of Fprimer-25bp-Fprimer75bp-Fprimer-(18bp)n-Rprimer. RUSS47 (and RUSS45, not presented here) had clusters of fragments that differed by 8bp, with a cluster-to-cluster distance of 145bp: Fprimer-[(8bp)n]N-Rprimer-145bp-Rprimer-145-Rprimer. RUSS57 amplified one monomorphic locus at 152 bp and another polymorphic locus. This is the first time that microsatellite markers have been developed for S. solidissima. Most of the markers developed here are highly polymorphic and in HWE. They should be useful in genetic studies on this important model and fishery species. Acknowledgemen

    An Amazonian rainforest and its fragments as a laboratory of global change

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    We synthesize findings from one of the world’s largest and longest-running experimental investigations, the Biological Dynamics of Forest Fragments Project (BDFFP). Spanning an area of ~1,000 km2 in central Amazonia, the BDFFP was initially designed to evaluate the effects of fragment area on rainforest biodiversity and ecological processes. However, over its 38-year history to date the project has far transcended its original mission, and now focuses more broadly on landscape dynamics, forest regeneration, regional- and global-change phenomena, and their potential interactions and implications for Amazonian forest conservation. The project has yielded a wealth of insights into the ecological and environmental changes in fragmented forests. For instance, many rainforest species are naturally rare and hence are either missing entirely from many fragments or so sparsely represented as to have little chance of long-term survival. Additionally, edge effects are a prominent driver of fragment dynamics, strongly affecting forest microclimate, tree mortality, carbon storage and a diversity of fauna. Even within our controlled study area, the landscape has been highly dynamic: for example, the matrix of vegetation surrounding fragments has changed markedly over time, succeeding from large cattle pastures or forest clearcuts to secondary regrowth forest. This, in turn, has influenced the dynamics of plant and animal communities and their trajectories of change over time. In general, fauna and flora have responded differently to fragmentation: the most locally extinction-prone animal species are those that have both large area requirements and low tolerance of the modified habitats surrounding fragments, whereas the most vulnerable plants are those that respond poorly to edge effects or chronic forest disturbances, and that rely on vulnerable animals for seed dispersal or pollination. Relative to intact forests, most fragments are hyperdynamic, with unstable or fluctuating populations of species in response to a variety of external vicissitudes. Rare weather events such as droughts, windstorms and floods have had strong impacts on fragments and left lasting legacies of change. Both forest fragments and the intact forests in our study area appear to be influenced by larger-scale environmental drivers operating at regional or global scales. These drivers are apparently increasing forest productivity and have led to concerted, widespread increases in forest dynamics and plant growth, shifts in tree-community composition, and increases in liana (woody vine) abundance. Such large-scale drivers are likely to interact synergistically with habitat fragmentation, exacerbating its effects for some species and ecological phenomena. Hence, the impacts of fragmentation on Amazonian biodiversity and ecosystem processes appear to be a consequence not only of local site features but also of broader changes occurring at landscape, regional and even global scales

    Jack superpolynomials with negative fractional parameter: clustering properties and super-Virasoro ideals

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    The Jack polynomials P_\lambda^{(\alpha)} at \alpha=-(k+1)/(r-1) indexed by certain (k,r,N)-admissible partitions are known to span an ideal I^{(k,r)}_N of the space of symmetric functions in N variables. The ideal I^{(k,r)}_N is invariant under the action of certain differential operators which include half the Virasoro algebra. Moreover, the Jack polynomials in I^{(k,r)}_N admit clusters of size at most k: they vanish when k+1 of their variables are identified, and they do not vanish when only k of them are identified. We generalize most of these properties to superspace using orthogonal eigenfunctions of the supersymmetric extension of the trigonometric Calogero-Moser-Sutherland model known as Jack superpolynomials. In particular, we show that the Jack superpolynomials P_{\Lambda}^{(\alpha)} at \alpha=-(k+1)/(r-1) indexed by certain (k,r,N)-admissible superpartitions span an ideal {\mathcal I}^{(k,r)}_N of the space of symmetric polynomials in N commuting variables and N anticommuting variables. We prove that the ideal {\mathcal I}^{(k,r)}_N is stable with respect to the action of the negative-half of the super-Virasoro algebra. In addition, we show that the Jack superpolynomials in {\mathcal I}^{(k,r)}_N vanish when k+1 of their commuting variables are equal, and conjecture that they do not vanish when only k of them are identified. This allows us to conclude that the standard Jack polynomials with prescribed symmetry should satisfy similar clustering properties. Finally, we conjecture that the elements of {\mathcal I}^{(k,2)}_N provide a basis for the subspace of symmetric superpolynomials in N variables that vanish when k+1 commuting variables are set equal to each other.Comment: 36 pages; the main changes in v2 are : 1) in the introduction, we present exceptions to an often made statement concerning the clustering property of the ordinary Jack polynomials for (k,r,N)-admissible partitions (see Footnote 2); 2) Conjecture 14 is substantiated with the extensive computational evidence presented in the new appendix C; 3) the various tests supporting Conjecture 16 are reporte

    The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

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    Beams of atoms and molecules are stalwart tools for spectroscopy and studies of collisional processes. The supersonic expansion technique can create cold beams of many species of atoms and molecules. However, the resulting beam is typically moving at a speed of 300-600 m/s in the lab frame, and for a large class of species has insufficient flux (i.e. brightness) for important applications. In contrast, buffer gas beams can be a superior method in many cases, producing cold and relatively slow molecules in the lab frame with high brightness and great versatility. There are basic differences between supersonic and buffer gas cooled beams regarding particular technological advantages and constraints. At present, it is clear that not all of the possible variations on the buffer gas method have been studied. In this review, we will present a survey of the current state of the art in buffer gas beams, and explore some of the possible future directions that these new methods might take

    Nonlinear Measures for Characterizing Rough Surface Morphologies

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    We develop a new approach to characterizing the morphology of rough surfaces based on the analysis of the scaling properties of contour loops, i.e. loops of constant height. Given a height profile of the surface we perform independent measurements of the fractal dimension of contour loops, and the exponent that characterizes their size distribution. Scaling formulas are derived and used to relate these two geometrical exponents to the roughness exponent of a self-affine surface, thus providing independent measurements of this important quantity. Furthermore, we define the scale dependent curvature and demonstrate that by measuring its third moment departures of the height fluctuations from Gaussian behavior can be ascertained. These nonlinear measures are used to characterize the morphology of computer generated Gaussian rough surfaces, surfaces obtained in numerical simulations of a simple growth model, and surfaces observed by scanning-tunneling-microscopes. For experimentally realized surfaces the self-affine scaling is cut off by a correlation length, and we generalize our theory of contour loops to take this into account.Comment: 39 pages and 18 figures included; comments to [email protected]

    Pioglitazone for secondary prevention after ischemic stroke and transient ischemic attack: Rationale and design of the Insulin Resistance Intervention after Stroke Trial

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    Background: Recurrent vascular events remain a major source of morbidity and mortality after stroke or transient ischemic attack (TIA). The IRIS Trial is evaluating an approach to secondary prevention based on the established association between insulin resistance and increased risk for ischemic vascular events. Specifically, IRIS will test the effectiveness of pioglitazone, an insulin-sensitizing drug of the thiazolidinedione class, for reducing the risk for stroke and myocardial infarction (MI) among insulin resistant, nondiabetic patients with a recent ischemic stroke or TIA. Design: Eligible patients for IRIS must have had insulin resistance defined by a Homeostasis Model Assessment-Insulin Resistance \u3e3.0 without meeting criteria for diabetes. Within 6 months of the index stroke or TIA, patients were randomly assigned to pioglitazone (titrated from 15 to 45 mg/d) or matching placebo and followed for up to 5 years. The primary outcome is time to stroke or MI. Secondary outcomes include time to stroke alone, acute coronary syndrome, diabetes, cognitive decline, and all-cause mortality. Enrollment of 3,876 participants from 179 sites in 7 countries was completed in January 2013. Participant follow-up will continue until July 2015. Summary: The IRIS Trial will determine whether treatment with pioglitazone improves cardiovascular outcomes of nondiabetic, insulin-resistant patients with stroke or TIA. Results are expected in early 2016

    Bodyweight Perceptions among Texas Women: The Effects of Religion, Race/Ethnicity, and Citizenship Status

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    Despite previous work exploring linkages between religious participation and health, little research has looked at the role of religion in affecting bodyweight perceptions. Using the theoretical model developed by Levin et al. (Sociol Q 36(1):157–173, 1995) on the multidimensionality of religious participation, we develop several hypotheses and test them by using data from the 2004 Survey of Texas Adults. We estimate multinomial logistic regression models to determine the relative risk of women perceiving themselves as overweight. Results indicate that religious attendance lowers risk of women perceiving themselves as very overweight. Citizenship status was an important factor for Latinas, with noncitizens being less likely to see themselves as overweight. We also test interaction effects between religion and race. Religious attendance and prayer have a moderating effect among Latina non-citizens so that among these women, attendance and prayer intensify perceptions of feeling less overweight when compared to their white counterparts. Among African American women, the effect of increased church attendance leads to perceptions of being overweight. Prayer is also a correlate of overweight perceptions but only among African American women. We close with a discussion that highlights key implications from our findings, note study limitations, and several promising avenues for future research
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