52 research outputs found
Hamiltonian submanifolds of regular polytopes
We investigate polyhedral -manifolds as subcomplexes of the boundary
complex of a regular polytope. We call such a subcomplex {\it -Hamiltonian}
if it contains the full -skeleton of the polytope. Since the case of the
cube is well known and since the case of a simplex was also previously studied
(these are so-called {\it super-neighborly triangulations}) we focus on the
case of the cross polytope and the sporadic regular 4-polytopes. By our results
the existence of 1-Hamiltonian surfaces is now decided for all regular
polytopes.
Furthermore we investigate 2-Hamiltonian 4-manifolds in the -dimensional
cross polytope. These are the "regular cases" satisfying equality in Sparla's
inequality. In particular, we present a new example with 16 vertices which is
highly symmetric with an automorphism group of order 128. Topologically it is
homeomorphic to a connected sum of 7 copies of . By this
example all regular cases of vertices with or, equivalently, all
cases of regular -polytopes with are now decided.Comment: 26 pages, 4 figure
Few smooth d-polytopes with n lattice points
We prove that, for fixed n there exist only finitely many embeddings of
Q-factorial toric varieties X into P^n that are induced by a complete linear
system. The proof is based on a combinatorial result that for fixed nonnegative
integers d and n, there are only finitely many smooth d-polytopes with n
lattice points. We also enumerate all smooth 3-polytopes with at most 12
lattice points. In fact, it is sufficient to bound the singularities and the
number of lattice points on edges to prove finiteness.Comment: 20+2 pages; major revision: new author, new structure, new result
Mental contrasting as a behaviour change technique: a systematic review protocol paper of effects, mediators and moderators on health
Background Mental contrasting is a self-regulation strategy that is required for strong goal commitment. In mental contrasting, individuals firstly imagine a desired future or health goal that contrasted with the reality proceeding the goal state, which after reflection is viewed as an obstacle (Oettingen et al. J Pers Soc Psychol 80:736–753, 2001). Mentally contrasting a positive future with reality enables individuals to translate positive attitudes and high efficacy into strong goal commitment. Methods A systematic review of the literature is proposed to explore the efficacy of mental contrasting as a behaviour change technique (Michie et al., Ann Behav Med 46: 81-95, 2013) for health. The review also aims to identify the effects of mental contrasting on health-related behaviour, as well as identifying mediator and moderator variables. Discussion This will be the first systematic review of mental contrasting as a health behaviour change technique. With sufficient studies, a meta-analysis will be conducted with sensitivity and sub group analyses. If meta-analysis is not appropriate, a narrative synthesis of the reviewed studies will be conducted. Systematic review registration Review protocol registered on PROSPERO reference CRD42016034202.N/
Permutonestohedra
There are several real spherical models associated with a root arrangement, depending on the choice of a building set. The connected components of these models are manifolds with corners which can be glued together to obtain the corresponding real De Concini–Procesi models. In this paper, starting from any root system with finite Coxeter group W and any W -invariant building set, we describe an explicit realization of the real spherical model as a union of polytopes (nestohedra) that lie inside the chambers of the arrangement. The main point of this realization is that the convex hull of these nestohedra is a larger polytope, a permutonestohedron, equipped with an action of W or also, depending on the building set, of Aut ( ). The permutonestohedra are natural generalizations of Kapranov’s permutoassociahedra
Flanker performance in female college students with ADHD: a diffusion model analysis
Attention-deficit hyperactivity disorder (ADHD) is characterized by poor adaptation to environmental demands, which leads to various everyday life problems. The present study had four aims: (1) to compare performance in a flanker task in female college students with and without ADHD (N = 39) in a classical analyses of reaction time and error rate and studying the underlying processes using a diffusion model, (2) to compare the amount of focused attention, (3) to explore the adaptation of focused attention, and (4) to relate adaptation to psychological functioning. The study followed a 2-between (group: ADHD vs. control) × 2-within (flanker conflict: incongruent vs. congruent) × 2-within (conflict frequency: 20 vs. 80 %) design. Compared to a control group, the ADHD group displayed prolonged response times accompanied by fewer errors in a flanker task. Results from the diffusion model analyses revealed that the members of the ADHD group showed deficits in non-decisional processes (i.e., higher non-decision time) and leaned more toward accuracy than participants without ADHD (i.e., setting higher boundaries). The ADHD group showed a more focused attention and less adaptation to the task conditions which is related to psychological functioning. Deficient non-decisional processes and poor adaptation are in line with theories of ADHD and presumably typical for the ADHD population, although this has not been shown using a diffusion model. However, we assume that the cautious strategy of trading speed of for accuracy is specific to the subgroup of female college students with ADHD and might be interpreted as a compensation mechanism
Maßnahmen und Strategien zur Unterrichtsgestaltung – nicht nur für Kinder mit ADHS. Übersetzt, angepasst und ergänzt von Bettine Reich, Caterina Gawrilow und Anke Zürcher
Objektive Bewegungsdaten als Grundlage für die Entwicklung digitaler Interventionen bei Kindern mit ADHS
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