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Environmental Attitudes in Cross-National Perspective: A Multilevel Analysis of the ISSP 1993 and 2000
Item type: Journal Article
Franzen, Axel; Meyer, Reto (2010)
This article discusses the determinants and the development of public concern for the state of the natural environment. First, we review some theoretical approaches that try to explain individual as well as cross-national differences in environmental attitudes. Particularly, we discuss Inglehart's theory of post-materialism, Dunlap and Mertig's globalization explanation, and the prosperity hypothesis. Second, we test these hypotheses by applying multilevel analysis to the International Social Survey Programme (ISSP) data from the years 1993 and 2000. The results support, above all, the prosperity hypothesis. Individuals with higher relative income within countries display higher levels of environmental concern than their compatriots, and additionally, more concern is reported in wealthier countries than in poorer nations. The results indicate that environmental concern is also closely associated with post-materialistic attitudes and various socio-demographic variables. Comparing the environmental concern measured in the ISSP in 1993 with that in 2000 shows that environmental concern has more or less stabilized since the early 1990s in the countries under scrutiny.
The location of halo formation and the peaks formalism
Item type: Journal Article
Hahn, Oliver; Paranjape, Aseem (2014)
We investigate the problem of predicting the halo mass function from the properties of the Lagrangian density field. We focus on a perturbation spectrum with a small-scale cut-off (as in warm dark matter cosmologies). This cut-off results in a strong suppression of low-mass objects, providing additional leverage to rigorously test which perturbations collapse and to what mass. We find that all haloes are consistent with forming near peaks of the initial density field, with a strong correlation between protohalo density and ellipticity. We demonstrate that, while standard excursion set theory with correlated steps completely fails to reproduce the mass function, the inclusion of the peaks constraint leads to the correct number of haloes but significantly underpredicts the masses of low-mass objects (with the predicted halo mass function at low masses behaving like dn/d ln m ∼ m2/3). This prediction is very robust and cannot be easily altered within the framework of a single collapse barrier. The nature of collapse in the presence of a small-scale cut-off thus reveals that excursion set calculations require a more detailed understanding of the collapse-time of a general ellipsoidal perturbation to predict the ultimate collapsed mass of a peak – a problem that has been hidden in the large abundance of small-scale structure in cold dark matter. We demonstrate how this problem can be resolved within the excursion set framework.
Genomic Profiles of Diversification and Genotype-Phenotype Association in Island Nematode Lineages
Item type: Journal Article
McGaughran, Angela; Rödelsperger, Christian; Grimm, Dominik G.; et al. (2016)
Understanding how new species form requires investigation of evolutionary forces that cause phenotypic and genotypic changes among populations. However, the mechanisms underlying speciation vary and little is known about whether genomes diversify in the same ways in parallel at the incipient scale. We address this using the nematode, Pristionchus pacificus, which resides at an interesting point on the speciation continuum (distinct evolutionary lineages without reproductive isolation), and inhabits heterogeneous environments subject to divergent environmental pressures. Using whole genome re-sequencing of 264 strains, we estimate FST to identify outlier regions of extraordinary differentiation (∼1.725 Mb of the 172.5 Mb genome). We find evidence for shared divergent genomic regions occurring at a higher frequency than expected by chance among populations of the same evolutionary lineage. We use allele frequency spectra to find that, among lineages, 53% of divergent regions are consistent with adaptive selection, whereas 24% and 23% of such regions suggest background selection and restricted gene flow, respectively. In contrast, among populations from the same lineage, similar proportions (34–48%) of divergent regions correspond to adaptive selection and restricted gene flow, whereas 13–22% suggest background selection. Because speciation often involves phenotypic and genomic divergence, we also evaluate phenotypic variation, focusing on pH tolerance, which we find is diverging in a manner corresponding to environmental differences among populations. Taking a genome-wide association approach, we functionally validate a significant genotype–phenotype association for this trait. Our results are consistent with P. pacificus undergoing heterogeneous genotypic and phenotypic diversification related to both evolutionary and environmental processes.
Foundations for a multiscale collaborative global Earth model
Item type: Journal Article
Afanasiev, Michael; Ermert, Laura; Peter, Daniel; et al. (2016)
We present a computational framework for the assimilation of local to global seismic data into a consistent model describing Earth structure on all seismically accessible scales. This Collaborative Seismic Earth Model (CSEM) is designed to meet the following requirements: (i) Flexible geometric parametrization, capable of capturing topography and bathymetry, as well as all aspects of potentially resolvable structure, including small-scale heterogeneities and deformations of internal discontinuities. (ii) Independence of any particular wave equation solver, in order to enable the combination of inversion techniques suitable for different types of seismic data. (iii) Physical parametrization that allows for full anisotropy and for variations in attenuation and density.While not all of these parameters are always resolvable, the assimilation of data that constrain any parameter subset should be possible. (iv) Ability to accommodate successive refinements through the incorporation of updates on any scale as new data or inversion techniques become available. (v) Enable collaborative Earth model construction. The structure of the initial CSEM is represented on a variable-resolution tetrahedral mesh. It is assembled from a long-wavelength 3-D global model into which several regional-scale tomographies are embedded. We illustrate the CSEM workflow of successive updating with two examples from Japan and the Western Mediterranean, where we constrain smaller scale structure using full-waveforminversion. Furthermore, we demonstrate the ability of the CSEM to act as a vehicle for the combination of different tomographic techniques with a joint fullwaveformand traveltime ray tomography of Europe. This combination broadens the exploitable frequency range of the individual techniques, thereby improving resolution. We perform two iterations of a whole-Earth full-waveform inversion using a long-period reference data set from 225 globally recorded earthquakes. At this early stage of the CSEM development, the broad global updates mostly act to remove artefacts from the assembly of the initial CSEM. During the future evolution of the CSEM, the reference data set will be used to account for the influence of small-scale refinements on large-scale global structure. The CSEM as a computational framework is intended to help bridging the gap between local, regional and global tomography, and to contribute to the development of a global multiscale Earth model. While the current construction serves as a first proof of concept, future refinements and additions will require community involvement, which is welcome at this stage already.
Cores of random graphs are born Hamiltonian
Item type: Journal Article
Krivelevich, Michael; Lubetzky, Eyal; Sudakov, Benny (2014)