Points Of Curve Research Articles

Learning curve and initial outcomes of a novel percutaneously endoscopic-assisted total hip arthroplasty through mini bikini direct anterior approach: an observational cohort study

ObjectiveAlthough the direct anterior approach can reduce muscle damage and ensure accurate prosthesis placement, the steep learning curve and increased risk of complications associated with DAA necessitate careful consideration. Therefore, we describe a technique for a novel percutaneously endoscopic-assisted total hip arthroplasty through mini bikini direct anterior approach (mDAA) and report the learning curve and initial outcomes.MethodsThe first 125 THA performed by a single surgeon between September 2020 and February 2022 using the anterior approach were included, comprising the initial 41 cases of bikini DAA (bDAA) and the subsequent 84 cases of mDAA. Outcome measures included perioperative outcomes and postoperative complications. The cumulative sum analysis (CUSUM) was used to determine the learning curve of anterior approach THA for each patient’s ORT. Multivariable analysis was performed to determine risk correlation.ResultsA total of 125 anterior approach THA completed between 2020 and 2022 were identified. Among these, 41 were performed via bDAA and 84 via mDAA. No statistically significant differences were observed between the groups in terms of age, gender distribution, BMI or follow-up time. A significant reduction in ORT was noted, from 140 min for bDAA to 130 min for mDAA. Furthermore, there was a consistent decrease in LOI, LOS, and wound-healing problems. There was no statistically significant difference between groups with respect to Harris Hip Scores and other postoperative complications. The curve inflection points of the learning curve for the bDAA and mDAA group were located in the 22nd and 68th cases, respectively. The reduction of hemoglobin indicated a predicted increase in ORT.ConclusionsIn this study, ORT, LOI, LOS, and wound-healing problems decreased overall in mDAA group. After mastering the bDAA technique, approximately 27 mDAA cases are needed to acquire proficiency in this technique. Hence, mDAA is a valuable alternative for those seeking smaller incisions, resolving wound healing problems, and aiming for enhanced recovery after surgery.

Bond Behavior and Failure Mechanisms of the Interface between Engineered Cementitious Composites and Shaped Steel

Due to their excellent ductility and crack-control ability, engineered cementitious composites (ECCs) combined with shaped steel can produce steel-reinforced engineering cementitious composite (SRECC) structures which exhibit significant advantages in prefabricated buildings. The interface bond behavior is the base for the cooperative working performance of the shaped steel and ECC. This study included push-out tests of one ordinary concrete control specimen and ten ECC specimens. The various parameters were the ECC compressive strength, fiber volume content, cover thickness, and the embedded length of shaped steel. The bond stress–slip curves at the loading and free end were obtained, and the effects of various parameters on the characteristic points of curves were analyzed. The results indicated that the ordinary concrete specimen failed in brittle splitting, with the cracks completely penetrating the surface of the specimen. Due to the fiber-bridging effect in ECCs effectively preventing the development and extension of cracks, the shaped steel at the free end was obviously pushed out, and the surrounding matrix maintained good integrity after testing finished. For ECC specimens, bond or splitting-bond failure occurred, exhibiting outstanding ductility. Compared with the ordinary concrete specimen, the standard ultimate and residual bond strength of ECC specimens improved by 37.9% and 27.4%, respectively. Besides the increase in ECC compressive strength, the fiber volume content and cover thickness had a significant positive influence on the ultimate and residual bond strength, whereas the effect of the embedded length was the opposite. Finally, the calculation equations of characteristic bond strength were proposed, and the calculated values matched well with the experimental values.

Investigation of nano-confinement effects on asphaltenic crude oil phase behavior in tight and shale reservoirs: Modeling using CPA-EOS

As a result of strong molecule–molecule and molecule–wall interactions, phase behavior in confined fluids differs significantly from that in bulk fluids. Asphaltene precipitation is a challenging issue for both conventional and unconventional (nano-scale) porous media. In this study, a new model based on cubic-plus-association equation of state (CPA-EOS) was developed for studying phase behavior of asphaltenic crude oil and asphaltene precipitation in nanoporous media. The developed model considers confinement phenomena including shift in the critical properties of components, high capillary pressure, and adsorption/desorption of fluid components on rock surface. For this purpose, necessary modifications were performed on both the EOS and phase equilibria calculations. The developed model was then used to analyze two-phase (vapor–liquid) and three-phase (vapor–liquid–asphaltene) behavior in confined systems. Results demonstrated that confinement phenomena shrink the two-phase envelope and shift the critical point of the mixture. It is also shown that instability of asphaltene in the solution is higher in nanoporous media and increases with reducing pore size. Therefore, the amount of precipitated asphaltene in nanoporous media is higher than that in conventional systems. As adsorption of components with higher molecular weights is more than that of low-molecular weight compounds, the crude oil sample is enriched with lighter components and hence, due to adsorption, bubble point pressure increases, upper branch of dew point curve shifts downward and its lower branch shifts upward, and asphaltene instability increases. Neglecting confinement phenomena results in overestimation or underestimation of saturation pressures as well as asphaltene upper and lower onset points and the proposed model can be of high importance in predicting the extent of asphaltene precipitation during natural depletion or solvent injection in tight oil reservoirs.

Depletion potential, correlation functions and demixing transition in model colloid-polymer mixtures

We describe a theoretical framework to calculate depletion potential between colloid particles induced by non-adsorbing ideal polymer chains (s-species) and correlation functions in a coarse-grained one-component system of colloids (c-species). A Padé approximant is used to express the depletion potential as a pair potential with many-body contributions subsumed in it. The depletion potential and correlation functions of c-species are calculated using a self-consistent procedure. Results for several values of size ratio q=σsσc (σs and σc are, respectively diameters of the polymer chain and a colloid particle) and packing fractions of s- and c-species are reported. The spinodal curve and critical point of demixing transition are determined for several values of q. Calculated values are compared with values found from other theories and simulations.

Model Parameter Calibration for Vibration Fatigue Analysis by Means of Bayesian Updating and Artificial Neural Network Based Surrogate Models

Abstract In this paper, a methodology for model parameter calibration for vibration fatigue analysis is proposed. It combines Bayesian updating of uncertain model parameters and artificial neural networks (ANNs). The calibrated parameters are used to increase the accuracy of fatigue lifetime calculations for components submitted to vibrational loads. The Bayesian updating uses eigenfrequencies, mode shapes, total mass, and the frequency response functions (FRFs). These quantities are predicted by ANN-based surrogate models to accelerate the Bayesian updating process. A novel strategy for the prediction of the magnitude and phase of FRFs with ANNs is proposed. The frequency is used as an additional input variable, and a schematic selection of significant points of the FRF curves is presented. A high prediction accuracy of the surrogate models could be achieved. The procedure includes the analysis of the relevant frequency range and a sensitivity analysis based on the Morris method to identify appropriate modes and the most-influential parameters. The proposed framework is applied to a current vehicle component subjected to vibrational loads. An experimental modal analysis is used for the calibration and consideration of real parameter uncertainty. First, the accuracy of the surrogate models and Bayesian updating is verified by a nominal reference simulation and then validated with experimental data. The measurable control parameter thickness and component mass are used to examine the calibration accuracy. Finally, a decrease in the dispersion of the vibration fatigue distribution is obtained with the calibrated parameters.

Multiple-trait genomic prediction for swine meat quality traits using gut microbiome features as a correlated trait.

Traits such as meat quality and composition are becoming valuable in modern pork production; however, they are difficult to include in genetic evaluations because of the high phenotyping costs. Combining genomic information with multiple-trait indirect selection with cheaper indicator traits is an alternative for continued cost-effective genetic improvement. Additionally, gut microbiome information is becoming more affordable to measure using targeted rRNA sequencing, and its applications in animal breeding are becoming relevant. In this paper, we investigated the usefulness of microbial information as a correlated trait in selecting meat quality in swine. This study incorporated phenotypic data encompassing marbling, colour, tenderness, loin muscle and backfat depth, along with the characterization of gut (rectal) microbiota through 16S rRNA sequencing at three distinct time points of the animal's growth curve. Genetic progress estimation and cross-validation were employed to evaluate the utility of utilizing host genomic and gut microbiota information for selecting expensive-to-record traits in crossbred individuals. Initial steps involved variance components estimation using multiple-trait models on a training dataset, where the top 25 associated operational taxonomic units (OTU) for each meat quality trait and time point were included. The second step compared the predictive ability of multiple-trait models incorporating different numbers of OTU with single-trait models in a validation set. Results demonstrated the advantage of including genomic information for some traits, while in some instances, gut microbial information proved advantageous, namely, for marbling and pH. The study suggests further investigation into the shared genetic architecture between microbial features and traits, considering microbial data's compositional and high-dimensional nature. This research proposes a straightforward method to enhance swine breeding programs for improving costly-to-record traits like meat quality by incorporating gut microbiome information.

FOR PSEUDORANDOM SEQUENCES BASED ON ELLIPTIC CURVE ISOGENIES GENERATING METHOD

The pseudorandom sequences generation is a cryptographic systems fundamental aspect that affects cryptographic strength. One of these sequences advanced generating methods involves the use of elliptic curves (ECs), in particular by exploiting the isogeny properties of ECs. This approach not only improves the security features of cryptographic algorithms, but also ensures efficiency and reliability in the generation process. The use of isogenic transformations - morphisms between elliptic curves that preserve their group structure - further enriches the technique by introducing complex algebraic operations that are difficult to solve. Recent research has detailed the effectiveness of pseudorandom sequence generators based on elliptic curves. Methods have been developed that exploit the properties of elliptic curves over finite fields to generate sequences with low correlation and high linear complexity. There is also another approach that uses linear shift feedback registers (LFSRs) in combination with elliptic curve points to generate pseudorandom sequences. The new obtained method makes it possible to increase the number of internal states of the Dual_EC_DRBG generator by √n times, where n is the number of cyclic subgroups of simple order of the initial curve. This increases the complexity of disclosing the law of formation of the DRBG by an attacker. The application of the developed method also allows to avoid the existing disadvantages of Dual_EC_DRBG The article investigates the use of EC isogenies in the generation of pseudorandom sequences, considering their potential for improving cryptographic strength. By means of a detailed analysis of the algebraic structure and properties of these transformations, a method for PSPs generating is developed that can potentially provide advantages over existing methods in terms of security and efficiency in the transition period to post-quantum cryptography.

Super-resolution deep learning reconstruction approach for enhanced visualization in lumbar spine MR bone imaging

ObjectivesThis study aims to assess the effectiveness of super-resolution deep-learning-based reconstruction (SR-DLR), which leverages k-space data, on the image quality of lumbar spine magnetic resonance (MR) bone imaging using a 3D multi-echo in-phase sequence. Materials and methodsIn this retrospective study, 29 patients who underwent lumbar spine MRI, including an MR bone imaging sequence between January and April 2023, were analyzed. Images were reconstructed with and without SR-DLR (Matrix sizes: 960 × 960 and 320 × 320, respectively). The signal-to-noise ratio (SNR) of the vertebral body and spinal canal and the contrast and contrast-to-noise ratio (CNR) between the vertebral body and spinal canal were quantitatively evaluated. Furthermore, the slope at half-peak points of the profile curve drawn across the posterior border of the vertebral body was calculated. Two radiologists independently assessed image noise, contrast, artifacts, sharpness, and overall image quality of both image types using a 4-point scale. Interobserver agreement was evaluated using weighted kappa coefficients, and quantitative and qualitative scores were compared via the Wilcoxon signed-rank test. ResultsSNRs of the vertebral body and spinal canal were notably improved in images with SR-DLR (p < 0.001). Contrast and CNR were significantly enhanced with SR-DLR compared to those without SR-DLR (p = 0.023 and p = 0.022, respectively). The slope of the profile curve at half-peak points across the posterior border of the vertebral body and spinal canal was markedly higher with SR-DLR (p < 0.001). Qualitative scores (noise: p < 0.001, contrast: p < 0.001, artifact p = 0.042, sharpness: p < 0.001, overall image quality: p < 0.001) were superior in images with SR-DLR compared to those without. Kappa analysis indicated moderate to good agreement (noise: κ = 0.56, contrast: κ = 0.51, artifact: κ = 0.46, sharpness: κ = 0.76, overall image quality: κ = 0.44). ConclusionSR-DLR, which is based on k-space data, has the potential to enhance the image quality of lumbar spine MR bone imaging utilizing a 3D gradient echo in-phase sequence.Clinical relevance statement: The application of SR-DLR can lead to improvements in lumbar spine MR bone imaging quality.

A New Methodology for Evaluating the Potential Impact of Residual Refractive Astigmatism in Pseudophakic Patients.

To validate a new methodology to evaluate the impact of astigmatism in pseudophakia using an astigmatic defocus curve. Hospital Oftalmológico de Brasilia, Brazil. Non-randomized cohort study. For every point of the defocus curve, from -2.00 to +3.00 with 0.50D intervals, visual acuity was assessed with optically induced astigmatism (0.50D, 1.00D and 1.50D at 90 and 180 degrees) in pseudophakic patients implanted with a refractive-enhanced intraocular lens. Twelve patients were analyzed. A statistically significant difference was found between the 90° (ATR) and 180°(WTR) axis with 1.50D astigmatism, providing better visual acuity in ATR astigmatism (p < 0.05). This new methodology is reproducible, useful and may predict residual astigmatism tolerance in pseudophakic patients, which may help with surgery planning and IOL decision-making.

Handheld Dynamometry Agrees With One-Repetition Maximum Testing With Cuff Weights for Knee Extension, Hip Abduction, and Hip Extension in Older Adults

This study compared handheld dynamometry (HHD) at the weakest point of the strength curve for hip extensors, hip abductors, and knee extensors in older adults and one-repetition maximum (1RM) of that same muscle groups with cuff weights. Fifty participants (62-94 years) were tested. Paired t tests indicated no significant differences between the 2 measures. Reliability testing for absolute agreement between 1RM and HHD yielded intraclass correlations of good to excellent. This demonstrates HHD at or near the weakest point of a muscle group provides an accurate measure of older individual’s 1RM for knee extension, hip extension, and hip abduction.

Effect of temperature on surfactant adsorption at the liquid-liquid interface: Insights from molecular dynamics simulations

Surfactant adsorption at liquid-liquid interfaces plays an important role in fossil energy fields such as enhanced oil recovery, and temperature is the main factor causing significant changes in surfactant adsorption at interfaces, thus determining the related interfacial tension. In this work, the effect of temperature on the interfacial structure of the tri-n-butyl phosphate (TBP) saturated water/octane was investigated through molecular dynamics simulations. We found that the lowest point of the interfacial tension curve occurs at 280 K. To explain this phenomenon, the effects of temperature on surfactant adsorption, interfacial stability, hydrogen bond network, and water extraction were focused. 280 K corresponds to the maximum adsorption concentration of surfactants, promoting the formation of the water-bridged TBP dimer adduct, TBP(H2O)TBP. These aggregates significantly reduce the connectivity between bridging water and the instantaneous interface, which in turn increases surface fluctuations and creates more protrusions, thus promoting subsequent water extraction processes. These results provide important theoretical clues for studying temperature-dependent surface heterogeneity.

Transportation and centering abilities of the race evo, edge file X7, fanta AF-F one, and 2shape Ni-Ti systems in simulated root canals: A comparative study

ABSTRACT Aim: This research investigated the transportation and centering ability of Race Evo (RE), Edge File X7 (EX7), Fanta AF F-one, and 2Shape (2S) file systems in artificial curved canals at various levels. Methods: Forty-eight simulated root canals divided into four groups of 12 specimens were tested. Each NiTi-prepared group: RE, EX7, Fanta AF F-one, and 2S system used for consistently preparing the canals, the blocks were photographed, then using Photoshop, before and after images of the preparation were superimposed. The measurement was done at five levels (level 1 was assessed at 5 mm from the orifice, level 2 at 7 mm from the orifice, level 3 at the curve’s beginning, level 4 at its highest point of curvature, and Level 5 at 1 mm from the apex). The Image Analysis Software (Digimizer) and SPSS 21 were used for statistical analysis. P ≤≤ 0.05 was chosen as the statistical significance level. Results: Regarding the levels at which canal transportation and centering ratio were measured a statistically significant difference (P &lt; 0.05) was observed, with the exception of level 1. The Fanta AF F-one system demonstrated the highest values of canal transportation and centering ratio at Levels 3 and 4. Whereas the 2S system exhibited the highest value at Levels 2 and 5. In contrast, the RE system recorded the lowest value at Levels 4 and 5, while the EX7 system had the lowest value at Levels 2 and 3. Conclusion: All file systems result in some degree of canal transportation and do not provide perfectly centered preparation. However, canal transportation was within acceptable ranges in the apical part of all tested groups. In the central and apical regions of the canal, the RE and EX7 systems outperformed the Fanta AF F-One and 2S systems in terms of preserving canal curvature.

Research on path planning for clear aligner flexible manufacturing

In recent years, clear aligner can enhance individual appearance with dental defects, so it used more and more widely. However, in manufacturing process, there are still some problems, such as low degree of automation and high equipment cost. The problem of coordinate system mismatch between gingival curve point cloud and dental CAD model is faced to. The PCA-ICP registration algorithm is proposed, which includes coarse match algorithm and improve-ICP registration algorithm. The principal component analysis (PCA) based method can roughly find the posture relationship between the two point clouds. Using z-level dynamic hierarchical, the ICP registration can accurately find the posture between these two clouds. The final registration maximum distance error is 0.03 mm, which is smaller than robot machining error. Secondly, the clear aligner machining process is conducted to verify the registration effectiveness. Before machining, the path is generated based on the well registered gingival curve. After full registration, the tool path is calculated by establishing a local coordinate system between the workpiece and the tool to avoid interference. This path is calculated and generated as an executable program for ABB industrial robots. Finally, the robot was used for flexible cutting of clear aligners and was able to extract products, ensuring the effectiveness of the proposed research. This method can effectively solve the limitations of traditional milling path planning under such complex conditions.

Fast and reliable method for analysis of derivatized plasma amino acids by liquid chromatography-single quadrupole-mass spectrometry

The pool of free, genetically encoded AA in plasma plays an essential role not only as substrate for every protein synthesized in the body but also as signaling molecules that regulate a wide range of physiological processes. Here we present a method for the analysis of 19 of the 20 encoded AA (except Cys) in dairy cow plasma. Isolated plasma or standards for the 19 AA were gravimetrically mixed with an internal standard mix consisting of 13C isotopes of each AA. Plasma proteins were precipitated on acetonitrile and supernatants transferred to glass vials. For pre-column derivatization, plasma supernatants were buffered with sodium borate (pH 9.5 −10), and AA were derivatized with 9-fluorenylmethoxycarbonyl (Fmoc) chloride. Analytes were isolated by solid-phase extraction using a strong-anionic ion exchange column and dry eluates were reconstituted in mobile phase consisting of 70% water solution of ammonium formate and 30% acetonitrile. Amino acid derivatives were separated by reverse phase liquid chromatography over 17.5 min with a C18 column in which acetonitrile increased to 80% over the first 11 min of the method, before returning to initial levels. Electrospray ionization on negative mode was used for most AA, except Arg and Pro, for which positive mode yielded superior results. Single or double (only Lys) derivatives were measured by single quadrupole mass spectrometry. We hypothesized that pre-column Fmoc derivatization would yield optimal resolution for quantitative analysis of the 19 targeted AA and their respective 13C internal standards, with limits of quantitation beyond physiological ranges. All the 19 AA were detected with minimal background noise. An 11-point standard curve was developed for each AA. Limits of quantitation were beyond concentrations observed in plasma samples of lactating dairy cows, except for Gly that upper curve points had to be removed to maintain linearity, limiting quantitation to the upper range of physiological concentration. After removing the 4 highest concentrations from the Gly standard curve, coefficients of determination were greater than 0.999 for all the AA. Recovery of spiked AA from plasma samples ranged from 89.9% for Phe to 100.3% for Trp. Instrument repeatability averaged 0.91 and ranged from 0.33 for Val to 2.29 for Arg. Meanwhile, sample preparation method repeatability averaged 2.02 and ranged from 1.14 for Tyr to 3.34 for Arg. While robust methods have been developed, they depend on either availability of sophisticated instruments, mostly limited to core facilities (i.e., tandem MS methods), long and expensive chromatography without specific internal standards for each AA (i.e., HPLC-UV and HPLC-FLD), or unstable derivatization (GC-MS). Here we describe a method with high throughput, stable derivatization, high precision and recovery, and potentially more affordable than most existing methods. This method could help dairy nutritionists to consider plasma AA information for diet formulation strategies, potentially reducing feeding costs and N emissions.

Shape reconstruction of trapezoidal surfaces from unorganized point clouds

A smooth T-surface can be thought of as a generalization of a surface of revolution in such a way that the axis of rotation is not fixed at one point but rather traces a smooth path on the base plane. Furthermore, the action, by which the aforementioned surface is obtained does not need to be merely rotation but any “suitable” planar equiform transformation applied to the points of a certain smooth profile curve. In analogy to the smooth setting, if the axis footpoints sweep a polyline on the base plane and if the profile curve is discretely chosen then a T-hedra (discrete T-surface) with trapezoidal faces is obtained.The goal of this article is to reconstruct a T-hedron from an already given unorganized point cloud of a T-surface. In doing so, a kinematic approach is taken into account, where the algorithm at first tries to find the aforementioned axis direction associated with the point cloud. Then the algorithm finds a polygonal path through which the axis footpoint moves. Finally, by properly cutting the point cloud with the planes passing through the axis and its footpoints, it reconstructs the surface. The presented method is demonstrated using examples.From an applied point of view, the straightforwardness of the generation of these surfaces predestines them for building and design processes. In fact, one can find many built objects belonging to the sub-classes of T-surfaces such as surfaces of revolution and moulding surfaces. Furthermore, the planarity of the faces of the discrete version paves the way for steel/glass construction in industry. Finally, these surfaces are also suitable for transformable designs as they allow an isometric deformation within their class.

Lokalizacja wlotów kratek ściekowych w celu zapewnienia skutecznego odwodnienia ulic w procesie projektowania ulic i planów nawierzchni w Bułgarii

This study analyses the existing requirements and standards for determining the locations of grate inlets on streets in Bulgaria. Effective drainage in street design is essential for managing stormwater runoff and preventing urban areas from flooding during heavy rains. To choose optimal locations of grate inlets plays a crucial role in this process. Solving this task is related with designing street slopes in grading plans and designing sewer systems. This article presents an approach, based on successful practices used in the USA and Australia, by proposing a hydraulic based procedure for locating grate inlets in the design process. The technique is adopted to all Bulgarian requirements and standards. As a main criterion it is suggested to use the maximum allowable water spread on the pavement of the traffic lanes. The proposed method considers various factors, such as longitudinal and cross slope, size of grate inlet, design frequency period, intercepted and bypass flow. It starts with determination of the grate inlet locations on continuous grade, then incorporates the specific sag points in vertical curves and intersections. It can be used in the process of designing streets and their grading plans to optimize the drainage efficiency of streets in Bulgaria. It is hydraulic reasoned, very flexible, and easy to apply for different street sections with different features. Implementing this approach can solve the problem of unclarity in locating grate inlets in Bulgaria. Also, the presented procedure could be used as a base to fill gaps in the existing Bulgarian regulations and manuals, related to the drainage of streets in urban areas.

Wavelet analysis on a generalized helix space curves and its examples

In this paper, wavelet transform on a generalized helix space curves are investigated, including of local continuous wavelet transform at some point and discrete wavelet transform on a class of helix curves. Firstly, a class of helix space curves are introduced and the parameter equations are given. Then the dilation operator and translation on the function ψ(ξ0)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\psi^{{(\\xi_{{0}} )}}$$\\end{document} is properly defined by the local projection at some point from a space curve on the unit sphere onto its tangent line. The local continuous wavelet transform and its reconstruction formula are deduced at some point of a space curve on the unit sphere. On the other hand, According to the discretization of length-preserving projection, discrete wavelet transform is lifted onto a helix space curve, such as a circular helix curve. Based on length-preserving projection, the some properties are discussed, such as two-scale sequences of scaling function and wavelet, orthogonality, decomposition formula and so on. Finally, two examples are given for our discussion. One example is illustrating the application of local continuous wavelet transform at some point of a space curve. The result shows the signal at some point of a space curve can be reconstructed by local continuous wavelet method. The norm of the error is 0.3783 between original signal and reconstructed signal in this example. The other numerical example is given for decomposing and reconstructing with the signal on a circular helix curve. The result shows the signal on a helix space curve can be decomposed and reconstructed by the length-preserving projection. The norm of the error is 8.0741 × 10−11 between original signal and reconstructed signal. The figures are shown for the simulation results.

Nonlinear energy absorption during optical breakdown in bulk dielectrics

Portion of energy employed by a single, tightly focused laser pulse in various transparent dielectrics was demonstrated versus the incident energy fluence or alternatively, intensity. The measurements were conducted for both the femtosecond and nanosecond laser pulses. Moreover, the energy scattered during the long-lived breakdown process was estimated within the integrating sphere. It appeared that the recorded strongly non-linear dependence of absorptance on the energy fluence (intensity) can be well approximated by the sigmoidal Hill function. The stationary points of the absorptance curve were used to determine threshold-like values characterizing breakdown development. In this way, we defined threshold for the non-linear absorption which can be considered as an empirical laser-induced breakdown threshold (LIBT). Additionally, the fitting parameters of the experimental data substantiated the absorption character for short and long laser pulses.

A Generalized MSST Algorithm for Counting Points of Elliptic Curves over $$\mathbb{F}_{p^{n}}$$

A Generalized MSST Algorithm for Counting Points of Elliptic Curves over $$\mathbb{F}_{p^{n}}$$

Reversible kink instability drives ultrafast jumping in nematodes and soft robots.

Entomopathogenic nematodes (EPNs) exhibit a bending-elastic instability, or kink, before becoming airborne, a feature hypothesized but not proven to enhance jumping performance. Here, we provide the evidence that this kink is crucial for improving launch performance. We demonstrate that EPNs actively modulate their aspect ratio, forming a liquid-latched closed loop over a slow timescale O (1 s), then rapidly open it O (10 µs), achieving heights of 20 body lengths (BL) and generating ∼ 10 4 W/Kg of power. Using jumping nematodes, a bio-inspired Soft Jumping Model (SoftJM), and computational simulations, we explore the mechanisms and implications of this kink. EPNs control their takeoff direction by adjusting their head position and center of mass, a mechanism verified through phase maps of jump directions in simulations and SoftJM experiments. Our findings reveal that the reversible kink instability at the point of highest curvature on the ventral side enhances energy storage using the nematode's limited muscular force. We investigated the impact of aspect ratio on kink instability and jumping performance using SoftJM, and quantified EPN cuticle stiffness with AFM, comparing it with C. elegans . This led to a stiffness-modified SoftJM design with a carbon fiber backbone, achieving jumps of ∼25 BL. Our study reveals how harnessing kink instabilities, a typical failure mode, enables bidirectional jumps in soft robots on complex substrates like sand, offering a novel approach for designing limbless robots for controlled jumping, locomotion, and even planetary exploration.