bluuebunny/crossref_metadata_2025 huggingface dataset:
Quadrupolar radiation in de Sitter: displacement memory and Bondi metric
Authors: Compère Geoffrey , Hoque Sk Jahanur , Kutluk Emine Şeyma
Published: June 2024

We obtain the closed form expression for the metric perturbation around de Sitter spacetime generated by a matter source below Hubble scale both in generalized harmonic gauge and in Bondi gauge up to quadrupolar order in the multipolar expansion, including both parities (i.e. both mass and current quadrupoles). We demonstrate that such a source causes a displacement memory effect close to future infinity that originates, in the even-parity sector, from a Λ-BMS transition between the two non-radiative regions of future infinity.
Equation of state of hot neutron star matter using finite range simple effective interaction
Authors: Routray T R , Sahoo S , Viñas X , Basu D N , Centelles M
Published: June 2024

The equation of state (EoS) of hot neutron star matter (NSM) of n+p+e+μ composition in β-equilibrium is studied for both neutrino-free isothermal and neutrino-trapped isoentropic conditions, using the formalism where the thermal evolution is built upon its zero-temperature predictions in a self-consistent manner. The accuracy of the parabolic approximation, often used in the finite temperature calculation of hot NSM, is verified by comparing with the results obtained from the exact evaluation in the neutrino-free NSM. The EoS of neutrino-trapped isoentropic matter at low entropic condition, relevant to the core-collapsing supernovae, is formulated. In the isoentropic matter, the particle fractions and EoS have marginal variance as entropy per particle vary between 1 and 3 (in the unit of k
B), but the temperature profile shows marked variation. The isentropes are found to be much less sensitive to the nuclear matter incompressibility, but have large dependence on the slope parameter L. The bulk properties of the neutron stars predicted by the isoentropic EoSs for different entropy are calculated. A model calculation for the early stage evolution of protoneutron star to neutron star configuration is also given.
Anisotropic complex permittivity measurement using a microstrip air line
Authors: Li Qunying , Wu Changying
Published: June 2024

A microstrip air line system for measuring the complex permittivity of anisotropic materials in the band from 0.3 to 1 GHz is proposed. The multireflect-thru method is used to calibrate the measurement system in the whole band with a single microstrip air line without suffering from the limited space resolution of time-gating technique. During the measurement, the material under test (MUT) is placed both above and below the strip. With this deployment, the TEM mode propagates along the microstrip in the MUT. Therefore, it is possible to measure the anisotropic permittivity. Since a small portion of the electric field is parallel to the ground plane around two edges of the strip, the extracted property is not purely along one direction. To obtain higher accuracy, with the help of linear combination, the properties along two directions are disentangled by two measurements. For validation of the method, an isotropic material and an anisotropic material in the microstrip air line were simulated and their permittivities were extracted from simulation results. An anisotropic material polytetrafluoroethylene (PTFE) and two anisotropic materials, FR4 and honeycomb absorber, were measured. The results of PTFE show that there is a maximum relative error of 1.4% and 2.5% for the permittivity extracted from simulation and measurement, respectively. The validity and the accuracy of the system for measuring anisotropic materials are verified by the simulation and measurement results.
Implementation of 3D-focusing in an ion momentum spectrometer
Authors: Wu Ruichang , Ding Bocheng , Liao Jianfeng , Feng Yunfei , Wu Kefei , Jin Xin , Liu Xiao-Jing
Published: June 2024

An ion momentum spectrometer is used to acquire an ion’s three-dimensional (3D) momentum by measuring its time-of-flight and position. Recently, 3D-focusing techniques were implemented by several groups to improve energy resolution. Here, we build a 3D-focusing momentum spectrometer and apply the nonlinear parameter scaling rule to improve the ion kinetic energy resolution. In the experimental test, the O+/O+ ion pairs are created by focusing 25 fs Ti: sapphire laser pulses on an O2 molecular jet. In the kinetic energy release spectrum of O+/O+ pairs, a resolution of 0.5 eV is obtained at 11.2 eV. Furthermore, the validity of the nonlinear parameter scaling rule is also confirmed in the analysis of O+/CO+ ion pairs from CO2 molecules. So it can be consistently applied to different ions in the spectrometer that uses a pure electric field.
Res2-UNet++: a deep learning image post-processing method for electrical resistance tomography
Authors: Huang Qiushi , Liang Guanghui , Tan Chao , Dong Feng
Published: June 2024

The monitoring of multiphase flow distribution in industrial processes in order to optimize production presents a challenge. Electrical resistance tomography (ERT) is a technique used to visualize the inner distribution of multiphase flow. Image reconstruction plays a vital role in ERT. However, the nonlinearity and ill-posedness of inverse problems make image reconstruction in ERT difficult. The development of advanced imaging algorithms has attracted much interest for this purpose. In this work, an improved U-shaped deep learning model is proposed, which combines the advantages of the multi-scale feature extraction of UNet++ and the residual feature fusion of Res2Net. The network is designed to post-process the pre-reconstruction results of traditional ERT image-reconstruction methods, combining the generalization ability of the model-based methods and the flexible feature-extraction advantage of deep learning methods. The post-processing includes super-resolution, image denoising and artifact removal. Simulations and experiments are designed to verify the generalization ability and effectiveness of the proposed post-processing model. Both simulation and experimental results show that the proposed U-shaped network approach outperforms other deep learning methods, and the proposed deep learning model is fit for post-processing in ERT, making it a robust solution for applications.
Time-resolved clinical dose volume metrics, calculations and predictions based on source tracking measurements and uncertainties to aid treatment verification and error detection for HDR brachytherapy—a proof-of-principle study
Authors: van Wagenberg Teun , Voncken Robert , van Beveren Celine , Berbee Maaike , van Limbergen Evert , Verhaegen Frank , Paiva Fonseca Gabriel
Published: June 2024

Objective. High-dose-rate (HDR) brachytherapy lacks routinely available treatment verification methods. Real-time tracking of the radiation source during HDR brachytherapy can enhance treatment verification capabilities. Recent developments in source tracking allow for measurement of dwell times and source positions with high accuracy. However, more clinically relevant information, such as dose discrepancies, is still needed. To address this, a real-time dose calculation implementation was developed to provide more relevant information from source tracking data. A proof-of-principle of the developed tool was shown using source tracking data obtained from a 3D-printed anthropomorphic phantom. Approach. Software was developed to calculate dose-volume-histograms (DVH) and clinical dose metrics from experimental HDR prostate treatment source tracking data, measured in a realistic pelvic phantom. Uncertainty estimation was performed using repeat measurements to assess the inherent dose measuring uncertainty of the in vivo dosimetry (IVD) system. Using a novel approach, the measurement uncertainty can be incorporated in the dose calculation, and used for evaluation of cumulative dose and clinical dose-volume metrics after every dwell position, enabling real-time treatment verification. Main results. The dose calculated from source tracking measurements aligned with the generated uncertainty bands, validating the approach. Simulated shifts of 3 mm in 5/17 needles in a single plan caused DVH deviations beyond the uncertainty bands, indicating errors occurred during treatment. Clinical dose-volume metrics could be monitored in a time-resolved approach, enabling early detection of treatment plan deviations and prediction of their impact on the final dose that will be delivered in real-time. Significance. Integrating dose calculation with source tracking enhances the clinical relevance of IVD methods. Phantom measurements show that the developed tool aids in tracking treatment progress, detecting errors in real-time and post-treatment evaluation. In addition, it could be used to define patient-specific action limits and error thresholds, while taking the uncertainty of the measurement system into consideration.
Characterization of the clinically approved MRI tracer resotran for magnetic particle imaging in a comparison study
Authors: Mohn Fabian , Scheffler Konrad , Ackers Justin , Weimer Agnes , Wegner Franz , Thieben Florian , Ahlborg Mandy , Vogel Patrick , Graeser Matthias , Knopp Tobias
Published: June 2024

Objective. The availability of magnetic nanoparticles (MNPs) with medical approval for human intervention is fundamental to the clinical translation of magnetic particle imaging (MPI). In this work, we thoroughly evaluate and compare the magnetic properties of an magnetic resonance imaging (MRI) approved tracer to validate its performance for MPI in future human trials. Approach. We analyze whether the recently approved MRI tracer Resotran is suitable for MPI. In addition, we compare Resotran with the previously approved and extensively studied tracer Resovist, with Ferrotran, which is currently in a clinical phase III study, and with the tailored MPI tracer Perimag. Main results. Initial magnetic particle spectroscopy (MPS) measurements indicate that Resotran exhibits performance characteristics akin to Resovist, but below Perimag. We provide data on four different tracers using dynamic light scattering, transmission electron microscopy, vibrating sample magnetometry measurements, MPS to derive hysteresis, point spread functions, and a serial dilution, as well as system matrix based MPI measurements on a preclinical scanner (Bruker 25/20 FF), including reconstructed images. Significance. Numerous approved MNPs used as tracers in MRI lack the necessary magnetic properties essential for robust signal generation in MPI. The process of obtaining medical approval for dedicated MPI tracers optimized for signal performance is an arduous and costly endeavor, often only justifiable for companies with a well-defined clinical business case. Resotran is an approved tracer that has become available in Europe for MRI. In this work, we study the eligibility of Resotran for MPI in an effort to pave the way for human MPI trials.
Two-dimensional Mo decorated borophenes: high critical temperature, large magnetic anisotropy, and stacking-dependent magnetism
Authors: Gao Zhen , Ma Fengxian , Wu Hongbo , Meng Weizhen , Jiao Yalong
Published: June 2024

Two-dimensional magnetic materials with high critical temperature, large magnetic anisotropy energy and intrinsic magnetism hold great promise for advancements in spintronics. However, synergizing these attributes within a single material remains challenging. Through the application of swarm-intelligence-based structure searching along with first-principles calculations, we identify two Mo decorated borophene variants, denoted as MoB4 and MoB6, are such candidates with high thermal and dynamical stabilities. MoB4 and MoB6 are characterized as either ferromagnetic or antiferromagnetic metals. Notably, both MoB4 and MoB6 display sizable magnetic anisotropy energy—924 and 932 μeV per Mo atom, respectively—surpassing that of the widely studied CrI3 monolayer, which measures 685 μeV per Cr atom. Monte Carlo simulation suggests the Curie temperature of MoB4 sheet is 390 K, which is above room temperature. Our examination uncovers that bilayer Mo
x
B
y
formations exhibit layer-specific van der Waals interactions, contrasting with bilayer borophenes produced experimentally, which display robust interlayer chemical bonding. We determine that the stacking order profoundly influence both the magnetic anisotropy energy and critical temperatures of the material. Specifically, the magnetic anisotropy energy for both structures doubles in their bilayer configurations, with AB-stacked MoB4 and AC-stacked MoB6 demonstrating critical temperatures of 550 K and 320 K, respectively. The exceptional electronic and magnetic characteristics of the Mo
x
B
y
monolayers position them as favorable candidates for future spintronic devices.
A finite-time quantum Otto engine with tunnel coupled one-dimensional Bose gases
Authors: Nautiyal V V , Watson R S , Kheruntsyan K V
Published: June 2024

We undertake a theoretical study of a finite-time quantum Otto engine cycle driven by inter-particle interactions in a weakly interacting one-dimensional (1D) Bose gas in the quasicondensate regime. Utilizing ac-field approach, we simulate the entire Otto cycle, i.e. the two work strokes and the two equilibration strokes. More specifically, the interaction-induced work strokes are modelled by treating the working fluid as an isolated quantum many-body system undergoing unitary evolution. The equilibration strokes, on the other hand, are modelled by treating the working fluid as an open quantum system tunnel-coupled to another quasicondensate which acts as either the hot or cold reservoir, albeit of finite size. We find that, unlike a uniform 1D Bose gas, a harmonically trapped quasicondensate cannot operate purely as aheatengine; instead, the engine operation is enabled by additionalchemicalwork performed on the working fluid, facilitated by the inflow of particles from the hot reservoir. The microscopic treatment of dynamics during equilibration strokes enables us to evaluate the characteristic operational time scales of this Ottothermochemicalengine, crucial for characterizing its power output, without any ad hoc assumptions about typical thermalization timescales. We analyse the performance and quantify the figures of merit of the proposed Otto thermochemical engine, finding that it offers a favourable trade-off between efficiency and power output, particularly when the interaction-induced work strokes are implemented via a sudden quench. We further demonstrate that in the sudden quench regime, the engine operates with an efficiency close to the near-adiabatic (near maximum efficiency) limit, while concurrently achieving maximum power output.
MHz cut-off frequency and permeability mechanism of iron-based soft magnetic composites
Authors: Jin 金 Xiao-Wei 校伟 , Li 李 Tong 通 , Shi 史 Hui-Gang 慧刚 , Xue 薛 De-Sheng 德胜
Published: June 2024

The lack of soft magnetic composites with high power density in MHz frequency range has become an obstacle in the efficient operation of the electrical and electronic equipments. Here, a promising method to increase the cut-off frequency of iron-based soft magnetic composites to hundreds of MHz is reported. The cut-off frequency is increased from 10 MHz to 1 GHz by modulating the height of the ring, the distribution of particles, and the particle size. The mechanism of cut-off frequency and permeability is the coherent rotation of domain modulated by inhomogeneous field due to the eddy current effect. An empirical formula for the cut-off frequency in a magnetic ring composed of iron-based particles is established from experimental data. This work provides an effective approach to fabricate soft magnetic composites with a cut-off frequency in hundreds of MHz.
Instruments and methods for coating of wavelength-shifting materials used for noble liquid technology
Authors: Canci N.
Published: June 2024

The use of wavelength-shifting coatings is of primary interest in the area of liquified
noble gases detectors. Argon and xenon are used as active medium in the neutrino physics and dark
matter experiments, because charged particles crossing the noble liquid volume produce excitation
and ionization followed by recombination and both the processes lead to the emission of VUV light.
Noble liquid scintillation light emitted in the VUV range needs to be converted to be detected by
conventional photosensors. Wavelength-shifting materials, such as TetraPhenyl-Butadiene and
p-TerPhenyl, are used for this conversion to the visible range. The wavelength-shifters are
particularly important in the case of large area detectors since only a fraction of the surface
can be instrumented. To this purpose dedicated set-ups have been built and specific techniques
have been adopted to produce and characterize very uniform wavelength-shifting coatings on highly
reflecting material substrates, optical filters and optical guides. Some type of the facilities
used to this task, with particular attention to the vacuum deposition systems, will be described,
operations for production of the coatings will be reported, methods for the characterization of
the samples will be briefly presented.
Charge amplification in low pressure CF4:SF6:He mixtures with a multi-mesh ThGEM for directional dark matter searches
Authors: Amaro F.D. , Baracchini E. , Benussi L. , Bianco S. , Borra F. , Capoccia C. , Caponero M. , Cardoso D.S. , Cavoto G. , Costa I.A. , Crane T. , Dané E. , D'Astolfo M. , Dho G. , Di Giambattista F. , D'Imperio G. , Di Marco E. , Dos Santos J.M.F. , Ezeribe A.C. , Fiorina D. , Iacoangeli F. , Lima Júnior H.P. , Lopes G.S.P. , Maccarrone G. , Mano R.D.P. , Marcelo Gregorio R.R. , Marques D.J.G. , Mazzitelli G. , McLean A.G. , Monteiro C.M.B. , Nobrega R.A. , Pains I.F. , Paoletti E. , Passamonti L. , Piacentini S. , Piccolo D. , Pierluigi D. , Pinci D. , Prajapati A. , Renga F. , Roque R.J.d.C. , Rosatelli F. , Russo A. , Saviano G. , Scarff A. , Spooner N.J.C. , Tesauro R. , Tomassini S. , Torelli S.
Published: June 2024

The CYGNO collaboration is developing next generation
directional Dark Matter (DM) detection experiments, using gaseous
Time Projection Chambers (TPCs), as a robust method for identifying
Weakly Interacting Massive Particles (WIMPs) below the Neutrino
Fog. SF6 is potentially ideal for this since it provides a high
fluorine content, enhancing sensitivity to spin-dependent
interactions and, as a Negative Ion Drift (NID) gas, reduces charge
diffusion leading to improved positional resolution. CF4,
although not a NID gas, has also been identified as a favourable gas
target as it provides a scintillation signal which can be used for a
complimentary light/charge readout approach. These gases can operate
at low pressures to elongate Nuclear Recoil (NR) tracks and
facilitate directional measurements. In principle, He could be added
to low pressure SF6/CF4 without significant detriment to the
length of 16S, 12C, and 19F recoils. This would
improve the target mass, sensitivity to lower WIMP masses, and offer
the possibility of atmospheric operation; potentially reducing the
cost of a containment vessel. In this article, we present gas gain
and energy resolution measurements, taken with a Multi-Mesh Thick
Gaseous Electron Multiplier (MMThGEM), in low pressure SF6 and
CF4:SF6 mixtures following the addition of He. We find that
the CF4:SF6:He mixtures tested were able to produce gas gains
on the order of 104 up to a total pressure of 100 Torr. These
results demonstrate an order of magnitude
improvement [1] in charge amplification in NID gas
mixtures with a He component.
Effects of different pretreatments on Ti/RuO2-TiO2 anode
Authors: Li Zhengyi , Xu Yang , Han Zhaohui , Zhou Shenggang , Wei Sikang , Xu Lei
Published: June 2024

In this study, H2C2O4, H2SO4, HNO3, and HCl were used to etch the TA2 titanium matrix at the same concentration and temperature, and the effects of different acid etching methods on the properties of the titanium matrix and Ru-Ti electrode were investigated. The surface morphology of the titanium substrate and anode after acid etching was observed by scanning electron microscopy (SEM), while the electrochemical performance of the anode was determined by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and tafel plots. SEM observations showed that H2C2O4 had the best etching effect on the titanium substrate, as the scratches were uniform, and the surface cracks of the prepared anode reached 4–6 μm; Analysis of the CV curves revealed that the Ti/RuO2-TiO2 anode prepared by H2C2O4 etching had the highest surface charge capacity (172 mC) compared to the anodes prepared by other acid etchings, while the LSV curves showed that the Ti/RuO2-TiO2 anode after H2C2O4 etching had the lowest polarization potential (1.232 V). Tafel curve analysis revealed that the corrosion potential of the Ti anode prepared by H2C2O4 etching was 0.203 V, and the self-corrosion current density was −5.11 A cm−2, indicating that the corrosion resistance of the Ti anode prepared by H2C2O4 treatment is the weakest. X-ray photoelectron spectroscopy analysis showed that the electrode surface changed from Ru4+ to Ru3+ after corrosion, with the Ti2p spectra showing similar transition from Ti4+ to Ti3+.
Optimizing drilling parameters for fly ash-filled hemp/epoxy composites: investigating drill bit geometries, feed rates, and spindle speeds
Authors: Roy Choudhury Mridusmita , Dutta Hrishikesh , Srinivas M Shanmuka , Debnath Kishore , Arunkumar T , Upadhyay Vikas
Published: June 2024

This article investigates the drilling behavior of hemp fiber-reinforced epoxy composites, both unfilled and fly ash-filled. Drilling performance tests were conducted at varying feed rates (8, 16, and 24 mm min−1) and spindle speeds (700, 1400, and 2100 RPM) using three drill geometries: parabolic, 8-facet, and dagger. The fly ash-filled hemp/epoxy composite showed significant reductions in maximum thrust force (25.09%, 19.92%, and 21.43%) and torque (80%, 79.87%, and 59.25%) when drilled with parabolic, 8-facet, and dagger drill bits, respectively, compared to the unfilled composite. The maximum drilling temperature reached 90.6 °C during cutting and decreased to 71.7 °C post-drilling. Overall, the fly ash-filled composites demonstrated superior performance in terms of drilling-induced stresses and damage.
Two-dimensional coherent spectrum of high-spin models via a quantum computing approach
Authors: Mootz Martin , Orth Peter P , Huang Chuankun , Luo Liang , Wang Jigang , Yao Yong-Xin
Published: June 2024

We present and benchmark a quantum computing approach to calculate the two-dimensional coherent spectrum (2DCS) of high-spin models. Our approach is based on simulating their real-time dynamics in the presence of several magnetic field pulses, which are spaced in time. We utilize the adaptive variational quantum dynamics simulation algorithm for the study due to its compact circuits, which enables simulations over sufficiently long times to achieve the required resolution in frequency space. Specifically, we consider an antiferromagnetic quantum spin model that incorporates Dzyaloshinskii-Moriya interactions and single-ion anisotropy. The obtained 2DCS spectra exhibit distinct peaks at multiples of the magnon frequency, arising from transitions between different eigenstates of the unperturbed Hamiltonian. By comparing the one-dimensional coherent spectrum with 2DCS, we demonstrate that 2DCS provides a higher resolution of the energy spectrum. We further investigate how the quantum resources scale with the magnitude of the spin using two different binary encodings of the high-spin operators: the standard binary encoding and the Gray code. At low magnetic fields both encodings require comparable quantum resources, but at larger field strengths the Gray code is advantageous. Numerical simulations for spin models with increasing number of sites indicate a polynomial system-size scaling for quantum resources. Lastly, we compare the numerical 2DCS with experimental results on a rare-earth orthoferrite system. The observed strength of the magnonic high-harmonic generation signals in the 2DCS of the quantum high-spin model aligns well with the experimental data, showing significant improvement over the corresponding mean-field results.
A novel high-performance TG-based SRAM cell with 5 nm FinFET technology
Authors: Pal Sandipan , Upadhyaya Bijoy Kumar , Majumder Tanmoy , Das Narottam , Bhattacharjee Abhishek
Published: June 2024

In this study, we investigate the performance and reliability of a novel static random-access memory (SRAM) cell utilizing advanced 5 nm FinFET technology. Our research aims to address critical challenges in SRAM design by integrating transmission gates and power gated transistors. Through extensive simulations using the Cadence Virtuoso tool, we optimize the SRAM cell’s read and write paths, resulting in substantial improvements in both functionalities. Additionally, our study unveils temperature-dependent variations in the read current and write margin, emphasizing the influence of temperature on SRAM performance. Compared to conventional FinFET SRAM circuits of equivalent bit-cell area and read latency, our innovative design showcases remarkable improvements across various parameters. Specifically, we achieve a commendable increase of 6.16% in the write static noise margin (WSNM) and 5.86% in the hold static noise margin (HSNM). Moreover, our findings reveal a substantial boost in read stability, increasing from 14.75% to 18.35%. These advancements underscore the promising potential of our approach in paving the way for future innovations in high-performance memory architectures. By leveraging state-of-the-art technology and meticulous optimization techniques, our research sets a new standard for SRAM design, offering enhanced performance, reliability, and efficiency in memory systems.
Variability-aware modeling of electrochemical metallization memory cells
Authors: Ahmad Rana Walied , Waser Rainer , Maudet Florian , Toprak Onur , Dubourdieu Catherine , Menzel Stephan
Published: June 2024

Resistively switching electrochemical metallization memory cells are gaining huge interest since they are seen as promising candidates and basic building blocks for future computation-in-memory applications. However, especially filamentary-based memristive devices suffer from inherent variability, originating from their stochastic switching behavior. A variability-aware compact model of electrochemical metallization memory cells is presented in this study and verified by showing a fit to experimental data. It is an extension of the deterministic model. Since this extension consists of several different features allowing for a realistic variability-aware fit, it depicts a unique model comprising physics-based, stochastically and experimentally originating variabilities and reproduces them well. In addition, a physics-based model parameter study is executed, which enables a comprehensive view into the device physics and presents guidelines for the compact model fitting procedure.
Using analogues to predict changes in future UK heatwaves*
Authors: Yule Emma L , Hegerl Gabriele C , Schurer Andrew , Ballinger Andrew , Hawkins Ed
Published: June 2024

The intensity and frequency of extreme heat events is increasing due to climate change, resulting in a range of societal impacts. In this paper, we use temporal analogues to analyse how past UK heatwave events, such as during the summer of 1923, may change if they were to occur under different global warming scenarios. We find that the six most intense early heat events are caused by circulation patterns similar to that of 1923, which can cause intense heat over the UK and parts of NW Europe. Circulation analogues for the 1923 heatwave are also linked to intense heat events in the future, although not all analogues are anomalously hot. At 4 °C of global warming, mean summer temperatures in England over the duration of the 1923 heatwave are between 4.9 and 6.4 degrees warmer than pre-industrial levels across the three models used. At that global mean warming level, future heat events with similar circulation as 1923 over England are estimated to be on average 6.9 °C–10.7 °C hotter than those at pre-industrial levels. Exploring how the intensity of events similar to past events may change in the future could be an effective risk communication tool for adaptation decision making, particularly if past events are stored in society’s memory, for example, due to high impacts.
The forest biodiversity index (FOBI): monitoring forest biodiversity potential over space and time
Authors: Bellamy Chloe , Rattey Andrew , Edwards Colin , Kortland Kenny , Stringer Andrew , Tew Eleanor , Bathgate Stephen , Kerecsenyi Nora , Moseley Darren , Watts Kevin , Broome Alice
Published: June 2024

Public forest agencies are obligated to take steps to conserve and where possible enhance biodiversity, but they often lack information and tools that support and evidence their decision making. To help inform and monitor impact of management actions and policies aimed at improving forest biodiversity, we have co-developed a quantitative, transparent and repeatable approach for assessing the biodiversity potential of the United Kingdom’s (UK) publicly owned forests over space and time. The FOrest Biodiversity Index (FOBI) integrates several forest biodiversity indicators or ‘metrics’, which characterise management-sensitive woodland and landscape features associated with biodiversity. These are measured or modelled annually using spatially comprehensive forest survey data and other well-maintained spatial environmental datasets. Following metric normalisation and a correlation analysis, a statistically robust selection of these metrics is aggregated using a hierarchical procedure to provide composite index scores. The FOBI metric and index results are provided for every individual public forest, and can be summarised across any reporting region of interest. Compared to existing indicators that rely on sample-based forest data, the results thus better support decisions and obligations at a range of scales, from locally targeted action to national, long-term biodiversity monitoring and reporting. We set out how the FOBI approach and associated bespoke online interfaces were co-developed to meet public forest agency needs in two constituent countries of the UK (England and Scotland), whilst providing a conceptual framework that can be adapted and transferred to other geographic areas and private forests. Example results are reported for England’s public forests for four annual timestamps between 2014 and 2021, which indicate improvements to the biodiversity potential of public forests and surrounding landscapes over this time via increases in their diversity, extent, condition and connectivity.
OEDG: Oscillation-eliminating discontinuous Galerkin method for hyperbolic conservation laws
Authors: Peng Manting , Sun Zheng , Wu Kailiang
Published: June 2024

Suppressing spurious oscillations is crucial for designing reliable high-order numerical schemes for hyperbolic conservation laws, yet it has been a challenge actively investigated over the past several decades. This paper proposes a novel, robust, and efficient oscillation-eliminating discontinuous Galerkin (OEDG) method on general meshes, motivated by the damping technique (see J. Lu, Y. Liu, and C. W. Shu [SIAM J. Numer. Anal. 59 (2021), pp. 1299–1324]). The OEDG method incorporates an oscillation-eliminating (OE) procedure after each Runge–Kutta stage, and it is devised by alternately evolving the conventional semidiscrete discontinuous Galerkin (DG) scheme and a damping equation. A novel damping operator is carefully designed to possess both scale-invariant and evolution-invariant properties. We rigorously prove the optimal error estimates of the fully discrete OEDG method for smooth solutions of linear scalar conservation laws. This might be the first generic fully discrete error estimate for nonlinear DG schemes with an automatic oscillation control mechanism. The OEDG method exhibits many notable advantages. It effectively eliminates spurious oscillations for challenging problems spanning various scales and wave speeds, without necessitating problem-specific parameters for all the tested cases. It also obviates the need for characteristic decomposition in hyperbolic systems. Furthermore, it retains the key properties of the conventional DG method, such as local conservation, optimal convergence rates, and superconvergence. Moreover, the OEDG method maintains stability under the normal Courant–Friedrichs–Lewy (CFL) condition, even in the presence of strong shocks associated with highly stiff damping terms. The OE procedure is nonintrusive, facilitating seamless integration into existing DG codes as an independent module. Its implementation is straightforward and efficient, involving only simple multiplications of modal coefficients by scalars. The OEDG approach provides new insights into the damping mechanism for oscillation control. It reveals the role of the damping operator as a modal filter, establishing close relations between the damping technique and spectral viscosity techniques. Extensive numerical results validate the theoretical analysis and confirm the effectiveness and advantages of the OEDG method.
Explicit formulae for the mean value of products of values of Dirichlet 𝐿-functions at positive integers
Authors: Louboutin Stéphane
Published: June 2024

Let

m
≥
1

m\ge 1

be a rational integer. We give an explicit formula for the mean value
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartFraction 2 Over phi left-parenthesis f right-parenthesis EndFraction sigma-summation Underscript chi left-parenthesis negative 1 right-parenthesis equals left-parenthesis negative 1 right-parenthesis Superscript m Baseline Endscripts StartAbsoluteValue upper L left-parenthesis m comma chi right-parenthesis EndAbsoluteValue squared comma">

2

ϕ
(
f
)

∑

χ
(
−
1
)
=
(
−
1

)
m

|
L
(
m
,
χ
)

|
2

,

\begin{equation*} \frac {2}{\phi (f)}\sum _{\chi (-1)=(-1)^m}\vert L(m,\chi )\vert ^2, \end{equation*}

where

χ
\chi

ranges over the

ϕ
(
f
)

/

2

\phi (f)/2

Dirichlet characters modulo

f
>
2

f>2

with the same parity as

m
m

. We then adapt our proof to obtain explicit means values for products of the form
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper L left-parenthesis m 1 comma chi 1 right-parenthesis midline-horizontal-ellipsis upper L left-parenthesis m Subscript n minus 1 Baseline comma chi Subscript n minus 1 Baseline right-parenthesis ModifyingAbove upper L left-parenthesis m Subscript n Baseline comma chi 1 midline-horizontal-ellipsis chi Subscript n minus 1 Baseline right-parenthesis With bar">

L
(

m
1

,

χ
1

)
⋯
L
(

m

n
−
1

,

χ

n
−
1

)

L
(

m
n

,

χ
1

⋯

χ

n
−
1

)

¯

L(m_1,\chi _1)\cdots L(m_{n-1},\chi _{n-1})\overline {L(m_n,\chi _1\cdots \chi _{n-1})}

.
Who Posts on Instagram? Using Natural Language Processing to Assess the Relationship Between Training Background and Content of 700,000 Posts
Authors: Etebari Cameron A , Braun Sterling E , Vazquez-Machado Maria C , Butterworth James A
Published: June 2024

Background

Instagram (Menlo Park, CA) is a major platform for the dissemination of plastic surgery (PS) information, but the training background of users is difficult to ascertain.

Objectives

We sought to better characterize the source and content of PS-related posts on Instagram.

Methods

Metadata from publicly available Instagram posts containing PS relevant hashtags was collected from December 2018 to August 2020 using Node.js (Node.js Foundation, San Francisco, CA). The data was characterized by account type, and post topics were analyzed using a custom dictionary of PS procedures applied with natural language processing. All data analyses were performed with R (The R Foundation, Vienna, Austria).

Results

Board-certified plastic surgeons account for 38% of posts on Instagram, followed by organizations (31%), nonplastics-trained physicians (19%), facial plastics (5%), oculoplastics (1%), and nonphysician providers (5%). Oculoplastics had the highest engagement rate with their posts (3.7 ± 5.1), whereas plastic surgeons had the lowest (2.7 ± 4.2). Breast aesthetics was the predominant topic posted by plastic surgeons (42%, P < .001), and board certification phrases distinguished their posts from other account types (23%, P < .001). Nonphysician posts focused on nonsurgical aesthetics like Botox and fillers (80%). However, nonplastics-trained physicians and organizations significantly contributed to procedural subcategories in a similar distribution to plastic surgeons.

Conclusions

Board-certified plastic surgeons are not the predominant source of PS content on Instagram. Furthermore, posts by plastic surgeons have the lowest rate of engagement out of all account types studied. Although declarations of board certification distinguish content from plastics disciplines, they are only used in 21% of posts.

Level of Evidence: 4
MolDy: molecular dynamics simulation made easy
Authors: Khan Mohd Imran , Pathania Sheetal , Al-Rabia Mohammed W , Ethayathulla Abdul S , Khan Mohammad Imran , Allemailem Khaled S , Azam Mohd , Hariprasad Gururao , Imran Mohammad Azhar
Published: June 2024

Motivation

Molecular dynamics (MD) is a computational experiment that is crucial for understanding the structure of biological macro and micro molecules, their folding, and the inter-molecular interactions. Accurate knowledge of these structural features is the cornerstone in drug development and elucidating macromolecules functions. The open-source GROMACS biomolecular MD simulation program is recognized as a reliable and frequently used simulation program for its precision. However, the user requires expertise, and scripting skills to carrying out MD simulations.

Results

We have developed an end-to-end interactive MD simulation application, MolDy for Gromacs. This front-end application provides a customizable user interface integrated with the Python and Perl-based logical backend connecting the Linux shell and Gromacs software. The tool performs analysis and provides the user with simulation trajectories and graphical representations of relevant biophysical parameters. The advantages of MolDy are (i) user-friendly, does not requiring the researcher to have prior knowledge of Linux; (ii) easy installation by a single command; (iii) freely available for academic research; (iv) can run with minimum configuration of operating systems; (v) has valid default prefilled parameters for beginners, and at the same time provides scope for modifications for expert users.

Availability and implementation

MolDy is available freely as compressed source code files with user manual for installation and operation on GitHub: https://github.com/AIBResearchMolDy/Moldyv01.git and on https://aibresearch.com/innovations.
Scaling DEPP phylogenetic placement to ultra-large reference trees: a tree-aware ensemble approach
Authors: Jiang Yueyu , McDonald Daniel , Perry Daniela , Knight Rob , Mirarab Siavash
Published: June 2024

Motivation

Phylogenetic placement of a query sequence on a backbone tree is increasingly used across biomedical sciences to identify the content of a sample from its DNA content. The accuracy of such analyses depends on the density of the backbone tree, making it crucial that placement methods scale to very large trees. Moreover, a new paradigm has been recently proposed to place sequences on the species tree using single-gene data. The goal is to better characterize the samples and to enable combined analyses of marker-gene (e.g., 16S rRNA gene amplicon) and genome-wide data. The recent method DEPP enables performing such analyses using metric learning. However, metric learning is hampered by a need to compute and save a quadratically growing matrix of pairwise distances during training. Thus, the training phase of DEPP does not scale to more than roughly 10 000 backbone species, a problem that we faced when trying to use our recently released Greengenes2 (GG2) reference tree containing 331 270 species.

Results

This paper explores divide-and-conquer for training ensembles of DEPP models, culminating in a method called C-DEPP. While divide-and-conquer has been extensively used in phylogenetics, applying divide-and-conquer to data-hungry machine-learning methods needs nuance. C-DEPP uses carefully crafted techniques to enable quasi-linear scaling while maintaining accuracy. C-DEPP enables placing 20 million 16S fragments on the GG2 reference tree in 41 h of computation.

Availability and implementation

The dataset and C-DEPP software are freely available at https://github.com/yueyujiang/dataset_cdepp/.
Piperacillin/tazobactam for surgical prophylaxis during pancreatoduodenectomy: meta-analysis
Authors: Kumar Jayant , Reccia Isabella , Carneiro Adriano , Podda Mauro , Virdis Francesco , Machairas Nikolaos , Nasralla David , Arasaradnam Ramesh P , Poon Kenneth , Gannon Christopher J , Fung John J , Habib Nagy , Llaguna Omar
Published: June 2024

Background

Pancreatoduodenectomy is associated with an increased incidence of surgical-site infections, often leading to a significant rise in morbidity and mortality. This trend underlines the inadequacy of traditional antibiotic prophylaxis strategies. Hence, the aim of this meta-analysis was to assess the outcomes of antimicrobial prophylaxis, comparing piperacillin/tazobactam with traditional antibiotics.

Methods

Upon registering in PROSPERO, the international prospective register of systematic reviews (CRD42023479100), a systematic search of various databases was conducted over the interval 2000–2023. This inclusive search encompassed a wide range of study types, including prospective and retrospective cohorts and RCTs. The subsequent data analysis was carried out utilizing RevMan 5.4.

Results

A total of eight studies involving 2382 patients who underwent pancreatoduodenectomy and received either piperacillin/tazobactam (1196 patients) or traditional antibiotics (1186 patients) as antibiotic prophylaxis during surgery were included in the meta-analysis. Patients in the piperacillin/tazobactam group had significantly reduced incidences of surgical-site infections (OR 0.43 (95% c.i. 0.30 to 0.62); P < 0.00001) and major surgical complications (Clavien–Dindo grade greater than or equal to III) (OR 0.61 (95% c.i. 0.45 to 0.81); P = 0.0008). Subgroup analysis of surgical-site infections highlighted significantly reduced incidences of superficial surgical-site infections (OR 0.34 (95% c.i. 0.14 to 0.84); P = 0.02) and organ/space surgical-site infections (OR 0.47 (95% c.i. 0.28 to 0.78); P = 0.004) in the piperacillin/tazobactam group. Further, the analysis demonstrated significantly lower incidences of clinically relevant postoperative pancreatic fistulas (grades B and C) (OR 0.67 (95% c.i. 0.53 to 0.83); P = 0.0003) and mortality (OR 0.51 (95% c.i. 0.28 to 0.91); P = 0.02) in the piperacillin/tazobactam group.

Conclusion

Piperacillin/tazobactam as antimicrobial prophylaxis significantly lowers the risk of postoperative surgical-site infections, major surgical complications (complications classified as Clavien–Dindo grade greater than or equal to III), clinically relevant postoperative pancreatic fistulas (grades B and C), and mortality, hence supporting the implementation of piperacillin/tazobactam for surgical prophylaxis in current practice.
Protein fibril aggregation on red blood cells: a potential biomarker to distinguish neurodegenerative diseases from healthy aging
Authors: Schneider Thomas Rudolf , Stöckli Luisa , Felbecker Ansgar , Nirmalraj Peter Niraj
Published: June 2024

Neurodegenerative diseases like Alzheimer’s disease are characterized by the accumulation of misfolded proteins into fibrils in the brain. Atomic force microscopy is a nanoscale imaging technique that can be used to resolve and quantify protein aggregates from oligomers to fibrils. Recently, we characterized protein fibrillar aggregates adsorbed on the surface of red blood cells with atomic force microscopy from patients with neurocognitive disorders, suggesting a novel Alzheimer’s disease biomarker. However, the age association of fibril deposits on red blood cells has not yet been studied in detail in healthy adults. Here, we used atomic force microscopy to visualize and quantify fibril coverage on red blood cells in 50 healthy adults and 37 memory clinic patients. Fibrillar protein deposits sporadically appeared in healthy individuals but were much more prevalent in patients with neurodegenerative disease, especially those with Alzheimer’s disease as confirmed by positive CSF amyloid beta 1–42/1–40 ratios. The prevalence of fibrils on the red blood cell surface did not significantly correlate with age in either healthy individuals or Alzheimer’s disease patients. The overlap in fibril prevalence on red blood cells between Alzheimer’s disease and amyloid-negative patients suggests that fibril deposition on red blood cells could occur in various neurodegenerative diseases. Quantifying red blood cell protein fibril morphology and prevalence on red blood cells could serve as a sensitive biomarker for neurodegeneration, distinguishing between healthy individuals and those with neurodegenerative diseases. Future studies that combine atomic force microscopy with immunofluorescence techniques in larger-scale studies could further identify the chemical nature of these fibrils, paving the way for a comprehensive, non-invasive biomarker platform for neurodegenerative diseases.
Disruption in functional networks mediated tau spreading in Alzheimer’s disease
Authors: Nabizadeh Fardin
Published: June 2024

Alzheimer’s disease may be conceptualized as a ‘disconnection syndrome’, characterized by the breakdown of neural connectivity within the brain as a result of amyloid-beta plaques, tau neurofibrillary tangles and other factors leading to progressive degeneration and shrinkage of neurons, along with synaptic dysfunction. It has been suggested that misfolded tau proteins spread through functional connections (known as ‘prion-like’ properties of tau). However, the local effect of tau spreading on the synaptic function and communication between regions is not well understood. I aimed to investigate how the spreading of tau aggregates through connections can locally influence functional connectivity. In total, the imaging data of 211 participants including 117 amyloid-beta-negative non-demented and 94 amyloid-beta-positive non-demented participants were recruited from the Alzheimer’s Disease Neuroimaging Initiative. Furthermore, normative resting-state functional MRI connectomes were used to model tau spreading through functional connections, and functional MRI of the included participants was used to determine the effect of tau spreading on functional connectivity. I found that lower functional connectivity to tau epicentres is associated with tau spreading through functional connections in both amyloid-beta-negative and amyloid-beta-positive participants. Also, amyloid-beta-PET in tau epicentres mediated the association of tau spreading and functional connectivity to epicentres suggesting a partial mediating effect of amyloid-beta deposition in tau epicentres on the local effect of tau spreading on functional connectivity. My findings provide strong support for the notion that tau spreading through connection is locally associated with disrupted functional connectivity between tau epicentre and non-epicentre regions independent of amyloid-beta pathology. Also, I defined several groups based on the relationship between tau spreading and functional disconnection, which provides quantitative assessment to investigate susceptibility or resilience to functional disconnection related to tau spreading. I showed that amyloid-beta, other copathologies and the apolipoprotein E epsilon 4 allele can be a leading factor towards vulnerability to tau relative functional disconnection.