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Constructing a Tutte polynomial for graphs embedded in surfaces
Get PDFThere are several different extensions of the Tutte polynomial to graphs embedded in surfaces. To help frame the different options, here we consider the problem of extending the Tutte polynomial to embedded graphs starting from first principles. We offer three different routes to defining such a polynomial and show that they all lead to the same polynomial. This resulting polynomial is known in the literature under a few different names including the ribbon graph polynomial, and 2-variable Bollobas-Riordan polynomial.Our overall aim here is to use this discussion as a mechanism for providing a gentle introduction to the topic of Tutte polynomials for graphs embedded in surfaces
Psychological Mechanisms Underlying Ingroup Favouritism in Cooperation:Revisiting the Reputation Management and Expectation Hypotheses
Get PDFTroubling Gender(S) and Consumer Well-Being:Going Across, Between and Beyond the Binaries to Gender/Sex/ual and Intersectional Diversity
Get PDFTroubling gender(s) invites an expansion of the way we study gender so that our scholarship might reflect lived realities. It calls for critical scholarship that seeks to disrupt, as well as explorative scholarship that seeks to leverage and expand categorizations, going “across, between and beyond” the binary. Troubling gender(s) encourages scholars to recognize the vast terrain of gender diversity, and how gender diversity crosses over with sex and sexual diversity and intersecting social locations of difference to shape consumers’ experiences of marketplace inequities, interactions with other people, and perceptions of self. Troubling gender asks scholars to rethink how they measure, use, or capture gender/sex/ual diversity. In short, troubling gender takes us that next step in thinking through how gender matters
Going back for the future:Incorporating Pleistocene fossil records of saiga antelope into habitat suitability models
Get PDFDoes urbanisation lead to parallel demographic shifts across the world in a cosmopolitan plant?
Get PDFUrbanisation is occurring globally, leading to dramatic environmental changes that are altering the ecology and evolution of species. In particular, the expansion of human infrastructure and the loss and fragmentation of natural habitats in cities is predicted to increase genetic drift and reduce gene flow by reducing the size and connectivity of populations. Alternatively, the ‘urban facilitation model’ suggests that some species will have greater gene flow into and within cities leading to higher diversity and lower differentiation in urban populations. These alternative hypotheses have not been contrasted across multiple cities. Here, we used the genomic data from the GLobal Urban Evolution project (GLUE), to study the effects of urbanisation on non-adaptive evolutionary processes of white clover (Trifolium repens) at a global scale. We found that white clover populations presented high genetic diversity and no evidence of reduced Ne linked to urbanisation. On the contrary, we found that urban populations were less likely to experience a recent decrease in effective population size than rural ones. In addition, we found little genetic structure among populations both globally and between urban and rural populations, which showed extensive gene flow between habitats. Interestingly, white clover displayed overall higher gene flow within urban areas than within rural habitats. Our study provides the largest comprehensive test of the demographic effects of urbanisation. Our results contrast with the common perception that heavily altered and fragmented urban environments will reduce the effective population size and genetic diversity of populations and contribute to their isolation
Undiscovered countries:Shakespearean shadows in Jean-François Ducis’s Hamlet
Get PDFTo English eyes, France’s first stageworthy adaptation of a Shakespeare play, Jean-François Ducis’s Hamlet (1769), is a pale but gloomy shadow of the original. One of the few elements of Shakespeare’s tragedy that Ducis retains is the Ghost of Hamlet’s father, who presses the hero on to avenge the original murder. But Ducis’s Ghost is both more savage and more ambiguous than Shakespeare’s; being perceptible to none but Hamlet, it may be no more than a hallucination. More bloodthirsty than its Shakespearean counterpart, it demands that Hamlet kill his mother Gertrude alongside Claudius, thus producing a conflict of loyalties that leads him to doubt the moral legitimacy of his mission. Although Ducis himself later felt compelled to rewrite his own ending, in all versions Hamlet’s sustained refusal to accede to the Ghost’s demands eventually marks his triumph over both his melancholy and his incapacities as incumbent ruler of Denmark
Plastid retrograde signaling:A developmental perspective
Get PDFChloroplast activities influence nuclear gene expression, a phenomenon referred to as retrograde signaling. Biogenic retrograde signals have been revealed by changes in nuclear gene expression when chloroplast development is disrupted. Research on biogenic signaling has focused on repression of Photosynthesis Associated Nuclear Genes (PhANGs) but this is just one component of a syndrome involving altered expression of thousands of genes involved in diverse processes, many of which are up-regulated. We discuss evidence for a framework that accounts for most of this syndrome. Disruption of chloroplast biogenesis prevents production of signals required to progress through discrete steps in the program of photosynthetic differentiation, causing retention of juvenile states. As a result, expression of PhANGs and other genes that act late during photosynthetic differentiation is not initiated, while expression of genes that act early is retained. The extent of juvenility, and thus the transcriptome, reflects the disrupted process: lack of plastid translation blocks development very early whereas disruption of photosynthesis without compromising plastid translation blocks development at a later stage. We discuss implications of these and other recent observations for the nature of the plastid-derived signals that regulate photosynthetic differentiation, and the role of GUN1, an enigmatic protein involved in biogenic signaling
Story Starter:A Tool for Controlling Multiple Virtual Reality Headsets with No Active Internet Connection
Get PDFImmersive events are becoming increasingly popular, allowing multiple people to experience a range of VR content simultaneously. Onboarders help people do VR experiences in these situations. Controlling VR headsets for others without physically having to put them on first is an important requirement here, as it streamlines the onboarding process and maximizes the number of viewers. Current off-the-shelf solutions require headsets to be connected to a cloud-based app via an active internet connection, which can be problematic in some locations. To address this challenge, we present Story Starter, a solution that enables the control of VR headsets without an active internet connection. Story Starter can start, stop, and install VR experiences, adjust device volume, and display information such as remaining battery life. We developed Story Starter in response to the UK-wide StoryTrails tour in the summer of 2022, which was held across 15 locations and attracted thousands of attendees who experienced a range of immersive content, including six VR experiences. Story Starter helped streamline the onboarding process by allowing onboarders to avoid putting the headset on themselves to complete routine tasks such as selecting and starting experiences, thereby minimizing COVID risks. Another benefit of not needing an active internet connection was that our headsets did not automatically update at inconvenient times, which we have found sometimes to break experiences. Converging evidence suggests that Story Starter was well-received and reliable. However, we also acknowledge some limitations of the solution and discuss several next steps we are considering
Global Sensitivity and Domain-Selective Testing for Functional-Valued Responses:An Application to Climate Economy Models
Get PDFComplex computational models are increasingly used by business and governments for making decisions, such as how and where to invest to transition to a low carbon world. Complexity arises with great evidence in the outputs generated by large scale models, and calls for the use of advanced Sensitivity Analysis techniques. To our knowledge, there are no methods able to perform sensitivity analysis for outputs that are more complex than scalar ones and to deal with model uncertainty using a sound statistical framework. The aim of this work is to address these two shortcomings by combining sensitivity and functional data analysis. We express output variables as smooth functions, employing a Functional Data Analysis (FDA) framework. We extend global sensitivity techniques to function-valued responses and perform significance testing over sensitivity indices. We apply the proposed methods to computer models used in climate economics. While confirming the qualitative intuitions of previous works, we are able to test the significance of input assumptions and of their interactions. Moreover, the proposed method allows to identify the time dynamics of sensitivity indices
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