Plateau Lengths Research Articles

Total variation denoising-based method of identifying the states of single molecules in break junction data

Break junction (BJ) measurements provide insights into the electrical properties of diverse molecules, enabling the direct assessment of single-molecule conductances. The BJ method displays potential for use in determining the dynamics of individual molecules, single-molecule chemical reactions, and biomolecules, such as deoxyribonucleic acid and ribonucleic acid. However, conductance data obtained via single-molecule measurements may be susceptible to fluctuations due to minute structural changes within the junctions. Consequently, clearly identifying the conduction states of these molecules is challenging. This study aims to develop a method of precisely identifying conduction state traces. We propose a novel single-molecule analysis approach that employs total variation denoising (TVD) in signal processing, focusing on the integration of information technology with measured single-molecule data. We successfully applied this method to simulated conductance traces, effectively denoise the data, and elucidate multiple conduction states. The proposed method facilitates the identification of well-defined plateau lengths and supervised machine learning with enhanced accuracies. The introduced TVD-based analytical method is effective in elucidating the states within the measured single-molecule data. This approach exhibits the potential to offer novel perspectives regarding the formation of molecular junctions, conformational changes, and cleavage.

Optical Trapping of a Single Molecule of Length Sub-1 nm in Solution

Optical Trapping of a Single Molecule of Length Sub-1 nm in Solution

Influence of Bone Morphology on In Vivo Tibio-Femoral Kinematics in Healthy Knees during Gait Activities.

An improved understanding of the relationships between bone morphology and in vivo tibio-femoral kinematics potentially enhances functional outcomes in patients with knee disorders. The aim of this study was to quantify the influence of femoral and tibial bony morphology on tibio-femoral kinematics throughout complete gait cycles in healthy subjects. Twenty-six volunteers underwent clinical examination, radiographic assessment, and dynamic video-fluoroscopy during level walking, downhill walking, and stair descent. Femoral computer-tomography (CT) measurements included medial condylar (MC) and lateral condylar (LC) width, MC and LC flexion circle, and lateral femoral condyle index (LFCI). Tibial CT measurements included both medial (MTP) and lateral tibial plateau (LTP) slopes, depths, lengths, and widths. The influence of bony morphology on tibial internal/external rotation and anteroposterior (AP)-translation of the lateral and medial compartments were analyzed in a multiple regression model. An increase in tibial internal/external rotation could be demonstrated with decreasing MC width β: −0.30 (95% CI: −0.58 to −0.03) (p = 0.03) during the loaded stance phase of level walking. An increased lateral AP-translation occurred with both a smaller LC flexion circle β: −0.16 (95% CI: −0.28 to −0.05) (p = 0.007) and a deeper MTP β: 0.90 (95% CI: 0.23 to 1.56) (p = 0.01) during the loaded stance phase of level walking. The identified relationship between in vivo tibio-femoral kinematics and bone morphology supports a customized approach and individual assessment of these factors in patients with knee disorders and potentially enhances functional outcomes in anterior cruciate ligament injuries and total knee arthroplasty.

A low-energy explosion yields the underluminous Type IIP SN 2020cxd

Context. We present our observations and analysis of SN 2020cxd, a low-luminosity (LL), long-lived Type IIP supernova (SN). This object is a clear outlier in the magnitude-limited SN sample recently presented by the Zwicky Transient Facility’s (ZTF) Bright Transient Survey. Aims. We demonstrate that SN 2020cxd is an additional member of the group of LL SNe and we discuss the rarity of LL SNe in the context of the ZTF survey. We consider how further studies of these faintest members of the core-collapse (CC) SN family might help improve the general understanding of the underlying initial mass function for stars that explode. Methods. We used optical light curves (LCs) from the ZTF in the gri bands and several epochs of ultraviolet data from the Neil Gehrels Swift observatory as well as a sequence of optical spectra. We constructed the colour curves and a bolometric LC. Then we compared the evolution of the ejecta velocity and black-body temperature for LL SNe as well as for typical Type II SNe. Furthermore, we adopted a Monte Carlo code that fits semi-analytic models to the LC of SN 2020cxd, which allows for the estimation of the physical parameters. Using our late-time nebular spectra, we also make a comparison against SN II spectral synthesis models from the literature to constrain the progenitor properties of SN 2020cxd. Results. The LCs of SN 2020cxd show a great similarity with those of LL SNe IIP in terms of luminosity, timescale, and colours. Also, the spectral evolution of SN 2020cxd is that of a Type IIP SN. The spectra show prominent and narrow P-Cygni lines, indicating low expansion velocities. This is one of the faintest LL SNe observed, with an absolute plateau magnitude of Mr = −14.5 mag and also one with the longest plateau lengths, with a duration of 118 days. Finally, the velocities measured from the nebular emission lines are among the lowest ever seen in a SN, with an intrinsic full width at half maximum value of 478 km s−1. The underluminous late-time exponential LC tail indicates that the mass of 56Ni ejected during the explosion is much smaller than the average of normal SNe IIP, we estimate M56Ni = 0.003 M⊙. The Monte Carlo fitting of the bolometric LC suggests that the progenitor of SN 2020cxd had a radius of R0 = 1.3 × 1013 cm, kinetic energy of Ekin = 4.3 × 1050 erg, and ejecta mass of Mej = 9.5 M⊙. From the bolometric LC, we estimated the total radiated energy Erad = 1.52 × 1048 erg. Using our late-time nebular spectra, we compared these results against SN II spectral synthesis models to constrain the progenitor zero-age main sequence mass and found that it is likely to be ≲15 M⊙. Conclusions. SN 2020cxd is a LL Type IIP SN. The inferred progenitor parameters and the features observed in the nebular spectrum favour a low-energy, Ni-poor, iron CC SN from a low-mass (∼12 M⊙) red supergiant.

Relationship Between Simulated Gadolinium-Based Contrast Agent Injection Profile and Achievable Resolution Metrics in Contrast-Enhanced Magnetic Resonance Angiography.

Contrast bolus variation during contrast-enhanced magnetic resonance angiography (CE-MRA) acquisition may lead to vessel blurring. To combine knowledge of how contrast signal intensity (SI) evolves for different injection strategies with anatomically familiar parametric computer models to measure and visually assess the effects of a wide range of variables on modeled CE-MRA, and in doing so develop contrast rate injection guidelines. Computer modeling. Digital three-dimensional phantom consisting of orthogonal "aorta," 7 mm diameter "renal arteries" (with 57% and 86% diameter stenoses), and 7 mm diameter "superior mesenteric artery" (with 57% diameter stenosis). One millimeter in-plane resolution arterial CE-MRA imaging at 3 T. "Background" (time invariant) and "vascular" (time varying) components of the phantom were each Fourier transformed into the spatial frequency domain, the latter modulated by the SI evolution of a contrast bolus of varying "plateau" lengths and "tail" heights. Data are presented as surface plots of stenosis measurement error and blurring vs. a reference-standard injection. Descriptive. Shorter plateau lengths and lower tail heights resulted in increased measured stenosis error and blurring vs. the reference standard. Under a 44-second acquisition, full width half maximum stenosis error of the 86% stenosis with 25% plateau length and 25% tail height is 24% as compared to that from the reference standard. As plateau length and tail height approach 100%, stenosis error and blurring approach a floor defined by the MR acquisition's limitations. We propose that to achieve minimal degradation with CE-MRA, one can create a contrast bolus with either 60% plateau and 50% tail height or 80% plateau with any tail. These considerations may well prove to be of practical importance, possibly via manipulating the tail by means of multiphasic contrast injections. 3 TECHNICAL EFFICACY: Stage 1.

Review of European design provisions for buckling of aluminium members with longitudinal welds – part 1

AbstractAs part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. Numerical investigations were conducted because a need for improvement was identified. This part 1 of the paper describes the individual steps of the revision and the modifications discussed, which include the introduction of longitudinally welded members. Before going into the numerical investigations in more detail, previous observations are presented regarding buckling classes and plateau lengths. In part 1 of the paper, explanations of the numerical investigations are limited to presenting the modelling of the geometry, the mechanical properties and the imperfections as well as their respective variation in the context of the parametric studies. The results of the numerical investigations and the proposed design approaches will be presented in detail in parts 2 and 3.

On the microstructure and superelastic evolution of laser annealed thin NiTinol wires

Shape setting is a crucial step of the production route of shape memory alloys (SMAs) elements for fixing their functional properties. For thin SMA wires, this peculiar setting can be performed by a laser beam scanning the wire length. In the present work the correlation among the functional properties, such as stress–strain curves, the microstructural properties and the laser power was studied on 100 μm pseudoelastic NiTi wire. A comparison between the performances of the laser treated and the commercial wires was discussed. It can be stated that the wire responses can be modulated as a function of the laser power; the optimal laser condition can induce functional properties at least comparable to the ones of the wire conventionally treated in a furnace. Laser induced superelasticity was obtained at room temperature and the corresponding microstructure suggests a texture effect associated with the directional and fast heating induced by the laser beam scan. A favorable condition for extended stress induced plateau lengths, compared to the one of the commercially available furnace treated wires, was induced by the laser scan.

Structure and Electron Transport at Metal Atomic Junctions Doped with Dichloroethylene.

We have investigated the structure and electron transport at dichloroethylene-doped metal atomic junctions at low temperatures (20 K) in ultra-high vacuum, using Fe, Ni, Pd, Cu, Ag, and Au. The metal atomic junctions were fabricated using the mechanically controllable break junction technique. After introducing the dichloroethylene (DCE), the conductance behavior of Fe, Ni, and Pd junctions was considerably changed, whereas little change was observed for Cu, Ag, and Au. For the Pd and Cu junctions, a clear peak was observed in their conductance histograms, showing that the single-molecule junction was selectively formed. To investigate the structure of the metal atomic junctions further, their plateau lengths were analyzed. The length analysis revealed that the Au atomic wire was elongated, and the metal atomic wires were formed for the other transition metals: those that do not normally form metal atomic wires without DCE doping, as DCE adsorption stabilized the metal atomic states. There is a strong interaction between DCE and the metals, where DCE supports the formation of the metal atomic wire for Fe, Ni, and Pd.

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

AbstractConcentration polarization is a diffusion‐limited phenomenon for ion transport in electrodialysis based desalination processes. Once a so‐called limiting current is reached, the resistance of the system rises notably manifested as a plateau region in the current–voltage curves. For long it is hypothesized that altering the surface properties of the membrane can overcome the diffusional transport limitation by the induction of electroconvective vortices mixing the laminar boundary layer. To systematically investigate the influence of geometrical and chemical membrane surface topology on the evolution of electroconvection, circular patterns of polystyrene, poly(2‐vinylpyridine) (P2VP), and P2VP microgels are inkjet printed on cation‐exchange membranes. All types of patterns cause an insignificant increase in membrane resistance but they reduce the plateau lengths indicating the desired accelerated onset of electroconvection. In case of polystyrene (PS) patterns, the drop in plateau length results in a small reduction in transport resistance for overlimiting currents. However, membranes modified with linear P2VP and P2VP microgel patterns do exhibit a significantly decreased resistance in this region at a simultaneous increase of the limiting current density. Direct numerical simulations support the interpretation that the surface charge of the printed patterns influences the direction of the vortices being advantageous during ion transport toward the membrane.

Influence of the co-ions on the transport of sulfate through anion exchange membranes

The increasing demand for clean industrial processes has intensified the use of electrodialysis (ED) in the treatment of metal containing effluents from plating processes. Nickel rinsewater is a multicomponent solution that can be treated by ED in order to recover chemicals and reuse water. The investigation of the different phenomena involved in the transport of anions through anion-exchange membranes in this wastewater has been performed in different synthetic solutions by chronopotentiometry. Parameters like the limiting current density (ilim), the plateau length (∆Um), the resistance of the ohmic region (Rohm) and the resistance of the overlimiting region (R3) were also determined. Even though an anion exchange membrane (AEM), the limiting current density was affected by the proton leakage phenomena, indicated that the proton H+ has a greater effect than the other co-ions (Ni2+, Mg2+ and Na+). Ohmic resistances were reduced and plateau lengths were increased in the presence of protons. For salts solutions (without acid) the highest diffusion coefficients and lowest co-ion hydrated radii gave the highest plateau lengths and ilim, but the lowest Rohm.

Carbon oxidation and its influence on self-discharge in aqueous electrochemical capacitors

The link between carbon oxidation and self-discharge is established for carbon-electrode, acidic-aqueous-electrolyte electrochemical capacitors. Using cyclic voltammetry, open-circuit self-discharge measurements, X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) a positive correlation is established between self-discharge and the rate of carbon oxidation. During oxidation, the Spectracarb 2225 carbon fabric is oxidized to CO2, and develops C–O and CO surface functionalities. The data show that C–O groups form initially, predominately during electrode charging; the CO groups form most significantly during the self-discharge. With repeated charge/self-discharge cycling, a decrease in self-discharge is observed, likely due to the depletion of active sites for carbon oxidation. Hence, eliminating these active surface sites, either through electrochemical oxidation or chemical oxidation, greatly reduces the self-discharge experienced by the positive carbon electrodes in aqueous electrochemical capacitors. The Spectracarb 2225 carbon exhibits ca. 50% less self-discharge when the carbon is fully oxidized (i.e., the surface sites are depleted) through electrochemical cycling versus the as-received carbon. We also show, for the first time, that surface site depletion results in longer plateau lengths and lower slopes on log-time self-discharge profiles; this is a useful diagnostic for identifying surface-site limited, activation-controlled reactions.

Energy-based scheme for reconstruction of piecewise constant signals observed in the movement of molecular machines.

Analyzing the physical and chemical properties of single DNA-based molecular machines such as polymerases and helicases requires to track stepping motion on the length scale of base pairs. Although high-resolution instruments have been developed that are capable of reaching that limit, individual steps are oftentimes hidden by experimental noise which complicates data processing. Here we present an effective two-step algorithm which detects steps in a high-bandwidth signal by minimizing an energy-based model (energy-based step finder, EBS). First, an efficient convex denoising scheme is applied which allows compression to tuples of amplitudes and plateau lengths. Second, a combinatorial clustering algorithm formulated on a graph is used to assign steps to the tuple data while accounting for prior information. Performance of the algorithm was tested on Poissonian stepping data simulated based on published kinetics data of RNA polymerase II (pol II). Comparison to existing step-finding methods shows that EBS is superior in speed while providing competitive step-detection results, especially in challenging situations. Moreover, the capability to detect backtracked intervals in experimental data of pol II as well as to detect stepping behavior of the Phi29 DNA packaging motor is demonstrated.

LIGHT CURVES OF CORE-COLLAPSE SUPERNOVAE WITH SUBSTANTIAL MASS LOSS USING THE NEW OPEN-SOURCE SUPERNOVA EXPLOSION CODE (SNEC)

We present the SuperNova Explosion Code (SNEC), an open-source Lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. Given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, SNEC generates the bolometric light curve, as well as the light curves in different wavelength bands assuming black body emission. As a first application of SNEC, we consider the explosions of a grid of 15 M_⊙ (at zero-age main sequence) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. The resulting light curves exhibit plateaus with durations of ∼20 − 100 days if & 1.5 − 2 M_⊙ of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. The shorter plateau lengths are unlike the Type IIP supernova light curves typically observed in nature. This suggests that, at least for zero-age main sequence masses . 20 M_⊙, hydrogen mass loss occurs as an all or nothing process, perhaps pointing to the important role binary interactions play in observed mass-stripped supernovae (i.e., Type Ib/c events). These light curves are also unlike what is typically seen for Type IIL supernovae, arguing that simply varying the amount of mass loss cannot explain these events. The most stripped models begin to show double-peaked light curves similar to what is often seen for Type IIb supernovae, confirming previous work that these supernovae can come from progenitors that have a small amount of hydrogen and a radius of ∼ 500 R_⊙.

Slow–fast dynamics of a time-delayed electro-optic oscillator

Square-wave oscillations exhibiting different plateau lengths have been observed experimentally by investigating an electro-optic oscillator. In a previous study, we analysed the model delay differential equations and determined an asymptotic approximation of the two plateaus. In this paper, we concentrate on the fast transition layers between plateaus and show how they contribute to the total period. We also investigate the bifurcation diagram of all possible stable solutions. We show that the square waves emerge from the first Hopf bifurcation of the basic steady state and that they may coexist with stable low-frequency periodic oscillations for the same value of the control parameter.

Strongly asymmetric square waves in a time-delayed system

Time-delayed systems are known to exhibit symmetric square waves oscillating with a period close to twice the delay. Here, we show that strongly asymmetric square waves of a period close to one delay are possible. The plateau lengths can be tuned by changing a control parameter. The problem is investigated experimentally and numerically using a simple bandpass optoelectronic delay oscillator modeled by nonlinear delay integrodifferential equations. An asymptotic approximation of the square-wave periodic solution valid in the large delay limit allows an analytical description of its main properties (extrema and square pulse durations). A detailed numerical study of the bifurcation diagram indicates that the asymmetric square waves emerge from a Hopf bifurcation.

CALTECH CORE-COLLAPSE PROJECT (CCCP) OBSERVATIONS OF TYPE II SUPERNOVAE: EVIDENCE FOR THREE DISTINCT PHOTOMETRIC SUBTYPES

We present R-Band light curves of Type II supernovae (SNe) from the Caltech Core Collapse Project (CCCP). With the exception of interacting (Type IIn) SNe and rare events with long rise times, we find that most light curve shapes belong to one of three distinct classes: plateau, slowly declining and rapidly declining events. The last class is composed solely of Type IIb SNe which present similar light curve shapes to those of SNe Ib, suggesting, perhaps, similar progenitor channels. We do not find any intermediate light curves, implying that these subclasses are unlikely to reflect variance of continuous parameters, but rather might result from physically distinct progenitor systems, strengthening the suggestion of a binary origin for at least some stripped SNe. We find a large plateau luminosity range for SNe IIP, while the plateau lengths seem rather uniform at approximately 100 days. As analysis of additional CCCP data goes on and larger samples are collected, demographic studies of core collapse SNe will likely continue to provide new constraints on progenitor scenarios.

The Association of Lateral Knee Sagittal Radius of Curvature with ACL Injury: Gender or Geometry? (SS-67)

Introduction Attributes of femoral condyle and tibial plateau geometry may play a role in the stability of the knee. We studied differences in lateral knee length and radial geometry in ACL-injured and uninjured cohorts. Methods 185 age- and activity-matched uninjured and non-contact unilateral (uACL)- and bilateral (bACL)-injured groups were included. MRI measurements of the articular cartilage surfaces in the mid-weight-bearing sagittal plane of the lateral compartment evaluated tibial plateau radius of curvature (TPr) and distal femoral radius of curvature (Fr). The Fr was measured at the weight-bearing segment of a best fit logarithmic curve (Fibonacci sequence). Measurements were also made of the maximum distance from anterior to posterior femur perpendicular to the femoral shaft (FAP) and anteroposterior tibial articular length (TPAP). Calculations of Fr:TPr and FAP:TPAP were used to adjust for individual variations in anatomic size. Measurements were made by 3 observers blinded to gender and injury group. Interclass correlation coefficient was performed to assess inter-rater reliability. Two-sampled Student t-tests were used to compare quantitive variables. All data represented a normal distribution. Results Combined gender: The mean lateral plateau radius of curvature, femoral radius of curvature, and tibial plateau lengths were all significantly smaller in ACL-injured versus non-injured groups (33.6 vs. 37.4mm, p=0.003; 25.1 vs. 24.2mm, p=0.01; 31.4 vs. 33.2mm, p=0.004; respectively). Femoral length was not different between ACL-injured and uninjured groups (p=0.19). Adjusting for size differences, FAP:TPAP was significantly larger in injured versus controls, indicating that the length of the tibial plateau was significantly smaller relative to the femur in injury groups. Gender Groups (Table 1): No significant differences existed between ACL-injured females and uninjured females with respect to femoral length, tibial length, femoral radius, tibial plateau radius or FAP:TPAP. Conversely, compared to uninjured males, ACL-injured males demonstrated significantly smaller tibial plateau radius (41.1 vs. 35.3mm), femoral radius (26.7 vs. 25.5mm), and tibial plateau length (35.5 vs. 33.1mm). No differences existed between femoral length between injured and uninjured males. FAP:TPAP differences suggested that the length of the tibial plateau was significantly shorter relative to the femur in ACL-injured males (p Conclusion Our data suggest that all females (injured or uninjured) and ACL-injured males share a common lateral knee geometry characterized by a shorter tibial plateau length relative to the femur and smaller (more convex) articulating surfaces of both the proximal tibia and distal femur. It is possible that the opposition of two highly-convex articulating surfaces may be inherently less stable to anterior tibial translation and rotation. These findings also may help to explain the apparent female predilection for ACL injury compared to males, but suggest that this may be as much driven by geometry as it is by gender.

The Flavours of SN II Light Curves

AbstractWe present R-Band light curves of Type II supernovae (SNe) from the Caltech Core Collapse Program (CCCP). With the exception of interacting (Type IIn) SNe and rare events with long rise times, we find that most light curve shapes belong to one of three distinct classes: plateau, slowly declining and rapidly declining events. The latter class is composed solely of Type IIb SNe which present similar light curve shapes to those of SNe Ib, suggesting, perhaps, similar progenitor channels. We do not find any intermediate light curves, implying that these subclasses are unlikely to reflect variance of continuous parameters, but rather might result from physically distinct progenitor systems, strengthening the suggestion of a binary origin for at least some stripped SNe. We find a large plateau luminosity range for SNe IIP, while the plateau lengths seem rather uniform at approximately 100 days. We present also host galaxy trends from the Palomar Transien Factory (PTF) core collapse SN sample, which augment some of the photometric results.

Optical and near-infrared coverage of SN 2004et: physical parameters and comparison with other Type IIP supernovae

We present new optical and near infrared (NIR) photometry and spectroscopy of the type IIP supernova, SN 2004et. In combination with already published data, this provides one of the most complete studies of optical and NIR data for any type IIP SN from just after explosion to +500 days. The contribution of the NIR flux to the bolometric light curve is estimated to increase from 15% at explosion to around 50% at the end of the plateau and then declines to 40% at 300 days. SN 2004et is one of the most luminous IIP SNe which has been well studied, and with a luminosity of log L = 42.3 erg/s, it is 2 times brighter than SN 1999em. We provide parametrised bolometric corrections as a function of time for SN 2004et and three other IIP SNe that have extensive optical and NIR data, which can be used as templates for future events. We compare the physical parameters of SN 2004et with those of other IIP SNe and find kinetic energies spanning the range of 10^50-10^51 ergs. We compare the ejected masses calculated from hydrodynamic models with the progenitor masses and limits derived from prediscovery images. Some of the ejected mass estimates are significantly higher than the progenitor mass estimates, with SN 2004et showing perhaps the most serious mass discrepancy. With current models, it appears difficult to reconcile 100 day plateau lengths and high expansion velocities with the low ejected masses of 5-6 Msun implied from 7-8 Msun progenitors. The nebular phase is studied using very late time HST photometry, along with optical and NIR spectroscopy. The light curve shows a clear flattening at 600 days in the optical and the NIR, which is likely due to the ejecta impacting on the CSM. We further show that the [Oi] 6300,6364 Angstrom line strengths of four type IIP SNe imply ejected oxygen masses of 0.5-1.5 Msun.

Formation and Evolution of Single-Molecule Junctions

We analyze the formation and evolution statistics of single-molecule junctions bonded to gold electrodes using amine, methyl sulfide, and dimethyl phosphine link groups by measuring conductance as a function of junction elongation. For each link, the maximum elongation and formation probability increase with molecular length, strongly suggesting that processes other than just metal-molecule bond breakage play a key role in junction evolution under stress. Density functional theory calculations of adiabatic trajectories show sequences of atomic-scale changes in junction structure, including shifts in the attachment point, that account for the long conductance plateau lengths observed.