Function Of Distance Research Articles

Automatic Estimation of Daily Volcanic Sulfur Dioxide Gas Flux From TROPOMI Satellite Observations: Application to Etna and Piton de la Fournaise

AbstractUnderstanding the dynamics of sulfur dioxide (SO2) degassing is of primary importance for tracking temporal variations in volcanic activity. Here we introduce the novel “disk method,” which aims at estimating the daily volcanic SO2 mass flux from satellite images (such as those provided by Sentinel‐5P/TROPOspheric Monitoring Instrument [TROPOMI]). The method calculates a “proto‐flux” using a regression, as a function of distance, of SO2 mass integrated in a series of nested circular domains centered on a volcano. After regression, a single multiplication by plume speed suffices to deduce the SO2 mass flux, without requiring a subsequent regression. This way, a range of plume speed and plume altitude scenarios can be easily explored. Noise level in the image is simultaneously evaluated by the regression, which allows for estimating posterior uncertainties on SO2 flux and improving the level of detection for weak sources in noisy environments. A statistical test is also introduced to automatically detect occurrences of volcanic degassing, lowering the risk of false positives. Application to multi‐year time‐series at Etna (2021) and Piton de la Fournaise (2021–2023) demonstrates (a) a reliable quantification of SO2 emissions across a broad range of degassing styles (from passive degassing to effusive or paroxysmal events), and (b) a reasonable day‐to‐day correlation between SO2 flux and seismic energy. The method is distributed as an open‐source software, and is implemented in an interactive web application within the “Volcano Space Observatory Portal,” facilitating near‐real‐time exploitation of the TROPOMI archive for both volcano monitoring and assessment of volcanic atmospheric hazards.

Beam-induced backgrounds measured in the ATLAS detector during local gas injection into the LHC beam vacuum

Inelastic beam-gas collisions at the Large Hadron Collider (LHC), within a few hundred metres of the ATLAS experiment, are known to give the dominant contribution to beam backgrounds. These are monitored by ATLAS with a dedicated Beam Conditions Monitor (BCM) and with the rate of fake jets in the calorimeters. These two methods are complementary since the BCM probes backgrounds just around the beam pipe while fake jets are observed at radii of up to several metres. In order to quantify the correlation between the residual gas density in the LHC beam vacuum and the experimental backgrounds recorded by ATLAS, several dedicated tests were performed during LHC Run 2. Local pressure bumps, with a gas density several orders of magnitude higher than during normal operation, were introduced at different locations. The changes of beam-related backgrounds, seen in ATLAS, are correlated with the local pressure variation. In addition the rates of beam-gas events are estimated from the pressure measurements and pressure bump profiles obtained from calculations. Using these rates, the efficiency of the ATLAS beam background monitors to detect beam-gas events is derived as a function of distance from the interaction point. These efficiencies and characteristic distributions of fake jets from the beam backgrounds are found to be in good agreement with results of beam-gas simulations performed with the Fluka Monte Carlo programme.

Comparison of coarse-grained models for cis-1,4-polyisoprene-graphite system

ABSTRACT Structural and dynamical properties of cis-1,4-polyisoprene-graphite system were compared by four coarse-grained models. Coarse-graining of graphene layers replaced four carbon atoms by a single bead while four mapping schemes were used for the polymer. Pressure-correction was applied to the nonbonded part of the coarse-grained potential among coarse-grained polyisoprene beads. Among structural properties density profiles, bond orientation and conformation tensor as function of distance from the graphite surface were studied. Bulk values were achieved at around 2 nm from the graphite surface. Higher degree of coarse-graining showed comparatively larger fluctuations in data. Among dynamical properties mean square displacement and autocorrelation of end-to-end unit vectors for varied distances from the graphite surface were studied. Dynamics study indicated that pressure-correction method used to optimise pressure of the system resulted in slower dynamics for the higher degree of coarse-graining.

Offline writer identification approach using moment features and high-order correlation functions

For text-independent writer identification(WI) tasks, this paper proposes a novel method based on semantic codebooks and two effective feature descriptors. This method requires constructing semantic codebooks consisting of various subimages and their labels. Moment features and high-order correlation functions are used to describe handwriting style, and the standard Euclidean distance function is used for distance measurement. Then, two-way analysis of variance(TW-ANOVA) is used to filter out character factors that affect identification accuracy. Finally, a combined measure obtained from multiple classifiers based on a fuzzy integral rule is used to determine the candidate writers. To verify the effectiveness of the system, experiments are performed using the Firemaker, IAM, CRUG-CN and Uyghur2016 databases. The evaluation results demonstrate better performance than most existing methods.

Integrated form-position measurement of large-aperture transparent elements based on stereoscopic phase measuring deflectometry

In the field of ultra-precision manufacturing and measurement, sub-aperture stitching is a widely employed technique for the measurement of complex optical components. Those influencing factors like system errors and numerical bias introduce notable stitching errors in the overlapped areas between sub-apertures, consequently degrading measurement accuracy. In addition, the surfaces forms, refractive indices, and positions are difficult to be specified simultaneously. In this paper, an integrated measurement method based on the stereo deflectometry is proposed, which can measure the surface form, refractive index, and relative position of large-aperture transparent components together. This method utilizes a Gaussian process regression model to decouple and predict the refractive index and relative positions of the upper and lower surfaces. Then, a robust sub-aperture stitching technique with an adaptive distance function is employed to correct the positioning errors of sub-apertures. The feasibility and effectiveness of this method are demonstrated. The final stitched surface results exhibit a measurement error of 320 nm and a thickness deviation of 28 μm.

Meta-learning integrated with Signed Distance Functions to Enhance Scene Text Segmentation

Meta-learning integrated with Signed Distance Functions to Enhance Scene Text Segmentation

The radial variation of the LMC-induced reflex motion of the Milky Way disc observed in the stellar halo

ABSTRACT We measure the kinematic signature arising from the Milky Way (MW) disc moving with respect to the outer stellar halo, which is observed as a dipole signal in the kinematics of stellar halo tracers. We quantify how the reflex motion varies as a function of Galactocentric distance, finding that (i) the amplitude of the dipole signal increases as a function of radius, and (ii) the direction moves across the sky. We compare the reflex motion signal against a compilation of published models that follow the MW–LMC interaction. These models show a similar trend of increasing amplitude of the reflex motion as a function of distance, but they do not reproduce the direction of the disc motion with respect to the stellar halo well. We also report mean motions for the stellar halo as a function of distance, finding radial compression in the outer halo and non-zero prograde rotation at all radii. The observed compression signal is also present in MW–LMC models, but the rotation is not, which suggests that the latter is not induced by the LMC. We extensively validate our technique to measure reflex motion against idealized tests. We discuss prospects for directly constraining the mass and orbital history of the LMC through the impact on the motion of the MW stellar disc, and how the modelling of the reflex motion can be improved as more and better data become available.

Inefficiency of laying hens farms in Benin: an input directional distance function approach

BackgroundIn Benin, the productivity of poultry production systems is a major concern. This paper aims first to estimate the cost, technical and allocative inefficiencies of modern and traditional poultry production systems, and then to determine the factors that influence these types of inefficiencies.ResultsThe study reveals significant cost inefficiencies, with just 9% and 18% of traditional and modern systems, respectively, being cost-efficient, highlighting the necessity of distinguishing production systems due to different operational requirements, particularly for modern systems. Addressing these inefficiencies requires crucial measures such as providing training, accessible credit, and mortality rate reduction to boost local production, with tailored support for small-scale farmers.ConclusionsThe poultry sector’s intense competition and the decline in local production, particularly among small-scale farmers, are primarily linked to high domestic production costs and local farmers' poor performance. Our study unveils substantial cost inefficiencies in both traditional and modern poultry farming systems, emphasizing the imperative to differentiate interventions based on their distinct operational requirements.

On functional successive minima

AbstractIn the classical Geometry of Numbers, the calculation of successive minima may be quite difficult, even in using the norm coming from a distance function associated to a set. In the literature, there seem to be hardly any analogues when is replaced by the algebraic closure of a function field in one variable and one uses a norm arising from the absolute height. Here, we calculate a one‐parameter family of examples that naturally arose in our recent paper on bounded heights. We also comment on whether the minima are attained.

The variation in the response of solar full-disc magnetographs

The utility of full solar disc magnetograms as a long-term record of the photospheric magnetic field requires an understanding of how stable these observations are with time and the systematic differences between the various instruments. We compared magnetograms from the KPVT/SPM, SoHO/MDI, SOLIS/VSM, and SDO/HMI with the aim of probing the effect on measured solar magnetism of the variation in instrument response with time, magnetogram signal level, and position on the solar disc. Taking near-simultaneous observations from the various instruments, we examined the surface coverage by magnetic activity and the effect of cross-calibrating the various instruments under different assumptions. By comparing the surface coverage by magnetic activity in the observations from the various instruments, we traced the effect of the time variation in instrument response on the longitudinal magnetogram signal and disc-integrated unsigned magnetic flux. This yielded evidence of acute changes in the response of MDI and VSM with certain events such as the SoHO vacation in 1998 and the upgrade of the VSM CCD camera in 2009. Excluding these changes, the effect of instrument instability on the magnetogram signal and disc-integrated magnetic flux appears to be rather benign, with an associated uncertainty of less than 2$<!PCT!>$. We determined the magnetogram signal ratio between each instrument pairing as a function of magnetogram signal level and distance from disc centre and with it cross-calibrated the various instruments. We compared the result with that from repeating the cross-calibration with the overall magnetogram signal ratio. This allowed us to estimate the uncertainty in the magnetogram signal associated with the variation in instrument response with magnetogram signal level and distance from disc centre to be about 8$<!PCT!>$ to 14$<!PCT!>$. The corresponding uncertainty in the disc-integrated magnetic flux is about 7$<!PCT!>$ to 23 $<!PCT!>$. To the best of our knowledge, this is the first study of its kind to quantify the uncertainty in measured magnetism from the variation in instrument response with time, magnetogram signal level, and disc position. The results here will be useful to the interpretation of SPM, MDI, VSM, and HMI magnetograms. As examples, we applied our findings to selected results from earlier studies based on such data.

Revealing the hidden structure of disordered materials by parameterizing their local structural manifold

Durable interest in developing a framework for the detailed structure of glassy materials has produced numerous structural descriptors that trade off between general applicability and interpretability. However, none approach the combination of simplicity and wide-ranging predictive power of the lattice-grain-defect framework for crystalline materials. Working from the hypothesis that the local atomic environments of a glassy material are constrained by enthalpy minimization to a low-dimensional manifold in atomic coordinate space, we develop a generalized distance function, the Gaussian Integral Inner Product (GIIP) distance, in connection with agglomerative clustering and diffusion maps, to parameterize that manifold. Applying this approach to a two-dimensional model crystal and a three-dimensional binary model metallic glass results in parameters interpretable as coordination number, composition, volumetric strain, and local symmetry. In particular, we show that a more slowly quenched glass has a higher degree of local tetrahedral symmetry at the expense of cyclic symmetry. While these descriptors require post-hoc interpretation, they minimize bias rooted in crystalline materials science and illuminate a range of structural trends that might otherwise be missed.

Enhancing endoscopic scene reconstruction with color-aware inverse rendering through neural SDF and radiance fields.

Virtual surgical training is crucial for enhancing minimally invasive surgical skills. Traditional geometric reconstruction methods based on medical CT/MRI images often fall short in providing color information, which is typically generated through pseudo-coloring or artistic rendering. To simultaneously reconstruct both the geometric shape and appearance information of organs, we propose a novel organ model reconstruction network called Endoscope-NeSRF. This network jointly leverages neural radiance fields and Signed Distance Function (SDF) to reconstruct a textured geometric model of the organ of interest from multi-view photometric images acquired by an endoscope. The prior knowledge of the inverse correlation between the distance from the light source to the object and the radiance improves the real physical properties of the organ. The dilated mask further refines the appearance and geometry at the organ's edges. We also proposed a highlight adaptive optimization strategy to remove highlights caused by the light source during the acquisition process, thereby preventing the reconstruction results in areas previously affected by highlights from turning white. Finally, the real-time realistic rendering of the organ model is achieved by combining the inverse rendering and Bidirectional Reflectance Distribution Function (BRDF) rendering methods. Experimental results show that our method closely matches the Instant-NGP method in appearance reconstruction, outperforming other state-of-the-art methods, and stands as the superior method in terms of geometric reconstruction. Our method obtained a detailed geometric model and realistic appearance, providing a realistic visual sense for virtual surgical simulation, which is important for medical training.

Reduced travel emissions through a carbon calculator with accessible environmental data: a case study in Madison, Wisconsin

The echoing environmental toll of the transportation system calls for a drastic need to move beyond carbon-intensive modes of transportation into more sustainable ones. With the rise of emerging modes of transportation, this transition is more promising than ever. In this work, we take a travel-centric approach to promoting and accelerating the transition away from carbon-intensive modes of transportation by informing travelers about their emissions. A carbon calculator—as a function of trip distance and Well-to-Wheel (WTW) Life Cycle Assessment (LCA)—was developed and embedded on a website platform. Users would input their trip distance, and the calculator outputs the carbon footprint (CO2e) of the trip if it was to be done through seven different modes: car (gasoline), car (hybrid), car (electric), bus, electric bike, bike, and walking. In addition, the calculator outputs the equivalent of CO2e as cheeseburgers for a more intuitive display. The overall goal of this work is to understand how travelers respond to being exposed to carbon footprint information. This serves as a step forward in realizing a sustainable transportation system. We make available the calculator online through this link. Study results indicated that trip distance, environmental awareness, age, income, and mode of transportation used were the most influential features in predicting modal shifts. Importantly, the majority of modal shifts resulted in reduced CO2e emissions.

Robust Spherical Laplacian Embedding.

Laplacian embedding (LE) aims to project high-dimensional input data samples, which often contain nonlinear structures, into a low-dimensional space. However, existing distance functions used in the embedding space fail to provide discriminative representations for real-world datasets, especially those related to text analysis or image processing. Cosine similarity measurements are advantageous in dealing with sparse data but are fragile to the impact of outliers and noise from samples or data features. In this work, we propose robust spherical LE (RS-LE), a powerful method that builds the LE on a novel metric that unifies the Euclidean distance and cosine similarity in a spherical space using a robust lp,p -norm. We introduce an efficient iterative algorithm, the proximal alternating linearized minimization (ALM) method, to solve the difficult optimization problem that arises from the new metric, which is neither convex nor smooth. This algorithm allows the solution to achieve both global and objective convergence. Our findings are presented in rigorous theoretical analysis and validated in experiments.

Uncertainty relation for symmetric Petz-Rényi relative entropy.

Holevo introduced a fidelity between quantum states that is symmetric and as effective as the trace distance in evaluating their similarity. This fidelity is bounded by a function of the trace distance, a relationship to which we will refer as Holevo's inequality. More broadly, Holevo's fidelity is part of a one-parameter family of symmetric Petz-Rényi relative entropies, which in turn satisfy a Pinsker's-like inequality with respect to the trace distance. Although Holevo's inequality is tight, Pinsker's inequality is loose for this family. We show that the symmetric Petz-Rényi relative entropies satisfy a tight inequality with respect to the trace distance, improving Pinsker's and reproducing Holevo's as a specific case. Additionally, we show how this result emerges from a symmetric Petz-Rényi uncertainty relation, a result that encompasses several relations in quantum and stochastic thermodynamics.

Metadynamics approach elucidating the free energy landscape and binding modes of vomicine with virulence factor towards anti-mpox drug discovery

This study targeted MPXV (mpox virus) virulence factor (MPXV_VF) for anti-mpox drug discovery using Strychnos nux-vomicaphytochemicals. Molecular docking showed stronger binding energy of phytochemicals (−7.1–−6.1 kcal/mol) compared to brincidofovir (−5.2–−4.9 kcal/mol). Molecular dynamics simulations authenticated the conformational stability of MPXV_VF-VCN complex. The most potent to inhibit MPXV_VF was VCN that exhibited favourable ADMET profiles comparable to brincidofovir. The metadynamics as a function of distance of Arg85Cα with VCN-C18, and phi Arg85 showed two deepest free energy basins (−129.144 and −109.250 kJ/mol) relative to unbound state. Thus, VCN could be used as main-stream drug candidate for mpox treatment.

Scenario Analysis of CO2 Reduction Potentials from a Carbon Neutral Perspective

As a major emitter of CO2, China needs to take responsibility for slowing down global warming. In this paper, the potential carbon emission intensity of provinces is firstly calculated using the non-radial directional distance function under the group- and meta-frontier techniques, and then six scenarios based on two factors (economic development and carbon intensity) are set up to estimate the emission reduction potential of China and each province. Considering the goal of carbon neutrality, the calculation of CO2 emission reduction potential quantifies the amount of emissions that can be reduced and the amount of emissions that should be balanced. Additionally, the degree of difficulty in achieving abatement potential is also calculated. The findings are as follows: First, assuming that the economic growth rate is reduced to 4.4% (achieving the second “100-year goal”) and each province adopts the most advanced low-carbon technologies, China could reduce carbon emissions by 5970.56 Mt compared to 2019 levels. To achieve net-zero emissions, the remaining 3824.2 Mt of carbon emissions should be removed by carbon reduction technologies. Second, the effect of slowing down economic growth and decreasing carbon intensity varies greatly among provinces. Hebei and Shandong should be prioritized as they have the greatest potential for emission reductions under both scenarios. Third, it is more difficult for Beijing, Shanghai, Hubei, Hunan, Inner Mongolia Autonomous Region, Chongqing, and Sichuan to achieve the abatement potential and they require more effort to reduce the same amount of carbon emissions compared to other provinces. The study provides a reference for achieving carbon neutrality and helps provinces to develop differentiated emission reduction strategies.

Reply to "Various issues around the $L_1$-norm distance"

A distance function between two random variables or vectors was proposed in 2003 in a Ph.D. dissertation. Initially called a probability metric, it is now known as "Łukaszyk-Karmowski metric" or LK-metric and has been successfully applied in various fields of science and technology. It does not satisfy the identity of indiscernible (Leibniz's law) axiom of the metric, the ontological axiom also invalidated by the ugly duckling theorem. This note addresses two false claims made in a preprint that LK-metric is the same as the mean absolute difference and that it is ill-defined. The fallacy of the first claim is straightforward: the mean absolute difference is defined solely for independent and identically distributed random variables, contrary to LK-metric. Thus, if one considers E|X-X|, then the random variable X must be independent of itself, which implies its degenerate probability distribution and E|X-X|=0. If X has a degenerate probability distribution, then Y, which is identically distributed as X, also has a degenerate probability distribution and E|X-X|=0=E|X-Y|, invalidating the second claim.

An endoscopic chisel: intraoperative imaging carves 3D anatomical models.

Preoperative imaging plays a pivotal role in sinus surgery where CTs offer patient-specific insights of complex anatomy, enabling real-time intraoperative navigation to complement endoscopy imaging. However, surgery elicits anatomical changes not represented in the preoperative model, generating an inaccurate basis for navigation during surgery progression. We propose a first vision-based approach to update the preoperative 3D anatomical model leveraging intraoperative endoscopic video for navigated sinus surgery where relative camera poses are known. We rely on comparisons of intraoperative monocular depth estimates and preoperative depth renders to identify modified regions. The new depths are integrated in these regions through volumetric fusion in a truncated signed distance function representation to generate an intraoperative 3D model that reflects tissue manipulation RESULTS: We quantitatively evaluate our approach by sequentially updating models for a five-step surgical progression in an ex vivo specimen. We compute the error between correspondences from the updated model and ground-truth intraoperative CT in the region of anatomical modification. The resulting models show a decrease in error during surgical progression as opposed to increasing when no update is employed. Our findings suggest that preoperative 3D anatomical models can be updated using intraoperative endoscopy video in navigated sinus surgery. Future work will investigate improvements to monocular depth estimation as well as removing the need for external navigation systems. The resulting ability to continuously update the patient model may provide surgeons with a more precise understanding of the current anatomical state and paves the way toward a digital twin paradigm for sinus surgery.

Generation of Propagation-Dependent OAM Self-Torque with Chirped Spiral Gratings

The application of non-uniform spiral gratings to control the structure, topological parameters and propagation of orbital angular momentum (OAM) beams was studied experimentally with coherent near-infrared light. Adapted digital spiral grating structures were programmed into the phase map of a high-resolution liquid-crystal-on-silicon spatial light modulator (LCoS-SLM). It is shown that characteristic spatio-spectral anomalies related to Gouy phase shift can be used as pointers to quantify rotational beam properties. Depending on the sign and gradient of spatially variable periods of chirped spiral gratings (CSGs), variations in rotation angle and angular velocity were measured as a function of the propagation distance. Propagation-dependent self-torque is introduced in analogy to known local self-torque phenomena of OAM beams as obtained by the superposition of temporally chirped or phase-modulated wavepackets. Applications in metrology, nonlinear optics or particle trapping are conceivable.