Dispersive Model Research Articles

Prospects for an Evangelical Rule of Life: A Case-Study in Living as a Dispersed Community of Missional Discipleship

From 2020 to 2023, I spent 3 years as the Prior of the Community of St Cuthbert based at St Nics Church in central Durham. St Nics is a classic UK evangelical city-centre church with a beloved history of Bible teaching, market-square engagement, and mission. In 2019 the church leadership discerned an opportunity to refresh the church’s (and wider) practice of discipleship by launching the Community of St Cuthbert, and I was recruited as its Prior. This article gives an account of some of the strengths and weaknesses of this endeavour, focused particularly on four issues: the importance of a clear, positive and upbuilding ‘rule of life’ statement; the core issue of how a Rule of Life can facilitate widespread missional discipleship in a dispersed community model; the importance of a clear marker of membership in the Community (and the difficulties around developing one); and the potential (albeit largely unrealised) to use the Community of St Cuthbert model as a way of establishing new worshipping communities. My own retrospective reflection as Prior concludes with two convictions that may be of relevance to those considering such a ‘Community’: the nature and challenge of keeping the focus on God rather than on policing practices; and the ways in which such a re-energising of discipleship can offer an evangelical contribution to the life of the whole church, rather than being limited to self-described evangelical churches.

Macro‐evolutionary dynamics dominated by dispersal promote the formation of regional biodiversity hotspot‐insights from hawkmoths (Lepidoptera: Sphingidae) in South China

AbstractAimRapid loss in global insect diversity has generated substantial public worry due to their critical ecological roles. However, there is controversy about the effectiveness of the global‐scale hotspots in guiding the conservation of diversity at the regional scale. Even worse, little is known about the knowledge of insect distributional dynamics in many understudied regions, such as East and Southeast Asia. Here, to guide for setting regional‐scale conservation priorities for insect diversity, we explore hawkmoths (Lepidoptera: Sphingidae) for their distributional dynamics and identify regional hotspots requiring protection.LocationSouth China (including Guangdong, Guangxi, Hainan, Hong Kong and Macau) and northern Vietnam (17°~26.5° N, 102°~117.5° E).MethodsSpecies distribution models were generated for 194 hawkmoth species based on 3597 occurrence records to predict their distributions. We calculated the spatial patterns of taxonomic and phylogenetic diversity and identified regional hotspots. Furthermore, the potential assembly mechanisms underlying insect diversity were explored by analysing the rates of speciation, extinction and dispersal between phyloregions.Results(a) The coastal regions of South China and northern Vietnam represent a regional hotspot of hawkmoths in East and Southeast Asia, with significantly higher α‐diversity than that in inland regions. (b) Dispersal played a more important role than local speciation and extinction in the formation of regional hawkmoth hotspots.Main ConclusionsIn this study, the ‘Out‐of‐the‐tropics model’ can explain the formation of the hawkmoth regional hotspots and the enhanced version of the ‘Pure dispersal model’ can explain the formation of the hotspots in Hainan Island. Compared with the local speciation and extinction, dispersal is the main driving factor that promoted the formation of the regional biodiversity hotspot of hawkmoths in South China. The case of Hainan Island suggests that protection within hotspots needs to account for specific regional macro‐evolutionary dynamics rather than indiscriminate coverage of identified hotspots.

Larval dispersal predictions are highly sensitive to hydrodynamic modelling choices

AbstractLarval dispersal is a critical ecological process in marine ecosystems, responsible for connecting and replenishing populations in patchy habitat. Because empirical measurements of larval dispersal are very challenging, coupled biological and oceanographic simulations (“biophysical models”) of larval dispersal are commonly used to answer ecological questions and support conservation management decisions. In the process of creating biophysical models, a series of choices must be made that do not have a single correct answer—sometimes because the oceanographic or ecological processes are uncertain; sometimes because trade-offs are required between different goals (e.g. computational time versus spatial resolution). In this paper, we demonstrate that larval dispersal estimates at management scales are strongly affected by these choices. Using three different hydrodynamic models of the Great Barrier Reef, we estimated the dispersal of crown-of-thorns starfish larvae in the spawning seasons between 2018 and 2021. Despite sharing similar physical forcings and using similar models of larval behaviour, we find that the different hydrodynamic models produce divergent predictions of larval dispersal between the reefs. If used to support crown-of-thorns starfish control decisions, these different predictions would recommend different priority reefs. Our results caution against the use of single models of larval dispersal, and suggest that multi-model ensembles may offer a valuable new perspective on dispersal patterns in marine environments.

Dispersive optical-model potential parameters for neutron scattering on 197Au up to 200 MeV

In this study, dispersive optical model (DOM) potential parameters were derived for the 197Au target nucleus up to an incident neutron energy of 200 MeV. The procedure involved fitting the theoretical total cross sections σtot with the experimental ones and thereby determining the valid free potential parameters at the lowest value of χ2/M. The contribution of compound nuclei mechanism at low energies was also incorporated in the calculations. The theoretical results obtained using the derived potential were compared to the experimental data for both the angular differential cross-section and the elastic cross-section. While there was a good agreement with the experimental values for the total cross section, a satisfactory agreement was achieved for the angular cross section. The obtained potential is useful for describing the n+197Au scattering system and its outputs over an extensive energy spectrum.

Provenance and sediment dispersal in Pearl River Estuary, southern China unraveled by magnetic properties

The Pearl River Estuary (PRE), with eight outlets supplied by multiple tributaries, is an excellent study area for reconstructing sediment provenance and transport pathways of a multi-sourced sediment-routing system. However, it less known the sediment source to sink dispersal model. This study aimed to estimate the PRE sediment budget by comparing the magnetic characteristics of estuarine surface sediments with those of all potential sources. In the bottom sediments of PRE and adjacent region, magnetic minerals, mainly magnetite and hematite, have a characteristic terrigenous signature. Source and sink comparison for magnetic parameters shows that the possible input of southwestern Taiwan rivers can be excluded, whereas the possibility of sediment contribution from nearby rivers, including Han, Rong, and Jiulong rivers, to the estuary could not be ruled out. Quantitative provenance analysis indicates that West River-sourced sediment dominates the western side of the estuary, the East River-sourced sediment is most important in the eastern side of the estuary, whereas sediment supplied by the North River is high only close to the outlets. A mixed-sediment contribution to the estuary is suggested, with a fluvial-dominated sediment input around the west river outlets and a tide-dominated sediment dispersal in the eastern side of the estuary. Overall, our study demonstrates the importance of fingerprinting changes in sediment supply using sediment magnetic properties and provides new insights into the PRE sediment-routing system.

FedSR: Federated Learning for Image Super-Resolution via detail-assisted contrastive learning

Federated learning (FL) is a distributed learning paradigm that collaboratively learns a global model from multiple decentralized clients without sharing raw data, providing an effective solution for privacy preservation. However, current FL works primarily focus on high-level visual tasks (e.g., classification), the exploration for image super-resolution (SR), a fundamental low-level visual task, is rarely addressed. In this study, we propose Federated Image Super-Resolution (FedSR), a novel FL approach for image SR task, aiming to generate high-quality images while preserving data privacy. Specifically, we introduce a detail-assisted contrastive loss at the decentralized client, aligning the shallow representations by rectifying the relationship of low-level features between local clients and global server. In addition, we develop a hierarchical aggregation policy at the central server to better integrate dispersed client models into the global model, with the aggregation weight determined based on the layer-wise similarity between the updated local models and the historical global model. Extensive experiments conducted on general SR benchmarks and facial image datasets demonstrate the superiority of our FedSR in terms of image quality and model performance. Notably, FedSR can be seamlessly integrated with various prevalent image SR methods, including CNN-based and Transformer-based architectures.

Quantification of volcanic degassing and analysis of uncertainties using numerical modeling: the case of Stephanos crater (Nisyros Island, Greece)

Nisyros Island (Greece) is affected by widespread gas emissions from fumarolic fields located at the bottom of hydrothermal craters in the southern part of its caldera. This morphology and the current low gas fluxes make Nisyros an ideal site for testing the limits of physics-based gas dispersal models in confined and low-emission conditions. Here, we focused our attention on the local scale volcanic gas dispersion from the Stephanos hydrothermal crater. In April 2023, a 1-week survey was carried out to measure weather data, CO2 and H2S gas fluxes, air concentrations from portable gas stations, and chemical composition of fumarolic gases and to acquire thermal images of the crater floor. These data were used as inputs and boundary conditions for numerical simulations using a DISGAS-2.6.0 model in order to quantify the present-day volcanic degassing and its associated uncertainties, accounting for the meteorological variability. Model results are provided in terms of H2S probabilistic exceedance and persistence maps, showing gas concentrations within the crater that fall below the thresholds indicated for the occurrence of serious respiratory problems. Since DISGAS-2.6.0 does not account for chemical reactions, this study represents a good opportunity to discuss the methodological limits of simulating the dispersion of H2S which is challenging due to its rapid degradation and dilution in the atmosphere. In this regard, we also provided an empirical law of the H2S depletion in low-emission conditions that takes into account the uncertainties related to the field measurements.

Structural model of bifraction ceramic dispersions

Structural model of bifraction ceramic dispersions

Deep learning insights into distinct patterns of polygenic adaptation across human populations.

Response to spatiotemporal variation in selection gradients resulted in signatures of polygenic adaptation in human genomes. We introduce RAISING, a two-stage deep learning framework that optimizes neural network architecture through hyperparameter tuning before performing feature selection and prediction tasks. We tested RAISING on published and newly designed simulations that incorporate the complex interplay between demographic history and selection gradients. RAISING outperformed Phylogenetic Generalized Least Squares (PGLS), ridge regression and DeepGenomeScan, with significantly higher true positive rates (TPR) in detecting genetic adaptation. It reduced computational time by 60-fold and increased TPR by up to 28% compared to DeepGenomeScan on published data. In more complex demographic simulations, RAISING showed lower false discoveries and significantly higher TPR, up to 17-fold, compared to other methods. RAISING demonstrated robustness with least sensitivity to demographic history, selection gradient and their interactions. We developed a sliding window method for genome-wide implementation of RAISING to overcome the computational challenges of high-dimensional genomic data. Applied to African, European, South Asian and East Asian populations, we identified multiple genomic regions undergoing polygenic selection. Notably, ∼70% of the regions identified in Africans are unique, with broad patterns distinguishing them from non-Africans, corroborating the Out of Africa dispersal model.

Effects of dissipation rates on dispersive waves and mode families in microresonators with avoided mode-crossing

In microresonators with avoided mode-crossing, the dispersive waves and mode families can be affected by dissipation rates, which also cause different hysteresis of the dispersive waves. Based on the Lugiato-Lefever equations and the single-mode dispersive wave model, the effects of dissipation rates on dispersive waves and mode families in microresonators are investigated. Results showed that the dispersive wave power curve exhibits hysteresis because of the avoided mode-crossing and the frequency shift curves can be convex, contrary to the absence of hysteresis. Moreover, the distribution of the two mode families in the microresonator is different at various detuning frequencies due to the dispersive wave, and it is relatively flat in the hysteresis state. The dispersive wave power and frequency shift are varied due to the different dissipation rates. The power of the two mode families decreases with the increase in mode dissipations. The results are significant for investigating dissipative Kerr solitons associated with dispersive waves in microresonators with avoided mode-crossing in practice.

The effect of earthquake fault rupture kinematics on tsunami generation: a numerical study of real events

Summary The study is devoted to the effect of the fault rupture kinematics in the earthquake source on tsunami generation. Sixteen events of 1992–2021 years are investigated. For each event, the kinematic tsunami source (bottom motion during the earthquake) and the static tsunami source (permanent bottom deformation) were calculated using the Finite Fault Models provided by the U.S. Geological Survey. For both sources, numerical tsunami simulations were carried out within the framework of linear long-wave theory. Comparison of the simulation results showed that in ten out of sixteen events, the energy of tsunami excited by the kinematic source is greater than that excited by the static source. The maximum energy amplification (9.1 per cent) is observed at the minimum ratio of average rupture velocity to long-wave velocity. The Illapel 2015 event has been investigated more thoroughly using dispersive tsunami models jagurs and cptm. This investigation showed that the kinematic source causes a spatial redistribution of tsunami amplitudes and a noticeable amplification of the high-frequency component in the time series of tsunami height. At some points along the Chilean coast, the difference between the kinematic and static calculations is more than 2 m.

Multiscale understanding of structural effect on explosive dispersal of granular media

Explosive dispersal of granular media widely occurs in nature across various length scales, enabling engineering applications ranging from commercial or military explosive systems to the loss prevention industry. However, the correlation between the explosive dispersal behaviour and the structure of dispersal system is far from completely understood, thereby compromising the prediction of the explosive dispersal outcome resulting from a specific dispersal system. Here, we investigate the dispersal behaviours of densely packed particle rings driven by the enclosed pressurized gases using coarse-grained computational fluid dynamics–discrete parcel method. Distinct dispersal modes emerge from the dispersal systems with vastly varying sets of the macro- and micro-scale structural parameters in terms of the dispersal completeness and the spatial uniformity of the dispersed mass. Further investigation reveals the variation in the dispersal modes arises from the collective effects of multiscale gas–particle coupling relationships. Specifically, the macroscale coupling dictates the cyclic momentum/energy transfer between gases and particle ring as an entirety. The mesoscale coupling relates to the inter-pore gas filtration through the thickness of the particle ring, leading to the mass/energy reduction of the explosive source. The microscale coupling involves the individual particle dynamics influenced by the local flow parameters. A persistent macroscale coupling results in an incomplete dispersal which takes the form of an aggregated annular band, whereas the meso- and micro-scale couplings alter the macroscale coupling to a different extent. By incorporating the effects of the variety of structural parameters on the multiscale gas–particle coupling relationships, a non-dimensional parameter referred to as the modified mass ratio is constructed, which shows an explicit correlation with the dispersal mode. We proceed to establish a dispersal ring model in the continuum frame which accounts for the macro and meso-scale coupling effects. This model proves to be capable of successfully predicting the ideal and validated failed dispersal modes.

Generalized kudryashov and extended auxiliary equation methods for novel solitons solutions to (1+1)-dimensional doubly dispersive equation of murnaghan’s rod

Abstract In this study, the Generalized Kudryashov method and the Extended Auxiliary Equations method are employed to investigate the strongly nonlinear (1+1)-dimensional Doubly Dispersive equation model of inhomogeneous Murnaghan’s rod for developing novel soliton solutions. These symbolic methods are famous for solving various problems involving nonlinear partial differential equations. The study finds novel solitons like hyperbolic, exponential, rational, and trigonometric. Moreover, 2D, 3D, and contour plots under tunable parameters depict graphical representations of the solutions that furnish dynamic wave behavior and insights into the material’s elastic properties under strain and stress.

Stochastic perturbation of analytical solutions for the dispersive concatenation model with spatio-temporal dispersion having multiplicative white noise

Stochastic perturbation of analytical solutions for the dispersive concatenation model with spatio-temporal dispersion having multiplicative white noise

A comparison of eight weakly dispersive Boussinesq-type models for non-breaking long-wave propagation in variable water depth

Weakly dispersive Boussinesq-type models are extensively used to model long-wave propagation in coastal areas and their interaction with coastal infrastructures. Many equations falling in this category have been formulated during the last decades, but few detailed comparisons between them can be found in the literature. In this work, we investigate theoretically and with computational experiments eight variants of the most popular models used by the coastal engineering community. Both weakly nonlinear and fully nonlinear models are considered, hoping to understand better when the additional complexity of the latter class of models is necessary or justified. We provide an overview and discuss the properties of these models, including the linear dispersion relation in uniform water depth, the second-order nonlinear coupling coefficient, the shoaling gradient, and the sensitivity to wave trough instabilities. The models are then numerically discretised using the same general strategy in a single numerical code, using fourth-order methods for time and space discretisation. Their capacity to simulate coastal wave propagation and their transformation when approaching the shore is assessed on three challenging one-dimensional benchmarks. It appears that fully nonlinear models are more consistent than their weakly nonlinear counterparts, which can occasionally perform better but show different behaviours depending on the case.

Neutron skins: A perspective from dispersive optical models

An overview of neutron skin predictions obtained using an empirical nonlocal dispersive optical model (DOM) is presented. The DOM links both scattering and bound-state experimental data through a subtracted dispersion relation which allows for fully consistent, data-informed predictions for nuclei where such data exist. Large skins were predicted for both 48Ca (Rskin48=0.25±0.023 fm in 2017) and 208Pb (Rskin208=0.25±0.05 fm in 2020). Whereas the DOM prediction in 208Pb is within 1σ of the subsequent PREX-2 measurement, the DOM prediction in 48Ca is over 2σ larger than the thin neutron skin resulting from CREX. From the moment it was revealed, the thin skin in 48Ca has puzzled the nuclear-physics community as no adequate theories simultaneously predict both a large skin in 208Pb and a small skin in 48Ca. The DOM is unique in its ability to treat both structure and reaction data on the same footing, providing a unique perspective on this Rskin puzzle. It appears vital that more neutron data be measured in both the scattering and bound-state domain for 48Ca to clarify the situation.

First test beam of the DMAPS-based proton tracker at the pMBRT facility at the Curie Institute

Objective.Proton radiotherapy's efficacy relies on an accurate relative stopping power (RSP) map of the patient to optimise the treatment plan and minimize uncertainties. Currently, a conversion of a Hounsfield Units map obtained by a common x-ray computed tomography (CT) is used to compute the RSP. This conversion is one of the main limiting factors for proton radiotherapy. To bypass this conversion a direct RSP map could be obtained by performing a proton CT (pCT). The focal point of this article is to present a proof of concept of the potential of fast pixel technologies for proton tracking at clinical facilities.Approach.A two-layer tracker based on the TJ-Monopix1, a depleted monolithic active pixel sensor (DMAPS) chip initially designed for the ATLAS, was tested at the proton minibeam radiotherapy beamline at the Curie Institute. The chips were subjected to 100 MeV protons passing through the single slit collimator (0.4×20mm2) with fluxes up to1.3×107p s-1 cm-2. The performance of the proton tracker was evaluated with GEANT4 simulations.Main results.The beam profile and dispersion in air were characterized by an opening of 0.031 mm cm-1, and aσx=0.172mm at the position of the slit. The results of the proton tracking show how the TJ-Monopix1 chip can effectively track protons in a clinical environment, achieving a tracking purity close to 70%, and a position resolution below 0.5 mm; confirming the chip's ability to handle high proton fluxes with a competitive performance.Significance.This work suggests that DMAPS technologies can be a cost-effective alternative for proton imaging. Additionally, the study identifies areas where further optimization of chip design is required to fully leverage these technologies for clinical ion imaging applications.

Larval dispersal and physical connectivity of Pheronema carpenteri populations in the Azores

The study of larval dispersal and connectivity between deep-sea populations is essential for the effective conservation and management of deep-sea environments and the design and implementation of Marine Protected Areas. Dense sponge aggregations, known as “sponge grounds”, are a key component of marine benthic ecosystems, by increasing the structural complexity of the sea floor and providing structure and habitat for many other species. These aggregations are characteristic of the Azores deep-sea environment. These sessile organisms rely primarily on larval dispersal for their reproduction. Connectivity between specific Pheronema carpenteri sponge aggregations in the Azores was studied using a 3-D biophysical dispersal model. Different biological trait scenarios were analyzed, considering spawning seasonality and pelagic larval duration. Model results indicate that regional circulation patterns drive larval dispersion, shaping population connectivity of P. carpenteri sponge aggregations in the Azores, particularly among aggregations in the Central Group of Azorean islands. Some areas present high retention rates, receiving larvae from several sponge aggregations while also being important larval source aggregations. In contrast, aggregations from the Eastern Group may be isolated from the others. Larval dispersal and connectivity patterns were analyzed concerning the current configuration of Marine Protected Areas (MPAs) in the Azores. The results underscored the importance of maintaining protection efforts in existing MPAs and identified stepping-stone locations and specific sites where additional measures could enhance species connectivity in the Azores.

The magicity, the radii of neutron orbits 1<i>f</i><sub>7/2</sub>, 2<i>p</i><sub>3/2</sub> and halo-like structure of <sup>52,54</sup>Ca nuclei

The evolution of neutron single-particle spectra of isotones with N = 32 and 34 new magic neutron numbers in the region 16 ≤ Z ≤ 32 was calculated in the dispersive optical model. It was shown that the minimum of the difference between the Fermi energy and the half-sum of the energy levels of the last predominantly occupied state and the first predominantly unoccupied state is achieved in the magic isotones with N = 32 and 34. The calculated root-mean-square radius of the neutron halo-like state 2p3/2 in double magic 52Ca nucleus exceeded the radius of the underlying 1f7/2 state by 0.8 fm. It is consistent with the recent experimental data and theoretical predictions that explain ‟unexpectedly” large root-mean-square charge radius of this nucleus.

Computations of energetic nearshore waves: Are weakly dispersive phase-resolving models telling the same story?

Three phase-resolving weakly dispersive wave models are used for 2DH (2D depth-integrated) computations of large-scale wave-by-wave processes induced by highly energetic sea/swell (SS) forcing near Haleʻiwa on the North Shore of Oʻahu, Hawaiʻi. The computed model results are compared to observations obtained over a nearshore cross-reef transect and from the basin of a small boat harbor. The level of agreement between the model results and observations in complex coastal environments under highly energetic wave forcing, along with the qualitative consistency among the three models, makes these models good candidates for operational applications in nearshore environments exposed to energetic wave forcing conditions.Spectral analyses inside the harbor and over the reef indicate that all three models generally account for infragravity (IG) spatial modal structures that are consistent with observations and the theory of edge and leaky waves. Over the reef, auto- and cross-spectral analyses reveal that the dominant waveforms are qualitatively reproduced by all three models, as indicated through: (i) the growth of IG wave amplitudes from deeper water to the shallow reef sites; (ii) the agreement of power spectral density peaks at the nearshore locations; and (iii) the remarkable similarity of spatial coherence functions among the models and between the models and observations. The computations of swell entering the small boat harbor at Haleʻiwa demonstrate that the models can successfully reproduce the variability in the narrow IG frequency bands that are spatially dependent and often subject to resonant amplifications.