Commentary: Task-Switching in Pigeons: Associative Learning or Executive Control?

A commentary on Task-Switching in Pigeons: Associative Learning or Executive Control? by Meier, C., Lea, S., and McLaren, I. (2016). J. Exp. Psychol. Anim. Learn. Cogn. 42, 163–176. doi: 10.1037/xan000010

How to perform aggregometry and lumi-aggregometry in mouse platelets

Light transmission aggregometry (LTA) and lumi-aggregometry are the gold standard platelet assays both clinically and for basic research. The availability of different strains of genetically modified mice, and mouse models of human disease means that often laboratories need to use mouse platelets in these assays. Overall, performing aggregometry and lumi-aggregometry with mouse platelets is similar to with human platelets, although methods need be adapted to accommodate their small size, reduced blood volume and different protein levels. This review aims to highlight these key considerations when planning aggregometry experiments with mouse platelets. These include the method of taking blood, including the use of anticoagulants, as well as the method of platelet preparation, and how to maximise yields. This review also covers how to maximise the number of aggregations that can be performed, both by understanding the minimum requirements of your aggregometer, or by considering new approaches. These include employing high throughput plate-based aggregometry (Optimul), or the use of TPO-mimetics to stimulate platelet production in mice to boost their platelet counts. Finally, phenotypic differences between mouse and human platelets, such as protein expression or sensitivity to agonists is discussed as an important consideration when planning experiments

Decoherence by a chaotic many-spin bath

We numerically investigate decoherence of a two-spin system (central system) by a bath of many spins 1/2. By carefully adjusting parameters, the dynamical regime of the bath has been varied from quantum chaos to regular, while all other dynamical characteristics have been kept practically intact. We explicitly demonstrate that for a many-body quantum bath, the onset of quantum chaos leads to significantly faster and stronger decoherence compared to an equivalent non-chaotic bath. Moreover, the non-diagonal elements of the system's density matrix decay differently for chaotic and non-chaotic baths. Therefore, knowledge of the basic parameters of the bath (strength of the system-bath interaction, bath's spectral density of states) is not always sufficient, and much finer details of the bath's dynamics can strongly affect the decoherence process.Comment: 4 pages, RevTeX, 5 eps figure

Illusory Increases in Font Size Improve Letter Recognition

Visual performance of human observers depends not only on the optics of the eye and early sensory encoding but also on subsequent cortical processing and representations. In two experiments, we demonstrated that motion adaptation can enhance as well as impair visual acuity. Observers who experienced an expanding motion aftereffect exhibited improved letter recognition, whereas observers who experienced a contracting motion aftereffect showed impaired letter recognition. We conclude that illusory enlargement and shrinkage of a visual stimulus can modulate visual acuity

Cooper problem in the vicinity of Anderson transition

We study numerically the ground state properties of the Cooper problem in the three-dimensional Anderson model. It is shown that attractive interaction creates localized pairs in the metallic noninteracting phase. This localization is destroyed at sufficiently weak disorder. The phase diagram for the delocalization transition in the presence of disorder and interaction is determined.Comment: revtex, 4 pages, 4 figure

2-Chloro-6,6-dimethyl-5,6-dihydro­indazolo[2,3-c]quinazoline

Two independent but virtually identical mol­ecules comprise the asymmetric unit of the title compound, C16H14ClN3. The mol­ecules have a slightly curved shape owing to puckering in the six-membered C4N2 ring; the respective dihedral angles formed between the benzene rings are 12.64 (7) and 11.72 (7)°. In the crystal, layers sustained by a combination of N—H⋯N hydrogen bonding as well as C—H⋯N and C—H⋯π contacts are formed; these stack along [011] and are connected by further C—H⋯π contacts

Transition to an Insulating Phase Induced by Attractive Interactions in the Disordered Three-Dimensional Hubbard Model

We study numerically the interplay of disorder and attractive interactions for spin-1/2 fermions in the three-dimensional Hubbard model. The results obtained by projector quantum Monte Carlo simulations show that at moderate disorder, increasing the attractive interaction leads to a transition from delocalized superconducting states to the insulating phase of localized pairs. This transition takes place well within the metallic phase of the single-particle Anderson model.Comment: revtex, 4 pages, 3 figure