Pathogen evolution following spillover from a resident to a migrant host population depends on interactions between host pace of life and tolerance to infection.

Changes to migration routes and phenology create novel contact patterns among hosts and pathogens. These novel contact patterns can lead to pathogens spilling over between resident and migrant populations. Predicting the consequences of such pathogen spillover events requires understanding how pathogen evolution depends on host movement behaviour. Following spillover, pathogens may evolve changes in their transmission rate and virulence phenotypes because different strategies are favoured by resident and migrant host populations. There is conflict in current theoretical predictions about what those differences might be. Some theory predicts lower pathogen virulence and transmission rates in migrant populations because migrants have lower tolerance to infection. Other theoretical work predicts higher pathogen virulence and transmission rates in migrants because migrants have more contacts with susceptible hosts. We aim to understand how differences in tolerance to infection and host pace of life act together to determine the direction of pathogen evolution following pathogen spillover from a resident to a migrant population. We constructed a spatially implicit model in which we investigate how pathogen strategy changes following the addition of a migrant population. We investigate how differences in tolerance to infection and pace of life between residents and migrants determine the effect of spillover on pathogen evolution and host population size. When the paces of life of the migrant and resident hosts are equal, larger costs of infection in the migrants lead to lower pathogen transmission rate and virulence following spillover. When the tolerance to infection in migrant and resident populations is equal, faster migrant paces of life lead to increased transmission rate and virulence following spillover. However, the opposite can also occur: when the migrant population has lower tolerance to infection, faster migrant paces of life can lead to decreases in transmission rate and virulence. Predicting the outcomes of pathogen spillover requires accounting for both differences in tolerance to infection and pace of life between populations. It is also important to consider how movement patterns of populations affect host contact opportunities for pathogens. These results have implications for wildlife conservation, agriculture and human health.

Mutualisms impact species' range expansion speeds and spatial distributions.

Species engage in mutually beneficial interspecific interactions (mutualisms) that shape their population dynamics in ecological communities. Species engaged in mutualisms vary greatly in their degree of dependence on their partner from complete dependence (e.g., yucca and yucca moth mutualism) to low dependence (e.g., generalist bee with multiple plant species). While current empirical studies show that, in mutualisms, partner dependence can alter the speed of a species' range expansion, there is no theory that provides conditions when expansion is sped up or slowed down. To address this, we built a spatially explicit model incorporating the population dynamics of two dispersing species interacting mutualistically. We explored how mutualisms impacted range expansion across a gradient of dependence (from complete independence to obligacy) between the two species. We then studied the conditions in which the magnitude of the mutualistic benefits could hinder versus enhance the speed of range expansion. We showed that either complete dependence, no dependence, or intermediate degree of dependence on a mutualist partner can lead to the greatest speeds of a focal species' range expansion based on the magnitude of benefits exchanged between partner species in the mutualism. We then showed how different degrees of dependence between species could alter the spatial distribution of the range expanding populations. Finally, we identified the conditions under which mutualistic interactions can turn exploitative across space, leading to the formation of a species' range limits. Our work highlights how couching mutualisms and mutualist dependence in a spatial context can provide insights about species range expansions, limits, and ultimately their distributions.

Branched copolymer surfactants impart thermoreversible gelation to LAPONITE® gels.

This investigation seeks to integrate LAPONITE® clay gels with thermoresponsive branched copolymer surfactants (BCSs) to develop advanced functional materials with temperature-induced sol-gel behaviour. It is known that a diverse range of molecules adsorb strongly to clays which may be used to control liberation of the species in healthcare applications, and as such the development of polymer/clay hybrid materials which can add function to the native clay behaviour are of great interest. BCS were synthesised with a structure that encompasses poly(ethylene glycol)methacrylate (PEGMA), ethylene glycol dimethacrylate (EGDMA), and dodecanethiol (DDT), conferring versatile and tuneable thermoresponsive attributes. Systematic modulation of the monomer : DDT/initiator ratio was used to facilitate the synthesis of BCS architectures spanning a range of molecular weights. Through application of small-amplitude oscillatory shear (SAOS) rheology and small-angle neutron scattering (SANS) in conjunction with controlled temperature variations, the sol-gel transition dynamics of these nanocomposite materials were elucidated. Complementary insights into the mechanisms underpinning this transition and temperature-induced alterations in the constituents are gleaned through the utilization of SANS techniques employing contrast-matching methodologies to mitigate clay and polymer scattering interference. It is found that heating systems from room- to body- temperature induces self-assembly of BCS in the bulk aqueous phase with concurrent structuration of clay in gel-forming samples with lower number average molecular weight (Mn). SANS study unpicks this phenomenon to find that gelation occurs with concurrent aggregation of BCS in the bulk, inducing clay-clay interactions only in lower Mn BCS systems with large nanoaggregates.

A unified evolutionary framework for understanding parasite infection and host migratory behaviour.

Animal migration impacts organismal health and parasite transmission: migrants are simultaneously exposed to parasites and able to reduce infection for both individuals and populations. However, these dynamics are difficult to study; empirical studies reveal disparate results while existing theory makes assumptions that simplify natural complexity. Here, we systematically review empirical studies of migration and infection across taxa, highlighting key gaps in our understanding. Next, we develop a unified evolutionary framework incorporating different selective pressures of parasite-migration interactions while accounting for ecological complexity that goes beyond previous theory. Our framework generates diverse migration-infection patterns paralleling those seen in empirical systems, including partial and differential migration. Finally, we generate predictions about which mechanisms dominate which empirical systems to guide future studies. Our framework provides an overarching understanding of selective pressures shaping migration patterns in the context of animal health and disease, which is critical for predicting how environmental change may threaten migration.

Take me for a ride: Herbivores can facilitate plant reinvasions.

Herbivores shape plant invasions through impacts on demography and dispersal, yet only demographic mechanisms are well understood. Although herbivores negatively impact demography by definition, they can affect dispersal either negatively (e.g., seed consumption), or positively (e.g., caching). Exploring the nuances of how herbivores influence spatial spread will improve the forecasting of plant movement on the landscape. Here, we aim to understand how herbivores impact how fast plant populations spread through varying impacts on plant demography and dispersal. We strive to determine whether, and under what conditions, we see net positive effects of herbivores, in order to find scenarios where herbivores can help to promote spread. We draw on classic invasion theory to develop a stage-structured integrodifference equation model that incorporates herbivore impacts on plant demography and dispersal. We simulate seven herbivore "syndromes" (combinations of demographic and/or dispersal effects) drawn from the literature to understand how increasing herbivore pressure alters plant spreading speed. We find that herbivores with solely negative effects on plant demography or dispersal always slow plant spreading speed, and that the speed slows monotonically as herbivore pressure increases. However, we also find that plant spreading speed can be hump shaped with respect to herbivore pressure: plants spread faster in the presence of herbivores (for low herbivore pressure) and then slower (for high herbivore pressure). This result is robust, occurring across all syndromes in which herbivores have a positive effect on plant dispersal, and is a sign that the positive effects of herbivores on dispersal can outweigh their negative effects on demography. For all syndromes we find that sufficiently high herbivore pressure results in population collapse. Thus, our findings show that herbivores can speed up or slow down plant spread. These insights allow for a greater understanding of how to slow invasions, facilitate native species recolonization, and shape range shifts with global change.

Pushed to the edge: Spatial sorting can slow down invasions.

Our ability to understand population spread dynamics is complicated by rapid evolution, which renders simple ecological models insufficient. If dispersal ability evolves, more highly dispersive individuals may arrive at the population edge than less dispersive individuals (spatial sorting), accelerating spread. If individuals at the low-density population edge benefit (escape competition), high dispersers have a selective advantage (spatial selection). These two processes are often described as forming a positive feedback loop; they reinforce each other, leading to faster spread. Although spatial sorting is close to universal, this form of spatial selection is not: low densities can be detrimental for organisms with Allee effects. Here, we present two conceptual models to explore the feedback loops that form between spatial sorting and spatial selection. We show that the presence of an Allee effect can reverse the positive feedback loop between spatial sorting and spatial selection, creating a negative feedback loop that slows population spread.

Gaps in modelling animal migration with evolutionary game theory: infection can favour the loss of migration.

Ongoing environmental changes alter how natural selection shapes animal migration. Understanding how these changes play out theoretically can be done using evolutionary game theoretic (EGT) approaches, such as looking for evolutionarily stable strategies. Here, we first describe historical patterns of how EGT models have explored different drivers of migration. We find that there are substantial gaps in both the taxa (mammals, amphibians, reptiles, insects) and mechanisms (mutualism, interspecific competition) included in past EGT models of migration. Although enemy interactions, including parasites, are increasingly considered in models of animal migration, they remain the least studied of factors for migration considered to date. Furthermore, few papers look at changes in migration in response to perturbations (e.g. climate change, new species interactions). To address this gap, we present a new EGT model to understand how infection with a novel parasite changes host migration. We find three possible outcomes when migrants encounter novel parasites: maintenance of migration (despite the added infection cost), loss of migration (evolutionary shift to residency) or population collapse, depending on the risk and cost of getting infected, and the cost currency. Our work demonstrates how emerging infection can alter animal behaviour such as migration. This article is part of the theme issue 'Half a century of evolutionary games: a synthesis of theory, application and future directions'.

Streamlining surgical trays for common pediatric urology Procedures: A quality improvement initiative.

INTRODUCTION: Procedures involving the external genitalia are the most common pediatric urologic operations. Our group identified excess instrumentation for these cases to be a potential cause of operating room (OR) inefficiency at our large, freestanding pediatric hospital. This quality improvement (QI) initiative aimed to streamline surgical instrumentation for the most-performed pediatric urologic procedures at our hospital. MATERIAL AND METHODS: Six Sigma DMAIC methodology (Define, Measure, Analyze, Improve, Control) guided this multidisciplinary, iterative QI effort. A stakeholder team utilized data review, direct observations, and multiple in-person discussions to create a new "Groin-Penis Tray" (GPT) to replace a larger tray for the 90 most common pediatric urologic procedures. Suture preference cards and expectations about which sutures would be opened for each case were updated. The primary outcome was estimated yearly cost-avoidance due to reduced sterile processing. Additional outcomes included: instruments opened/case, % cases with complete trays, Mayo stand set-up time, and % cases with unused sutures. Balancing measures included: total median OR time and tray weights. Baseline and post-implementation measures were characterized and compared. RESULTS: A QI professional, 10 pediatric urologists, 2 pediatric urology fellows, and multiple OR and sterile processing staff members participated. The Summary Figure compares baseline and post-implementation measurements. The number of instruments opened/case decreased from 146 to 65. Annual sterile reprocessing costs decreased by >$51,000. Median Mayo stand set-up time decreased from 7.3 to 3.5 min (p < 0.001). The number of cases with complete trays increased from 7/20 (35%) to 11/20 (55%, p = 0.34). The new GPT is 2.7 kg lighter than the prior tray. Median OR time remained stable (baseline: 91 min; post-implementation: 102 min, p = 0.44). The number of cases with suture waste decreased from 78% to 0% immediately post-implementation but increased to 40% one year later. DISCUSSION: This systematic, iterative QI process spanned the course of ∼2 years, including planning, building, and updating new trays, then assessing longer-term success via the control phase. The new GPT is used for most pediatric urologic procedures at our hospital, and benefits include sterile reprocessing cost savings and ergonomics. Our team gained valuable experience related to assessing QI project scope, determining key stakeholders and roles, and strategies for sustainability that we will apply to future initiatives. CONCLUSIONS: Streamlining surgical trays for common pediatric urologic procedures at a large freestanding children's hospital using established QI methodology reduced OR cost by >$51,000/year and Mayo stand set-up times without compromising balancing measures.

Rare Case of Mixed Phenotype Acute Leukemia Presenting as a Myeloid Sarcoma Without Leukemic Involvement.

INTRODUCTION: Mixed phenotype acute leukemia (MPAL) is a rare type of acute leukemia with immunophenotypic features of both myeloid-derived and lymphoid-derived lineages. CASE PRESENTATION: We present an atypical case of a 32-year-old woman presenting with an anterior mediastinal mass and pericardial/pleural involvement that was initially diagnosed as primary mediastinal diffuse large B-cell lymphoma. However, flow cytometry on pleural fluid confirmed the diagnosis of MPAL of B-cell/myeloid lineage without peripheral blood/bone marrow involvement. The patient was treated with an acute lymphoblastic leukemia-type regimen and proceeded with myeloablative allogeneic hematopoietic cell transplantation in first complete remission. CONCLUSION: MPAL can rarely present with isolated extramedullary disease without leukemic involvement and can often be misdiagnosed as a non-Hodgkin lymphoma. Careful integration of all the clinical data, particularly flow cytometry results, can clarify the diagnosis and change the treatment plan.

How to study parasites and host migration: a roadmap for empiricists.

Animal migration (round-trip, predictable movements) takes individuals across space and time, bringing them into contact with new communities of organisms. In particular, migratory movements shape (and are shaped by) the costs and risk of parasite transmission. Unfortunately, our understanding of how migration and parasite infection interact has not proceeded evenly. Although numerous conceptual frameworks (e.g. mathematical models) have been developed, most empirical evidence of migration-parasite interactions are drawn from pre-existing empirical studies that were conducted using other conceptual frameworks, which limits our understanding. Here, we synthesise and analyse existing work, and then provide a roadmap for future (especially empirical) studies. First, we synthesise the conceptual frameworks that have been developed to understand interactions between migration and parasites (e.g. migratory exposure, escape, allopatry, recovery, culling, separation, stalling and relapse). Second, we highlight current challenges to studying migration and parasites empirically, and to integrating empirical and theoretical perspectives, particularly emphasizing the challenge of feedback loops. Finally, we provide a guide to overcoming these challenges in empirical studies, using comparative, observational and experimental approaches. Beyond guiding future empirical work, this review aims to inspire stronger collaboration between empiricists and theorists studying the intersection of migration and parasite infection. Such collaboration will help overcome current limits to our understanding of how migration and parasites interact, and allow us to predict how these critical ecological processes will change in the future.

Differential retention contributes to racial/ethnic disparity in U.S. academia.

Several racial and ethnic identities are widely understood to be under-represented within academia, however, actual quantification of this under-representation is surprisingly limited. Challenges include data availability, demographic inertia and identifying comparison points. We use de-aggregated data from the U.S. National Science Foundation to construct a null model of ethnic and racial representation in one of the world's largest academic communities. Making comparisons between our model and actual representation in academia allows us to measure the effects of retention (while controlling for recruitment) at different academic stages. We find that, regardless of recruitment, failed retention contributes to mis-representation across academia and that the stages responsible for the largest disparities differ by race and ethnicity: for Black and Hispanic scholars this occurs at the transition from graduate student to postdoctoral researcher whereas for Native American/Alaskan Native and Native Hawaiian/Pacific Islander scholars this occurs at transitions to and within faculty stages. Even for Asian and Asian-Americans, often perceived as well represented, circumstances are complex and depend on choice of baseline. Our findings demonstrate that while recruitment continues to be important, retention is also a pervasive barrier to proportional representation. Therefore, strategies to reduce mis-representation in academia must address retention. Although our model does not directly suggest specific strategies, our framework could be used to project how representation in academia might change in the long-term under different scenarios.

Let's move out together: a framework for the intersections between movement and mutualism.

Movement is a widespread behavior across organisms and is driven in part by interspecific interactions. Generally, negative interspecific interactions (such as competition and natural enemies) are more often studied in the context of movement than positive interactions (mutualism). Mutualistic relationships are incredibly common, yet only a subset are studied in the context of movement (transportation mutualisms). Overall, the costs and benefits that an individual experiences are shaped both by their movement behavior and their mutualistic relationships, as well as the intersection between these. Here we argue that the intersection between movement behavior and mutualistic relationships is understudied, and we present a conceptual framework to synthesize the links between movement and mutualisms and give examples of species that exhibit each. Our framework serves both to highlight the ways that mutualism can shape movement (and vice versa) and to draw parallels across different organisms (enabling a more abstract perspective of these biological systems, complementing the system-focused perspective). Finally, we show how considering movement in light of mutualisms (and vice versa) presents a number of new research questions to be answered by each empirical and theoretical approach going forward.

Migration and tolerance shape host behaviour and response to parasite infection.

Numerous theoretical models have demonstrated that migration, a seasonal animal movement behaviour, can minimize the risks and costs of parasite infection. Past work on migration-infection interactions assumes migration is the only strategy available to organisms for dealing with the parasite infection, that is they migrate to a different environment to recover or escape from infection. Thus, migration is similar to the non-spatial strategy of resistance, where hosts prevent infection or kill parasites once infected. However, an alternative defence strategy is to tolerate the infection and experience a lower cost to the infection. To our knowledge, no studies have examined how migration can change based on combining two host strategies (migration and tolerance) for dealing with parasites. In this paper, we aim to understand how both parasite transmission and infection tolerance can influence the host's migratory behaviour. We constructed a model that incorporates two host strategies (migration and tolerance) to understand whether allowing for tolerance affects the proportion of the population that migrates at equilibrium in response to infection. We show that the benefits of tolerance can either decrease or increase the host's migration. Also, if the benefit of migration is great, then individuals are more likely to migrate regardless of the presence of tolerance. Finally, we find that the transmission rate of parasite infection can either decrease or increase the tolerant host's migration, depending on the cost of migration. These findings highlight that adopting two defence strategies is not always beneficial to the hosts. Instead, a single strategy is often better, depending on the costs and benefits of the strategies and infection pressures. Our work further suggests that multiple host-defence strategies as a potential explanation for the evolution of migration to minimize the parasite infection. Moreover, migration can also affect the ecological and evolutionary dynamics of parasite-host interactions.

A Learning Collaborative to Improve Antibiotic Prescribing in Primary Care Pediatric Practices.

An American Academy of Pediatrics State Chapter organized a 6-month, mostly online quality improvement learning collaborative to improve antibiotic prescribing and patient education for upper respiratory infection (URI) and acute otitis media (AOM). Practices submitted data on quality measures at baseline, monthly, and 4 months post-project. Fifty-three clinicians from 6 independent, private primary care pediatric practices participated. Use of first-line antibiotics for AOM increased from 63.5% at baseline to 80.4% 4 months post-project. Use of safety-net antibiotic prescriptions (SNAP) for AOM increased from 4.5% to 16.9%. Educating patients about management for URI increased from 66.1% to 88.0% and for AOM from 20.4% to 85.6%. Practices maintained high performance for not prescribing antibiotics for URI (94.4% to 96.2%). Leveraging local relationships and national resources, this replicable antibiotic stewardship project engaged independent private practices to improve patient education for URI and AOM and prescribing and use of SNAP for AOM.

Pliant pathogens: Estimating viral spread when confronted with new vector, host, and environmental conditions.

Pathogen spread rates are determined, in part, by the performance of pathogens under altered environmental conditions and their ability to persist while switching among hosts and vectors.To determine the effects of new conditions (host, vector, and nutrient) on pathogen spread rate, we introduced a vector-borne viral plant pathogen, Barley Yellow Dwarf Virus PAV (BYDV-PAV) into hosts, vectors, and host nutrient supplies that it had not encountered for thousands of viral generations. We quantified pathogen prevalence over the course of two serial inoculations under the new conditions. Using individual-level transmission rates from this experiment, we parameterized a dynamical model of disease spread and projected spread across host populations through a growing season.A change in nutrient conditions (increased supply of phosphorus) reduced viral transmission whereas shifting to a new vector or host species had no effect on infection prevalence. However, the reduction in the new nutrient environment was only temporary; infection prevalence recovered after the second inoculation. Synthesis. These results highlight how robust the pathogen, BYDV-PAV, is to changes in its biotic and abiotic environment. Our study also highlights the need to quantify longitudinal infection information beyond snapshot assessments to project disease risk for pathogens in new environments.

Lessons from movement ecology for the return to work: Modeling contacts and the spread of COVID-19.

Human behavior (movement, social contacts) plays a central role in the spread of pathogens like SARS-CoV-2. The rapid spread of SARS-CoV-2 was driven by global human movement, and initial lockdown measures aimed to localize movement and contact in order to slow spread. Thus, movement and contact patterns need to be explicitly considered when making reopening decisions, especially regarding return to work. Here, as a case study, we consider the initial stages of resuming research at a large research university, using approaches from movement ecology and contact network epidemiology. First, we develop a dynamical pathogen model describing movement between home and work; we show that limiting social contact, via reduced people or reduced time in the workplace are fairly equivalent strategies to slow pathogen spread. Second, we develop a model based on spatial contact patterns within a specific office and lab building on campus; we show that restricting on-campus activities to labs (rather than labs and offices) could dramatically alter (modularize) contact network structure and thus, potentially reduce pathogen spread by providing a workplace mechanism to reduce contact. Here we argue that explicitly accounting for human movement and contact behavior in the workplace can provide additional strategies to slow pathogen spread that can be used in conjunction with ongoing public health efforts.

Consequences of ignoring dispersal variation in network models for landscape connectivity.

Habitat loss and fragmentation can negatively influence population persistence and biodiversity, but the effects can be mitigated if species successfully disperse between isolated habitat patches. Network models are the primary tool for quantifying landscape connectivity, yet in practice, an overly simplistic view of species dispersal is applied. These models often ignore individual variation in dispersal ability under the assumption that all individuals move the same fixed distance with equal probability. We developed a modeling approach to address this problem. We incorporated dispersal kernels into network models to determine how individual variation in dispersal alters understanding of landscape-level connectivity and implemented our approach on a fragmented grassland landscape in Minnesota. Ignoring dispersal variation consistently overestimated a population's robustness to local extinctions and underestimated its robustness to local habitat loss. Furthermore, a simplified view of dispersal underestimated the amount of habitat substructure for small populations but overestimated habitat substructure for large populations. Our results demonstrate that considering biologically realistic dispersal alters understanding of landscape connectivity in ecological theory and conservation practice.

Consecuencias de la Omisión de la Variación en la Dispersión en los Modelos de Redes para la Conectividad de Paisajes Resumen La pérdida y la fragmentación del hábitat pueden influir negativamente la persistencia de poblaciones y biodiversidad. Sin embargo, estos efectos pueden ser mitigados si las especies tienen una dispersión exitosa entre los fragmentos aislados de hábitat. Los modelos de redes son la herramienta principal para la cuantificación de la conectividad del paisaje, no obstante en la práctica, se tiende a usar una visión excesivamente simplista de la dispersión de especies. Es común que estos modelos ignoren la variación que existe entre individuos en sus habilidades de dispersión y que asuman que todos los individuos se pueden mover la misma distancia y con la misma probabilidad. En este estudio, desarrollamos una estrategia de modelaje para (minimizar o aminorar) estas limitaciones incorporando kernels de dispersión dentro de los modelos de redes para determinar cómo la variación individual de la dispersión altera el entendimiento de la conectividad a nivel de paisaje. Como un ejemplo, implementamos esta estrategia en un paisaje de pastizal fragmentado en Minnesota. Omitir la variación en la dispersión generó una sobreestimación sistemática de la robustez de la población ante las extinciones locales y una subestimación de la robustez ante la pérdida local del hábitat. Además, una visión simplificada de la dispersión subestimó la complejidad de hábitat para las poblaciones pequeñas, sin emgargo sobreestimó la complejidad para las poblaciones grandes. Nuestros resultados demuestran que incorporar parámetros que describan una dispersión biológica realista tiene implicaciones importantes en la teoría de conectividad de paisajes e implementación de practicas de conservación.

Parasite intensity and the evolution of migratory behavior.

Migration can allow individuals to escape parasite infection, which can lead to a lower infection probability (prevalence) in a population and/or fewer parasites per individual (intensity). Because individuals with more parasites often have lower survival and/or fecundity, infection intensity shapes the life-history trade-offs determining when migration is favored as a strategy to escape infection. Yet, most theory relies on susceptible-infected (SI) modeling frameworks, defining individuals as either healthy or infected, ignoring details of infection intensity. Here, we develop a novel modeling approach that captures infection intensity as a spectrum, and ask under what conditions migration evolves as function of how infection intensity changes over time. We show that relative timescales of migration and infection accumulation determine when migration is favored. We also find that population-level heterogeneity in infection intensity can lead to partial migration, where less-infected individuals migrate while more infected individuals remain resident. Our model is one of the first to consider how infection intensity can lead to migration. Our results frame migratory escape in light of infection intensity rather than prevalence, thus demonstrating that decreased infection intensity should be considered a benefit of migration, alongside other typical drivers of migration.

Orchard layout and plant traits influence fruit yield more strongly than pollinator behaviour and density in a dioecious crop.

Mutualistic plant-pollinator interactions are critical for the functioning of both non-managed and agricultural systems. Mathematical models of plant-pollinator interactions can help understand key determinants in pollination success. However, most previous models have not addressed pollinator behavior and plant biology combined. Information generated from such a model can inform optimal design of crop orchards and effective utilization of managed pollinators like western honey bees (Apis mellifera), and help generate hypotheses about the effects of management practices and cultivar selection. We expect that the number of honey bees per flower and male to female flower ratio will influence fruit yield. To test the relative importance of these effects, both singly and simultaneously, we utilized a delay differential equation model combined with Latin hypercube sampling for sensitivity analysis. Empirical data obtained from historical records and collected in kiwifruit (Actinidia chinensis) orchards in New Zealand were used to parameterize the model. We found that, at realistic bee densities, the optimal orchard had 65-75% female flowers, and the most benefit was gained from the first 6-8 bees/1000 flowers, with diminishing returns thereafter. While bee density significantly impacted fruit production, plant-based parameters-flower density and male:female flower ratio-were the most influential. The predictive model provides strategies for improving crop management, such as choosing cultivars which have their peak bloom on the same day, increasing the number of flowers with approximately 70% female flowers in the orchard, and placing enough hives to maintain more than 6 bees per 1000 flowers to optimize yield.

Synthesis strategies for non-symmetric, photochromic diarylethenes.

Diarylethenes (DAEs) represent an important class of photochromes with notable characteristics, like thermally irreversible photoisomerization and high fatigue resistance. Structural diversification of the DAE scaffold has enabled further refinement of photochromic properties and realization of new applications, ranging from advanced materials to tools for studying biological systems. In particular, methods for synthesizing non-symmetric DAE scaffolds, which are typically more challenging to synthesize than their symmetric counterparts, have grown over the past 20 years. These developments are surveyed in this review, with discussion of how access to these compounds has contributed to the improvement of photochromic properties and paved the way for exploring new applications of DAEs. First, non-symmetric DAE structures are classified and their uses and applications are overviewed. Subsequent sections discuss the main strategies that have been used to access non-symmetric DAEs with examples illustrating the impact of non-symmetric DAEs in the growing field of light-controlled molecular systems.