Negative Synergies Research Articles

Synergistic effects of bacteria, enzymes, and cyclic mechanical stresses on the bond strength of composite restorations

Predicting how tooth and dental material bonds perform in the mouth requires a deep understanding of degrading factors. Yet, this understanding is incomplete, leading to significant uncertainties in designing and evaluating new dental adhesives. The durability of dental bonding interfaces in the oral microenvironment is compromised by bacterial acids, salivary enzymes, and masticatory fatigue. These factors degrade the bond between dental resins and tooth surfaces, making the strength of these bonds difficult to predict. Traditionally studied separately, a combined kinetic analysis of these interactions could enhance our understanding and improvement of dental adhesive durability. To address this issue, we developed and validated an original model to evaluate the bond strength of dental restorations using realistic environments that consider the different mechanical, chemical, and biological degradative challenges working simultaneously: bacteria, salivary esterases, and cyclic loading. We herein describe a comprehensive investigation on dissociating the factors that degrade the bond strength of dental restorations. Our results showed that cariogenic bacteria are the number one factor contributing to the degradation of the bonded interface, followed by cyclic loading and salivary esterases. When tested in combinatorial mode, negative and positive synergies towards the degradation of the interface were observed. Masticatory loads (i.e., cycling loading) enhanced the lactic acid bacterial production and the area occupied by the biofilm at the bonding interface, resulting in more damage at the interface and a reduction of 73 % in bond strength compared to no-degraded samples. Salivary enzymes also produced bond degradation caused by changes in the chemical composition of the resin/adhesive. However, the degradation rates are slowed compared to the bacteria and cyclic loading. These results demonstrate that our synergetic model could guide the design of new dental adhesives for biological applications without laborious trial-and-error experimentation.

About positive and negative synergies of social projects: Treating correlation in participatory value evaluation

About positive and negative synergies of social projects: Treating correlation in participatory value evaluation

Spatiotemporal Dynamics of Ecosystem Services and Their Trade-Offs and Synergies in Response to Natural and Social Factors: Evidence from Yibin, Upper Yangtze River

During the rapid urbanization phase, the trade-off between ecosystem services is the most severe and also the most effective stage to implement ecological management. Exploring the natural—social driving mechanisms for trade-offs contributes to the coordinated development of the social economy and nature. Taking the typical mountainous city (Yibin) that is currently in the rapid urbanization phase and ecologically fragile as an example, utilizing a combination of difference comparison, trade-off–synergy index (TSI), optimal-parameter-based geographical detector model (OPGD), and multi-scale geographically weighted regression (MGWR), we spatially assess the nature and intensity of ES relationships and explore its social–natural driving mechanisms. Our findings reveal the following: (1) Varied geospatial patterns of four ESs—habitat quality (HQ), carbon storage (CS), soil conservation (SC), and water yield (WY)—with the greatest fluctuations in WY. (2) Significant changes in the nature and intensity of ES relationships over time, showing predominant positive synergies between WY-HQ, WY-SC, and HQ-CS, and negative synergies between HQ and SC, and trade-offs between WY-CS and SC-CS. (3) Distinct, time-varying driving factors for different ES relationships: climate and topography for WY, vegetation and topography for CS, topography and economic factors for HQ, and climate and topography for SC. Rapid urbanization has diminished the role of natural factors. (4) The regression coefficients reveal the local mechanisms of various driving factors, based on which targeted recommendations can be proposed. For instance, the establishment of interconnected small wetlands and green spaces in urban areas contributes to the enhancement of multiple ESs. The purpose of this study is to provide scientific insights into the driving mechanisms and optimizations of the key ecosystem services’ relationships in areas that are currently undergoing rapid urbanization.

Mitigating the macroeconomic impact of severe natural disasters in Africa: policy synergies

ABSTRACT This study evaluates the economic impact of severe natural disasters in Africa using the generalised synthetic control method. In other words, it assesses how gross domestic product (GDP) would have been affected, had severe natural disasters not occurred. Moreover, it explores the determinants of the destructiveness of the impact of natural disasters, focusing on the role played by capital. We find that severe natural disasters induce a significant and continuous reduction of GDP many years after the event. Indeed, economic losses caused by disasters depend on the level of capital (human capital, employment and capital stock) and aspects of governance quality (political stability and absence of violence). In other words, negative synergies are apparent because while capital stock, employment and human capital unconditionally reduce the macroeconomic impact of natural disasters, the corresponding conditional or interactive effects with political stability are also negative. Policy implications are discussed.

Spatiotemporal Variation in Water-Related Ecosystem Services during 2000–2020 and Ecological Management Zoning in the Xiangjiang River Basin, China

Exploring the spatiotemporal distribution and interrelationships among water-related ecosystem services (WESs) and conducting ecological management zoning are crucial for regional sustainable development. Taking the Xiangjiang River Basin (XJRB) as an example, this study first quantified three primary WESs, including water conservation, soil retention, and water purification, from 2000 to 2020. Second, the spatiotemporal variation in the interrelationships among WESs were analyzed using global and local bivariate spatial autocorrelation. Third, a water ecological zoning rule was constructed to divide the watershed into three primary and eight secondary water ecological management zones. The results indicate a strong consistency in the changes in the three WESs throughout the period from 2000 to 2020 in the XJRB. Precipitation patterns and urban expansion were the primary factors affecting alterations in the WESs. Spatial heterogeneity and dependence were evident across these ecosystem services. Both trade-offs and synergies were observed among WESs, with synergies playing a dominant role. Positive synergies occurred primarily in woodlands and grasslands, while negative synergies were observed in cultivated land, water areas, and construction land. Three water ecological management zones, including core water ecological management zones, general management zones, and restoration management zones, were delineated at the grid and country scales according to the aggregation properties of the WESs. Ecological management strategies were proposed for different zones. These findings can offer valuable insights for policy makers in land use planning and water ecological management within the XJRB, and can facilitate similar management endeavors in other regions.

Codevelopment Versus Outsourcing: Who Should Innovate in Supply Chains

Outsourcing has long been a strategy to decrease cost. Increasingly firms recognize the value in their supply chains and call on suppliers to innovate, both in products and processes. Innovation to increase quality and demand or to reduce costs is critical to firm and supply chain success. In a two-stage supply chain, we investigate the impact of focal firm and supplier innovation costs (and capabilities) on the type of outsourcing chosen and the resulting investments in process and product innovation. The focal firm determines whether to perform design (including product innovation in the form of quality enhancement) and manufacturing (including process innovation in the form of cost reduction) in-house, to outsource manufacturing/process innovation while insourcing design/product innovation, to outsource both manufacturing/process innovation and design/product innovation, or to codevelop product innovation while outsourcing manufacturing/process innovation. We also examine the conditions under which codevelopment is favorable, given the supply chain faces potential positive and negative synergies from either the colocation of the innovation activities or costs of collaboration. After characterizing the optimal outsourcing decision, we find that the decision to outsource is more nuanced than simply which activities to outsource but must include options to collaborate on particular activities and specifically product innovation. We offer the insight to managers that codevelopment, despite the costs of collaboration, can benefit the firm and result in higher profits. This occurs through the improvement of demand via higher quality products.

How do I want the city council to spend our budget? Conceiving MaaS from a citizen's perspective … (as well as biking infrastructure and public transport)

While several governmental and research efforts are set upon mobility-as-a-service (MaaS), most of them are driven by individual travel behavior and potential usage. However, considering only individuals’ preferences carries the risk of neglecting societal benefits going beyond individual travel behavior. This study addresses the valuation of different features of MaaS-services from a social desirability perspective as compared to social investments in biking infrastructure and in public transport, and aims at eliciting trade-offs between different features of such projects. This analysis is conducted on the basis of Participatory Value Evaluation (PVE). In PVE-experiments, individuals select their preferred portfolio of government projects given a constrained public budget and societal preferences for (the impacts of) government projects can be determined based on these choices.The results show that the population of Rotterdam exhibits a willingness to allocate public resources to all types of investment projects considered in the analysis. However, the willingness to allocate resources to bike infrastructure projects and public transport seems to be higher than the willingness to dedicate resources to MaaS subsidies. Within the different types of MaaS subsidies considered, subsidies aimed at sustainability exhibit a larger social valuation. Strong negative synergies among similar projects exist, signalizing that individuals prefer diversifying the use of public resources across different types of investment projects.

Interactive Effects of CEOs’ Firm-Specific Experience and Versatile Experiences on Pursuit of New Growth Opportunity

Prior research has opposing views about the merits of firm-specific managerial experience, and empirical findings are mixed. To address this problem, we ask when firm-specific managerial experience is helpful versus harmful in pursuit of new growth opportunities. We propose that when CEOs’ firm-specific experience is combined with versatile managerial experiences, its growth-constraining effect is alleviated due to increased adaptability of CEOs' human capital to support growth in new business domains. We find support for this argument in a sample of U.S. food firms and their pursuit of the organic food opportunity during 1997 to 2007. We also find that CEOs’ versatile experience by itself is not sufficient for the pursuit of new growth, but it is when the two types of experience are combined synergistically that firms can achieve higher rates of opportunity pursuit. In this vein, our research reconciles the alternative theoretical perspectives on firm-specific experience and invites further consideration of experience combinations where both positive and negative synergies drive the ultimate impact of key managerial experiences.

Cross-Feedings, Competition, and Positive and Negative Synergies in a Four-Species Synthetic Community for Anaerobic Degradation of Cellulose to Methane.

Complex interactions exist among microorganisms in a community to carry out ecological processes and adapt to changing environments. Here, we constructed a quad-culture consisting of a cellulolytic bacterium (Ruminiclostridium cellulolyticum), a hydrogenotrophic methanogen (Methanospirillum hungatei), an acetoclastic methanogen (Methanosaeta concilii), and a sulfate-reducing bacterium (Desulfovibrio vulgaris). The four microorganisms in the quad-culture cooperated via cross-feeding to produce methane using cellulose as the only carbon source and electron donor. The community metabolism of the quad-culture was compared with those of the R. cellulolyticum-containing tri-cultures, bi-cultures, and mono-culture. Methane production was higher in the quad-culture than the sum of the increases in the tri-cultures, which was attributed to a positive synergy of four species. In contrast, cellulose degradation by the quad-culture was lower than the additive effects of the tri-cultures which represented a negative synergy. The community metabolism of the quad-culture was compared between a control condition and a treatment condition with sulfate addition using metaproteomics and metabolic profiling. Sulfate addition enhanced sulfate reduction and decreased methane and CO2 productions. The cross-feeding fluxes in the quad-culture in the two conditions were modeled using a community stoichiometric model. Sulfate addition strengthened metabolic handoffs from R. cellulolyticum to M. concilii and D. vulgaris and intensified substrate competition between M. hungatei and D. vulgaris. Overall, this study uncovered emergent properties of higher-order microbial interactions using a four-species synthetic community. IMPORTANCE A synthetic community was designed using four microbial species that together performed distinct key metabolic processes in the anaerobic degradation of cellulose to methane and CO2. The microorganisms exhibited expected interactions, such as cross-feeding of acetate from a cellulolytic bacterium to an acetoclastic methanogen and competition of H2 between a sulfate reducing bacterium and a hydrogenotrophic methanogen. This validated our rational design of the interactions between microorganisms based on their metabolic roles. More interestingly, we also found positive and negative synergies as emergent properties of high-order microbial interactions among three or more microorganisms in cocultures. These microbial interactions can be quantitatively measured by adding and removing specific members. A community stoichiometric model was constructed to represent the fluxes in the community metabolic network. This study paved the way toward a more predictive understanding of the impact of environmental perturbations on microbial interactions sustaining geochemically significant processes in natural systems.

Shareholder Value Creation through Corporate Spin-Offs in Europe—An Empirical Analysis

Through a spin-off of a business unit, the parent company aims to have a positive impact on its enterprise value. The parent company often pursues the spin-off transaction to strengthen the focus on its core business, reduce negative synergies and increase operational efficiency. Based on studies already established in the literature, it is assumed that the spin-off transaction increases shareholder wealth. Despite the high relevance of spin-offs as restructuring measure, empirical research in Europe has not sufficiently addressed this issue yet. Accordingly, this paper examines both the short-term effects of a spin-off announcement for the parent company and the long-term effects of the implementation of the spin-off at the level of the parent company and the spin-off company on the European capital market. A sample of 24 European companies is examined. The time horizon of the empirical research is from January 2015 to December 2020. For the short-term study, five event windows were chosen around the announcement date and for the long-term study, 3 event periods were chosen over 3, 6 and 12 months after the spin-off transaction. The short-term examination of parent companies yields a cumulative average abnormal return over the investigated event windows around the announcement date of 3.40%. In the long-term research, the parent company generates a buy-and-hold average abnormal return over the studied event periods after the implementation of the spin-off transaction of ?4.11%. The spin-off companies generate a buy-and-hold average abnormal return of 13.76% in the same event periods.

Interactions and rheology of guar gum–mucin mixtures

This work studies the molecular interactions of guar gum, one of the major hydrocolloids, with mucin as to understand guar gum's behavior and functionality upon consumption. Guar gum, mucin, and their binary mixtures were studied at different pH values. The phase stability and particle size distributions were recorded over a pH range of 1–7, and at a range of guar gum to mucin ratios. Aggregations leading to phase separations are more pronounced at low pH, especially when mucin is involved. The effect of electrostatic repulsions on phase stability as function of pH is discussed. The shear viscosity of these systems is dominated by the presence of guar gum, with few, if any, apparent synergies with mucin. The image changes in extensional viscosity, where strong negative synergies are encountered when mucin co-exists with guar gum. Taking into account the intrinsic viscosity and existing thermodynamic data, these synergies are attributed to transient steric interactions. The different effect of mucin on the shear and extensional rheologies of guar gum are discussed on the basis of molecular interactions. The discussion highlights the potentially important implications in the behavior of these systems during oral and other processes. • The interactions between guar gum and mucin are studied. • Phase separations and particle sizes are mapped for a range of pH values. • Shear rheology is dominated by the presence of guar gum. • The presence of mucin strongly affects the extensional rheology of guar gum. • Synergies and antagonisms in rheology are attributed to intermolecular interactions.

Virtuous cycles and research for a regenerative urban ecology: The case of urban wood systems in Baltimore

The field of urban ecology has progressed since the mid-1990s through four major phases: an ecology in, of, for, and with cities. This progression reflects an interest to address the complexity of urban systems with social-ecological approaches. Further, this progression signifies an interest to address societal issues by co-designing and co-producing research in collaboration with diverse stakeholders from government, non-governmental organizations (NGOs), businesses, and community associations. What remains unaddressed in this progression is a research mission orientation. While there may be a range of goals for an ecology with cities, a focus on regenerative urban ecologies is crucial. Regenerative ecologies may be seen as an endpoint along a continuum from degenerative ecologies to sustainability to regenerative ecologies. Regenerative ecologies rely upon feedback loops, similar to coral reefs and climax forests. In urban systems, these feedbacks in social-ecological systems may be considered virtuous cycles that create reinforcing, positive benefits for people and nature over time. Virtuous cycles or feedbacks are often conceived as a singular, positive feedback loop. However, virtuous cycles may be most impactful, adaptive, and resilient when they contain multiple positive and negative feedbacks and synergies. Research has several important roles in advancing virtuous cycles and regenerative urban ecologies. In this paper, we use our urban wood systems project in Baltimore as both a case study and model to illustrate an approach and lessons learned for regenerative ecologies, virtuous cycles, and the role of research. We conclude with lessons learned and consider opportunities and constraints for virtuous cycles, research, and regenerative urban ecologies in Baltimore and to other urban systems.

An Anthropocene species of trouble? Negative synergies between earth system change and geological destratification

It is already well understood that unbinding materials and energy from their lithic reservoirs impacts upon Earth systems. But that is just the first stage of a cycle of ‘Anthropocene trouble’. This paper tracks the multiple ways in which subsequent Earth system change reacts back upon the social infrastructures of subsurface exploitation and the landscapes they produce. Shifting fire regimes, intensifying hydrometeorological events and sea level rise impact upon the infrastructures of hydrocarbon extraction, hydroclimatic change impacts upon infrastructures and landscapes of mineral extraction, and both pyroclimatic and hydroclimatic change impact upon nuclear infrastructures and on landscapes already contaminated by radioactive materials. To make sense of these ‘negative synergies’ we draw upon social science diagnoses of late modern hazards as well Anthropocene science’s deepening collaboration between ‘hard rock’ geology and Earth system science.

The context-dependent, combinatorial logic of BMP signaling.

Cell-cell communication systems typically comprise families of ligand and receptor variants that function together in combinations. Pathway activation depends on the complex way in which ligands are presented extracellularly and receptors are expressed by the signal-receiving cell. To understand the combinatorial logic of such a system, we systematically measured pairwise bone morphogenetic protein (BMP) ligand interactions in cells with varying receptor expression. Ligands could be classified into equivalence groups based on their profile of positive and negative synergies with other ligands. These groups varied with receptor expression, explaining how ligands can functionally replace each other in one context but not another. Context-dependent combinatorial interactions could be explained by a biochemical model based on the competitive formation of alternative signaling complexes with distinct activities. Together, these results provide insights into the roles of BMP combinations in developmental and therapeutic contexts and establish a framework for analyzing other combinatorial, context-dependent signaling systems.

Paradoxes and synergies: optimizing management of a deadly virus in an endangered carnivore.

Pathogen management strategies in wildlife are typically accompanied by an array of uncertainties such as the efficacy of vaccines or potential unintended consequences of interventions. In the context of such uncertainties, models of disease transmission can provide critical insight for optimizing pathogen management, especially for species of conservation concern. The endangered Florida panther experienced an outbreak of feline leukemia virus (FeLV) in 2002-04, and continues to be affected by this deadly virus. Ongoing management efforts aim to mitigate the effects of FeLV on panthers, but with limited information about which strategies may be most effective and efficient.We used a simulation-based approach to determine optimal FeLV management strategies in panthers. We simulated use of proactive FeLV management strategies (i.e., proactive vaccination) and several reactive strategies, including reactive vaccination and test-and-removal. Vaccination strategies accounted for imperfect vaccine-induced immunity, specifically partial immunity in which all vaccinates achieve partial pathogen protection. We compared the effectiveness of these different strategies in mitigating the number of FeLV mortalities and the duration of outbreaks.Results showed that inadequate proactive vaccination can paradoxically increase the number of disease-induced mortalities in FeLV outbreaks. These effects were most likely due to imperfect vaccine immunity causing vaccinates to serve as a semi-susceptible population, thereby allowing outbreaks to persist in circumstances otherwise conducive to fadeout. Combinations of proactive vaccination with reactive test-and-removal or vaccination, however, had a synergistic effect in reducing impacts of FeLV outbreaks, highlighting the importance of using mixed strategies in pathogen management.Synthesis and applications: Management-informed disease simulations are an important tool for identifying unexpected negative consequences and synergies among pathogen management strategies. In particular, we find that imperfect vaccine-induced immunity necessitates further consideration to avoid unintentionally worsening epidemics in some conditions. However, mixing proactive and reactive interventions can improve pathogen control while mitigating uncertainties associated with imperfect interventions.

Páramo Lakes of Colombia: An Overview of Their Geographical Distribution and Physicochemical Characteristics

The páramo lakes, Colombia, situated in the neotropical region, are of great value both as natural heritage and as water source to the most populated areas of the Andes, but are threatened by expanding agriculture, livestock, mining, and landscape fragmentation. Nonetheless, a general assessment of the lakes’ distribution and biogeochemical characteristics was lacking. We made a complete inventory of the Colombian páramo lakes and characterized their morphometry and water chemistry based on a survey of 51 lakes in the Eastern Cordillera. There are 3250 lakes distributed across 28 páramo complexes in Colombia, mainly located between 3600 and 4400 m a.s.l. The lakes are usually small (<10 ha) and shallow (<10 m). Most of them are slightly acidic (average pH~6), with high nutrient (total phosphorus ~0.6 mg/L, total nitrogen ~1 mg/L) and total organic carbon (~6 mg/L) concentrations and low oxygen (~3.5 mg/L) at the bottom. Water chemistry varies according to two main independent gradients related to watershed bedrock geology and trophic state. Global change pressures may be challenging the preservation of these unique ecosystems. Increasing the protection of more lake watersheds should reduce these potential impacts by mitigating negative synergies with local pressures.

Value Creation and Tension in Coopetition: The Emergence of Virtuous and Vicious Cycles

Literature on tension in coopetition has focused almost exclusively on ‘simultaneity tension’, which is rooted in the interplay of simultaneous competition and cooperation. Our paper identifies and unpacks a distinct ‘value tension’ which occurs due to simultaneous firm value creation and joint value creation in coopetition. We layout incompatibilities between firm value creation, which is collaborative, and joint value creation, which is cooperative, and articulate the inherent challenges of pursuing both simultaneously. Efforts to pursue both can pull resources in opposing directions, forego scale and scope advantages, and undermine isolating mechanisms that are at odds with each other. We illuminate positive and negative synergies depending on the extent to which firm value creation and joint value creation are pursued simultaneously and how the ensuing tension is managed. We suggest that subsequent behaviors may reinforce the positives, leading to virtuous cycles, or negatives, leading to vicious cycles. Our integration of the coopetition literatures on tension and value with broader strategic management discourse regarding value creation provides novel future-focused insights concerning coopetition and interorganizational relationships.

Long-term multi-criteria improvement planning

This paper proposes a novel framework to support the generation of strategies for multi-criteria long-term improvement. It can be applied to general preference models but it is illustrated in this article on a Multi-Attribute Value Theory model. The novel contributions to the literature are twofold. Firstly, the framework addresses the issue of resistance to change that may arise during the implementation of a strategy. It constrains a step of improvement to be focused on a single criterion, and minimizes the intensity of operational changes. Secondly, it addresses the realism of the improvement scenarios by treating three types of structural dependencies differently: the positive synergies, the negative synergies and the bottlenecks. The scenarios are generated by finding a set of efficient solutions to a shortest path problem in a graph whose edges represent possible steps of improvement. Each edge is characterized by an increase of rank or level and two penalty functions relating to the difficulty of its execution, one representing a risk associated to bottleneck mechanisms and the other to operational change relative to a previous edge. A case-study using the Shanghai Academic Ranking of World Universities is presented in order to illustrate how this framework could be useful to generate a sequence of strategic actions for the Université libre de Bruxelles.

COVID-19 demand-induced scarcity effects on nutrition and environment: investigating mitigation strategies for eggs and wheat flour in the United Kingdom.

The COVID-19 pandemic has drawn attention to food insecurity in developed countries. Despite adequate levels of agricultural production, consumers experienced demand-induced scarcity. Understanding the effects on nutrition and the environment is limited, yet critical to informing ecologically embedded mitigation strategies. To identify mitigation strategies, we investigated wheat flour and egg retail shortages in the United Kingdom (UK), focusing on consumer behavior during the COVID-19 lockdown. The 6 Steps for Quality Intervention Development (6SQuID) framework informed the methodology. Mixed qualitative and quantitative methods were used to pinpoint the causes of the shortages, and ecological impacts of consumer behavior were related using survey results (n = 243) and environmental and nutritional databases. This research confirmed consumers’ narrowed consideration set, willingness to pay, and significant reliance on processed foods which indicates agronomic biofortification, breeding strategies, selective imports and improved processed food quality are important mitigation strategies. We identified positive and negative synergies in consumer, producer and retailer behavior and related these to mitigation strategies in support of a circular bio-economy for food production. We found that the substitutes or alternative foods consumed during the COVID-19 lockdown were nutritionally inadequate. We identified the most ecological substitute for wheat flour to be corn flour; and for eggs, yogurt. Our findings also indicate that selenium deficiency is a risk for the UK population, especially to the increasing fifth of the population that is vegetarian. Due to the need to implement short-, medium-, and long-term mitigation strategies, a coordinated effort is required by all stakeholders.

Markov Switching Modelling of Shooting Performance Variability and Teammate Interactions in Basketball

SummaryIn basketball, measures of individual player performance provide critical guidance for a broad spectrum of decisions related to training and game strategy. However, most studies on this topic focus on performance level measurement, neglecting other important factors, such as performance variability. Here we model shooting performance variability by using Markov switching models, assuming the existence of two alternating performance regimes related to the positive or negative synergies that specific combinations of players may create on the court. The main goal of this analysis is to investigate the relationships between each player's performance variability and team line-up composition by assuming shot-varying transition probabilities between regimes. Relationships between pairs of players are then visualized in a network graph, highlighting positive and negative interactions between teammates. On the basis of these interactions, we build a score for the line-ups, which we show correlates with the line-up's shooting performance. This confirms that interactions between teammates detected by the Markov switching model directly affect team performance, which is information that would be enormously useful to coaches when deciding which players should play together.