Systemic antibiotic treatment of cows with metritis early postpartum does not change the progression of uterine disease or the uterine microbiome at 1 month postpartum.

Background: Postpartum uterine disease (metritis) is common in dairy cows. The disease develops within 1 week after calving and is associated with microbial dysbiosis, fever, and fetid uterine discharge. Cows with metritis have a greater likelihood of developing endometritis and infertility later postpartum. Antibiotic treatment is used to relieve symptoms of metritis but the capacity of antibiotic treatment to improve fertility later postpartum is inconsistent across published studies. We hypothesized that an antibiotic has only a short-term effect on the uterine microbiome and does not change the progression of disease from metritis to endometritis. To test this hypothesis, we studied the effects of systemic antibiotic given to cows diagnosed with metritis and healthy cows early postpartum on the development of endometritis and the uterine microbiome at 1 month postpartum. Results: Cows diagnosed with metritis were compared to healthy ones in a 2 × 2 factorial design, where they were either treated with an antibiotic (ceftiofur hydrochloride) at 7 to 10 days postpartum or left untreated. Cows were slaughtered at one month postpartum and the uterus was assessed for endometritis (presence of purulent material in the uterine lumen and inflammation in the endometrium) and uterine samples were collected for bacteriology and metagenomics (16S rRNA gene sequencing). As expected, the uterine microbiome at disease diagnosis had dysbiosis of typical metritis pathogens (e.g., Fusobacterium, Bacteroides, and Porphyromonas) in diseased compared with healthy cows. At one month postpartum, there was a tendency for more endometritis in metritis cows compared with healthy but antibiotic treatment had no effect on endometritis prevalence regardless of the original disease diagnosis. Likewise, when bacteria were cultured or sequenced, there were a greater number of species (culture) or amplicon sequence variants (ASV; sequencing) in the uterine lumen of cows with metritis. However, antibiotic treatment had no effect on the prevalence of cultured species or the composition of the detected ASV. The uterine microbiome at 1 month postpartum was associated with the clinical observation of the uterus (endometritis or healthy). Conclusions: Early postpartum antibiotic treatment only provides temporary resolution of uterine dysbiosis that is not sustained long-term. Failure to resolve the dysbiosis is associated with a greater prevalence of endometritis in cows with metritis, and the occurrence of endometritis significantly impacts fertility later postpartum.

Toxigenic Endophyte-Infected Tall Fescue and Ergot Alkaloids.

"Fescue toxicosis" and reproductive ergotism present identical toxidromes in late-gestational mares and, likely, other equids. Both toxic syndromes are caused by ergopeptine alkaloids (EPAs) of fungal origin, and they are collectively referred to as equine ergopeptine alkaloid toxicosis (EEPAT). EPAs are produced by either a toxigenic endophyte (Epichloë coenophiala) in tall fescue and/or a nonendophytic fungus (Claviceps purpurea), infecting small grains and grasses. EEPAT can cause hypoprolactinemia-induced agalactia/dysgalactia, prolonged gestation, dystocia, and other reproductive abnormalities in mares, as well as failure of passive transfer in their frequently dysmature/overmature/postmature foals. Prevention relies on eliminating exposures and/or reversing hypoprolactinemia.

Dynamics of technology emergence in innovation networks.

To create the next innovative product, participants in science need to understand which existing technologies can be combined, what new science must be discovered, and what new technologies must be invented. Knowledge of these often arrives by means of expert consensus or popularity metrics, masking key information on how intellectual efforts accumulate into technological progress. To address this shortcoming, we first present a method to establish a mathematical link between technological evolution and complex networks: a path of events that narrates innovation bottlenecks. Next, we quantify the position and proximity of documents to these innovation paths. The result is an innovation network that more exhaustively captures deterministic knowledge flows with respect to a marketed innovative product. Our dataset, containing over three million biomedical citations, demonstrates the possibility of quantifying the accumulation, speed, and division of labour in innovation over a sixty-year time horizon. The significance of this study includes the (i) use of a purpose-generated dataset showing causal paths from research to development to product; (ii) analysis of the innovation process as a directed acyclic graph; (iii) comparison between calendar time and network time; (iv) ordering of science funders along technology lifecycles; (v) quantification of innovative activities' importance to an innovative outcome; and (vi) integration of publication, patent, clinical trial, regulatory data to study innovation holistically.

Plants Causing Toxic Myopathies.

Boxelder and sycamore maple contain hypoglycin A (HGA), the toxic metabolite of which, MCPA-CoA, inhibits fatty acid ß-oxidation, causing seasonal pasture myopathy (SPM) or atypical myopathy (AM), respectively. White snakeroot and rayless goldenrod contain multiple benzofuran ketones (BFKs). The identity/toxicity of BFKs appear variable, possibly involving interactions between toxins/toxic metabolites, but ultimately inhibit cellular energy metabolism. Unthrifty horses grazing sparse pastures during the fall appear predisposed to these plant-associated, frequently fatal, toxic myopathies. Toxidromes are characterized by varying degrees of rhabdomyolysis and cardiac myonecrosis, with plant toxins remaining toxic in hay and being excreted in milk.

Embedding anti-racism in Schools of Public Health: a pathway to accountability for progress towards equity.

The importance of seeing race as a socially constructed idea continues to produce unfair differences between humans and establishes power relations that lead to injustice and exposure to death. Since the racial justice movement in early 2020, there has been a heightened awareness of, and increased interest in, addressing historic racial disparities across Schools of Public Health (SPH) in Canada. Steps have been taken to recognize systemic racism and increase diversity through structural reforms to advance equity and inclusion; however, addressing racism demands collectively uprooting racist institutional designs still inherent in learning, teaching, research, service, and community engagement. This commentary highlights the need for sustained commitment to establishing longitudinal benchmarks for greater racial equity among students, staff, and faculty; revising curricula to include historic and contemporary narratives of colonialism and slavery; and providing community-engaged learning opportunities as instrumental to dismantle systemic drivers of racial health inequities locally and globally. We also advocate for intersectoral collaboration, mutual learning, and sharing of resources across SPH and partner agencies to accomplish a continual collective agenda for racial health equity and inclusion that is intersectional in Canada, while being held accountable to Indigenous and racialized communities.

RéSUMé: L'importance de voir la race comme une idée socialement construite continue de produire des différences inéquitables entre les gens et d'établir des relations de pouvoir qui mènent à l'injustice et à l'exposition à la mort. Depuis que le mouvement pour la justice raciale s'est enclenché au début de 2020, il existe une conscience aiguë des disparités raciales historiques entre les écoles de santé publique (ESP) du Canada et un intérêt accru pour le redressement de ces disparités. Des mesures ont été prises pour reconnaître le racisme systémique et accroître la diversité par des réformes structurelles visant à promouvoir l'équité et l'inclusion; cependant, pour aborder le racisme, il faut collectivement arracher les modèles institutionnels racistes qui font encore partie intégrante de l'apprentissage, de l'enseignement, de la recherche, des services et de la participation de la communauté. Dans notre commentaire, nous soulignons le besoin d'un engagement soutenu à établir des repères longitudinaux pour une plus grande équité raciale dans la population étudiante, au sein du personnel et dans le corps professoral, à revoir les programmes d'études pour y inclure les discours historiques et contemporains du colonialisme et de l'esclavage, et à offrir des possibilités d'enseignement faisant appel aux communautés, car elles contribueront à démanteler les moteurs systémiques des iniquités raciales en santé à l'échelle locale et mondiale. Nous promulguons aussi la collaboration intersectorielle, l'apprentissage mutuel et le partage des ressources entre les ESP et les organismes partenaires afin de concrétiser un plan d'action collective continue en faveur de l'équité raciale en santé et de l'inclusion ­ un plan qui sera intersectionnel au Canada et qui rendra des comptes aux communautés autochtones et racisées.

Opposite-sex associations are linked with annual fitness, but sociality is stable over lifetime.

Animal sociality, an individual's propensity to associate with others, has fitness consequences through mate choice, for example, directly, by increasing the pool of prospective partners, and indirectly through increased survival, and individuals benefit from both. Annually, fitness consequences are realized through increased mating success and subsequent fecundity. However, it remains unknown whether these consequences translate to lifetime fitness. Here, we quantified social associations and their link to fitness annually and over lifetime, using a multi-generational, genetic pedigree. We used social network analysis to calculate variables representing different aspects of an individual's sociality. Sociality showed high within-individual repeatability. We found that birds with more opposite-sex associates had higher annual fitness than those with fewer, but this did not translate to lifetime fitness. Instead, for lifetime fitness, we found evidence for stabilizing selection on opposite-sex sociality, and sociality in general, suggesting that reported benefits are only short-lived in a wild population, and that selection favors an average sociality.

Physico-Chemical Properties of Magnetic Dicationic Ionic Liquids with Tetrahaloferrate Anions.

A series of imidazolium-based symmetrical and asymmetrical dicationic ionic liquids (DcILs) with alkyl spacers of different length and with [FeCl3 Br]- as counter ion have been synthesized. The synthesized DcILs are characterized by using FTIR and Raman spectroscopy as well as mass spectrometry, along with single-crystal XRD analysis. Physicochemical properties such as solubility, thermal stability and magnetic susceptibility are also measured. These compounds show low melting points, good solubility in water and organic solvents, thermal stability, and paramagnetism. The products of molar susceptibility and temperature (χmol ⋅T) for the synthesized DcILs have been found between 4.05 to 4.79 emu mol-1 K Oe-1 and effective magnetic moment values have also been determined to be compared to that expected from the spin-only approximation.

Influence of iron ore properties on dioxin emissions during iron ore sintering.

Iron ores are principal input materials for iron and steel-making industries. Quality of iron ores is one of the critical parameters for formation of environmental pollutants related to the steel-making process. Dioxins are identified as one of the most toxic pollutants emitted during ironmaking, specifically during the sintering process. This study applied four types of iron ores and analyzed their moisture, density, particle size distribution and element concentrations to investigate their effect on the dioxin formation during sintering. Each type of iron ore was processed in a sinter pot grate. During each processing route, exhausted dust and generated sinter products were collected and subjected to PCDD/F and PCB analysis. Statistical analysis was applied to assess correlations between properties of iron ores and exhausted dioxin emissions, identifying key contributors to dioxin formation during sintering process. Results showed that Fe in iron ores was positively and significantly related to PCB 114 formation in dust and confirmed its co-catalytic effect on dioxin formation. Concentrations of Al, Ti and Cl in iron ores greatly increased PCDD/F and PCB emissions in the sintered products compared to dioxins in dust samples. The S levels and density of iron ores were highly related to the increasing PCDD/F and PCB emissions in both sinter and dust samples. By contrast, concentrations of Si in iron ores played a significant role in decreasing PCDD/F and PCB emissions in both sinter and dust samples. This study also confirmed the optimum size (< 1 mm-2.59 mm) for iron ores, which helps reduce dioxin emissions without affecting the quality of iron and steel-making products.

WALES 2021 Active Healthy Kids (AHK) Report Card: The Fourth Pandemic of Childhood Inactivity.

This is the fourth Active Healthy Kids (AHK) Wales Report Card. The 2021 card produced grades on children and young people's physical activity (PA) using pre-COVID-19 data that were not used in previous versions. Eleven quality indicators of PA were graded through expert consensus and synthesis of the best available evidence. Grades were assigned as follows: Overall PA-F; Organised Sport and PA-C; Active Play-C+; Active Transportation-C-; Sedentary Behaviours-F; Physical Fitness-C-; Family and Peer Influences-D+; School-B-; Community and the Built Environment-C; National Government and Policy-C; and Physical Literacy-C-. All but three grades remained the same or decreased from the 2018 AHK-Wales Report Card (Active Play increased from C- to C+; Active Transportation, D+ to C-; Family and Peers, D to D+). This is concerning for children's health and well-being in Wales, particularly given recent evidence that PA has further decreased during the COVID-19 pandemic. The results from the Report Card should be used to inform the decision making of policy makers, practitioners and educators to improve children and young people's PA levels and opportunities and decrease PA inequalities.

Effects of Sex, Training, and Maturity Status on the Cardiopulmonary and Muscle Deoxygenation Responses during Incremental Ramp Exercise.

Whilst participation in regular exercise and sport has generally increased over recent decades globally, fundamental questions remain regarding the influence of growth, maturation, and sex on the magnitude of training response throughout adolescence. Trained (108 participants, 43 girls; age: 14.3 ± 1.8 years) and untrained (108 participants, 43 girls; age: 14.7 ± 1.7 years) adolescents completed an incremental ramp test to exhaustion during which breath by gas exchange, beat-by-beat heart rate (HR), stroke volume (SV) and cardiac output (Q·) and muscle deoxygenation were assessed. Device-based physical activity was also assessed over seven consecutive days. Boys, irrespective of training status, had a significantly higher absolute (2.65 ± 0.70 L min−1 vs. 2.01 ± 0.45 L min−1, p < 0.01) and allometrically scaled (183.8 ± 31.4 mL·kg−b min−1 vs. 146.5 ± 28.5 mL·kg−b min−1, p < 0.01) peak oxygen uptake (V·O2) than girls. There were no sex differences in peak HR, SV or Q· but boys had a higher muscle deoxygenation plateau when expressed against absolute work rate and V·O2 (p < 0.05). Muscle deoxygenation appears to be more important in determining the sex differences in peak V·O2 in youth. Future research should examine the effects of sex on the response to different training methodologies in youth.

Temporal and spatial variations of air pollution across China from 2015 to 2018.

This study investigated concentrations of PM2.5, PM10, SO2, NO2, CO and O3, and air quality index (AQI) values across 368 cities in mainland China during 2015-2018. The study further examined relationships of air pollution status with local industrial capacities and vehicle possessions. Strong correlations were found between industrial capacities (coal, pig iron, crude steel and rolled steel) and air pollution levels. Although statistical and significant reductions of PM2.5, PM10, SO2, NO2, CO and AQI values were observed in response to various laws and regulations in industrial sectors, both particle and gaseous pollutants still had annual average concentrations above recommended limits. In order to further reduce air pollution, more efforts can be done to control traffic emissions caused by minicars and heavy trucks, which was revealed after investigating 16 vehicle types. This was also consistent with the apparent air quality improvement during the COVID-19 lockdown period in China in 2020, despite industrial operations being still active at full capacities.

Higher-order temporal network effects through triplet evolution.

We study the evolution of networks through 'triplets'-three-node graphlets. We develop a method to compute a transition matrix to describe the evolution of triplets in temporal networks. To identify the importance of higher-order interactions in the evolution of networks, we compare both artificial and real-world data to a model based on pairwise interactions only. The significant differences between the computed matrix and the calculated matrix from the fitted parameters demonstrate that non-pairwise interactions exist for various real-world systems in space and time, such as our data sets. Furthermore, this also reveals that different patterns of higher-order interaction are involved in different real-world situations. To test our approach, we then use these transition matrices as the basis of a link prediction algorithm. We investigate our algorithm's performance on four temporal networks, comparing our approach against ten other link prediction methods. Our results show that higher-order interactions in both space and time play a crucial role in the evolution of networks as we find our method, along with two other methods based on non-local interactions, give the best overall performance. The results also confirm the concept that the higher-order interaction patterns, i.e., triplet dynamics, can help us understand and predict the evolution of different real-world systems.

Life cycle impact assessment of metal production industries in Australia.

Metal production industries are associated with positive economic benefits, however their activities are significantly resource and energy intensive, contributing to emission of pollutants and greenhouse gases to the environment. The balance between the economic inputs and environmental footprint of the metal production industries determines their contribution to sustainability. This work provides environmental impact assessment of the production of aluminium, copper, gold, iron and steel, lead, nickel and zinc, and considers their contribution to the economy. The emissions of selected representative industries in Australia were sourced from public national emission inventories and used as input parameters in the openLCA software. ReCiPe midpoint and endpoint hierarchist impact assessment methods were used to investigate the environmental impacts of the selected industries. The results indicate that lead, followed by aluminium and nickel production had the largest environmental impacts. The work further revealed the specific emissions for better control for each industry taking into consideration their relative environmental and economic impacts. For instance, adoption of renewable energy sources would significantly decrease the greenhouse gas emissions and the associated environmental impacts of the copper, zinc, gold, and iron and steel production industries. Improvement of sustainability of the production of lead would require further control of trace metal emissions, while for aluminium and nickel production, improved control of emissions of particles and the acidic gases SO2 and NOx.

Factors predicting statin prescribing for primary prevention: a historical cohort study.

BACKGROUND: Initiation of statins for the primary prevention of cardiovascular disease (CVD) should be based on CVD risk estimates, but their use is suboptimal. AIM: To investigate the factors influencing statin prescribing when clinicians code and do not code estimated CVD risk (QRISK2). DESIGN AND SETTING: A historical cohort of patients who had lipid tests in a database (IQVIA Medical Research Data) of UK primary care records. METHOD: The cohort comprised 686 560 entries (lipid test results) between 2012 and 2016 from 383 416 statin-naive patients without previous CVD. Coded QRISK2 scores were extracted, with variables used in calculating QRISK2 and factors that might influence statin prescribing. If a QRISK2 score was not coded, it was calculated post hoc. The outcome was initiation of a statin within 60 days of the lipid test result. RESULTS: Of the entries, 146 693 (21.4%) had a coded QRISK2 score. Statins were initiated in 6.6% (95% confidence interval [CI] = 6.4% to 6.7%) of those with coded and 4.1% (95% CI = 4.0% to 4.1%) of uncoded QRISK2 (P<0.001). Statin initiations were consistent with National Institute for Health and Care Excellence guideline recommendations in 85.0% (95% CI = 84.2% to 85.8%) of coded and 44.2% (95% CI = 43.5% to 44.9%) of uncoded QRISK2 groups (P<0.001). When coded, QRISK2 score was the main predictor of statin initiation, but total cholesterol was the main predictor when a QRISK2 score was not coded. CONCLUSION: When a QRISK2 score is coded, prescribing is more consistent with guidelines. With no QRISK2 score, prescribing is mainly based on total cholesterol. Using QRISK2 is associated with statin prescribing that is more likely to benefit patients. Promoting the routine CVD risk estimation is essential to optimise decision making.

Primary health care, the Declaration of Astana and COVID-19.

Four decades after the Declaration of Alma-Ata, its vision of health for all and strategy of primary health care are still an inspiration to many people. In this article we evaluate the current status of primary health care in the era of the Declaration of Astana, the sustainable development goals, universal health coverage and the coronavirus disease 2019 pandemic. We consider how best to guide greater application of the primary health care strategy, reflecting on tensions that remain between the political vision of primary health care and its implementation in countries. We also consider what is required to support countries to realize the aspirations of primary health care, arguing that national needs and action must dominate over global preoccupations. Changing contexts and realities need to be accommodated. A clear distinction is needed between primary health care as an inspirational vision and set of values for health development, and primary health care as policy and implementation space. To achieve this vision, political action is required. Stakeholders beyond the health sector will often need to lead, which is challenging because the concept of primary health care is poorly understood by other sectors. Efforts on primary health care as policy and implementation space might focus explicitly on primary care and the frontline of service delivery with clear links and support to complementary work on social determinants and building healthy societies. Such efforts can be partial but important implementation solutions to contribute to the much bigger political vision of primary health care.

Quarante ans après la Déclaration d'Alma-Ata, sa vision en matière de santé universelle et sa stratégie de soins de santé primaires demeurent une inspiration pour de nombreuses personnes. Dans cet article, nous évaluons l'état actuel des soins de santé primaires à l'ère de la Déclaration d'Astana, des objectifs de développement durable, de la couverture maladie universelle et de la pandémie de maladie à coronavirus 2019 (COVID-19). Nous tentons de déterminer quel est le meilleur moyen de favoriser une application plus vaste de la stratégie de soins de santé primaires, en tenant compte des tensions qui subsistent entre la vision politique des soins de santé primaires et leur mise en œuvre dans les différents pays. Nous identifions également les éléments qui aident les pays à concrétiser les aspirations liées aux soins de santé primaires, et affirmons que les besoins et actions à l'échelle nationale doivent primer sur les préoccupations internationales. L'évolution des contextes et des réalités doit être prise en considération. Il est impératif d'opérer une nette distinction entre les soins de santé primaires comme source d'inspiration et ensemble de valeurs guidant le développement sanitaire d'une part, et comme espace politique et de mise en œuvre de l'autre. Pour y parvenir, des actes politiques sont indispensables. Des intervenants n'appartenant pas au secteur de la santé devront souvent prendre l'initiative, ce qui représente un défi car le concept des soins de santé primaires suscite l'incompréhension dans les autres secteurs. Les efforts en matière d'espace politique et de mise en œuvre pourraient se concentrer explicitement sur les soins de santé primaires et la première ligne des prestations de service, avec des liens clairement établis et un soutien aux travaux complémentaires consacrés aux déterminants sociaux et à la création d'une société saine. De tels efforts peuvent offrir des solutions partielles mais essentielles à l'élaboration d'une vision politique bien plus large des soins de santé primaires.

Cuatro décadas después de la Declaración de Almá Atá, su visión de la salud para todos y su estrategia de atención primaria de salud siguen siendo una inspiración para muchas personas. En este artículo se evalúa el estado actual de la atención primaria de salud en la era de la Declaración de Astaná, los objetivos de desarrollo sostenible, la cobertura sanitaria universal y la pandemia de la enfermedad por coronavirus de 2019. Se analiza la mejor manera de orientar una mayor aplicación de la estrategia de atención primaria de salud al estudiar las tensiones que subsisten entre la visión política de la atención primaria de salud y su aplicación en los países. También se analiza lo que se requiere para ayudar a los países a materializar las aspiraciones de la atención primaria de salud al argumentar que las necesidades y las medidas nacionales deben prevalecer sobre las preocupaciones mundiales. Se deben tener en cuenta los contextos y las realidades cambiantes. Hay que establecer una clara diferencia entre la atención primaria de salud como visión inspiradora y conjunto de valores para el desarrollo de la salud, y la atención primaria de salud como entorno normativo y de aplicación. Por consiguiente, se requiere la adopción de medidas políticas para hacer realidad esta visión. Con frecuencia, las partes interesadas que no pertenecen al sector sanitario tendrán que tomar la iniciativa, lo que supone un reto porque el concepto de atención primaria de salud no se comprende bien en otros sectores. Los esfuerzos relacionados con la atención primaria como entorno normativo y de aplicación se podrían centrar de manera explícita en la atención primaria y en la prestación de servicios de primera línea a través de vínculos claros y el apoyo a la labor complementaria sobre los determinantes sociales y la construcción de sociedades sanas. Esos esfuerzos pueden ser soluciones parciales pero importantes de aplicación para contribuir a la visión política mucho más amplia de la atención primaria de salud.

Evaluation of the uptake and delivery of the NHS Health Check programme in England, using primary care data from 9.5 million people: a cross-sectional study.

OBJECTIVES: To describe the uptake and outputs of the National Health Service Health Check (NHSHC) programme in England. DESIGN: Observational study. SETTING: National primary care data extracted directly by NHS Digital from 90% of general practices (GP) in England. PARTICIPANTS: Individuals aged 40-74 years, invited to or completing a NHSHC between 2012 and 2017, defined using primary care Read codes. INTERVENTION: The NHSHC, a structured assessment of non-communicable disease risk factors and 10-year cardiovascular disease (CVD) risk, with recommendations for behavioural change support and therapeutic interventions. RESULTS: During the 5-year cycle, 9 694 979 individuals were offered an NHSHC and 5 102 758 (52.6%) took up the offer. There was geographical variation in uptake between local authorities across England ranging from 25.1% to 84.7%. Invitation methods changed over time to incorporate greater digitalisation, opportunistic delivery and delivery by third-party providers.The population offered an NHSHC resembled the English population in ethnicity and deprivation characteristics. Attendees were more likely to be older and women, but were similar in terms of ethnicity and deprivation, compared with non-attendees. Among attendees, risk factor prevalence reflected population survey estimates for England. Where a CVD risk score was documented, 25.9% had a 10-year CVD risk ≥10%, of which 20.3% were prescribed a statin. Advice, information and referrals were coded as delivered to over 2.5 million individuals identified to have risk factors. CONCLUSION: This national analysis of the NHSHC programme, using primary care data from over 9.5 million individuals offered a check, reveals an uptake rate of over 50% and no significant evidence of inequity by ethnicity or deprivation. To maximise the anticipated value of the NHSHC, we suggest continued action is needed to invite more eligible people for a check, reduce geographical variation in uptake, prioritise engagement with non-attendees and promote greater use of evidence-based interventions especially where risk is identified.

Diagnostic Challenges and Guidelines Pertaining to Suspected Ruminant Intoxications.

This article addresses diagnostic challenges involving toxicology cases that are multifactorial in nature, often involving sublethal exposures to multiple toxicants and/or other etiologies that are not toxic. Gold standard diagnostic approaches were developed under the assumption that cases were undoubtedly intoxications, and they still are applicable to those cases. A more integrated diagnostic approach, focusing on the initial problem list, is consistent with how veterinarians diagnose most cases. Livestock ownership attitudes continue to evolve. Ongoing threats to the financial well-being of animal agriculture ultimately will have an impact on the ability of producers to maintain health and performance of livestock.

Understanding the transition from paroxysmal to persistent atrial fibrillation.

Atrial fibrillation (AF) is the most common cardiac arrhytmia, characterized by the chaotic motion of electrical wavefronts in the atria. In clinical practice, AF is classified under two primary categories: paroxysmal AF, short intermittent episodes separated by periods of normal electrical activity; and persistent AF, longer uninterrupted episodes of chaotic electrical activity. However, the precise reasons why AF in a given patient is paroxysmal or persistent is poorly understood. Recently, we have introduced the percolation-based Christensen-Manani-Peters (CMP) model of AF which naturally exhibits both paroxysmal and persistent AF, but precisely how these differences emerge in the model is unclear. In this paper, we dissect the CMP model to identify the cause of these different AF classifications. Starting from a mean-field model where we describe AF as a simple birth-death process, we add layers of complexity to the model and show that persistent AF arises from reentrant circuits which exhibit an asymmetry in their probability of activation relative to deactivation. As a result, different simulations generated at identical model parameters can exhibit fibrillatory episodes spanning several orders of magnitude from a few seconds to months. These findings demonstrate that diverse, complex fibrillatory dynamics can emerge from very simple dynamics in models of AF.