Coevolution of parasite virulence and host mating strategies

This is the author accepted manuscript. The final version is available from National Academy of Sciences via the DOI in this record.Parasites are thought to play an important role in sexual selection and the evolution of mating strategies, which in turn are likely to be critical to the transmission and therefore the evolution of parasites. Despite this clear interdependence we have little understanding of parasite-mediated sexual selection in the context of reciprocal parasite evolution. Here we develop a general coevolutionary model between host mate preference and the virulence of a sexually transmitted parasite. We show when the characteristics of both the host and parasite lead to coevolutionarily stable strategies or runaway selection, and when coevolutionary cycling between high and low levels of host mate choosiness and virulence is possible. A prominent argument against parasites being involved in sexual selection is that they should evolve to become less virulent when transmission depends on host mating success. The present study, however, demonstrates that coevolution can maintain stable host mate choosiness and parasite virulence or indeed coevolutionary cycling of both traits. We predict that choosiness should vary inversely with parasite virulence and that both relatively long and short life spans select against choosy behavior in the host. The model also reveals that hosts can evolve different behavioral responses from the same initial conditions, which highlights difficulties in using comparative analysis to detect parasite-mediated sexual selection. Taken as a whole, our results emphasize the importance of viewing parasite-mediated sexual selection in the context of coevolution.Funding for this work was provided by the Natural Environment Research Council (Grant NE/K014617/1) and a Biotechnology and Biological Sciences Research Council studentship

Orthogonally Decoupled Variational Gaussian Processes

Gaussian processes (GPs) provide a powerful non-parametric framework for reasoning over functions. Despite appealing theory, its superlinear computational and memory complexities have presented a long-standing challenge. State-of-the-art sparse variational inference methods trade modeling accuracy against complexity. However, the complexities of these methods still scale superlinearly in the number of basis functions, implying that that sparse GP methods are able to learn from large datasets only when a small model is used. Recently, a decoupled approach was proposed that removes the unnecessary coupling between the complexities of modeling the mean and the covariance functions of a GP. It achieves a linear complexity in the number of mean parameters, so an expressive posterior mean function can be modeled. While promising, this approach suffers from optimization difficulties due to ill-conditioning and non-convexity. In this work, we propose an alternative decoupled parametrization. It adopts an orthogonal basis in the mean function to model the residues that cannot be learned by the standard coupled approach. Therefore, our method extends, rather than replaces, the coupled approach to achieve strictly better performance. This construction admits a straightforward natural gradient update rule, so the structure of the information manifold that is lost during decoupling can be leveraged to speed up learning. Empirically, our algorithm demonstrates significantly faster convergence in multiple experiments

Host-parasite fluctuating selection in the absence of specificity

Fluctuating selection driven by coevolution between hosts and parasites is important for the generation of host and parasite diversity across space and time. Theory has focused primarily on infection genetics, with highly specific ‘matching allele’ frameworks more likely to generate fluctuating selection dynamics (FSD) than ‘gene-for-gene’ (generalist-specialist) frameworks. However, the environment, ecological feedbacks, and life-history characteristics may all play a role in determining when FSD occurs. Here, we develop eco- evolutionary models with explicit ecological dynamics to explore the ecological, epidemiological and host life-history drivers of FSD. Our key result is to demonstrate for the first time that specificity between hosts and parasites is not required to generate FSD. Furthermore, highly specific host-parasite interactions produce unstable, less robust stochastic fluctuations in contrast to interactions that lack specificity altogether or those that vary from generalist to specialist, which produce predictable limit cycles. Given the ubiquity of ecological feedbacks and the variation in the nature of specificity in host parasite interactions, our work emphasizes the underestimated potential for host- parasite coevolution to generate fluctuating selection

Pumpkin is “yucky”!: A prospective study of overt and covert restriction in the development of young children's food preferences

© 2018 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (January 2019) in accordance with the publisher’s archiving policyThe aim of the study was to investigate maternal feeding strategies as prospective predictors of young children's food preferences. Participants were 106 mother – child dyads with data collected when children were aged 4 (Time 1) and then again at 6 years old (Time 2). Mothers completed an initial questionnaire at Time 1 which contained measures of restrictive and covert feeding strategies. Children were interviewed concerning their food preferences and had their height and weight measured at Time 1 and again two years later (Time 2). Longitudinal regression results showed that Time 1 parental restrictive feeding predicted decreased child-reported preferences for fruit and vegetables and increased preferences for salty food and sweets at Time 2. Conversely, Time 1 parental covert control predicted greater child-reported preferences for fruit and vegetables over time. The results provide longitudinal evidence of the negative impact of restrictive feeding, and of the positive impact of covert control, on the development of young children's food preferences

Large UK retailers' initiatives to reduce consumers' emissions: a systematic assessment

In the interest of climate change mitigation, policy makers, businesses and non-governmental organisations have devised initiatives designed to reduce in-use emissions whilst, at the same time, the number of energy-consuming products in homes, and household energy consumption, is increasing. Retailers are important because they are at the interface between manufacturers of products and consumers and they supply the vast majority of consumer goods in developed countries like the UK, including energy using products. Large retailers have a consistent history of corporate responsibility reporting and have included plans and actions to influence consumer emissions within them. This paper adapts two frameworks to use them for systematically assessing large retailers’ initiatives aimed at reducing consumers’ carbon emissions. The Framework for Strategic Sustainable Development (FSSD) is adapted and used to analyse the strategic scope and coherence of these initiatives in relation to the businesses’ sustainability strategies. The ISM ‘Individual Social Material’ framework is adapted and used to analyse how consumer behaviour change mechanisms are framed by retailers. These frameworks are used to analyse eighteen initiatives designed to reduce consumer emissions from eight of the largest UK retail businesses, identified from publicly available data. The results of the eighteen initiatives analysed show that the vast majority were not well planned nor were they strategically coherent. Secondly, most of these specific initiatives relied solely on providing information to consumers and thus deployed a rather narrow range of consumer behaviour change mechanisms. The research concludes that leaders of retail businesses and policy makers could use the FSSD to ensure processes, and measurements are comprehensive and integrated, in order to increase the materiality and impact of their initiatives to reduce consumer emissions in use. Furthermore, retailers could benefit from exploring different models of behaviour change from the ISM framework in order to access a wider set of tools for transformative system change

Coexistence of hexatic and isotropic phases in two-dimensional Yukawa systems

We have performed Brownian dynamics simulations on melting of two-dimensional colloidal crystal in which particles interact with Yukawa potential. The pair correlation function and bond-orientational correlation function was calculated in the Yukawa system. An algebraic decay of the bond orientational correlation function was observed. By ruling out the coexistence region, only a unstable hexatic phase was found in the Yukawa systems. But our work shows that the melting of the Yukawa systems is a two-stage melting not consist with the KTHNY theory and the isotropic liquid and the hexatic phase coexistence region was found. Also we have studied point defects in two-dimensional Yukawa systems.Comment: 9 pages, 8 figures. any comments are welcom

Effect of dual actuating strip guidance systems in a continuous steel annealing line

In the past, Royal Hoogovens, a main primary steel and aluminum manufacturer in the Netherlands, used pre-shaped rolls and sophisticated tension tables to guarantee good strip tracking for all strip geometry's in both their Continuous Annealing lines. However: with an increasing product mix (wider range of geometrical dimensions: widths between 800 - 1200 mm and thickness' between. 0.15 - 0.30 mm) in combination with high annealing temperatures of approximately 1000 K, these methods were not sufficient anymore. The steel strips became too vulnerable for wrinkles. To prevent wrinkles and tracking problems, Hoogovens Packaging Steel improved the flexibility of a processing line by partly substituting the pre-shaped rolls by flat rolls and new steering rolls. Before this process was started, a lot of time was spent, developing a suitable new steering roll type. This steering roll, it is called the DUal Actuating strip guidance System (DUAS), has a minimal influence on the strip tension distribution, basically consists of a flat roll and two hydraulic actuators mounted on a small frame and fits in an existing installations without large modifications. In December '95 the first system was placed in the furnace of one of the Hoogovens annealing lines and in November '96 another two

IMPACT: The Journal of the Center for Interdisciplinary Teaching and Learning. Volume 11, Issue 1, Winter 2022

This special issue of the journal is devoted to creating antiracist classrooms through interdisciplinary teaching, learning, curriculum, and leadership. The essays in this special issue explore a variety of issues related to doing the work—both personally and in the curriculum—of creating antiracist classrooms and universities. Indeed, the first essay of this special issue details the author’s thinking about and experiences with constructing a 21- day programmatic approach that offered structured learning along with accountability measures for graduate students, staff, and faculty at Boston University who were interested in unlearning racism and learning antiracism. After cautioning readers that antiracist efforts run the risk of being molded by neoliberal racist academia, the second essay explores how contingent faculty might be impacted in unique ways compared to their more secure counterparts when those faculty teach antiracist curriculum without institutional support to do this work. In light of the fact that Critical Race Theory (CRT) has been publicly debated and even banned in some places in the American education system, the third essay argues that successfully curating and teaching an antiracist curriculum cannot be done without properly understanding the value of CRT in teacher education. It also offers an example assignment for an antiracist composition and rhetoric curriculum as well as the author’s experience participating in an antiracist reading group for faculty at her university. The fourth and final essay explores intersectionality in both a case study of and interview with Dr. Carmen Twillie Ambar, an African-American woman who has successfully advanced through successive layers of academic positions in public and private institutions to become the president at two different American liberal arts colleges. Detailing Dr. Ambar’s emphasis on personal integrity and concern about historically disadvantaged student groups, it also explores her philosophy and varied experiences as a woman leader in academia. Additionally, this essay details the five foci of Dr. Ambar’s Presidential Initiative at Oberlin, which offer a heuristic model for other organizations doing antiracist work at universities. Our Impact book reviews explore texts that address antiracist classroom strategies. Both reviewers examine books initially written for K-12 educators, but show how these books can serve all educators in their classrooms, including university educators. Our first reviewer details an author’s practical guide to class discussions about race that also offers guidance for more effective classroom experiences. Our second reviewer explores an author’s call to decenter whiteness in schools both by helping their teacher candidates understand their racism and oppression as part of their teacher development training and by offering concrete strategies to disrupt the focus on whiteness in curriculum and curricular decisions. By offering these two windows into anti-racist curricula and practices for younger learners, we suggest that post-secondary educators also can deepen their understanding of some incoming students’ experiences and expectations regarding antiracism in their classrooms

An Essential Difference between the Flavonoids MonoHER and Quercetin in Their Interplay with the Endogenous Antioxidant Network

Antioxidants can scavenge highly reactive radicals. As a result the antioxidants are converted into oxidation products that might cause damage to vital cellular components. To prevent this damage, the human body possesses an intricate network of antioxidants that pass over the reactivity from one antioxidant to another in a controlled way. The aim of the present study was to investigate how the semi-synthetic flavonoid 7-mono-O-(β-hydroxyethyl)-rutoside (monoHER), a potential protective agent against doxorubicin-induced cardiotoxicity, fits into this antioxidant network. This position was compared with that of the well-known flavonoid quercetin. The present study shows that the oxidation products of both monoHER and quercetin are reactive towards thiol groups of both GSH and proteins. However, in human blood plasma, oxidized quercetin easily reacts with protein thiols, whereas oxidized monoHER does not react with plasma protein thiols. Our results indicate that this can be explained by the presence of ascorbate in plasma; ascorbate is able to reduce oxidized monoHER to the parent compound monoHER before oxidized monoHER can react with thiols. This is a major difference with oxidized quercetin that preferentially reacts with thiols rather than ascorbate. The difference in selectivity between monoHER and quercetin originates from an intrinsic difference in the chemical nature of their oxidation products, which was corroborated by molecular quantum chemical calculations. These findings point towards an essential difference between structurally closely related flavonoids in their interplay with the endogenous antioxidant network. The advantage of monoHER is that it can safely channel the reactivity of radicals into the antioxidant network where the reactivity is completely neutralized

On subsequential spaces

AbstractSimple generators for the coreflective category of subsequential spaces, one of them countable, are constructed. Every such must have subsequential order ω1. Subsequentialness is a local property and a countable property, both in a strong sense. A T2-subsequential space may be pseudocompact without being sequential, in contrast to T2-subsequential compact (countably compact, sequentially compact) spaces all being sequential. A compact subsequential space need not be sequential