Circular Field Research Articles

Mapping and Ablation of left atrial macro-reentrant tachycardia with a novel circular pulsed field ablation catheter

Mapping and Ablation of left atrial macro-reentrant tachycardia with a novel circular pulsed field ablation catheter

Methods and techniques to optimize energy delivery using the circular array pulsed field ablation catheter

Pulsed field ablation (PFA) is a novel method of cardiac ablation in which electrical fields are used to create microscopic pores in the cardiomyocyte cell membrane, resulting in cell death. Unlike traditional thermal radiofrequency and cryoablation technologies, PFA is cardiomyocyte preferential, reducing the risk of collateral damage to the esophagus and phrenic nerve. However, achieving durable lesions with PFA is dependent on the proximity to the tissue and presently approved systems do not provide contact force sensing. The PulseSelect PFA system is the first Food and Drug Administration–approved/CE–marked/Pharmaceuticals and Medical Devices Agency–approved system for PFA of atrial fibrillation; however, there is no consensus on workflow and best practices. We present here real-world experience from our centers in the United States, Europe, and Japan, and propose techniques and methods for incorporating fluoroscopy, electroanatomic mapping, and intracardiac echocardiography to assure optimal lesion delivery and predictability.

Concentric circular flow field to improve mass transport in large-scale proton exchange membrane water electrolysis cells

Uniform reactant supply is challenging for high-performance proton exchange membrane water electrolysis (PEMWE) in renewable energy storage. The anode flow-field pattern, anode flow-field orientation, and stoichiometric ratio influence mass transport. In this study, the performances of two flow-field patterns were compared for a single PEMWE cell with an active area of 100 cm2. Straight serpentine was used as the reference model and a concentric circle with an arc shape was designed. In addition, the optimal anode flow field orientation and stoichiometric ratio were determined. The results indicate that the optimal anode flow-field pattern differs depending on the stoichiometric ratio. At low flow rates, mass transfer via diffusion was dominant; therefore, a straight serpentine flow was preferred. In contrast, a concentric circle, which induces a significant differential pressure between adjacent channels, is preferable at a high flow rate. This is because convection is dominant in mass transfer. Maintaining a stoichiometric ratio of 10 or more is recommended during the operation. At a ratio of less than 10, the reactant was depleted at a high current density, and the mass transfer resistance increased. In addition, water is better distributed by gravity and buoyancy when the electrolyte membrane is parallel to the ground, and the anode flow path is above the porous medium. This leads to high PEMWE cell performance.

Band configurations and seasonality influence the predictions of common boreal tree species using UAS image data

Key messageData acquisition of remote sensing products is an essential component of modern forest inventories. The quality and properties of optical remote sensing data are further emphasised in tree species-specific inventories, where the discrimination of different tree species is based on differences in their spectral properties. Furthermore, phenology affects the spectral properties of both evergreen and deciduous trees through seasons. These confounding factors in both sensor configuration and timing of data acquisition can result in unexpectedly complicated situations if not taken into consideration. This paper examines how the timing of data acquisition and sensor properties influence the prediction of tree species proportions and volumes in a boreal forest area dominated by Norway spruce and Scots pine, with a smaller presence of deciduous trees.ContextThe effectiveness of remote sensing for vegetation mapping depends on the properties of the survey area, mapping objectives and sensor configuration.AimsThe objective of this study was to investigate the plot-level relationship between seasonality and different optical band configurations and prediction performance of common boreal tree species. The study was conducted on a 40-ha study area with a systematically sampled circular field plots.MethodsTree species proportions (0–1) and volumes (m3 ha−1) were predicted with repeated remote sensing data collections in three stages of the growing season: prior (spring), during (summer) and end (autumn). Sensor band configurations included conventional RGB and multispectral (MS). The importance of different wavelengths (red, green, blue, near-infrared and red-edge) and predictive performance of the different band configurations were analysed using zero–one-inflated beta regression and Gaussian process regression.ResultsPrediction errors of broadleaves were most affected by band configuration, MS data resulting in lower prediction errors in all seasons. The MS data exhibited slightly lower prediction errors with summer data acquisition compared to other seasons, whereas this period was found to be less suitable for RGB data.ConclusionThe MS data was found to be much less affected by seasonality than the RGB data. Spring was found to be the least optimal season to collect MS and RGB data for tree species-specific predictions.

Diophantine Equation Generated by the Subfield of a Circular Field

Diophantine Equation Generated by the Subfield of a Circular Field

Environmental hotspots, frontiers and analytical framework of Blue Carbon research: a quantitative analysis of knowledge map based on CiteSpace

Blue Carbon is increasingly popular worldwide, and it also belongs to circular economy field which would last a long period in academy. To further understand the development and characteristics of Blue Carbon, this study uses CiteSpace software to perform quantitative analysis on literature published on Web of Science and Chinese CNKI database with the main topic of “Blue Carbon.” The results show that: (1) Since 2009, increasing attention has been paid to Blue Carbon research, among which the United States, Australia and China are the leading countries. (2) Keywords such as “Blue Carbon,” “mangrove,” “carbon sequestration” and “carbon neutrality” are the high-frequency keywords appearing both in China and the World in recent years. (3) Spartina alterniflora, soil organic carbon, livestock, trophic cascade, biodiversity and seagrass ecosystem clustering are hot topics related to international Blue Carbon research, while organic carbon, seagrass-conservation, methodology, sustainable development, climate change, carbon neutralization, coastal zone and carbon storage are hot topics related to Chinese Blue Carbon research. In addition, based on the research trends of Blue Carbon, this paper attempts to sort out the research framework from three levels: core characteristics, theoretical basis and research methods, respectively. Facing a series of challenges brought by climate change, Blue Carbon research should strengthen the accurate estimations of Blue Carbon sink and its market potential, and explore the reasonable market mechanism and protection mechanism, to respond to realistic demands, solve major concerns and promote new progress in Blue Carbon theory and practice.

Toward the Circular Economy in the Aquaculture Sector: Bibliometric, Network and Content Analyses

This paper offers an overview of circular economy strategies applied to the aquaculture sector. The growing challenges imposed on the sector by the strategies of the Green Deal impose new growth strategies in the name of sustainability. The scalability of these strategies is increasingly hampered by regulatory voids and by the absence of a universally accepted assessment method for measuring the impacts of current aquaculture systems. More than ever, a review of knowledge in the circular economy field is required to comprehend where the aquaculture sector is heading, and in order to make the required transition. The present review proposes a bibliometric analysis, a network analysis and a content analysis, which highlight a very new and expanding field of research. The studies were firstly analyzed from a micro (animal metabolism) to a macro perspective (policies, markets and society), emphasizing where research is still lacking. Furthermore, a second level of classification concerns the type of circularity approach proposed for the aquaculture system, which can be divided into open-loop or closed-loop strategies. Regarding the open-loop-related studies, the focus of the evaluation is devoted to the different bioeconomic values of the circularity strategies proposed for the biological flows entering and exiting the aquaculture system. The literature review offered insights into the identification of research threads that are developing around the aquaculture sector.

Unlocking circular supply chain 4.0: identifying key barriers through bibliometrics and TISM-MICMAC

PurposeThis paper examines the dynamic interplay between Circular Economy (CE) and Supply Chain (SC). Further, this paper develops a framework indicating the transition from conventional SC to SC 4.0. As it addresses the separate bodies of literature on CE and SC 4.0, the study attempts to bridge the gap by examining barriers to SC 4.0 adoption in CE.Design/methodology/approachThe article integrates bibliometric analysis with Total Interpretive Structural Modeling (TISM) and MICMAC analysis, thereby enriching the methodological rigour in investigating the barriers to SC 4.0 adoption within the CE context.FindingsThe paper provides insights into research trends, influential scholars, journals and prominent institutions through bibliometric analysis. Also, the findings identify four broad areas of driving, autonomous, linkage and dependent barriers to facilitate a comprehensive understanding of their impact and interdependencies.Research limitations/implicationsThe findings imply that effective policy interventions, enhanced management practices, and the adoption of technological innovations are essential for overcoming barriers to SC 4.0. The research recommends that stakeholders focus on fostering collaborative networks, building competencies in line with CE requirements, and leveraging big data for strategic supply chain decision-making.Originality/valueThis work contributes to the advancement of the circular digital supply field by consolidating research streams, uncovering innovation prospects, and shaping a well-informed research agenda. The distinct contribution lies in its categorization of these barriers into driving, autonomous, linkage, and dependent barriers, offering a novel perspective on the structural dynamics impeding the integration of SC 4.0 in CE.

Research on the annual average thermal power of heliostat field in tower solar energy

The concentrating mirror field is a concentrating and heat collecting subsystem in the tower solar thermal power station, and its optical performance directly affects the solar energy utilization efficiency of the power station. In this paper, the coordinate system of heliostat field and single heliostat is established, and the grid division technology is introduced to describe its reflection effect on sunlight and its occlusion. In this paper, the shadow occlusion loss that affects the optical efficiency is divided into three parts, including incident light occlusion loss, reflected light occlusion loss and absorption tower shadow occlusion loss. For any time, the output power of the heliostat near the solar direction is small, while the output power of the heliostat far away from the solar direction is large. Compared with other influencing factors, the cosine loss has the greatest influence on the heliostat field, and the center of the absorption tower installed in the circular heliostat field is obtained. The size of the heliostat is a square with a side length of 6m, the installation height is 4m, and the annual average optical efficiency is 0.6216 when the position of the heliostat is determined. The annual average output thermal power is 36.3958 MW, and the annual average output thermal power per unit mirror area is 0.5794 .

Explanations for the positive storm surges on the left side of landfall typhoons in China

The coastal regions of Southeast China frequently experience unusual positive storm surges on the left side of landfalling typhoons, a phenomenon historically overlooked and inadequately explained by conventional circular wind field models. In this study, a high resolution, two-dimensional storm surge model based on ADCIRC along with tide gauge data were used to investigate the spatiotemporal distribution of these surges and proposes underlying mechanisms, informed by a comparative analysis of circular and ERA5 reanalysis wind fields during typical typhoon event 9711 Winnie. Analyzing tide gauge data spanning from 1986 to 2016, the study uncovers a distinct pattern of left-side positive storm surges along the southeastern coast, notably on the Fujian coast and within the Taiwan Strait, which are found to be comparable to those on the cyclone’s right side. The research also documents a significant escalation in both the frequency and intensity of these left-side surges over the past three decades. Simulation results highlights the inadequacies of circular wind field models in operational forecasting and emphasizes the necessity of accounting for topographic influences and the structural complexity of wind fields in storm surge predictions. This is particularly pertinent in semi-enclosed seas with intricate hydrodynamics, such as the Taiwan Strait. The insights gleaned from this study are pivotal for enhancing the real-time simulation and prediction of storm surges, which are vital for coastal safety and disaster prevention measures.

The electron jet in relativistic laser-plasma with circular magnetic fields

Self-generated magnetic field and electron jet are observed when ultra-intense lasers (>1×1018W/cm2) interact with plasma. It is found that the self-generated magnetic field plays a significant role in the generation of electron jets. The generation mechanism of electron jets under the influence of a self-generated circular magnetic field is examined. It is revealed that magnetic modulation of self-generated magnetic fields can result in the collapse of these fields, consequently leading to the production of electron jets. Furthermore, it has been discovered that the velocity of the electron jets is associated with the maximum growth rate of the modulational instability. As the maximum growth rate of the modulational instability decreases, the velocity of the electron jets is reduced. The present work aids in getting a deeper understanding of the generation of electron jets in relativistic laser plasmas.

Circular Economy Strategies in Practice: A Qualitative Examination of Industry Adaptation and Innovation

Objective: This study explores how companies across various industries are implementing circular economy strategies in practice, focusing on the drivers, practices, challenges, enablers, and outcomes of their efforts. Theoretical Framework: The study draws upon multiple theoretical perspectives, including the multi-level perspective on sustainability transitions, the resource-based view of the firm, and institutional theory, to understand the complex factors influencing the adoption and implementation of circular economy strategies. Method: A qualitative, multiple-case study design was employed, involving semi-structured interviews with key informants from 20-30 companies actively engaged in circular economy initiatives. Data were analyzed using a combination of deductive and inductive coding approaches, with member checking and peer debriefing used to enhance trustworthiness. Results and Discussion: The findings reveal that environmental sustainability concerns are the primary driver for companies adopting circular economy strategies, with regulatory pressures, competitive advantage, customer demands, and resource scarcity also playing significant roles. Companies are implementing a wide range of circular economy practices, including eco-design, circular business models, reverse logistics, and industrial symbiosis. Key challenges identified include lack of technical knowledge and skills, inadequate infrastructure and technology, and regulatory barriers, while enablers such as leadership commitment, collaboration and partnerships, and employee engagement are crucial for successful implementation. The study also highlights the positive outcomes of circular economy adoption, including environmental benefits, economic gains, innovation and competitive advantage, customer satisfaction, and employee engagement. Research Implications: This study contributes to the theoretical development of the circular economy field and offers practical implications for managers and policymakers. Originality/Value: This study addresses the lack of comprehensive, cross-sectoral research on circular economy implementation in practice, providing valuable insights into the experiences of companies across different industries.

Mirror field optimization model based on thermal power maximization

Optimization of the heliostat field is very important in order to improve the performance of solar power tower (SPT) and reduce the construction cost. In this paper, we simulate and analyze the reflection relationship of the heliostats in the heliostat field and find the adjacent heliostats to the current heliostat by solving the distance matrix. The neighboring heliostats are projected onto the plane of the current heliostat, and the shadow-free region of the heliostat is obtained by the ray-tracing method and by considering the sunlight as a cone of light. The shadow blocking efficiency can be calculated based on the number of light strips in the region, and similarly the truncation efficiency can be calculated. Based on the circular heliostat field, a new cross-density distribution model based on the circular heliostat field is proposed. Under the condition of confirming the annual average thermal power, the distribution of the heliostat mirror field with the maximum thermal power per unit area, the optimal installation height and mirror size can be obtained.

Controllable concentric electric field line distribution for simultaneous separation of DNA

An approach for the controllable separation and concentration of nucleic acid using a circular nonuniform electric field was proposed and developed. Using six different lengths of DNA molecules as standard samples, the distribution of the gradient electric field was increased from the outer circular electrode to the inner rod-shaped electrode, contributing to the migration of DNA molecules at a velocity gradient towards the region with the strongest inner electric field. The DNA molecules were arranged in a distribution of concentric circles that aligned with the distribution of concentric equipotential lines. The concentration of DNA multiplied with the alternation of radius. As a result, this platform allowed simultaneous DNA separation, achieving a resolution range of 1.17–3.03 through an extended electrophoresis time, resulting in enhanced concentration factors of 1.08–6.27. Moreover, the manipulation of the relative height of the inner and outer electrodes enabled precise control over the distribution and the deflection degree of electric field lines, leading to accurate control over DNA deflection.

Organization of spontaneous spatial behaviors under dark conditions is unaffected in adult male and female long-Evans rats after moderate prenatal alcohol exposure.

Prenatal alcohol exposure can produce disruptions in a wide range of cognitive functions, but it is especially detrimental to spatial navigation. In open environments, rodents organize their spatial behaviors around centralized locations, termed home bases, from which they make circuitous and slow locomotor trips (progressions) into the rest of the environment. Open-field behaviors are organized even under darkened test conditions, suggesting a role for self-motion cues (vestibular, motor, etc.). The impact of moderate prenatal alcohol exposure (mPAE) on the organization of spontaneous open-field behaviors under darkened conditions has not been investigated. Here we tested adult female and male rats with mPAE or saccharin control exposure in a circular open field for 30 min in a testing room that was made completely dark. While general locomotion, as measured by reductions in travel distance and increased stop duration, decreased across the test session, the organization of these behaviors, as measured by stop duration, home base establishment, home base stability, progression accuracy, and scaling of peak speeds with progression length, did not differ between mPAE and saccharin control rats. Together, the findings strongly suggest that spontaneous movement organization in relation to self-motion cues remains intact in adult mPAE rats. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Characterization of a novel VenusX orthogonal dual-layer multileaf collimator.

To investigate and characterize the performance of a novel orthogonal dual-layer alpha multileaf collimator (αMLC) mounted on the LinaTech VenusX linac. We evaluated leaf positioning accuracy and reproducibility using an electronic portal imaging device through the picket fence test. The average, interleaf, intraleaf, and leaf tip transmissions of the single and dual layers were measured using an ionization chamber. Square and rhombus fields were used to evaluate the leaf penumbra of αMLC. To investigate the advantages of the orthogonal dual-layer multileaf collimator (MLC) in field shaping, right triangular and circular pattern fields were formed using both the dual layers and single layers of the αMLC. The average maximum positioning deviations of the upper and lower αMLC over 1 year were 0.76±0.09mm and 0.62±0.07mm, respectively. The average transmissions were 1.87%, 1.83%, and 0.03% for the upper-, lower- and dual-layer αMLC, respectively. The maximum interleaf transmissions of the lower- and dual-layer were 2.43% and 0.17%, respectively. The leaf tip transmissions were 9.34% and 0.25%, respectively. The penumbra of the square field was 6.2mm in the X direction and 8.0mm in the Y direction. The average penumbras of the rhombus fields with side lengths of 5 and 10cm were 3.6 and 4.9mm, respectively. For the right triangular and circular fields, the fields shaped by the dual-layer leaves were much closer to the set field than those shaped by single-layer leaves. The dose undulation amplitude of the 50% isodose lines and leaf stepping angle change of the dual-layer leaves were smaller than those of the single-layer leaves. The αMLC benefits from its orthogonal dual-layer design. Leaf transmission, dose undulations at the field edge, and MLC field dependence of the leaf stepping angle of the dual-layer αMLC were remarkably reduced.

From greenwashing to ESG‐washing: A focus on the circular economy field

AbstractIn the field of Corporate Social Responsibility (CSR) today, Environmental, Social and Governance (ESG) factors play a fundamental and increasingly central role in the evaluation of corporate performance worldwide. The purpose of this paper is to investigate whether the recent phenomenon of ESG issues has given rise to a new form of greenwashing in a broad sense, not limited to the environmental sphere, but also extended to social and governance issues. The paper examines whether companies engaged in the transition to sustainable and in particular to circular models are actually focusing on concrete sustainable actions and less on distorted communication. Specifically, ESG performance measures were collected for 366 companies from the most impactful industries in different countries around the world to test the relationships between ESG performance, adoption of circular economy models and ‘washing’ practices related to stakeholder communication. As the transition to sustainable and circular models requires not only substantive action but also transparency, further research and efforts are needed to better understand the relationship between these elements in corporate behavior.

Imagining density distribution of molecular orbitals in IR+XUV co-rotating circular laser fields by frequency-domain theory

Abstract We have investigated the angle-resolved ATI spectrum of oriented molecules in the IR+XUV co-rotating circular laser fields. According to the different roles of IR and XUV laser in the ionization process, we purposefully adjust the photon energy of XUV and the intensity of IR laser to make the ionization spectrum of the molecule distributed in a suitable momentum region. Moreover, under the same laser conditions, the background fringes in the ionization spectrum of the molecule can be removed by using the ionization spectrum of the atom with the same ionization energy as the molecule, so that the molecular orbital density distribution in the suitable momentum region can be obtained. That is, for any unknown molecule, as long as the ionization energy of the molecule can be measured, the density distribution of the molecular orbital can be imaged in a definite momentum region by adjusting the laser field conditions, which may shed light on the experimental detection of molecular orbitals.

Design, construction and test of a prototype coil with demountable CuBe joints for pulsed table-top tokamaks

In a classic small tokamak, the magnetic confinement is achieved by toroidal coils that fit into a donut-shape mechanical structure. To facilitate their handling and maintenance as well as the access to various auxiliaries components, their design has evolved toward a modular configuration. For such demountable design, it is important to guarantee the electrical continuity of the winding of the coil across the modular parts through electrical contacts. The resulting joints rely on pressure and specific materials to transfer high current densities at a good mechanical stability and manageable losses. In the present work, a prototype of a circular demountable toroidal field coil (CDTFC) was designed and built to test some technical choices to be used in the final coils of a table-top tokamak referred to as TPM-1U. For this small tokamak, the magnet wires to wind the toroidal coils should be able to handle large pulsed currents in the tens of thousands of Amperes whereas the coil joints should handle a peak current density of at least 75 kA/cm2. The case study here is the TPM-U1 table-top tokamak. Its conceptual design is recalled and mechanical and magnetic details of the demountable coil prototype are provided. For the experimental test, the contacts were slightly pressed using a custom-made contact assembly and current pulses between 4 kA and 8 kA were fedto the coil prototype. The degradation of the joint was visually estimated by assessing the amount of micro-melting, plastic deformation and oxidation appearing at the interface between the materials in contact. It is shown that the selected AWG-04 magnet wire is appropriate for carrying kiloAmpere range pulsed currents and that the CuBe contacts are able to withstand current densities larger than the specification, up to 263 kA/cm2, under low contact pressures of a few mega-Pascal simplifying their handling. Some technical choices have been probed on a prototype coil yielding a generic sequence of tasks to build and test mechanically and electromagnetically demountable coils and their joints.

Motion Planning Using Reactive Circular Fields: A 2-D Analysis of Collision Avoidance and Goal Convergence

Motion Planning Using Reactive Circular Fields: A 2-D Analysis of Collision Avoidance and Goal Convergence