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ObjectiveTo investigate the risk of transmission among potentially infectious SARS-CoV-2-positive football players while participating in training or matches at amateur, youth and professional levels.MethodsBetween August 2020 and March 2021, football players who tested positive for SARS-CoV-2 and participated in matches or training during the period of potential contagiousness were identified through media search (professional level) and a nationwide registry in Germany (amateur and youth level) to determine symptoms, source of infection and hygiene measures adopted. The definition of potentially infectious players was based on the time of a positive PCR testing and symptom onset. Transmission-relevant contacts on the pitch were evaluated through doubly reviewed video analysis.ResultsOut of 1247 identified football matches and training sessions (1071 amateur and youth level, 176 professional level), 104 cases (38 training sessions, 66 matches) with 165 potentially infectious players were detected. Follow-up PCR testing at the professional level (44 cases) revealed no transmission. At the amateur and youth level, the combination of partial PCR testing (31 of 60 cases) and symptom monitoring within 14 days post-exposure (46 of 60 cases) identified 2 of 60 matches in which follow-up infections occurred that were attributed to non-football activities. This is consistent with the video analysis of 21 matches demonstrating frontal contacts were ConclusionOn-field transmission risk of SARS-CoV-2 in football is very low. Sources of infections in football players are most likely not related to activities on the pitch.

Antibiotic resistance of pathogenic bacteria needs to be urgently addressed by the development of new antibacterial entities. Although the prokaryotic cell wall comprises a valuable target for this purpose, development of novel cell wall-active antibiotics is mostly missing today. This is mainly caused by hinderances in the assessment of isolated enzymes of the co-dependent murein synthesis machineries, e.g. the elongasome and divisome. We therefore present imaging methodologies to evaluate inhibitors of bacterial cell wall synthesis by high-resolution atomic force microscopy on isolated Escherichia coli murein sacculi. With the ability to elucidate the peptidoglycan ultrastructure of E. coli individuals, unprecedented molecular insights into the mechanisms of antibiotics were established. The nanoscopic impairments introduced by ampicillin, amoxicillin and fosfomycin were not only identified by AFM but readily correlated to their known mechanism of action. These valuable in vitro capabilities will facilitate the identification and evaluation of new antibiotic leads in the future.

Cannibalism, once viewed as a rare or aberrant behavior, is now recognized to be widespread and to contribute broadly to the self-regulation of many populations. Cannibalism can produce endogenous negative feedback on population growth because it is expressed as a conditional behavior, responding to the deteriorating ecological conditions that flow, directly or indirectly, from increasing densities of conspecifics. Thus, cannibalism emerges as a strongly density-dependent source of mortality. In this synthesis, we review recent research that has revealed a rich diversity of pathways through which rising density elicits increased cannibalism, including both factors that (a) elevate the rate of dangerous encounters between conspecifics and (b) enhance the likelihood that such encounters will lead to successful cannibalistic attacks. These pathways include both features of the autecology of cannibal populations and features of interactions with other species, including food resources and pathogens. Using mathematical models, we explore the consequences of including density-dependent cannibal attack rates on population dynamics. The conditional expression of cannibalism generally enhances stability and population regulation in single-species models but also may increase opportunities for alternative states and prey population escape from control by cannibalistic predators.

For species primarily regulated by a common predator, the P * rule of Holt & Lawton (Holt & Lawton, 1993. Am. Nat. 142 , 623–645. ( doi:10.1086/285561 )) predicts that the prey species that supports the highest mean predator density ( P *) excludes the other prey species. This prediction is re-examined in the presence of temporal fluctuations in the vital rates of the interacting species including predator attack rates. When the fluctuations in predator attack rates are temporally uncorrelated, the P * rule still holds even when the other vital rates are temporally auto-correlated. However, when temporal auto-correlations in attack rates are positive but not too strong, the prey species can coexist due to the emergence of a positive covariance between predator density and prey vulnerability. This coexistence mechanism is similar to the storage effect for species regulated by a common resource. Negative or strongly positive auto-correlations in attack rates generate a negative covariance between predator density and prey vulnerability and a stochastic priority effect can emerge: with non-zero probability either prey species is excluded. These results highlight how temporally auto-correlated species’ interaction rates impact the structure and dynamics of ecological communities.

Rapid environmental change is affecting many organisms; some are coping well but many species are in decline. A key mechanism for facilitating success following environmental change is phenotypic plasticity. Organisms use cues to respond phenotypically to environmental conditions; many incorporate recent information (within-generation plasticity) and information from previous generations (transgenerational plasticity). We extend an existing evolutionary model where organisms utilize within-generational plasticity, transgenerational plasticity, rapid evolution, and bet-hedging. We show how, when rapid evolution of plasticity is not possible, the effect of environmental change (altering the environment mean, variance, or autocorrelation, or cue reliability) on population growth rate depends on selection for within-generation plasticity and transgenerational plasticity under historical environmental conditions. We then evaluate the predictions that populations adapted to highly variable environments, or with greater within-generational plasticity, are more likely to successfully respond to environmental change. We identify when these predictions fail, and show environmental change is most detrimental when previously reliable cues become unreliable. When multiple cues become unreliable, environmental change can cause deleterious effects regardless of the population’s evolutionary history. Overall, this work provides a general framework for understanding the role of plasticity in population responses to rapid environmental change.

The risk of viral transmission of SARS-CoV-2 associated with football (soccer) training and match play is unknown. Therefore, studies on infection-relevant contacts in football are of utmost importance.A retrospective video-based analysis was performed over 3 matches with 18 SARS-CoV-2 positive players (age: 17.6 ± 3.1 years; 2 professional, 2 semi-professional and 14 youth academy players) during the pre-season in August and September 2020 in Germany. Repeated RT-PCR tests were performed in 5 of 6 teams and pre-match RT-PCR tests in 4 of 6 teams. The last RT-PCR test ranged between 5 - 14 days post-match. The most important result was that no case of virus transmission was found as documented by RT-PCR tests (and symptom monitoring up to 14 days post-match). Physical contact between contagious and non-infected players never lasted longer than 3 seconds each and the position of players during duels was almost exclusively laterally or behind each other.In conclusion, very low risk of SARS-CoV-2 transmission during football match play has been documented. Nevertheless, due to the observational retrospective design of the study, which was based on ethical reasons, inconsistent RT-PCR testing should be regarded as limitation and larger studies are needed to confirm a low probability of virus transmission.

We aimed to analyze the number and type of contacts involving the risk of respiratory disease transmission during football match play.We analysed videos of 50 matches from different levels of play (professional, amateur, youth). Two reviewers evaluated the contacts of all players in the field of view in each match. We focused on between-player contacts (duels), crowding, actions with potentially increased aerosol and droplet production (speaking, shouting, spitting) and within-player hand-to-head contacts. We categorized the duels with direct contact into frontal (face-to-face) and other ones and measured contact duration.The number of between-player contacts were similar between playing levels (median 28.3 [IQR 22.6,33] contacts per player-hour). Frontal contacts summed up to 8% of all contacts. Contacts involving the head occurred on average less than once per player during a 90-min match with none in frontal positioning and none lasting longer than 3 s. Crowding included on average between two and six players and the duration was mostly less than 10 s. Only goal celebrations lasted more than twice as long in professionals (median 21.4 s [IQR 13.8,24.8]) and amateurs (median 18.6 s [IQR 16.3,22]) compared to youth players (median 8.9 s [IQR 0,14.8]). Aerosol and droplet producing activities were three to four times more frequent in adult compared to youth players.Our results suggest that the risk of respiratory pathogen transmission is low during football matches. This conclusion is based on the finding that most close contact situations are of short duration and on the fact that it is mainly an outdoor sport.

In this study, we analyze the trading behavior of banks with lending relationships. We combine detailed German data on banks' proprietary trading and market making with lending information from the credit register and then examine how banks trade stocks of their borrowers around important corporate events. We find that banks trade more frequently and also profitably ahead of events when they are the main lender (or relationship bank) for the borrower. Specifically, we show that relationship banks are more likely to build up positive (negative) trading positions in the two weeks before positive (negative) news events, and also that they unwind these positions shortly after the event. This trading pattern is more pronounced for unscheduled earnings events, M&A transactions, and after borrower obtain new bank loans. Our results suggest that lending relationships endow banks with important information, highlighting the potential for conflicts of interest in banking, which has been a prominent concern in the regulatory debate.

The relative arrival time of species often affects species interactions within a community, contributing to priority effects. Recent studies on phenological shifts under climate change have generated renewed interest on priority effects, but their role in shaping long-term dynamics of seasonal communities is poorly resolved. Here we use a general stage-structure competition model to determine how different types of priority effects influence long-term coexistence of species in seasonal systems. We show that while shifts in mean and variance of relative arrival time can alter persistence and coexistence conditions of species, these effects depend on season length and type of priority effect. In “slow” systems with one or a few cohorts per season, changes in mean and seasonal variation of relative arrival time strongly altered species persistence through trait-mediated priority effects. In contrast, competition outcome in “fast” systems is largely determined by numeric priority effects due to interaction between many overlapping generations. These results suggest that empirically observed priority effects may arise from fundamentally different mechanisms, and that fast-generating systems may be less impacted by seasonal variation in phenology. Our model provides important insight into how natural communities respond to increasing variation in phenology over seasons under climate change.

Nanoparticles based on biodegradable polymers are well-known as approved carrier systems for a diversity of drugs. Despite their advantages, such as the option of an active drug targeting or the physicochemical protection of instable payloads, the controlled drug release often underlies intra- and interindividual influences and is therefore difficult to predict. To circumvent this limitation, the release behavior can be optimized using light-responsive materials for the nanoparticle preparation. The resulting light-responsive nanoparticles are able to release the embedded drug after an external light-stimulus, thereby increasing efficacy and safety of the therapy. In the present study light-responsive self-immolative polymers were used for the nanoparticle manufacturing. Light-responsive polycarbonates (LrPC) as well as PEGylated LrPC (LrPC-PEG) were synthesized via ring-opening polymerization of trimethylene carbonate-based monomers and fully physico-chemically characterized. Light-responsive nano formulations were obtained by blending LrPC or (LrPC-PEG) with the FDA-approved polymer poly(DL-lactide-co-glycolide) (PLGA). The nanoparticles were loaded with the photosensitizer 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (mTHPC). The light-induced nanoparticle degradation was analyzed as well as the drug release behavior with and without illumination. Furthermore, biological safety of the degradation products was investigated in an in vitro cell culture study.

Mechanical properties of microalloyed steels are enhanced by fine precipitates, that ensure grain growth control during subsequent heat treatment. This study aims at predicting austenite grain growth kinetics coupling a precipitation model and a grain growth model. These models were applied to a titanium and niobium microalloyed steel. The precipitate size distributions were first characterized by TEM and SEM and prior austenite grain boundaries were revealed by thermal etching after various isothermal treatments. From CALPHAD database, a solubility product was determined for (Ti,Nb)C precipitates. A numerical model based on the classical nucleation and growth theories was used to predict the time evolution of (Ti,Nb)C size distributions during various isothermal heat treatments. The precipitation model was validated from TEM/SEM analysis. The resulting precipitate size distributions served as entry parameters to a simple grain growth model based on Zener pinning. The pinning pressure was calculated using the whole size distribution. The resulting austenite grain growth kinetics were in good agreement with the experimental data obtained for all investigated heat treatments., The authors gratefully acknowledge the funding received from the European Commission, Research Fund for Coal and Steel, under grant agreement 709803 (NANOFORM). Thanks are due to the CLYM (www.clym.fr) for access to the 2010F microscope, and to Nicholas Blanchard for access and help on the JEOL 2100 microscope.

Motivated by the recent interest in non-equilibrium phenomena in quantum many-body systems, we study strongly interacting fermions on a lattice by deriving and numerically solving quantum Boltzmann equations that describe their relaxation to thermodynamic equilibrium.The derivation is carried out by inspecting the hierarchy of correlations within the framework of the 1/Z-expansion. Applying the Markov approximation, we obtain the dynamic equations for the distribution functions. Interestingly, we find that in the strong-coupling limit, collisions between particles and holes dominate over particle-particle and hole-hole collisions -- in stark contrast to weakly interacting systems. As a consequence, our numerical simulations show that the relaxation time scales strongly depend on the type of excitations (particles or holes or both) that are initially present., Comment: 15 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1812.08581