Computing and Mathematical Sciences Papers

Permanent URI for this collectionhttps://researchcommons.waikato.ac.nz/handle/10289/6

This collection houses research from the School of Computing and Mathematical Sciences at the University of Waikato.

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SGLT2 inhibitor use and disparities in all-cause mortality in type 2 diabetes: Insights from a multi-ethnic population
(Springer, 2026) Chepulis, Lynne; Gan, Han; Simmons, David; Rodrigues, Mark William; Keenan, Rawiri; Murphy, Rinki; Kenealy, Tim; Te Karu, Leanne; Magliano, Dianna; Scott-Jones, Jo; Moffitt, Allan; Lao, Chunhuan; Lawrenson, Ross; Paul, Ryan G.
Aims/hypothesis: Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are known to reduce cardiovascular and all-cause mortality in people with type 2 diabetes, but there are limited data regarding mortality outcomes in different ethnic groups (including Indigenous peoples). This study reports on mortality outcomes in a population in Aotearoa New Zealand (hereafter New Zealand) with type 2 diabetes, following the funded availability of the SGLT2i empagliflozin with prioritised access for Māori and Pacific people. Methods: Data were collected from primary care records for those aged 18–75 years with type 2 diabetes (Auckland/Waikato regions of New Zealand; February 2021 to December 2023; n=59,505). These data were linked to national medication-dispensing and mortality records for 2021–2024 via national health identifier numbers. Following propensity matching and Cox modelling for ethnicity, age, gender, medication use, baseline HbA1c and cardiovascular and/or renal disease/risk (CVRD) status (yes/no), mortality rates were compared by ethnicity in those with and without CVRD and who did/did not initiate empagliflozin. This study was reported in accordance with the CONSIDER statement, used to strengthen the reporting of research involving Indigenous peoples. The study was funded by the Health Research Council of New Zealand. Results: Following matching, two groups of 12,792 individuals were identified. Annualised crude mortality (deaths per 1000 individuals per year) was higher in those not dispensed with SGLT2i than in those receiving SGLT2i (35.2 vs 13.1 in those with CVRD and 7.7 vs 3.6 in those without CVRD, respectively). After adjustment, the greatest difference in mortality with SGLT2i use was seen in Māori (HR 0.475; 95% CI 0.336, 0.672; p<0.001), followed by Pacific people (HR 0.507; 95% CI 0.395, 0.651; p<0.001) and European people (HR 0.667; 95% CI 0.545, 0.816; p<0.001). Conclusions/interpretation: The protective effect of SGLT2i use on mortality appears to differ by ethnicity and is greater in Indigenous Māori and Pacific populations in New Zealand with type 2 diabetes. SGLT2i use in Indigenous and minority populations may support improved health equity.
Slab turbulence in the very local interstellar medium and the IBEX ribbon
(IOP Publishing, 2025) Zirnstein, Eric J.; McComas, David J.; Giacalone, Joe; Zank, Gary P.; Guo, Fan; Heerikhuisen, Jacob; Li, Hui; Reisenfeld, Daniel B.
In this study, we analyze an important property of the very local interstellar medium, i.e., turbulence that affects the intensity and shape of the Interstellar Boundary Explorer (IBEX) ribbon. Specifically, we simulate the propagation of the ribbon’s parent ions before they become secondary energetic neutral atoms that can be observed at 1 au by IBEX. We then test how different slab/2D turbulence fractions affect the intensity and shape of the modeled ribbon and compare to the latest IBEX ribbon-separated data. We compare 1D cuts across the modeled and observed ribbon as a function of angle away from the ribbon center. We find that the intensities of the modeled ribbon are larger than most of the data, except near the ecliptic plane. However, the model intensities are sensitive to how we model the neutral solar wind, which forms the source ion population for the ribbon. We then compare the model and data by normalizing the fluxes to their respective peak intensities and find the peaks’ angular distances from the ribbon center. We find that most of the model peaks lie within 3° of the data peaks, which we consider our 1σ uncertainty (half the size of an IBEX pixel). By averaging the instances where the model peaks match the data peaks (within 3°), we find that the mean is slab-50%, with a standard deviation of ±28% and standard error of ±5%.
A novel inversion method for electrical impedance tomography with a radial basis operator network
(MDPI, 2026) Kurz, Jason A.; Pangia, Andrew; Khan, Taufiquar
We apply a new operator neural network to solve the Electrical Impedance Tomography (EIT) inverse problem. The EIT inverse problem involves reconstructing the conductivity inside a specific body or domain, given the electric potential along the boundary of said body. Mathematically speaking, the inverse problem is known to be severely ill-posed, that is, hard to reliably solve. However, we demonstrate the efficacy of our proposed algorithm utilizing the aforementioned neural network, dubbed the Radial Basis Operator Network (RBON) in its seminal work, when applied to the EIT inverse problem.
D-inverse constellations
(Shahid Beheshti University, 2026) Gould, Victoria; Stokes, Tim E.
Constellations are partial algebras in the sense that they possess a partial product, and a unary operation modelling domain. They were first used to give an ESN-style theorem for left restriction semigroups in terms of so-called inductive constellations. Here, we consider constellations in which elements have a suitable notion of inverse, giving the notion of a D-inverse constellation. We show that there is a categorical isomorphism between the category of ordered groupoids and the category of D-inverse constellations. This may be viewed as a generalisation of the ESN theorem, which relates the category of inductive groupoids to the category of inverse semigroups.
Particle transport from first principles in the early heliosphere: κ1 Ceti as a case study for the young Sun
(IOP Publishing, 2026) Engelbrecht, N. Eugene; Herbst, Konstantin; Scherer, Klaus; Oughton, Sean; Airapetian, Vladimir S.
Several studies of Galactic cosmic-ray (GCR) modulation within the astrospheres of stars deemed to be proxies for the young Sun have concluded that the intensities of these particles would, at early stages of the Sun’s evolution, be negligible at 1 au. These studies, however, do not take into account the varying interstellar conditions the young Sun would have encountered as it traversed its Galactic orbit, nor do they realistically model the transport of GCRs. The present study, for the first time, examines the influence of various interstellar parameters in the Galactic spiral arms on the astrosphere of κ1 Ceti, a young Sun proxy, through magnetohydrodynamic modelling. We demonstrate that these conditions lead to an astrosphere with considerably smaller dimensions than previous estimates. We also model the transport of turbulence parameters within said astrosphere for the first time, demonstrating that turbulence levels could be significantly higher than observed in the heliosphere. Finally, these insights are implemented in a 3D, ab initio GCR transport model to compute GCR intensities at 1 au, demonstrating the importance of drift effects in astrospheric modulation: full drift effects lead to GCR intensities comparable to modern observations, while turbulence-reduced drift coefficients lead to significantly smaller intensities.
Towards sustainable IoT: A digital signature‐enhanced federated learning approach
(Wiley, 2025) Qureshi, Shahida Hafeezan; Malik, Saif Ur Rehman; Haseeb, Junaid; Moqurrab, Syed Atif; Bukht, Tanvir Fatima Naik; Srivastava, Gautam
Federated Learning (FL) is emerging as a premier paradigm for privacy‐preserved Machine Learning (ML), enabling devices to train models without central data pooling collaboratively. In the contemporary Internet of Things (IoT) landscape, characterized by escalating energy consumption and associated carbon footprint, FL is recognized not merely for its privacy features. Intrinsic to decentralized architectures such as FL, secure communication is based on digital signatures to guarantee integrity. This is particularly evident in sensitive sectors such as the Internet of Vehicles (IoV), banking, and healthcare. Integrating FL becomes imperative and intricate as these sectors are intertwined with the IoT fabric. Our study unveils “Secure Federated Learning Framework (SecFL),” a pioneering decentralized framework combining FL and sustainable computing. SecFL offers defences against adversarial attacks such as data poisoning and label flipping. Utilizing the Rivest‐Shamir‐Adleman (RSA) asymmetric encryption algorithm for securing digital communications and transactions, combined with ElGamal encryption and a private Ethereum blockchain, ensures enhanced client‐specific security. Our research emphasizes the formal modeling of adversarial dynamics using High‐Level Petri nets (HLPN) within the FL‐IoT ecosystem, balancing system dynamics and energy conservation. Our model consistently outperforms contemporary solutions in accuracy and time efficiency after validation. As IoT burgeons into domains like environmental monitoring, smart cities, and energy grids, the SecFL framework, fostering FL, optimizes energy utilization and bolsters resource efficiency. In our comparative analysis, the Elliptic Curve Digital Signature Algorithm (ECDSA) algorithm demonstrates superior transaction latency and verification time compared to RSA and Elliptic Curve Cryptography (ECC).
Salvador Urban Network Transportation (SUNT): A landmark spatiotemporal dataset for public transportation
(Springer, 2025) Ferreira, Marcos V.; Souza, Matheus; Rios, Tatiane N.; Fernandes, Islame F. C.; Nery, Jorge; Gama, João; Bifet, Albert; Rios, Ricardo A.
Efficient public transportation management is essential for the development of large urban centers, providing several benefits such as comprehensive coverage of population mobility, reduction of transport costs, better control of traffic congestion, and significant reduction of environmental impact limiting gas emissions and pollution. Realizing these benefits requires a deeply understanding the population and transit patterns and the adoption of approaches to model multiple relations and characteristics efficiently. This work addresses these challenges by providing a novel dataset that includes various public transportation components from three different systems: regular buses, subway, and BRT (Bus Rapid Transit). Our dataset comprises daily information from about 700,000 passengers in Salvador, one of Brazil’s largest cities, and local public transportation data with approximately 2,000 vehicles operating across nearly 400 lines, connecting almost 3,000 stops and stations. With data collected from March 2024 to March 2025 at a frequency lower than one minute, SUNT stands as one of the largest, most comprehensive, and openly available urban datasets in the literature.
Estimation of effective viscosity to quantify collisional behavior in collisionless plasma
(IOP Publishing, 2025) Adhikari, Subash; González, Carols A.; Yang, Yan; Oughton, Sean; Pecora, Francesco; Bandyopadhyay, Riddhi; Matthaeus, William H.
While dissipation in collisional plasma is defined in terms of viscosity and resistivity, the exact functional form of dissipation, i.e., the so-called dissipation function in nearly collisionless plasma, is unknown. Nevertheless, previous studies have suggested that there exists viscous-like energy conversion in collisionless plasma with scaling characteristics analogous to collisional plasma, and in particular that the average dissipation is proportional to the square of the rate of strain as in hydrodynamics. In this study, using 2.5D kinetic particle-in-cell (PIC) simulation of collisionless plasma turbulence, we provide an estimate of effective viscosity at each scale, obtained via a scale-filtering approach. We then compare the turbulent dynamics of the PIC simulation with that from MHD and two-fluid simulations in which the viscosity is equal to the effective viscosity estimate obtained from the PIC simulation. We find that the global behavior in these MHD and two-fluid simulations has a striking similarity to that in their kinetic/PIC counterpart. In addition, we explore the scale dependence of the effective viscosity and discuss implications of this approach for space plasmas.
A database of multimodal myography and hand kinematics during realistic daily life activities
(Nature, 2025-08-28) Andreas, D; Werner, D; Hou, Z; Dwivedi, Anany; Castellini, C; Beckerle, P
This paper introduces MyoKi, a database capturing multimodal myography and hand kinematics during various realistic daily life activities. MyoKi emphasizes the complexity of real-world settings, addressing limitations of existing databases, which often reflect controlled laboratory conditions. The database includes two subsets of participants designed to evaluate different sensor configurations. Both subsets contain surface electromyography (sEMG) and inertial measurement unit (IMU) data, along with hand kinematics covering 18 finger and wrist joints. For the second subset, additional force myography (FMG) data was collected. The database captures hand movements of 35 participants performing 74 tasks, with varying arm orientations and movements involving different grips and motions. By offering detailed participant profiles and systematically categorizing each task, the MyoKi database enables in-depth exploration of task complexity, sensor influence, and the impact of demographic and anthropometric factors on control system performance. The database is designed to facilitate research in continuous hand control, enhancing the robustness and reliability of myoelectric devices for daily activities, moving towards user-friendly and effective control of robotic and prosthetic hands.
Global heliospheric termination shock strength in the solar–interstellar interaction
(Springer Nature, 2025) Zirnstein, Eric J.; Kumar, R.; Shrestha, Bishwas L.; Swaczyna, Paweł; Dayeh, Maher A.; Heerikhuisen, Jacob; Szalay, J R.
A heliospheric termination shock (HTS) surrounds our Solar System at approximately 100 astronomical units from the Sun, where the expanding solar wind (SW) is compressed and heated before encountering the interstellar medium. HTS-accelerated particles govern the pressure balance with the interstellar medium, but little is known about the global properties of the HTS beyond in situ measurements from Voyager in only two directions of the sky. Here we fill this gap by extracting the HTS strength using particle-in-cell, test particle and magnetohydrodynamic simulations, constrained by Interstellar Boundary Explorer observations of energetic neutral atoms produced from HTS-accelerated particles. Our results reveal there is a higher compression near the poles during solar minimum compared with solar maximum due to the higher Mach number flow. North–south asymmetries arise from the disparate evolution of the polar coronal holes, while minimum compression near the flanks is probably due to SW slowing from mass loading over a greater distance to the HTS. The results imply a strong connection between the HTS strength and the SW and interstellar medium dynamics.
A numerical model for the dynamics of pickup ions outside the heliopause and IBEX “ribbon” observation
(IOP Publishing, 2025) Huang, Yifan; Guo, Fan; Zirnstein, Eric J.; Noh, Sung Jun; Li, Hui; Reisenfeld, Daniel B.; Heerikhuisen, Jacob
The leading mechanism for the origin of the Interstellar Boundary Explorer (IBEX) “ribbon” of enhanced energetic neutral atoms (ENAs) from the outer heliosphere is the so-called secondary ENA process. In this mechanism, neutralized ions escape the heliosphere, and after several times of charge exchange collision,s some propagate back toward Earth in directions nearly perpendicular to the local interstellar magnetic field. However, the physical processes governing the distribution of the pickup ions (PUIs) outside the heliopause are still unclear. In this study, we build a new global model of the IBEX ribbon, where a key component is to calculate the dynamics of the PUIs outside the heliopause by solving the gyrophase-averaged focused transport equations on top of the background magnetohydrodynamic-kinetic model for the heliosphere-interstellar medium interaction. We discuss how the properties of the simulated ribbon change with different scattering parameters and show simulation results of the ENA sky maps, ribbon centers, ribbon profiles at several azimuthal slices, the ribbon ENA source region, and the velocity distribution of PUIs in the ENA source region for different scattering frequencies. Our results show that the model can provide reasonable ribbon sky maps comparable to the observed ribbon when the PUI mean free path is on the order of several thousand astronomical units.
Energetic neutral atom fluxes from the Voyager 1 and 2 directions
(IOP Publishing, 2025) Fuselier, Stephen A.; Zirnstein, Eric J.; Heerikhuisen, Jacob; Galli, André; Richardson, John D.; Reisenfeld, Daniel B.; Schwadron, Nathan A.; Dayeh, Maher A.; McComas, David J.; Funsten, Herbert O.; Sokół, Justyna M.; Opher, Merav; Kornbleuth, Marc Z.; Gasser, Jonathan
IBEX observes a globally distributed energetic neutral atom (ENA) flux from the heliosheath and very local interstellar medium (VLISM). Over a 14 yr period, Voyager 1 and Voyager 2 traversed the heliosheath from the termination shock to the heliopause. In situ observations from these spacecraft place important constraints on the parent ion populations of the ENAs from the heliosheath in two directions on the upwind side of the heliosphere, i.e., the direction of motion of the Sun in the local interstellar medium. In this study, an MHD model that is constrained by Voyager in situ observations is used to estimate the contribution from the heliosheath to the total ENA fluxes observed by IBEX. At energies greater than about 0.5 keV, the heliosheath provides a significant fraction of the observed ENA flux. However, at energies less than about 0.5 keV, the heliosheath provides an insignificant fraction of the observed ENA flux. These results are the same for both directions, and since the Voyager 1 and 2 directions are not particularly unique, the results are likely to be applicable for much of the upwind hemisphere. Fundamentally, it is the physics of the termination shock and the thickness of the heliosheath that determine the energy-dependent contributions to the observed ENA flux from this region. Because the heliosheath source is insignificant, most ENAs at energies less than about 0.5 keV probably come from the VLISM.
Viewing global changes in the heliosheath with IMAP’s energetic neutral atom imagers
(IOP Publishing, 2025) Zirnstein, Eric J.; Heerikhuisen, Jacob; McComas, David J.; Bower, J.; Clark, G.; Dayeh, Maher A.; Funsten, Herbert O.; Gkioulidou, Matina; Mitchell, Donald G.; Reisenfeld, Daniel B.; Schwadron, Nathan A.
We present a simulation analysis of NASA’s upcoming Interstellar Mapping and Acceleration Probe (IMAP) energetic neutral atom (ENA) instrument capabilities in viewing “global” changes in the heliosheath (HS) plasma, and the resulting ENA flux changes detected near Earth. This is done by simulating ENA emissions produced by charge exchange in a simulated heliosphere, utilizing the instruments’ energy coverage, and calculating the time it takes for the SW to travel from 1 au to the HS and for ENAs to travel back. We aim to answer the following: (i) What are the time delays as a function of energy and direction; (ii) at what energies can we observe changes the soonest; and (iii) what might the ENA source distributions affecting the time delays look like? We find the following: (i) The time delay depends on energy and direction in the sky, taking from >20 yr to <2 yr to see a response. The time delay does not decrease monotonically with increasing ENA energy, because of the energy-dependent, H+p charge exchange cross section. (ii) The quickest changes can be observed at ∼15 keV (without HS energy diffusion), intersecting IMAP-Hi and IMAP-Ultra energies. (iii) The ENA source distributions, and how far out IMAP can “see” the heliosphere, strongly depend on energy: IMAP-Lo and IMAP-Ultra should be able to view the farthest back in the heliotail but with long delay times. Finally, we show how energy diffusion in the HS affects the time delays and ENA source distributions, increasing ENA fluxes and prolonging time delays.
Energy management and edge-driven trading in fractal-structured microgrids: A machine learning approach
(MDPI, 2025) Pasandideh, Mostafa; Kurz, Jason A.; Jason A. , Mark
The integration of renewable energy into residential microgrids presents significant challenges due to solar generation intermittency and variability in household electricity demand. Traditional forecasting methods, reliant on historical data, fail to adapt effectively in dynamic scenarios, leading to inefficient energy management. This paper introduces a novel adaptive energy management framework that integrates streaming machine learning (SML) with a hierarchical fractal microgrid architecture to deliver precise real-time electricity demand forecasts for a residential community. Leveraging incremental learning capabilities, the proposed model continuously updates, achieving robust predictive performance with mean absolute errors (MAE) across individual households and the community of less than 10% of typical hourly consumption values. Three battery-sizing scenarios are analytically evaluated: centralised battery, uniformly distributed batteries, and a hybrid model of uniformly distributed batteries plus an optimised central battery. Predictive adaptive management significantly reduced cumulative grid usage compared to traditional methods, with a 20% reduction in energy deficit events, and optimised battery cycling frequency extending battery lifecycle. Furthermore, the adaptive framework conceptually aligns with digital twin methodologies, facilitating real-time operational adjustments. The findings provide critical insights into sustainable, decentralised microgrid management, emphasising improved operational efficiency, enhanced battery longevity, reduced grid dependence, and robust renewable energy utilisation.
Constraining solar wind transport model parameters using Bayesian analysis
(IOP Publishing, 2025) Bishop, Mark A.; Oughton, Sean; Parashar, Tulasi N.; Perrott, Yvette C.
We apply nested-sampling Bayesian analysis to a model for the transport of magnetohydrodynamic-scale solar wind fluctuations. The dual objectives are to obtain improved constraints on parameters present in the turbulence transport model (TTM) and to support quantitative comparisons of the quality of distinct versions of the transport model. The TTMs analyzed are essentially the 1D steady-state ones presented in Breech et al. that describe the radial evolution of the energy, correlation length, and normalized cross helicity of the fluctuations, together with the proton temperature, in prescribed background solar wind fields. Modeled effects present in the TTM include nonlinear turbulence interactions, shear driving, and energy injection associated with pickup-ions. Each of these modeled effects involves adjustable parameters that we seek to constrain using Bayesian analysis. We find that, given the TTMs and observational data sets analyzed, the most appropriate TTM to recommend corresponds to 2D fluctuations and has von Kármán-Howarth parameters of α ≈ 0.16 and β ≈ 0.10, along with reasonably standard values for the other adjustable parameters. The analysis also indicates that it is advantageous to include pickup ion effects in the lengthscale evolution equation by assuming Z^2β/αλ is locally conserved. Such Bayesian analysis is readily extended to more sophisticated solar wind models, space weather models, and might lead to improved predictions of, for example, solar flare and coronal mass ejection interactions with the Earth.
Understanding device integrations within diabetes apps: Mixed methods analysis of app features and user reviews
(JMIR Publications, 2025) Turner, Jessica Dawn; Stawarz, Katarzyna
Background: Diabetes management involves a large degree of data collection and self-care in order to accurately administer insulin. Several mobile apps are available that allow people to track and record various factors that influence their blood sugar levels. Existing diabetes apps offer features that enable integrations with various devices that streamline diabetes management, such as continuous glucose monitors, insulin pumps, or regular activity trackers. While this reduces the tracking burden on the users, the research highlighted several issues with diabetes apps, including issues with reliability and trustworthiness. As pumps and continuous glucose monitors are safety-critical systems—where issues can result in serious harm or fatalities—it is important to understand what issues and vulnerabilities could be introduced by relying on popular diabetes apps as an interface for interacting with such devices. Objective: As there is a lack of research examining in detail the integrations and potential suitability of apps as part of a wider self-management ecosystem, our goal was 2-fold. First, we aimed to understand the current landscape of device integrations within diabetes apps and how well they meet users’ needs. Second, we identified the key issues users of the most popular apps face currently and what features are the source of these issues. Methods: Through searches in Android and iPhone app stores, we systematically identified 21 diabetes apps that offer integrations. We conducted a detailed analysis of 602 user reviews. For each review, we recorded its sentiment, features and issues, and additional contextual information provided by the review writers. We used descriptive statistics to analyze the features and issues. We also analyzed the reviews thematically to identify additional trends related to the context of use and the consequences of issues reported by the users. Results: The reviews focused on key features that users found the most important, including device integrations (n=259, 43%), tracking (n=194, 32.2%), data logging (n=86, 14.3%), and notifications (n=70, 11.6%). We found that 327 (54.3%) of the reviews were negative versus 187 (31.1%) positive and 88 (14.6%) neutral or mixed, and the majority of reviews (n=378, 62.8%) mentioned issues. The biggest issues related to device integrations included inability to connect with external devices (n=95, 25.1%), inability to store, manage, or access data (n=49, 22%), unreliable notifications and alerts (n=35, 9.2%), issues caused by or related to software updates (n=31, 8.5%), hardware issues (n=24, 6.4%), and issues with accessing the app, related services, or associated hardware (n=12, 3.2%). Conclusions: Apps for diabetes management are a useful part of self-care only if they are reliable and trustworthy, reduce burden, and increase health benefits. Our results provide a useful overview of desired features for diabetes apps alongside key issues for existing integrations and highlight the future challenges for artificial pancreas system development.
Simulating turbulence in galactic halos and in the outer heliosphere
(IOP Publishing, 2025) Kleimann, Jens; Oughton, Sean; Fichtner, Horst
First, simulations of the wind-filled halos of starburst galaxies are performed in the framework of single-fluid magnetohydrodynamics, suitably extended to also track the self-consistent evolution of additional turbulence-related quantities. These quantities comprise the turbulent energy density, the cross-helicity, and the turbulent length scale. After a brief discussion of these extended equations and the employed numerical approach, we present selected simulation results, both for non-magnetized benchmark runs as well as for tests using the full system of equations. The dominant and unexpected feature of the former is a macroscopic flow instability near the rotational axis that prevents the outflow from reaching a steady state. Methods to determine the cause and nature of this instability are presented, followed by a preliminary analysis of the resulting turbulent properties. Second, the above framework is extended further to account for a non-constant energy difference (or residual energy), a quantity not conserved in the absence of dissipation, in addition to the Elsasser energies and by allowing each of these quantities its own characteristic correlation length scale. This setting is then applied to the outer heliosphere beyond the termination shock, where the solar wind expands both sub-Alfveńically and nonradially. The resulting solutions of this six-equation model are illustrated and studied in some detail.
Simulating a steady-state heliosphere
(IOP Publishing, 2025) Heerikhuisen, Jacob; Zirnstein, Eric J.; Pogorelov, Nikolai V.
Ever since the discovery of the solar wind, it has been understood that our solar system resides within a bubble of solar wind plasma that originates from the Sun. Due to its vast size, the geometry of this bubble, known as the heliosphere, remains a topic of conjecture and debate. Three-dimensional simulations, employing magnetohydrodynamics coupled to neutral particles, provide a key way of understanding the global flow dynamics on macroscopic scales. While many of these models suggest a comet-like shape with a single heliotail for the heliosphere, others have suggested geometries with two distinct outflows of solar wind plasma. In this paper we show how numerical simulations with the same boundary conditions may evolve differently, depending on factors such as initial conditions and run time. We find that the eventual steady state is the same comet-like shape, even for less than optimal choices of the initial condition.
Debiasing large language models: Research opportunities
(Royal Society Te Aparangi, 2025) Yogarajan, Vithya; Dobbie, Gillian; Keegan, Te Taka Adrian Gregory
Large language models (LLMs) are powerful decision-making tools widely adopted in healthcare, finance, and transportation. Embracing the opportunities and innovations of LLMs is inevitable. However, LLMs inherit stereotypes, misrepresentations, discrimination, and societies' biases from various sources–including training data, algorithm design, and user interactions–resulting in concerns about equality, diversity, and fairness. The bias problem has triggered increased research towards defining, detecting and quantifying bias and developing debiasing techniques. The predominant focus in tackling the bias problem is skewed towards resource-rich regions such as the US and Europe, resulting in a scarcity of research in other societies. As a small country with a unique history, culture and social composition, there is an opportunity for Aotearoa New Zealand's (NZ) research community to address this inadequacy. This paper presents an experimental evaluation of existing bias metrics and debiasing techniques in the NZ context. Research gaps derived from the study and a literature review are outlined, current and ongoing research in this space are discussed, and the suggested scope of research opportunities for NZ are presented.
A wearable bidirectional human–machine interface: Merging motion capture and vibrotactile feedback in a wireless bracelet
(MDPI, 2024) Kindel, Julian; Andreas, Daniel; Hou, Zhongshi; Dwivedi, Anany; Beckerle, Philipp
Humans interact with the environment through a variety of senses. Touch in particular contributes to a sense of presence, enhancing perceptual experiences, and establishing causal relations between events. Many human–machine interfaces only allow for one-way communication, which does not do justice to the complexity of the interaction. To address this, we developed a bidirectional human–machine interface featuring a bracelet equipped with linear resonant actuators, controlled via a Robot Operating System (ROS) program, to simulate haptic feedback. Further, the wireless interface includes a motion sensor and a sensor to quantify the tightness of the bracelet. Our functional experiments, which compared stimulation with three and five intensity levels, respectively, were performed by four healthy participants in their twenties and thirties. The participants achieved an average accuracy of 88% estimating three vibration intensity levels. While the estimation accuracy for five intensity levels was only 67%, the results indicated a good performance in perceiving relative vibration changes with an accuracy of 82%. The proposed haptic feedback bracelet will facilitate research investigating the benefits of bidirectional human–machine interfaces and the perception of vibrotactile feedback in general by closing the gap for a versatile device that can provide high-density user feedback in combination with sensors for intent detection.

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