bluuebunny/crossref_metadata_2025 huggingface dataset:
Surprising Homolytic Gas Phase Co−C Bond Dissociation Energies of Organometallic Aryl‐Cobinamides Reveal Notable Non‐Bonded Intramolecular Interactions
Authors: Tsybizova Alexandra , Brenig Christopher , Kieninger Christoph , Kräutler Bernhard , Chen Peter
Published: February 2021

Aryl‐cobalamins are a new class of organometallic structural mimics of vitamin B12 designed as potential ‘antivitamins B12’. Here, the first cationic aryl‐cobinamides are described, which were synthesized using the newly developed diaryl‐iodonium method. The aryl‐cobinamides were obtained as pairs of organometallic coordination isomers, the stereo‐structure of which was unambiguously assigned based on homo‐ and heteronuclear NMR spectra. The availability of isomers with axial attachment of the aryl group, either at the ‘beta’ or at the ‘alpha’ face of the cobalt‐center allowed for an unprecedented comparison of the organometallic reactivity of such pairs. The homolytic gas‐phase bond dissociation energies (BDEs) of the coordination‐isomeric phenyl‐ and 4‐ethylphenyl‐cobinamides were determined by ESI‐MS threshold CID experiments, furnishing (Co−C
)‐BDEs of 38.4 and 40.6 kcal mol−1, respectively, for the two β‐isomers, and the larger BDEs of 46.6 and 43.8 kcal mol−1 for the corresponding α‐isomers. Surprisingly, the observed (Co−C
)‐BDEs of the Coβ‐aryl‐cobinamides were smaller than the (Co−C
)‐BDE of Coβ‐methyl‐cobinamide. DFT studies and the magnitudes of the experimental (Co−C
)‐BDEs revealed relevant contributions of non‐bonded interactions in aryl‐cobinamides, notably steric strain between the aryl and the cobalt‐corrin moieties and non‐bonded interactions with and among the peripheral sidechains.
Visible‐Light‐Induced Palladium‐Catalyzed Dehydrogenative Carbonylation of Amines to Oxalamides
Authors: Meyer Tim , Rabeah Jabor , Brückner Angelika , Wu Xiao‐Feng
Published: February 2021

The palladium‐catalyzed oxidative carbonylation of amines toward the synthesis of oxalamides has been established around 30 years ago and it usually needs the presence of (over)stoichiometric amounts of oxidant. In this work, the first transformation of this type in which the oxidant was replaced by visible light is described. The new approach uses a simple robust Pd complex, which can even be partially recycled. A mechanistic reason is provided and supported by control experiments and EPR studies, showing that PdI was formed and Pd0 was the active species. Both nitrogen‐ and the intermediate acyl radical can be detected. Moreover, the formation of hydrogen was confirmed by gas GC.
Scalable Synthesis of Porous SiFe@C Composite with Excellent Lithium Storage
Authors: Lu Tongzhou , Gong Junjie , Xu Zeyu , Yin Jiaqian , Shao Haibo , Wang Jianming
Published: February 2021

Utilizing cost‐effective raw materials to prepare high‐performance silicon‐based anode materials for lithium‐ion batteries (LIBs) is both challenging and attractive. Herein, a porous SiFe@C (pSiFe@C) composite derived from low‐cost ferrosilicon is prepared via a scalable three‐step procedure, including ball milling, partial etching, and carbon layer coating. The pSiFe@C material integrates the advantages of the mesoporous structure, the partially retained FeSi2 conductive phase, and a uniform carbon layer (12–16 nm), which can substantially alleviate the huge volume expansion effect in the repeated lithium‐ion insertion/extraction processes, effectively stabilizing the solid–electrolyte interphase (SEI) film and markedly enhancing the overall electronic conductivity of the material. Benefiting from the rational structure, the obtained pSiFe@C hybrid material delivers a reversible capacity of 1162.1 mAh g−1 after 200 cycles at 500 mA g−1, with a higher initial coulombic efficiency of 82.30 %. In addition, it shows large discharge capacities of 803.1 and 600.0 mAh g−1 after 500 cycles at 2 and 4 A g−1, respectively, manifesting an excellent electrochemical lithium storage. This work provides a good prospect for the commercial production of silicon‐based anode materials for LIBs with a high lithium‐storage capacity.
Helical Antimicrobial Peptide Foldamers Containing Non‐proteinogenic Amino Acids
Authors: Yokoo Hidetomo , Hirano Motoharu , Misawa Takashi , Demizu Yosuke
Published: February 2021

Antimicrobial peptides (AMPs) are potential novel therapeutic drugs against microbial infections. Most AMPs function by disrupting microbial membranes because of their amphipathic properties and ordered secondary structures. In this minireview, we describe recent efforts to develop helical AMP foldamers containing non‐proteinogenic amino acids, such as α,α‐disubstituted α‐amino acids, β‐amino acids, γ‐amino acids, side‐chain stapling and N‐alkyl glycines.
Fitness and prostate cancer screening, incidence, and mortality: Results from the Henry Ford Exercise Testing (FIT) Project
Authors: Reiter‐Brennan Cara , Dzaye Omar , Al‐Mallah Mouaz H. , Dardari Zeina , Brawner Clinton A. , Lamerato Lois E. , Keteyian Steven J. , Ehrman Jonathan K. , Blaha Michael J. , Visvanathan Kala , Marshall Catherine H.
Published: February 2021

Background

The relation between cardiorespiratory fitness (CRF) and prostate cancer is not well established. The objective of this study was to determine whether CRF is associated with prostate cancer screening, incidence, or mortality.

Methods

The Henry Ford Exercise Testing Project is a retrospective cohort study of men aged 40 to 70 years without cancer who underwent physician‐referred exercise stress testing from 1995 to 2009. CRF was quantified in metabolic equivalents of task (METs) (<6 [reference], 6‐9, 10‐11, and ≥12 METs), estimated from the peak workload achieved during a symptom‐limited, maximal exercise stress test. Prostate‐specific antigen (PSA) testing, incident prostate cancer, and all‐cause mortality were analyzed with multivariable adjusted Poisson regression and Cox proportional hazard models.

Results

In total, 22,827 men were included, of whom 739 developed prostate cancer, with a median follow‐up of 7.5 years. Men who had high fitness (≥12 METs) had an 28% higher risk of PSA screening (95% CI, 1.2‐1.3) compared with those who had low fitness (<6 METs. After adjusting for PSA screening, fitness was associated with higher prostate cancer incidence (men aged <55 years,P= .02; men aged >55 years,P≤ .01), but not with advanced prostate cancer. Among the men who were diagnosed with prostate cancer, high fitness was associated with a 60% lower risk of all‐cause mortality (95% CI, 0.2‐0.9).

Conclusions

Although men with high fitness are more likely to undergo PSA screening, this does not fully account for the increased incidence of prostate cancer seen among these individuals. However, men with high fitness have a lower risk of death after a prostate cancer diagnosis, suggesting that the cancers identified may be low‐risk with little impact on long‐term outcomes.
Research on case preprocessing based on deep learning
Authors: Zhang Chuyue , Cai Manchun , Zhao Xiaofan , Wang Dawei
Published: February 2021

Considering the problem of missing fields in the criminal case system, this article proposes a deep learning algorithm to extract the features of the case description and fill in the missing value. Due to Chinese expressions and characteristics of criminal cases, we make both character vectors and word vectors to present text embedding. Character vectors are from bert model. Word vector is trained by long short‐term memory model with attention. The experiment uses 13,890 data totally. This work is an extension of our short conference proceeding paper. The results show that the combination of characters and words can effectively improve the accuracy of the conference paper by 9%. This is the first time to cascade the character and word dimensions on the criminal case information preprocess and it can provide higher quality data especially for the crime data mining.
Multipopulation artificial bee colony algorithm based on a modified probability selection model
Authors: Xu Minyang , Wang Wenjun , Wang Hui , Xiao Songyi , Huang Zhikai
Published: February 2021

Artificial bee colony (ABC) performs excellently over many problems, but it has some shortcomings, such as weak exploitation as well as slow convergence. For the sake of dealing with these issues, a modified ABC known as MPABC is presented. Firstly, the entire population is partitioned into two different subpopulations at the stage of employed bees, and they use different search strategies. Then, a new probability selection strategy is designed on the basis of the principle of Soft Maximum function. Finally, a novel search method is constructed for improving the intensity of exploitation by gradually increasing the ratio of the current optimal solutions. In order to comprehensively validate the capability of MPABC, 12 benchmark problems are employed. Computational results clearly demonstrate MPABC surpasses the basic ABC and some other famous ABCs.
Carrot or stick? An empirical analysis of the different implementation strategies of the EU directive on nonfinancial information across Europe
Authors: Mio Chiara , Fasan Marco , Marcon Carlo , Panfilo Silvia
Published: February 2021

The recent EU Directive on nonfinancial information (NFI) disclosure allows Member States some discretion regarding its implementation. More specifically, it allows countries to decide whether: (a) information assurance is compulsory; (b) companies can waive NFI disclosure because of possible competitive harms (safe harbor); and (c) fines can be imposed on companies not disclosing NFI. We empirically test the impact of different implementation strategies on NFI quantity and quality, and we find that regulations providing incentives ('carrots') are more effective than regulations imposing costs ('sticks'). More specifically, while mandatory assurance and safe harbor have a positive impact on NFI quantity, fines do not. Our results contribute to the literature on NFI disclosure and inform regulators on the effectiveness of different implementation strategies.
Ka‐band distributed microelectromechanical systems transmission line phase shifter using metal air metal switch
Authors: Teymoori Mir Majid , Dousti Massoud , Afrang Saeid
Published: February 2021

A new approach for designing a two‐state unit cell for a six‐bit distributed coplanar waveguide microelectromechanical systems (MEMS) phase shifter is proposed in this study. The proposed structure includes metal air metal (MAM) capacitors as switches and consists of a unit cell with one MEMS and two MAM switches to produce two phase shifts per unit cell. In the first state, the MAM switches are pulled down and a 5.625° phase shift is achieved, and in the second state, the MEMS switch is actuated to yield a phase shift of 11.25°. The designed structure is modeled using equivalent transmission line circuit model and simulated in the Ka‐band at 34 GHz, employing advanced design system (ADS), ANSOFT HFSS and COMSOL software. Based on the modeling and simulation results, the root‐mean‐square (RMS) phase error is 1.4°, and maximum return loss and minimum insertion loss for all 64 states are better than −10.1 and −1.45 dB, respectively. The main advantages of the designed structure are its small size, low loss, low phase error and a simple phase shift mechanism. A fabrication process is also proposed for the distributed MEMS transmission line (DMTL) phase shifter that shows the feasibility of the proposed design. The proposed structure can be easily scaled to other bands and used in applications with more bits as complex as phased array antennas.
Endoscopic ultrasound‐guided treatment for malignant afferent loop obstruction after Roux‐en‐Y reconstruction
Authors: Mandai Koichiro , Uno Koji , Yasuda Kenjiro
Published: February 2021

The usefulness of endoscopic ultrasound (EUS)‐guided gastrojejunostomy (EUS‐GJ) using a lumen‐apposing metal stent (LAMS) has been reported. However, LAMS is not available in many countries and is more expensive than a conventional fully covered self‐expandable metal stent (FCSEMS). We treated cases of malignant afferent loop obstruction after Roux‐en‐Y reconstruction: three patients underwent EUS‐guided hepaticoenterostomy (EUS‐HES) and one patient underwent EUS‐GJ with a conventional biliary FCSEMS, instead of EUS‐GJ with a LAMS. In two of the cases, EUS‐GJ or EUS‐guided jejunojejunostomy was not indicated because the afferent loop was far from the stomach or jejunum, and EUS‐HES was performed. In one case, in which both EUS‐HES and EUS‐GJ were feasible, EUS‐HES was performed because of unavailability of LAMS for EUS‐GJ in Japan. In another case, EUS‐HES was not indicated because of massive ascites around the liver, and thus, EUS‐GJ using a 10 mm FCSEMS combined with a 7 Fr large‐loop double‐pigtail plastic stent was performed. In all four cases, the patients’ symptoms improved without any adverse events. Stent occlusion did not occur in three of the four cases until the patients died of advanced cancer progression. EUS‐GJ using a 10 mm FCSEMS with a 7 Fr large‐loop double‐pigtail plastic stent or EUS‐HES is likely safe and effective for managing malignant afferent loop obstruction.
Analysing detection gaps in acoustic telemetry data to infer differential movement patterns in fish
Authors: Williamson Michael J. , Tebbs Emma J. , Dawson Terence P. , Curnick David J. , Ferretti Francesco , Carlisle Aaron B. , Chapple Taylor K. , Schallert Robert J. , Tickler David M. , Harrison Xavier A. , Block Barbara A. , Jacoby David M.P.
Published: February 2021

A wide array of technologies are available for gaining insight into the movement of wild aquatic animals. Although acoustic telemetry can lack the fine‐scale spatial resolution of some satellite tracking technologies, the substantially longer battery life can yield important long‐term data on individual behavior and movement for low per‐unit cost. Typically, however, receiver arrays are designed to maximize spatial coverage at the cost of positional accuracy leading to potentially longer detection gaps as individuals move out of range between monitored locations. This is particularly true when these technologies are deployed to monitor species in hard‐to‐access locations.

Here, we develop a novel approach to analyzing acoustic telemetry data, using the timing and duration of gaps between animal detections to infer different behaviors. Using the durations between detections at the same and different receiver locations (i.e., detection gaps), we classify behaviors into “restricted” or potential wider “out‐of‐range” movements synonymous with longer distance dispersal. We apply this method to investigate spatial and temporal segregation of inferred movement patterns in two sympatric species of reef shark within a large, remote, marine protected area (MPA). Response variables were generated using network analysis, and drivers of these movements were identified using generalized linear mixed models and multimodel inference.

Species, diel period, and season were significant predictors of “out‐of‐range” movements. Silvertip sharks were overall more likely to undertake “out‐of‐range” movements, compared with gray reef sharks, indicating spatial segregation, and corroborating previous stable isotope work between these two species. High individual variability in “out‐of‐range” movements in both species was also identified.

We present a novel gap analysis of telemetry data to help infer differential movement and space use patterns where acoustic coverage is imperfect and other tracking methods are impractical at scale. In remote locations, inference may be the best available tool and this approach shows that acoustic telemetry gap analysis can be used for comparative studies in fish ecology, or combined with other research techniques to better understand functional mechanisms driving behavior.
Biogeography of the West Indies: A complex scenario for species radiations in terrestrial and aquatic habitats
Authors: Rodriguez‐Silva Rodet , Schlupp Ingo
Published: February 2021

Studies of the biogeography of the West Indies are numerous but not all taxonomic groups have received the same attention. Many of the contributions to this field have historically focused on terrestrial vertebrates from a perspective closely linked to the classical theory of island biogeography. However, some recent works have questioned whether some of the assumptions of this theory are too simplistic. In this review, we compiled information about the West Indies biogeography based on an extensive and rigorous literature search. While we offer some background of the main hypotheses that explain the origin of the Caribbean biota, our main purpose here is to highlight divergent diversification patterns observed in terrestrial versus aquatic groups of the West Indian biota and also to shed light on the unbalanced number of studies covering the biogeography of these groups of organisms. We use an objective method to compile existing information in the field and produce a rigorous literature review. Our results show that most of the relevant literature in the field is related to the study of terrestrial organisms (mainly vertebrates) and only a small portion covers aquatic groups. Specifically, livebearing fishes show interesting deviations from the species‐area relationship predicted by classical island biogeography theory. We found that species richness on the Greater Antilles is positively correlated with island size but also with the presence of elevations showing that not only island area but also mountainous relief may be an important factor determining the number of freshwater species in the Greater Antilles. Our findings shed light on mechanisms that may differently drive speciation in aquatic versus terrestrial environments suggesting that ecological opportunity could outweigh the importance of island size in speciation. Investigations into freshwater fishes of the West Indies offer a promising avenue for understanding origins and subsequent diversification of the Caribbean biota.
Occurrence data uncover patterns of allopatric divergence and interspecies interactions in the evolutionary history of Sceloporus lizards
Authors: Rivera Julio A. , Rich Heather N. , Michelle Lawing A. , Rosenberg Michael S. , Martins Emília P.
Published: February 2021

As shown from several long‐term and time‐intensive studies, closely related, sympatric species can impose strong selection on one another, leading to dramatic examples of phenotypic evolution. Here, we use occurrence data to identify clusters of sympatric Sceloporus lizard species and to test whether Sceloporus species tend to coexist with other species that differ in body size, as we would expect when there is competition between sympatric congeners. We found that Sceloporus species can be grouped into 16 unique bioregions. Bioregions that are located at higher latitudes tend to be larger and have fewer species, following Rapoport's rule and the latitudinal diversity gradient. Species richness was positively correlated with the number of biomes and elevation heterogeneity of each bioregion. Additionally, most bioregions show signs of phylogenetic underdispersion, meaning closely related species tend to occur in close geographic proximity. Finally, we found that although Sceloporus species that are similar in body size tend to cluster geographically, small‐bodied Sceloporus species are more often in sympatry with larger‐bodied Sceloporus species than expected by chance alone, whereas large‐bodied species cluster with each other geographically and phylogenetically. These results suggest that community composition in extant Sceloporus species is the result of allopatric evolution, as closely related species move into different biomes, and interspecies interactions, with sympatry between species of different body sizes. Our phyloinformatic approach offers unique and detailed insights into how a clade composed of ecologically and morphologically disparate species are distributed over large geographic space and evolutionary time.
New data on the evolutionary history of the European bison (Bison bonasus) based on subfossil remains from Southeastern Europe
Authors: Neov Boyko , Spassov Nikolai , Hristova Latinka , Hristov Peter , Radoslavov Georgi
Published: February 2021

The origin and evolutionary history of the European bison Bison bonasus (wisent) have become clearer after several morphological, genomic, and paleogenomic studies in the last few years, but these paleogenomic studies have raised new questions about the evolution of the species. Here, we present additional information about the population diversity of the species based on the analysis of new subfossil Holocene remains from the Balkan Peninsula. Seven ancient samples excavated from caves in Western Stara Planina in Bulgaria were investigated by mitochondrial D‐loop (HVR1) sequence analysis. The samples were dated to 3,800 years BP by radiocarbon analysis. Additionally, a phylogenetic analysis was performed to investigate the genetic relationship among the investigated samples and all mitochondrial DNA sequences from the genus Bison available in GenBank. The results clustered with the sequences from the extinct Holocene South‐Eastern (Balkan) wisent to the fossil Alpine population from France, Austria, and Switzerland, but not with those from the recent Central European (North Sea) one and the now extinct Caucasian population.

In conclusion, these data indicate that the Balkan wisent that existed in historical time represented a relict and probably an isolated population of the Late Pleistocene‐Holocene South‐Western mountainous population of the wisent.
Mechanistic reconciliation of community and invasion ecology
Authors: Latombe Guillaume , Richardson David M. , McGeoch Melodie A. , Altwegg Res , Catford Jane A. , Chase Jonathan M. , Courchamp Franck , Esler Karen J. , Jeschke Jonathan M. , Landi Pietro , Measey John , Midgley Guy F. , Minoarivelo Henintsoa O. , Rodger James G. , Hui Cang
Published: February 2021

Community and invasion ecology have mostly grown independently. There is substantial overlap in the processes captured by different models in the two fields, and various frameworks have been developed to reduce this redundancy and synthesize information content. Despite broad recognition that community and invasion ecology are interconnected, a process‐based framework synthesizing models across these two fields is lacking. Here we review 65 representative community and invasion models and propose a common framework articulated around six processes (dispersal, drift, abiotic interactions, within‐guild interactions, cross‐guild interactions, and genetic changes). The framework is designed to synthesize the content of the two fields, provide a general perspective on their development, and enable their comparison. The application of this framework and of a novel method based on network theory reveals some lack of coherence between the two fields, despite some historical similarities. Community ecology models are characterized by combinations of multiple processes, likely reflecting the search for an overarching theory to explain community assembly and structure, drawing predominantly on interaction processes, but also accounting largely for the other processes. In contrast, most models in invasion ecology invoke fewer processes and focus more on interactions between introduced species and their novel biotic and abiotic environment. The historical dominance of interaction processes and their independent developments in the two fields is also reflected in the lower level of coherence for models involving interactions, compared to models involving dispersal, drift, and genetic changes. It appears that community ecology, with a longer history than invasion ecology, has transitioned from the search for single explanations for patterns observed in nature to investigate how processes may interact mechanistically, thereby generating and testing hypotheses. Our framework paves the way for a similar transition in invasion ecology, to better capture the dynamics of multiple alien species introduced in complex communities. Reciprocally, applying insights from invasion to community ecology will help us understand and predict the future of ecological communities in the Anthropocene, in which human activities are weakening species’ natural boundaries. Ultimately, the successful integration of the two fields could advance a predictive ecology that is urgently required in a rapidly changing world.
Coastal protection assessment: a tradeoff between ecological, social, and economic issues
Authors: Trégarot Ewan , Catry Thibault , Pottier Auréa , El‐Hacen El‐Hacen M. , Sidi Cheikh Mohamed Ahmed , Cornet Cindy C. , Maréchal Jean‐Philippe , Failler Pierre
Published: February 2021

Marine coastal ecosystems are crucial to human populations in reducing disaster risk. Least Developed Countries are particularly vulnerable to the effects of climate change, such as sea‐level rise and storm surges. The Mauritanian coast, West Africa, ranks among the most vulnerable worldwide to sea‐level rise, and coastal communities in the National Park of Banc d’Arguin (PNBA) are particularly at risk. Here, we assessed the service of coastal protection in PNBA by (1) mapping the coastal marine ecosystems with Sentinel‐2 imagery and determining their spatial wave height attenuation rates; (2) assessing the vulnerability of villages and natural habitats to coastal hazard risk; and (3) assessing the applicability of coastal protection measures in the PNBA. We found that a total of 83% of the populated coastline presents a moderate to high risk of flooding and erosion, with Iwik and R’Gueiba being the most threatened villages in the PNBA. As for the ecological risk, two low‐elevated islands, which support breeding colonies of birds, are particularly vulnerable to sea‐level rise. However, in other areas, the rupture in the dune cord created new lagoons that present valuable ecological and economic interests like the Lagoon of Bellaat. Improving the comprehension of wave attenuation provided by coastal habitats, combined with identifying the vulnerability and applicability of coastal protection measures, is essential for achieving the Sendai Framework for Disaster Risk Reduction goals. In the PNBA, relocation of identified villages at risk is probably the best cost‐effective solution with the least disturbance to both breeding and wintering birds. Protection of coastal ecosystems will also ensure a continued provision of other ecosystem services, including food supply for sea dependent populations, and contribute to achieving the Paris Agreement and Sustainable Development Goals.
Enzootic plague reduces survival of Mexican woodrats (Neotoma mexicana) in Colorado
Authors: Biggins Dean E. , Ramakrishnan Shantini , Rocke Tonie E. , Williamson Judy L. , Wimsatt Jeffrey
Published: February 2021

Plague is a flea‐vectored disease introduced to North America c. 1900. It is lethal to many American mammal species, causes major die‐offs (epizootics) in some populations, and may be ecologically disruptive even at lower interepizootic (enzootic) levels of transmission. We sought to determine the effects of enzootic plague on survival of Mexican woodrats (Neotoma mexicana) and to test the hypothesis that the causative bacterium Yersinia pestis can be maintained by a highly plague‐susceptible species like these woodrats. We compared apparent survival for woodrats in groups with and without plague management. Woodrat groups were (1) treated for vector control with an insecticide (deltamethrin), (2) vaccinated against plague, (3) treated with both vaccine and vector control, and (4) without plague management treatments. Flea prevalence on woodrats was reduced >90% in response to deltamethrin. Apparent survival during May–September, 2010, was 31.1% for non‐vaccinated adult woodrats living in deltamethrin‐treated nests, compared to 9.6% for woodrats in non‐treated nests. During May–September of 2010 and 2011, vaccinated juvenile woodrat survival was 16.8%, compared to 8.4% for non‐vaccinated juveniles. Peak numbers of woodrats captured were 139 for the first trapping session of 2010 and 76 for the first session of 2011, suggesting a population decline consistent with the relatively low estimated survival rates. Survival results suggest that this highly plague‐susceptible species can locally maintain enzootic plague while encountering substantial rates of mortality.
Allelopathy and micropredation paradigms reconcile with system stoichiometry
Authors: Cagle Sierra E. , Roelke Daniel L. , Muhl Rika W.
Published: February 2021

Allelopathy, a type of interference competition involving exuded chemicals, has been documented for several types of organisms including terrestrial plants, aquatic macrophytes, microbes, and planktonic algae. However, due to the dynamic nature of the aquatic environment it is unclear whether allelopathy is an evolutionarily stable competition mechanism in such a setting. In this research, we consider a cosmopolitan harmful algae species, Prymnesium parvum, for which multiple ecological roles of its produced deleterious chemicals have been suggested, including broadcast allelopathy (chemicals produced and exuded) and micropredation via cell–cell interactions (chemicals produced and held within the cell). To further investigate the ecological role of the deleterious chemicals, bioassays (with phytoplankton and zooplankton target organisms) were conducted using various fractions of a P. parvum culture grown under balanced N:P stoichiometry or imbalanced, P‐reduced stoichiometry. In addition, time‐series counts were generated with cell density enumerations and observations of behavior of a mixed species culture at intervals over a 24‐h period. Our results suggest that the apparent ecological role of the chemicals in a relatively high‐density population shifts depending on system stoichiometry in regard to nitrogen and phosphorus. We show that under balanced N:P conditions, deleterious chemical production is low and cell contact mediates mortality of prey. Differently, under imbalanced, P‐reduced conditions chemical effect is high and mass mortality occurs independent of cell contact. Thus, imbalanced N:P ratios shift the apparent ecological role of the deleterious chemicals from one of micropredation to one of broadcast allelopathy. These differences likely influence bloom dynamics and result in different ecological outcomes for systems affected by blooms. Further, we suggest that these differences indicate the importance of predatory mixotrophic feeding in the evolutionary maintenance of deleterious chemical production and the occurrence of allelopathic effects as a byproduct.
Thermal conditions during embryogenesis influence metabolic rates of juvenile brown troutSalmo trutta
Authors: Durtsche Richard D. , Jonsson Bror , Greenberg Larry A.
Published: February 2021

The projected climate change and increase in thermal conditions in northern latitudes over the next 60 yr has the potential to alter the metabolic scope and potential fitness of aquatic ectotherms. Here, we experimentally tested if elevated egg incubation temperature affected metabolic scope in juvenile brown trout (Salmo trutta) as a phenotypically plastic response. Cohorts of brown trout from anadromous and resident crosses were raised through embryogenesis in either natural river temperatures (cold) or elevated (+3°C, warm) temperatures until they could feed exogenously. The standard metabolic rate (SMR), maximum metabolic rate (MMR), and aerobic scope (AS = MMR − SMR) of juveniles from four anadromous‐resident crosses and from both incubation temperatures were tested at 13°C. We found that metabolic measures (SMR, MMR, AS) were lower in warm than cold‐incubated fish. There was no difference in the metabolic rates of fish from different anadromous‐resident crosses. The results of this experiment are consistent with the countergradient variation hypothesis (CGV) in which phenotypic variation, in this case variation in metabolic rates, is inversely related to thermal conditions, originally proposed in relation to altitudinal or latitudinal gradients. While previous studies have related CGV to genetic differences between populations, our study shows that thermal differences encountered at the embryonic stage can produce a phenotypic pattern consistent with CGV. It is difficult to predict the consequences of these metabolic changes in a future warmer climate, as lower metabolic rates indicate that brown trout will probably expend less energy, but a reduced aerobic scope may counteract this affect, limiting their ability as a top predator and in escaping predators. Our results suggest that there are mechanisms used to adjust to elevated water temperature that can be initiated during embryogenesis. Given that there were no differences among crosses, it is likely that temperature‐induced differences are the result of plastic responses.
Nitrogen dynamics in grain cropping systems integrating multiple ecologically based management strategies
Authors: Isbell Sarah A. , Bradley Brosi A. , Morris Andrew H. , Wallace John M. , Kaye Jason P.
Published: February 2021

Nitrogen (N) management is a critical agronomic challenge, as N losses are a source of pollution affecting both waterways and air quality and a potential economic loss for farmers. One approach to N conservation is through ecologically based agricultural systems that reduce tillage and incorporate cover crops. However, these systems exhibit considerable complexity resulting in potential agronomic trade‐offs. To address these concerns, four crop management systems were implemented within an organically managed corn–soy–winter grain crop rotation. These systems varied in tillage frequency and intensity, cover crop species selection, cover crop termination and establishment methods, fertilizer management, and cash crop season length. We used field measurements to investigate the impact of each system on N pools and to reveal the strengths and weaknesses of each system in addressing N provisioning services, with a focus on the supply and retention of N before and after the corn phase of the rotation. All systems had greater estimated N inputs (via manure and N‐fixation) than outputs (via crop harvest) at the end of the three‐year rotation, demonstrating the importance of prioritizing N retention in cover crops. Interactions among system components were important drivers of temporal N dynamics; cover crop species traits and timing of manure application contributed to differences in total aboveground plant biomass N among systems. For example, one cropping system which included a no‐till corn planting into a rolled cover crop mulch had soil inorganic N availability that was asynchronous with the N needs of the corn crop even though it received the same amount of N inputs as the other systems. In general, neither interseeding cover crop mixtures nor reducing tillage resulted in marked N benefits at the system level; we did not observe improved N retention from either practice in these systems, and there was no increase in N uptake by corn. What did clearly emerge from this experiment is the importance of managing for synchrony between soil inorganic N availability and cash crop N demand as influenced by the N retention capacity of cover crops and the timing of N mineralization due to tillage.
Revisiting the paradigm of shark‐driven trophic cascades in coral reef ecosystems
Authors: Desbiens Amelia A. , Roff George , Robbins William D. , Taylor Brett M. , Castro‐Sanguino Carolina , Dempsey Alexandra , Mumby Peter J.
Published: February 2021

Global overfishing of higher‐level predators has caused cascading effects to lower trophic levels in many marine ecosystems. On coral reefs, which support highly diverse food webs, the degree to which top‐down trophic cascades can occur remains equivocal. Using extensive survey data from coral reefs across the relatively unfished northern Great Barrier Reef (nGBR), we quantified the role of reef sharks in structuring coral reef fish assemblages. Using a structural equation modeling (SEM) approach, we explored the interactions between shark abundance and teleost mesopredator and prey functional group density and biomass, while explicitly accounting for the potentially confounding influence of environmental variation across sites. Although a fourfold difference in reef shark density was observed across our survey sites, this had no impact on either the density or biomass of teleost mesopredators or prey, providing evidence for a lack of trophic cascading across nGBR systems. Instead, many functional groups, including sharks, responded positively to environmental drivers. We found reef sharks to be positively associated with habitat complexity. In turn, physical processes such as wave exposure and current velocity were both correlated well with multiple functional groups, reflecting how changes to energetic conditions and food availability, or modification of habitat affect fish distribution. The diversity of species within coral reef food webs and their associations with bottom‐up drivers likely buffers against trophic cascading across GBR functional guilds when reef shark assemblages are depleted, as has been demonstrated in other complex ecosystems.
Pollinator community species richness dilutes prevalence of multiple viruses within multiple host species
Authors: Fearon Michelle L. , Tibbetts Elizabeth A.
Published: February 2021

Most pathogens are embedded in complex communities composed of multiple interacting hosts, but we are still learning how community‐level factors, such as host diversity, abundance, and composition, contribute to pathogen spread for many host–pathogen systems. Evaluating relationships among multiple pathogens and hosts may clarify whether particular host or pathogen traits consistently drive links between community factors and pathogen prevalence. Pollinators are a good system to test how community composition influences pathogen spread because pollinator communities are extremely variable and contain several multi‐host pathogens transmitted on shared floral resources. We conducted a field survey of four pollinator species to test the prevalence of three RNA viruses (deformed wing virus, black queen cell virus, and sacbrood virus) among pollinator communities with variable species richness, abundance, and composition. All three viruses showed a similar pattern of prevalence among hosts. Apis mellifera and Bombus impatiens had significantly higher viral prevalence than Lasioglossum spp. and Eucera pruinosa. In each species, lower virus prevalence was most strongly linked with greater pollinator community species richness. In contrast, pollinator abundance, species‐specific pollinator abundance, and community composition were not associated with virus prevalence. Our results support a consistent dilution effect for multiple viruses and host species. Pollinators in species‐rich communities had lower viral prevalence than pollinators from species‐poor communities, when accounting for differences in pollinator abundance. Species‐rich communities likely had lower viral prevalence because species‐rich communities contained more native bee species likely to be poor viral hosts than species‐poor communities, and all communities contained the highly competent hosts A. mellifera and B. impatiens. Interestingly, the strength of the dilution effect was not consistent among hosts. Instead, host species with low viral prevalence exhibited weaker dilution effects compared to hosts with high viral prevalence. Therefore, host species susceptibility and competence for each virus may contribute to variation in the strength of dilution effects. This study expands biodiversity–disease studies to the pollinator–virus system, finding consistent evidence of the dilution effect among multiple similar pathogens that infect “replicate” host communities.
Impact of telemedicine on the management of heart failure patients during coronavirus disease 2019 pandemic
Authors: Afonso Nogueira Marta , Ferreira Fernanda , Raposo Ana Filipa , Mónica Lurdes , Simões Dias Sara , Vasconcellos Rafael , Proença Gonçalo
Published: February 2021

Aims

Chronic heart failure (HF) is a major comorbidity accounting for an increased severity and mortality related to coronavirus disease 2019 (COVID‐19). To reduce the risk of COVID‐19 in HF patients, telemedicine has been encouraged.

Methods and results

During the COVID‐19 pandemic, telemedical management with mainly over‐the‐phone appointments became a major strategy of follow‐up of our HF clinic patients. Previously, the large majority of patients have been seen in the hospital with direct patient‐provider contact. We compared both strategies of follow‐up, in pre‐pandemic (PPP) and pandemic (PP) periods, regarding total mortality and hospitalizations/emergency department (ED) visits due to HF exacerbation. We prospectively studied a cohort of 196 patients. The mean follow‐up time in PPP was 1.4 years. In this period, 20 patients died. In PP (follow‐up of 71 days), there was one additional death. Total mortality in the first year of follow‐up was 12.0%, matching the mortality predicted by the Meta‐Analysis Global Group in Chronic Heart Failure score. Considering hospitalizations/ED visits due to decompensated HF, there was no statistically significant difference between PPP and PP. Only one patient was diagnosed with COVID‐19.

Conclusions

In the light of an increase in telemedical management of this cohort of HF patients, we were able to maintain a low rate of admissions due to HF decompensation, without an increment in mortality. Regarding these results, we encourage the incremental use of telemedicine in HF patients in the context of this or future pandemics and also in situations in which physical consultation might not be possible due to logistic issues.
Impella versus extracorporal life support in cardiogenic shock: a propensity score adjusted analysis
Authors: Wernly Bernhard , Karami Mina , Engström Annemarie E. , Windecker Stephan , Hunziker Lukas , Lüscher Thomas F. , Henriques Jose P. , Ferrari Markus W. , Binnebößel Stephan , Masyuk Maryna , Niederseer David , Abel Peter , Fuernau Georg , Franz Marcus , Kelm Malte , Busch Mathias C. , Felix Stephan B. , Thiele Holger , Lauten Alexander , Jung Christian
Published: February 2021

Aims

The mortality in cardiogenic shock (CS) is high. The role of specific mechanical circulatory support (MCS) systems is unclear. We aimed to compare patients receiving Impella versus ECLS (extracorporal life support) with regard to baseline characteristics, feasibility, and outcomes in CS.

Methods and results

This is a retrospective cohort study including CS patients over 18 years with a complete follow‐up of the primary endpoint and available baseline lactate level, receiving haemodynamic support either by Impella 2.5 or ECLS from two European registries. The decision for device implementation was made at the discretion of the treating physician. The primary endpoint of this study was all‐cause mortality at 30 days. A propensity score for the use of Impella was calculated, and multivariable logistic regression was used to obtain adjusted odds ratios (aOR).

In total, 149 patients were included, receiving either Impella (n = 73) or ECLS (n = 76) for CS. The feasibility of device implantation was high (87%) and similar (aOR: 3.14; 95% CI: 0.18–56.50; P = 0.41) with both systems. The rates of vascular injuries (aOR: 0.95; 95% CI: 0.10–3.50; P = 0.56) and bleedings requiring transfusions (aOR: 0.44; 95% CI: 0.09–2.10; P = 0.29) were similar in ECLS patients and Impella patients. The use of Impella or ECLS was not associated with increased odds of mortality (aOR: 4.19; 95% CI: 0.53–33.25; P = 0.17), after correction for propensity score and baseline lactate level. Baseline lactate level was independently associated with increased odds of 30 day mortality (per mmol/L increase; OR: 1.29; 95% CI: 1.14–1.45; P < 0.001).

Conclusions

In CS patients, the adjusted mortality rates of both ECLS and Impella were high and similar. The baseline lactate level was a potent predictor of mortality and could play a role in patient selection for therapy in future studies. In patients with profound CS, the type of device is likely to be less important compared with other parameters including non‐cardiac and neurological factors.
A New Requirement for Publication: Access to Effective Drugs for Ethical Reasons, The Example of Heart Failure
Authors: Roubille François , Lamblin Nicolas
Published: February 2021

The past decade has witnessed the publication of many trials in the field of heart failure, several of which have demonstrated that new drugs could potentially reduce major cardiac events and sometimes even decrease total mortality. Most medical practitioners have experimented with withdrawal of the drug under investigation, having no knowledge of what the patient had received, consistent with a blinded design. In some such cases, the patient's clinical status may be rapidly compromised after withdrawal, suggesting (i) that the patient had been receiving the active drug and (ii) that the drug under investigation might exert beneficial effects. The patients should receive early benefit from the drug, but they are left most often without this beneficial treatment not only until the trial results are complete but also until after the guidelines are updated and after the reimbursement (months to years after the results). Here, we propose that the study sponsor should plan from study conception that all participating patients (regardless of whether they are in the placebo or active drug group) will have access to the drug upon trial completion—once safety is verified and until the results are known. Nowadays, it is not conceivable to submit the results of a large trial for publication without approval from a suitable ethical committee. Similarly, the access to the effective drug should be considered as a requirement for clinical research, not only for ethics committee approval, and for the registration of the trial in an international database until publication.
Contributions of cardiac dysfunction and volume status to central haemodynamics in chronic heart failure
Authors: Miller Wayne L. , Sorimachi Hidemi , Grill Diane E. , Fischer Karen , Borlaug Barry A.
Published: February 2021

Aims

Elevated cardiac filling pressures producing clinical congestion in heart failure (HF) patients may be secondary to intravascular volume expansion or abnormalities in cardiac diastolic properties. The objective of this study was to assess the extent to which measures of myocardial function and intravascular volume correlate with haemodynamic abnormalities in chronic HF.

Methods and results

Subjects underwent invasive haemodynamic assessment, measurement of total blood volume (TBV) using radiolabel indicator‐dilution methodology, and echocardiography to evaluate cardiac structure and function. Patients were divided into those with hypervolaemia (defined as TBV > +8% above referenced normal volume) and normal volume (‘euvolaemia’) (TBV ≤ + 8%). Of 66 patients, 39 (59%) were hypervolaemic and 27 (41%) normal TBV. Central venous pressure (CVP, P = 0.01) and pulmonary capillary wedge pressure (PCWP, P < 0.001) were higher in hypervolaemic compared with euvolaemic patients; however, 15% of hypervolaemic patients displayed normal pressures. Of euvolaemic patients, 70% displayed elevated CVP and 63% elevated PCWP. PCWP was moderately correlated with TBV (r = 0.42), left ventricular diastolic function (e′ velocity, r = −0.44), and left atrial strain (r = −0.47). In multivariable regression TBV, left ventricular e′, and left atrial strain were independently associated with PCWP (all P < 0.05).

Conclusions

While hypervolaemic patients displayed elevations in filling pressures, a substantial proportion (15%) had normal pressures, and of all subjects with elevated filling pressures nearly one third had normal TBVs. Importantly, of patients with normal volumes, a majority (>60%) display elevated filling pressures. Combined analysis of volume, pressure, and cardiac function may be helpful to guide comprehensive assessments of HF status.