Tetartohedral crystal twinning is discussed as a particular case of (pseudo)merohedral twinning when the number of twinned domains is four. Tetartohedrally twinned crystals often possess pseudosymmetry, with the rotational part of the pseudosymmetry operators coinciding with the twinning operators. Tetartohedrally twinned structures from the literature are reviewed and the recent structure dete...

LetN be a normal subgroup of a groupG and let p be a prime. We prove that if the p-part of jx j is a constant for every prime-power order element x 2 N n Z.N /, then N is solvable and has normal p-complement.

While nature is widely acknowledged to contribute to people's well-being, nature based well-being indicators at city-level appear to be underprovided. This study aims at filling this gap by introducing a novel indicator based on the proximity of city-residents to nature that is of high-amenity. High-amenity nature is operationalized by combining unique systematic data on people's perceptions of...

Classification image analysis is a psychophysical technique in which noise components of stimuli are analyzed to produce an image that reveals critical features of a task. Here we use classification images to gain greater understanding of perceptual learning. To achieve reasonable classification images within a single session, we developed an efficient classification image procedure that employ...

A local system, defined on the complement of a divisor Z ⊆ X in a complex manifold, can in general not be extended to all of X because of local monodromy. This paper describes the construction of a normal analytic space that naturally extends the étale space T of the local system, in the case when Z is a divisor with normal crossings and the local system has unipotent local monodromy.

Recently, genome-wide association studies have substantially expanded our knowledge about genetic variants that influence the susceptibility to complex diseases. Although standard statistical tests for each single-nucleotide polymorphism (SNP) separately are able to capture main genetic effects, different approaches are necessary to identify SNPs that influence disease risk jointly or in comple...

In a recent paper, Manning et al. (Popul Res Policy Rev 23:135–139, 2004) examine the stability of marital and cohabiting unions from the perspective of children and find that children born to cohabiting parents are more likely to experience a parental separation than children born to married parents. They find, further, that subsequent marriage among cohabiting parents is associated with incre...