A danger foreseen is a danger avoided: how chemical cues of different tadpoles influence parental decisions of a Neotropical poison frog

The protection of offspring against predators and competitors is especially important in organisms using spatially separated breeding resources, impeding the offspring’s chances to escape. One example of such isolated reproductive resources are phytotelmata (small water bodies in plant axils), exploited by the Neotropical poison frog Ranitomeya variabilis (Dendrobatidae) for both clutch and tadpole deposition. Because poison frog tadpoles are often cannibalistic, parents tend to avoid deposition with conspecifics. Previous studies have shown that this avoidance is based on chemical cues produced by conspecific tadpoles. Further, cues produced by phylogenetically less-related tadpoles (Bufonidae) were avoided for clutch but not tadpole depositions. We analyzed how the different responses to tadpole cues are triggered. We tested the reactions of parental R. variabilis to tadpole cues of species differing in two aspects: whether or not they are dendrobatids, and whether or not they reproduce in phytotelmata. We found that for clutch deposition, tadpole cues were always avoided, i.e., all tadpoles were treated by the frogs as if they pose a danger to the eggs. However, responses varied for tadpole depositions: while dendrobatid larvae living in phytotelmata were avoided, those breeding in streams were not. Non-poison frog tadpoles were ignored when associated with habitat other than phytotelmata, but they were preferred when living in phytotelmata. This suggests that both phylogeny and tadpole habitat are important triggers for the decisions made by R. variabilis. Only tadpoles using the same breeding resources are considered as relevant for the frog’s own larvae (i.e., as a potential danger or food resource), while further decisions are related to evolutionary relationship.     

Set-Point Theory and Societal Collapse: The Case of Russia

Can a society’s overall level of happiness change? Until recently, it was widely held that happiness fluctuates around set-points, so that neither individuals nor societies can lastingly increase their happiness. However, data from surveys carried out in Russia from 1982 to 2011 show that happiness fell substantially following the collapse of the Soviet Union, and has begun to rise again only recently. Additional data sources, including suicide rates and indices of negative affect expression, confirm these shifts. Contrary to set-point theory, we find that the recent increase has been driven as much by generational replacement as by mean reversion among individuals. The collapse of communism led to a permanent drop in subjective wellbeing among mid-life cohorts that was subsequently never fully recovered. Happiness can be substantially and permanently impacted by life-events, including those affecting society as a whole, and societal-level happiness can rise or fall over time as a result.     

Interpolation in 16-Valued Trilattice Logics

In a recent paper we have defined an analytic tableau calculus \({{\mathbf {\mathsf{{PL}}}}}_{\mathbf {16}}\) for a functionally complete extension of Shramko and Wansing’s logic based on the trilattice \({SIXTEEN}_3\). This calculus makes it possible to define syntactic entailment relations that capture central semantic relations of the logic—such as the relations Open image in new window , Open image in new window , and Open image in new window that each correspond to a lattice order in \({SIXTEEN}_3\); and Open image in new window , the intersection of Open image in new window and Open image in new window . It turns out that our method of characterising these semantic relations—as intersections of auxiliary relations that can be captured with the help of a single calculus—lends itself well to proving interpolation. All entailment relations just mentioned have the interpolation property, not only when they are defined with respect to a functionally complete language, but also in a range of cases where less expressive languages are considered. For example, we will show that Open image in new window , when restricted to \(\mathcal {L}_{tf}\), the language originally considered by Shramko and Wansing, enjoys interpolation. This answers a question that was recently posed by M. Takano.     

The impact of concurrent visual feedback on coding of on-line and pre-planned movement sequences

The purpose of this study was to determine the extent to which participants could effectively switch from on-line (OL) to pre-planned (PP) control (or vice versa) depending on previous practice conditions and whether concurrent visual feedback was available during transfer testing. The task was to reproduce a 2000 ms spatial–temporal pattern of a sequence of elbow flexions and extensions. Participants were randomly assigned to one of two practice conditions termed OL or PP. In the OL condition the criterion waveform and the cursor were provided during movement production while this information was withheld during movement production for the PP condition. A retention test and two effector transfer tests were administered to half of the participants in each acquisition conditions under OL conditions and the other half under PP conditions. The mirror effector transfer test required the same pattern of muscle activation and limb joint angles as required during acquisition. The non-mirror transfer test required movements to the same visual–spatial locations as experienced during acquisition. The results indicated that when visual information was available during the transfer tests performers could switch from PP to OL. When visual information was withdrawn, they shifted from the OL to the PP-control mode. This finding suggests that performers adopt a mode of control consistent with the feedback conditions provided during testing.     

William King’s Influence on Locke’s Second Edition Change of Mind about Human Action and Freedom

ABSTRACT

Locke’s influential discussion of agency in the chapter ‘Of Power’ in the Essay Concerning Human Understanding underwent important changes between the first and second edition. He reconsidered many of his central claims about the mind’s deliberation about actions. Locke’s position in the two editions is not only different but, as he himself points out, sometimes incompatible. This has suggested to some commentators that his change of mind was at least partly due to an external influence. Locke himself gestures towards this conclusion in the new ‘Epistle’ in the second edition Essay. One view is that William Molyneux was a notable influence, while another position is that Ralph Cudworth’s work on free will, either directly or indirectly through the influence of his daughter Damaris Masham, was an important influence. The position I develop in this paper is that the strongest candidate for an important external influence on Locke’s second edition revision is Molyneux’s close associate and friend, Irish philosopher and Archbishop of Dublin, William King. I argue that King’s criticism is a plausible influence on Locke’s reconceptualization of will and desire. Finally, and perhaps most significantly, King’s criticism appears to have been instrumental in Locke’s new emphasis on the agent’s capacity to determine what to value.     

Soul searching on the wings of my wheels: Motorcyclists’ happiness

This study aimed to investigate how personal characteristics of motorcyclists influenced their affect and sense of happiness with their motorcycles. Data on personal characteristics, motorcycle characteristics, feelings about owning a motorcycle, discreet emotions, and overall happiness were collected from 367 motorcyclists attending the annual charity run event (female = 29%, male = 71%, average age ranged between 40 and 49). Results, following Structural Equation Modelling, indicated male and younger motorcyclists to experience higher discreet positive emotions compared to females and those with a preference for outdoors lifestyle. Male motorcyclists reported being happier, overall, with their motorcycles compared to female motorcyclists. Amongst males, those reporting to be self-employed and with a social life involving drinking places, tended to report higher discreet negative emotions than other male motorcyclists. Lifestyle characteristics of motorcyclists appear to have a direct effect on their overall happiness.