Current Circulation Research Articles

A survey on the occurrence of papaya ringspot virus-P (PRSV-P) in Malaysia and genetic diversity assessment of the coat protein region.

Papaya ringspot virus (PRSV) is a plant virus transmitted by aphids that has spread throughout many countries, including Malaysia, causing yield losses and economic impacts to the papaya industry worldwide. PRSV infection in papaya-distinctive ring-shaped patterns on papaya leaves resulted in stunted growth and reduced fruit quality. Management strategies such as the use of resistant varieties, cultural practices, and vector control are employed to mitigate the spread of PRSV. However, the evolution of new virus strains and the uncertainties posed by climate change pose ongoing challenges for the management of PRSV worldwide. Therefore, in this present study, we aim to confirm the presence of PRSV in symptomatic papaya leaves, to depict the current status of PRSV in Malaysia. Using reverse-transcription PCR (RT-PCR) targeting PRSV partial nuclear inclusion b protein (NIb) and coat protein (CP), 13 out of 40 papaya leaves collected were found positive for the PRSV strain-P (PRSV-P). Nucleotide analysis revealed a high similarity with strains from Taiwan and India, showing 96.83%, 97.03%, and 97.03% identity with the Taiwan strains (DQ340771, AY027810) and the India strain (KJ755852), respectively. Compared to the CP gene of Malaysian isolates reported in 2016 (EU082207), several nonsynonymous mutations have been discovered suggesting genetic diversity within the PRSV population in Malaysia. Overall, this study confirms the current circulation of PRSV infection in Malaysia since it was first identified in Johore in 1991. The re-occurrence of PRSV-P in this study highlights the need for continuous monitoring and targeted management strategies to prevent the further spread of PRSV-P in Malaysia.

Equatorial Dynamics Significantly Weakened the Southward Somali Current Circulation during 1997–98

Abstract Based on reanalysis data and numerical model, this study documented an unusually weak southward Somali Current (SSC) circulation, an anticlockwise circulation in the western Arabian Sea, during the winter of 1997 to spring 1998, throughout the two-decade period from 1994 to 2017. Theoretical analysis and model simulations suggest that the exceptionally weak SSC circulation was primarily caused by abnormal wind forcing around the equator, associated with extreme climate events. The strong equatorial easterly anomalies are mainly responsible for the weakening of the SSC circulation north of ∼6°N and contribute to about half of the weakening south of ∼6°N, by regulating the layer thickness along the eastern boundary, following the time-dependent Sverdrup relation. The large negative wind stress curl anomalies near the equator contribute to another half of the weakening south of ∼6°N. This research underscores the dynamic connection between the circulation in the western basin and equatorial dynamics during extreme climate modes. Significance Statement The dynamic linkage between the western basin circulation and the equatorial forcing remains elusive. Based on reanalysis data, theoretical analysis, and numerical simulations, this study has confirmed that the exceptionally weak southward Somali Current circulation during the winter of 1997 to spring 1998 was significantly influenced by abnormal wind patterns around the equator, triggered by extreme climate modes.

Morphodynamic Cartography Visualization of Wulan River Estuary Systems from Space to Numerical Approach Based on Multi-Season Analysis

This research aims to investigate the morphodynamics of the Wulan River estuary in Demak Regency using the integration of multispectral remote sensing images and numerical modeling. In this study, PlanetScope for a manualvisual analysis of estuary morphodynamics and Sentinel-2 MSI Level 2A to obtain periodic total suspended solids (TSS) information for the east and west monsoon seasons. MIKE by DHI software used to develop hydrodynamic numerical modeling in order to characterize the current circulation and sediment transport model. Based on a marine cartography aspect, the obtained results illustrated that the climatological phenomenon of seasonal forcing plays a role in the development of the current circulation and indirectly influences the sediment transport. During the west season, the morphodynamics in the Wulan River estuary are much more massive and significant as compared to the east season. A projection of the deposition that results from the sediment transport is described in the bed-thickness change; this occurs in the western part of the Wulan River estuary during the east season, while the bed-thickness change occurs predominantly in the northern part during the west season (where there was previously a beach sandbar phenomenon). This was verified through multi-temporal satellite imagery that the deposition that occurs in the northern part of the Wulan River estuary during the west season is increasingly progressive and massive.

Projected North Equatorial Current/Countercurrent Towards an El Niño-Like Condition in the Western Pacific under Moderate and Worst-case CO2 Emission Scenarios

Abstract Validating the mean state and historical trends of the North Equatorial Current and Countercurrent (NEC and NECC) in 36 Coupled Model Intercomparison Project (CMIP) phase 5 models and 32 CMIP phase 6 models with those in ocean reanalysis products, this study extracts the most qualified 17 model outputs to explore the projected changes in NEC and NECC in the western Pacific Ocean under scenarios of moderate and worst-case CO2 emissions. NEC and NECC are robustly predicted to have an El Niño-like change, in which the NEC (NECC) tends to intensify with a poleward (equatorward) movement, during the 21st century under both scenarios. Meanwhile, the Kuroshio and Mindanao Current are projected to become weaker. Change in meridional gradient of basin-scale wind stress curl in the tropical Pacific Ocean is the major contributor to the centennial changes in NEC and NECC; however, anomalous wind stress curl dipole on the two sides of NEC off the eastern Philippines is the major factor in controlling the western boundary currents. This study not only represents a step forward in understanding the impact of global warming on the western tropical Pacific surface circulation, but also serves as a reference for downscaled modeling, which can better resolve regional circulation and western boundary currents, for selecting suitable inputs from a large number of CMIP models.

Distribution and Controlling Factors of the Contourites on the Northern Continental Slope of the South China Sea

ABSTRACTThe northern continental margin of the South China Sea (SCS) is an important component of deep‐water circulation, providing excellent conditions for studying bottom currents in a marginal sea. Seismic data were employed to discern the sedimentary patterns prevalent in the deep‐water continental slope sediments on the northern continental margin of the SCS, encompassing gravity flow, contourite and mixed depositional systems. The contourite depositional system includes various types of deposits (such as separated mounded drifts, patch or channel‐related drifts, deformed sheeted drifts, composite drifts, bottom current sediment waves, plastered contourite drifts) and various morphologic erosional features eroded by the bottom current (such as moats, non‐depositional surfaces, troughs and scarps). These contourite features are related to the continental slope's morphology and its sources. The Dongsha slope exhibits distinctive characteristics marked by intense bottom current erosion and deposition, featuring separated mounded drifts and deformed sheeted drifts along its lower slope. The lower slope of the Pearl River showcases a spectrum of bottom current‐induced features, including sediment wave fields, erosion fields and contourite drifts. The southern flank of the Shenhu slope is characterised by a bottom current erosion field, a non‐depositional surface, a sediment wave field and isolated mounded drifts. On the Yingqiong slope, the contourite drifts are limited to its southern flank where gravity flow action is absent, and the complex geomorphology interacts with the bottom current, forming a complex contourite depositional system. The results of this study serve as a foundational framework for further global research on bottom current circulation and hydrodynamics.

Assessing the spatial variability of cage movement and velocity attenuation of an off-bottom oyster farm and its influence on eastern oyster (Crassostrea virginica) growth performance

The global shellfish aquaculture industry has expanded over the last seven decades. Similarly, the size of individual shellfish farming operations has grown in some states. Circulation processes in natural water bodies are dynamic and vary across multiple temporal and spatial scales. How gear installation affects the circulation of currents and waves, and subsequent phytoplankton delivery to crops within farms, is largely unknown. Documenting and understanding variability in wave and current energy within an individual farm could help optimize production. Our study sought to understand the variability in oyster growth attributable to hydrodynamic and atmospheric forcing across an active commercial shellfish aquaculture lease in the Patuxent River, Maryland. We observed a 17 % reduction in water flow downstream of the farm (rho = −0.673, p = 0.002, Spearman rank test), suggesting the bottom cages attenuated downstream current velocity during flood tides. Differences in flow speed and the movement of cages and oysters throughout the farm correlated with variances in oyster shell morphology and oyster survival while in bottom cages. Our results demonstrate the occurrence of variability in production within an individual farm location. Further, our findings suggest that insight into the spatial growth patterns across a lease can be practical for forecasting growth and quality of cultured oysters and may enable growers to strategically place oysters within their farm to improve yield and product consistency.

Core-winding of Sodium Cold Fast Reactor Based on CFD Method Numerical Study of Flow Characteristics

Abstract Liquid metal cooled fast reactor often uses spiral winding wire as the positioning component of fuel rod bundle. Besides fixing, spiral winding has the functions of strengthening subchannel mixing and heat transfer. These characteristics have a very important impact on the internal flow temperature characteristics of the fuel assembly and the safety of the core system, so it is necessary to conduct in-depth research on the flow field distribution of the fuel rod bundle channel with wire wound, the transverse and axial flow characteristics of the edge channel and its internal channel, the flow characteristics of the circulation and eddy current, the local temperature field, and the outlet temperature distribution characteristics. In the actual research, there are some problems such as high cost, difficulty and high risk to carry out thermal hydraulic characteristic experiment directly. This paper uses CFD fine simulation technology to study 7 rod bundles with wire winding, uses Fluent meshing to partition high-quality polyhedral unstructured mesh, uses ANSYS Fluent to conduct numerical simulation, studies the influence of the presence of rod bundles with wire winding on the distribution of flow field and local temperature field, and forms a mature and reliable simulation experiment scheme. The temperature change curve and lateral mixing phenomenon obtained by CFD simulation were investigated. The outlet temperature differences of side channel, inner channel and corner channel were investigated, and the convective heat transfer characteristics between channels were investigated due to the existence of wire winding.

Harmonic voltage compensation and harmonic current sharing strategy of grid-forming inverter

In a multi-inverter parallel system, the harmonic governance control strategy may worsen the system's current circulation problem due to the line impedance difference, which could further affect the stable operation of the system. To solve the problem, the strategy considering both power sharing and harmonic control is proposed in this paper. First, the microgrid system with background harmonics is modeled and analyzed. Based on the modeled system, a comprehensive control strategy for the grid inverter with harmonic voltage compensation and harmonic current sharing is established. In this paper, the output signal is controlled by frequency division. This paper adopts grid-forming control in the fundamental wave domain and employs harmonic voltage compensation control in the harmonic domain. The harmonic voltage is synthesized by collecting the specific harmonic current through the band-pass filter, compensating for the harmonic voltage drop on the line to improve the harmonic voltage quality of the point of common coupling(PCC). Aiming at the sharing problem caused by line impedance difference, virtual impedance control is introduced, harmonic impedance is redesigned according to the adjusted output impedance, and the harmonic output impedance before and after adjustment is measured and compared. The simulation results show that the proposed control strategy can not only reduce the harmonic content of the PCC voltage but also achieve the effect of equal harmonic current division.

Research on the optimization of investment structure of China's high-tech industries under the new development model of dual circulation

On May 14, 2021, at the Standing Committee of the Political Bureau of the CPC Central Committee, General Secretary Xi Jinping first proposed the concept of "dual circulation", emphasizing the construction of a new development pattern in which domestic and international dual circulations promote each other. Capital circulation is the primary link in opening up the circulation, and high-tech industries are the key areas in this new development pattern. In this context, it is of great significance and value to study the optimization of the investment structure of high-tech industries. This study takes the new dual circulation model as the starting point and conducts an in-depth analysis of high-tech industries from the perspective of investment structure optimization. By applying theories such as capital circulation, dynamic comparative advantage, and investment portfolio, the relationship between China's current economic development status and dual circulation is explained. At the same time, the development status of China's high-tech industries is compared with that of foreign high-tech industries, and the advantages, gaps, and problems between China's high-tech industries and developed countries are analyzed. The research plan explores the rationality of the investment structure of high-tech industries in the internal circulation, external circulation, and dual circulation from multiple perspectives such as industrial growth, investment efficiency, industrial upgrading, and global value chain. This will provide a theoretical basis and practical guidance for optimizing the investment structure of high-tech industries and help China achieve high-quality development under the new development pattern.

KAJIAN EFEKTIFITAS POLA SIRKULASI KAWASAN WISATA DESA TRADISONAL PENGLIPURAN

Bali, as one of the main tourist destinations in Indonesia, has a variety of attractions, including the Penglipuran Traditional Tourism Village in Bangli Regency. The popularity of this tourist village has led to a significant increase in vehicle flow, especially on weekends and holidays, resulting in congestion around tourist areas. Vehicles parked carelessly on the side of the road interfere with mobility for both locals and other tourists. This study aims to evaluate the effectiveness of current circulation patterns and identify potential solutions. Using a qualitative method with a naturalistic approach, this study will observe and analyze vehicle movement patterns, parking behavior, and their impact on traffic and visitor comfort. The results of this study are expected to provide recommendations for more effective circulation pattern arrangement, including parking management, alternative routes, and road infrastructure improvements. With the implementation of the right solutions, it is hoped that the comfort and experience of tourists in the Penglipuran Traditional Tourism Village can be significantly improved, while maintaining smooth traffic for local residents.

Interplay and feedback between tectonic regime, faulting, sealing horizons, and fluid flow in a hydrocarbon-hosting extensional basin: The Val d'Agri Basin case, Southern Italy

Understanding the factors that govern past fluid circulation in tectonically active and/or hydrocarbon-rich basins is crucial for elucidating present-day fluid-flow scenarios. We investigate the circulation of paleo-fluids in the extensional-transtensional Val d'Agri Basin (southern Italy), home to a giant oil field and significantly affected by both natural and human-induced seismicity. Our aim is to understand how faulting and the variable thickness of the clay-rich tectonic mélange, which constitutes the seal of the hydrocarbon reservoir, influenced past fluid flow under different tectonic regimes. To achieve this, we combined multiscale structural observations with isotope (C, O, clumped, and Sr) and Rare Earth and Yttrium (REY) analyses of fault-related calcite mineralizations. Using analytical methodologies that allow the analysis of sub-milligram samples for carbonate clumped isotopes, we provided a detailed characterization of the variability in precipitation temperatures and composition of parental fluids in both space and time. Our results reveal five main types of parental fluids, ranging from meteoric to intraformational and deep crustal, which were differently involved in the tectonic evolution of the Val d'Agri Basin. During orogenic shortening, vertical fluid circulation was mostly limited and compartmentalized, whereas post-orogenic extensional faulting promoted the ascent of deep fluids. Our findings indicate that the sealing properties of the mélange were likely enhanced locally by increased thickness but were also compromised by fault activity and associated seismic events. Fluid circulation in the study area has been influenced by the prevailing tectonic regime (compressive vs. extensional), stratigraphic-structural architecture, properties of impermeable horizons, and seismic events. The model proposed for the Val d'Agri Basin elucidates past processes that are useful for understanding current fluid circulation in the basin itself and can be applied to other basins where fluid circulation is partly manipulated by human activities.

Molecular and pathological screening of the current circulation of fowlpox and pigeon pox virus in backyard birds

Avian pox is a disease that has devastating impacts on both poultry and wild bird species. Avian pox is caused by various strains of avipoxviruses (APV). Nevertheless, the virus has been detected in pigeons and chickens that are raised in backyard areas, leading to substantial financial damage for small-scale producers. There is a lack of comprehensive information regarding the transmission of APV among birds in the backyards and residential areas. Hence, the present investigation closely monitored and observed APV in domesticated birds residing in backyard areas, with the aim of impeding the transmission of the virus to nearby poultry farms. In 2023, a total of fifty backyard flocks were surveyed for the presence of avian pox disease. Sixteen backyards (14 pigeons and 2 chickens) exhibited warty nodular lesions on their heads and nonfeathered body parts. APV was confirmed in nodular lesions by polymerase chain reaction (PCR) amplification and genetic sequencing. All samples from the lesions showed successful amplification of the p4b locus (core protein p4b). Four confirmed samples were tested for pathogenicity on the chicken embryo chorioallantoic membrane (CAM). Histopathological examination revealed ballooning degeneration and numerous intracytoplasmic inclusion bodies (Bollinger bodies) in the ectoderm of the infected CAM. Phylogenetic analysis revealed that the strains clustered into main clade A, with 11 in subclade A2 and 5 in subclade A1. Amino acid identity showed 100% similarity between the vaccine (fowlpox/VSVRI/Egypt) and some detected strains (PP537574 and PP537575). In addition, the PP537576.1 to PP537580.1 and PP537582.1 to PP537585.1 had 2-point mutations compared to the fowlpox/VSVRI/Egypt vaccine. The overall finding of low biosecurity levels in the investigated backyard birds emphasizes the significance of establishing sanitary measures and control vectors to reduce virus transmission routes and disease severity. In conclusion, it is necessary to emphasize the tracking of APV in backyard birds. Concurrently, we advised enhancing hygiene protocols, vector management, and subsequent vaccination to restrict the occurrence of APV outbreaks and prevent their transmission to neighboring poultry farms. Furthermore, it is crucial to incorporate molecular studies in order to enhance the vaccine seeds for disease management.

Nuʻupia Ponds’ Water Circulation Characteristics: Exploring Water Exchange and Residence Time for Marine Ecosystem Management

Nuʻupia Ponds, a traditional Hawaiian fishpond system, are located at Marine Corps Base Hawaiʻi (MCBH) and part of the Nuʻupia Ponds Wildlife Management Area, a wetland refuge for native, endangered, and protected birds and Hawaiian green sea turtles, as well as many native fish species. Currently, there is uncertainty regarding the ecological status and condition of the fishponds following prior modification of wetland habitats in and around the ponds. This study examines circulation dynamics and characterizes water exchange, pond volume, and residence time across the full tidal spectrum at the Nuʻupia fishponds. Our results indicate a general west to east gradient in current flow; with higher flushing rates and lower residence times of fishponds in the western ponds of the Nuʻupia system compared to the eastern ponds. We further found low flushing rates at several sites causing limited water exchange with Kāneʻohe Bay, as well as within the Nuʻupia Pond system. Sufficient water circulation plays a fundamental role in maintaining a healthy balance of fishpond flora and fauna and preserving ecosystem health. The results from this study provide a baseline for current physical water circulation dynamics and implications for ecosystem health, as well as informing science-based conservation and management strategies moving forward.

Impact of geomagnetic activity on stratosphere and upper troposphere

During active geomagnetic conditions, a large amount of energy is deposited in the polar atmosphere in the form of particle precipitation that leads to Joule heating creating circulation of intense currents in the auroral region. It can affect the existing background pressure fluctuations in the stratospheric and tropospheric heights, leading to anomalous changes in the vertical temperature (T), zonal (u) and meridional (v) wind. In this study, we demonstrate the effect of active geomagnetic conditions on these atmospheric variables in different longitudinal regions. The investigation involves daily, monthly and seasonal variation of active geomagnetic conditions. Active geomagnetic conditions are selected using geomagnetic activity indices like auroral activity index |AL|>1000 nT, Disturbed Storm time index Dst < -150 and polar cap index PC > 5. Events are identified during November to March for 1990 to 2020 period. Among them 99 active geomagnetic conditions occurred in the month of March which are considered for further investigation. Composite analysis of T, u and v reflects that the temperature shows an increase in the entire atmospheric column; the anomalies in u (u′) and v (v′) show a regional dependence and strengthen in their amplitudes. It is seen from the monthly investigation of March that the Western Pacific, Canadian and East Pacific sectors respond to the active geomagnetic conditions at upper atmospheric pressure levels (approximately 40–70 km altitude) in the polar region. This is indicative of a vertical translation of energy to lower atmosphere during active geomagnetic conditions.

Air Current Circulation as a Possible Cause of Preseismic Anomalies in the Surface Electric Field

Ground-based measurements of the vertical atmospheric electric field of the Earth sometimes show bay-like anomalies that precede certain earthquakes. In some cases, these anomalies have even been accompanied by a change in the sign of the field under fair weather conditions. Possible causes of this phenomenon are typically attributed to anomalous changes in electrical conductivity in the surface air and increased radon emission from the soil. This paper proposes another mechanism of atmospheric electrical anomalies that involves the entrainment of charged aerosols and light and heavy ions by air flows. Such flows can be produced by small temperature anomalies observed before some seismic events. Theoretical analysis shows that anomalously strong electrical variations may occur even in the presence weak air flows provided that they persist for a long time and there is a specific structure of the velocity field with vertical air circulation and particle exchange between different atmospheric layers. For this type of flows, an analytical solution is derived and spatial distributions of atmospheric electric perturbations are obtained. The results of calculations and estimates confirm that the proposed mechanism can explain the observational data.

The Epidemiological Features and Pathogen Spectrum of Respiratory Tract Infections, Istanbul, Türkiye, from 2021 to 2023.

Respiratory tract infections (RTIs) can lead to both recurrent seasonal epidemic outbreaks and devastating pandemics. The aim of this study was to evaluate the epidemiologic characteristics and pathogen spectrum of RTIs using a multiplex RT-PCR panel. A total of 9354 cases with suspected RTIs between February 2021 and July 2023 were included in this study. A total of 11,048 nasopharyngeal and oropharyngeal samples from these patients were analyzed for 23 respiratory tract pathogens using multiplex RT-PCR. H. influenzae and S. pneumoniae were considered as colonizing bacteria. At least one pathogen was detected in 70.66% of the samples; viral pathogens were detected in 48.41% of the samples, bacterial pathogens were detected in 16.06% of the samples, and viral + bacterial pathogens were detected in 35.53% of the samples. The most frequently detected viral pathogen was rhinovirus/enterovirus (RV/EV) (19.99%). Interestingly, in 2021, respiratory syncytial virus A/B showed atypical activity and replaced RV/EV as the most prevalent pathogen. Human bocavirus, H. influenzae, and S. pneumoniae were detected at higher rates in males (p: 0.038, p: 0.042, and p: 0.035, respectively), while SARS-CoV-2 and B. pertussis were detected at higher rates in females (p < 0.001 and p: 0.033). RTIs were found at higher rates in children (p < 0.001). SARS-CoV-2 and human coronaviruses 229E were detected at higher rates in adults (p < 0.001 and p: 0.001). This comprehensive study with a large sample size investigating RTI pathogens was the first in Türkiye. Understanding the current viral circulation using multiplex RT-PCR panels enables clinicians to predict the most likely pathogens affecting patients and contributes to patient management, in addition to anticipating potential threats.

Innovative model predictive control for HVDC: circulating current mitigation and fault resilience in Modular Multilevel converters

This study presents an advanced Model Predictive Control (MPC) technique designed to mitigate Circulating Current (CC) in HVDC systems equipped with Modular Multilevel Converters (MMC). This MPC strategy eliminates the need for traditional PI regulators and pulse width modulation, improving system dynamics and control accuracy. It excels in managing output currents and mitigating voltage fluctuations in sub-module capacitors. Moreover, the paper introduces a novel communication-free Fault Ride-Through (FRT) method that makes a DC chopper redundant, enabling rapid recovery from disturbances. To reduce the computational burden of standard MPC algorithms, an aggregated MMC model is proposed, significantly decreasing the computational complexity. Simulation studies validate the new MPC algorithm’s capability in regulating AC side current, reducing CC, and ensuring capacitor voltage stability under varying conditions. The findings indicate that the proposed MPC controller outperforms traditional PI and PR-based methods, offering enhanced dynamic response, decreased steady-state error, and lowered converter losses, which contribute to smoother DC link voltages. Future research will focus on system scalability, renewable energy integration, and empirical validation through hardware-in-the-loop testing.

Professional Training Of Librarians And Service Delivery In Public Libraries In Nigeria

The main purpose of the paper was to examine professional training of librarians and service delivery in public libraries in Nigeria. It is an opinion paper and therefore expository in nature. The paper discussed the history of public libraries in Nigeria and service delivery. The paper critically reviewed the professional training of librarians in public libraries. It also exposed various library services, such as current awareness, user education, inter-library loan, circulation, reprographic service and challenges affecting the services in the public libraries. The paper recommended among others, professional training for librarians with digital skills to enhance their productivity for efficient and effective service delivery.

Research on harmonic suppression characteristics and control methods for low-frequency resonance suppressor

The problem of low-frequency harmonics and their resonance seriously threatens the safety of the fusion power supply system, and is one of the key issues that urgently need to be solved during high-power operation of fusion devices. The low-frequency resonance suppressor (LFRS) can compensate for the low frequency harmonic suppression effect of passive filter and active filter and the limitation of voltage and capacity, which is a new approach to solve the low frequency resonance problem of fusion power system. However, the performance of the LFRS is affected by the power grid parameters and the fundamental current circulation between the active filter and passive filter branches. The low frequency harmonic current and its resonance suppression characteristics are analyzed based on the multi-reference vector control strategy in this paper. On this foundation, a current double closed loop control method is proposed, which can ensure the safe and reliable operation of the LFRS system and the suppression effect of low frequency harmonic current. The correctness and effectiveness of the theoretical analysis are verified by RT-LAB Hardware-in-the-loop simulation.

The virus is out of the barn: the emergence of HPAI as a pathogen of avian and mammalian wildlife around the globe.

Highly pathogenic avian influenza (HPAI) has persisted as a One Health threat whose current circulation and impact are addressed in the companion Currents in One Health by Puryear and Runstadler, JAVMA, May 2024. Highly pathogenic avian influenza emerged as a by-product of agricultural practices and adapted to endemic circulation in wild bird species. Over more than 20 years, continued evolution in a complex ecology involving multiple hosts has produced a lineage that expanded globally over the last 2 years. Understanding the continued evolution and movement of HPAI relies on understanding how the virus is infecting different hosts in different contexts. This includes understanding the environmental factors and the natural ecology of viral transmission that impact host exposure and ultimately evolutionary trajectories. Particularly with the rapid host expansion, increased spillover to mammalian hosts, and novel clinical phenotypes in infected hosts, despite progress in understanding the impact of specific mutations to HPAI viruses that are associated with spillover potential, the threat to public health is poorly understood. Active research is focusing on new approaches to understanding the relationship of viral genotype to phenotype and the implementation of research and surveillance pipelines to make sense of the enormous potential for diverse HPAI viruses to emerge from wild reservoirs amid global circulation.