Diversification of clearwing butterflies with the rise of the Andes

Aim Despite the greatest butterfly diversity on Earth occurring in the Neotrop- ical Andes and Amazonia, there is still keen debate about the origins of this exceptional biota. A densely sampled calibrated phylogeny for a widespread butterfly subtribe, Oleriina (Nymphalidae: Ithomiini) was used to estimate the origin, colonization history and diversification of this species-rich group. Location Neotropics. Methods Ancestral elevation and biogeographical ranges were reconstructed using data generated from detailed range maps and applying the dispersal-ex- tinction-cladogenesis model using stratified palaeogeographical time slice matrices. The pattern of diversification through time was examined by compar- ing constant and variable rate models. We also tested the hypothesis that a change in elevation is associated with speciation. Results The Oleriina likely originated in the Andes in the Early to Middle Miocene and rapidly diversified to include four genera all of which also origi- nated in the Andes. These clades, together with four species groups, experi- enced varying spatial and temporal patterns of diversification. An overall early burst and decreasing diversification rate is identified, and this pattern is reflected for most subclades. Main conclusions Changes in the palaeogeological landscape, particularly the prolonged uplift of the Andes, had a profound impact on the diversification of the subtribe. The Oleriina mostly remained within the Andes and vicariant spe- ciation resulted in some instances. Dynamic dispersal occurred with the disap- pearance of geological barriers such as the Acre System and the subtribe exploited newly available habitats. Our results confirm the role of the Andean uplift in the evolution of Neotropical biodiversity

Rotation symmetry breaking in La2−xSrxCuO4{\mathrm{La}}_{2-x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4} revealed by angle-resolved photoemission spectroscopy

Using angle-resolved photoemission spectroscopy it is revealed that in the vicinity of optimal doping the electronic structure of La2−xSrxCuO4 cuprate undergoes an electronic reconstruction associated with a wave vector qa=(π,0). The reconstructed Fermi surface and folded band are distinct to the shadow bands observed in BSCCO cuprates and in underdoped La2−xSrxCuO4 with x≤0.12, which shift the primary band along the zone diagonal direction. Furthermore, the folded bands appear only with qa=(π,0) vector, but not with qb=(0,π). We demonstrate that the absence of qb reconstruction is not due to the matrix-element effects in the photoemission process, which indicates the fourfold symmetry is broken in the system

Speed/Accuracy Trade-Off between the Habitual and the Goal-Directed Processes

Instrumental responses are hypothesized to be of two kinds: habitual and goal-directed, mediated by the sensorimotor and the associative cortico-basal ganglia circuits, respectively. The existence of the two heterogeneous associative learning mechanisms can be hypothesized to arise from the comparative advantages that they have at different stages of learning. In this paper, we assume that the goal-directed system is behaviourally flexible, but slow in choice selection. The habitual system, in contrast, is fast in responding, but inflexible in adapting its behavioural strategy to new conditions. Based on these assumptions and using the computational theory of reinforcement learning, we propose a normative model for arbitration between the two processes that makes an approximately optimal balance between search-time and accuracy in decision making. Behaviourally, the model can explain experimental evidence on behavioural sensitivity to outcome at the early stages of learning, but insensitivity at the later stages. It also explains that when two choices with equal incentive values are available concurrently, the behaviour remains outcome-sensitive, even after extensive training. Moreover, the model can explain choice reaction time variations during the course of learning, as well as the experimental observation that as the number of choices increases, the reaction time also increases. Neurobiologically, by assuming that phasic and tonic activities of midbrain dopamine neurons carry the reward prediction error and the average reward signals used by the model, respectively, the model predicts that whereas phasic dopamine indirectly affects behaviour through reinforcing stimulus-response associations, tonic dopamine can directly affect behaviour through manipulating the competition between the habitual and the goal-directed systems and thus, affect reaction time

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Abstract: A photovoltaic/thermal (PV/T) device is a combined solar thermal device and photovoltaic device in a single unit. The capability of PV/T devices to produce thermal energy and electricity simultaneously bestows them promising market value in near future. The higher specific heat and lower fluctuation during variation irradiance of liquid compared to air make liquid-based devices more advantageous. This study reviews the available literature on flat plate, water-based PV/T collectors, conducts an economic analysis and discusses future development. Detailed analysis of the performance of the device is also included, in terms of thermal, electrical and overall efficiency. Previous experimental work and simulations are also reported, including several selected case studies. Some of the drawbacks need to be solved to make water-based PV/T systems cost effective and ready for the market