Position Of Minimum Research Articles

Self-diffusion in polycrystalline Li1+x Ti2-x Al x (PO4)3 (0.2 ≤ x ≤ 0.4) samples followed by 7Li PFG (pulse field gradient) NMR spectroscopy.

Short and long range lithium motions in powder Li1+x Ti2-x Al x (PO4)3 (LTAP) NASICON compounds prepared by ceramic (x = 0.2 and 0.4) and sol-gel (x = 0.3 and 0.4) routes are discussed. ND diffraction and MAS-NMR spectroscopy were previously used to investigate structural features of these compounds. In particular, Fourier map differences showed that the amount of Li atoms allocated at M3 increases at the expense of M1 sites when the Li content increases. In this work, PFG-NMR results show that diffusion coefficients rise with the amount of lithium and temperature. The restricted diffusion inside NASICON particles is compared with "free" diffusion processes. At 300 K, diffusion coefficients D PFG ∼ 5 × 10-12 m2 s-1 have been deduced in ceramic x = 0.2 and 0.4 samples, decreasing with diffusion time Δ used in PFG experiments. In sol-gel samples, diffusion coefficients are near those of ceramic samples, but decrease faster with diffusion Δ times, as a consequence of the Li confinement inside sub-micrometric crystallites. The NMR spin-echo signal displays minima at specific q(γgδ) values that are related to the crystallite size. From R dif ∼ q m -1 distances, calculated from the position of minima, and from diffusion coefficients deduced for high Δ values, the mean crystallite size was estimated. Finally, from the temperature dependence of conductivity and diffusion coefficients, the activation energy and charge carriers concentrations were determined.

Quench dynamics of a spin-orbital coupled Bose-Einstein condensate with nonlinear interactions

In this work, we study the non-equilibrium quench dynamics from the superfluid stripe phase to the supersolid phase of a two dimensional spin-orbital coupled interacting Bose-Einstein condensate in the presence of a one dimensional optical lattice. The quench protocol here is constructed through varying the lattice depth linearly with the evolution time. By using the time-dependent Gutzwiller method, various physical quantities, such as the vortex number and the overlap of wave-function, have been investigated with respect to the quench time. Through analyzing the dynamical behavior of the above physical quantities, we find out the transition time of the quench procedure, which captures the freeze out time indicating the moment that the system catches the quench speed beginning to evolve quickly. Before the transition time, the dynamics is frozen and the state of the system cannot follow the changes in the Hamiltonian. While passing the transition time, we find that there are significant alterations to both the vortex number and the wave-function. At the transition time, on one hand the vortex number abruptly increases from zero; on the other hand the overlap of wave-function departures from 1 shortly. These signatures indicate that the system evolves rapidly when passing the transition time. Furthermore, we also find that due to the presence of spin-orbital coupling, the spin texture represents a periodic magnetic structure accompanying with the emergence of the supersolid dynamically. It is shown that during the quench procedure, the density distribution of the system are always accompanied with the spatial structure of spin texture, i.e., the central position of topological spin skyrmion (antiskyrmion) corresponding to the minimum position of the density distribution. The topological charge of the above spin structures also shows interesting dynamical properties. We find that the quantized topological charge appears with the emergence of the supersolid dynamically.

Effect of Local Stress on Accurate Modeling of Bacterial Outer Membranes Using All-Atom Molecular Dynamics.

Biological membranes are fundamental components of living organisms that play an undeniable role in their survival. Molecular dynamics (MD) serves as an essential computational tool for studying biomembranes on molecular and atomistic scales. The status quo of MD simulations of biomembranes studies a nanometer-sized membrane patch periodically extended under periodic boundary conditions (PBCs). In nature, membranes are usually composed of different lipids in their two layers (referred to as leaflets). This compositional asymmetry imposes a fixed ratio of lipid numbers between the two leaflets in a periodically constrained membrane, which needs to be set appropriately. The widely adopted methods of defining a leaflet lipid ratio suffer from the lack of control over the mechanical tension of each leaflet, which could significantly influence research findings. In this study, we investigate the role of membrane-building protocol and the resulting initial stress state on the interaction between small molecules and asymmetric membranes. We model the outer membrane of Pseudomonas aeruginosa bacteria using two different building protocols and probe their interactions with the Pseudomonas quinolone signal (PQS). Our results show that differential stress could shift the position of free energy minimum for the PQS molecule between the two leaflets of the asymmetric membrane. This work provides critical insights into the relationship between the initial per-leaflet tension and the spontaneous intercalation of PQS.

Induced color charge and quark propagation at Polyakov’s loop background

In quark­gluon plasma, the presence of the A0 (Polyakov loop (PL)) condensate results in the color Z(3) symmetry breaking and the Furry theorem violation. Due to these peculiarities, new phenomena ­ the induced color charges and other even­number diagram effects ­ are realized. Using the R̄ξ gauge, we ob­tain the ξ­-independent two­loop effective potential W (A0classical) expressed in terms of the PL. Its minimum position detects the value of the condensate. We calculate the one­loop tadpole diagram with one gluon line and the induced color charges Qind. Having these, we investigate the influence of the color charges on quark propagation and derive and partially investigate the contribution of them into the Schwinger­-Dyson equation for quarks. It is found that the presence of Qind effectively increases the strength of the A0 potential acting on colored particles in the plasma.

Accuracy and precision of responses to visual analog scales: Inter- and intra-individual variability

Visual analog scales (VASs) are gaining popularity for collecting responses in computer administration of psychometric tests and surveys. The VAS format consists of a line marked at its endpoints with the minimum and maximum positions that it covers for respondents to place a mark at their selected location. Creating the line with intermediate marks along its length was discouraged, but no empirical evidence has ever been produced to show that their absence does any good. We report a study that asked respondents to place marks at pre-selected locations on a 100-unit VAS line, first when it only had numerical labels (0 and 100) at its endpoints and then when intermediate locations (from 0 to 100 in steps of 20) were also labeled. The results show that settings are more accurate and more precise when the VAS line has intermediate tick marks: The average absolute error decreased from 3.02 units without intermediate marks to 0.82 units with them. Provision of intermediate tick marks also reduced substantially inter- and intra-individual variability in accuracy and precision: The standard deviation of absolute error decreased from 0.87 units without tick marks to 0.25 units with them and the standard deviation of signed distance to target decreased from 1.16 units without tick marks to 0.24 units with them. These results prompt the recommendation that the design of VASs includes intermediate tick marks along the length of the line.

Portfolio construction as linearly constrained separable optimization

Mean–variance portfolio optimization problems often involve separable nonconvex terms, including penalties on capital gains, integer share constraints, and minimum nonzero position and trade sizes. We propose a heuristic algorithm for such problems based on the alternating direction method of multipliers (ADMM). This method allows for solve times in tens to hundreds of milliseconds with around 1000 securities and 100 risk factors. We also obtain a bound on the achievable performance. Our heuristic and bound are both derived from similar results for other optimization problems with a separable objective and affine equality constraints. We discuss a concrete implementation in the case where the separable terms in the objective are piecewise quadratic, and we empirically demonstrate its effectiveness for tax-aware portfolio construction.

On the role of intermolecular vibrational motions for ice polymorphs. IV. Anisotropy in the thermal expansivity and the nonaffine deformation for ice IX and III.

We explore anisotropic properties in the thermal expansivities of hydrogen-ordered ice IX and its hydrogen-disordered counterpart, ice III. The free energies of these ice forms are calculated to obtain the lattice constants for the tetragonal unit cell and the thermal expansivities at various thermodynamic conditions in the framework of quasi-harmonic approximation, taking account of their anisotropic nature. The thermal expansivities are also examined by applying a thermodynamic relation that connects them with the Grüneisen parameters and the elastic compliances. Both calculations suggest that ice III and IX exhibit a negative thermal expansion along the a-axis but have a positive one along the c-axis at low temperatures. It is found that nonaffine deformation in the variation of the lattice constant beyond affine transformation (the Born approximation) is essential in the theoretical calculation of the thermal properties of ice III and IX. We also find that the nonaffine deformation is described by the shift of the minimum energy positions in the potential manifold of hydrogen-ordered ice along a limited number of the normal mode coordinates, which is irrelevant to the system size. These modes become unstable against an applied strain, so that the potential minimum moves along those normal coordinates away from that of the affine-transformed structure. The unstable modes are all symmetry-preserving modes, and the space-group symmetry is an invariant under displacement along either of those normal coordinates. The number of the unstable modes in ice IX is 8 while it is 1 in another hydrogen-ordered ice VIII.

Performance Analysis of 4-DOF RPRR Robot Manipulator Actuation Strategy for Pick and Place Application in Healthcare Environment

Direct and indirect physical contact of humans and objects become the main medium of transmissible diseases such as COVID-19. Some strategies have been proposed to mitigate the risks of infections by minimizing physical contact, such as using robotics technology. Tele-robotics is one of the sub-fields in robotics that aims to implement physical surrogates for monitoring and controlling robots from remote distances, either autonomous, semi-autonomous, or manually guided. This paper discusses experimental research for evaluating the performance of a 4-DOF robot manipulator for pick and place tasks on small medical objects, such as test tubes in table-top scenarios. The robot manipulator is designed as an RPRR manipulator and is equipped with a gripper attached to its end-effector. Inverse kinematics and trajectory planning methods have been successfully implemented in real-time. The inverse kinematic method utilizes a pseudo-inverse Jacobian solver, and the trajectory generation utilizes a sigmoid function. The performance analysis results show that pick and place missions have been demonstrated with minimum tolerable position error, which is not more than 3.5 mm. The robot manipulator can satisfy high precision during repetitive experiments and maintain its accuracy in picking and placing standard test tubes from one rack to another within its working space. The smooth trajectories of the end-effector are achieved by implementing the sigmoid function. Thus, it satisfies the requirement for handling objects with minimum vibrations even during the actuation process with maximum speed.

Low Energy Positron Scattering by F and F2.

We have determined integral and differential elastic cross sections for positron scattering with atomic F and F2 molecules from 0.01 to 1000 eV with different theoretical approaches. Higher order polarizabilities were successively considered in the scattering potential, and we observed that the differential and integral cross sections converge only when the pure dipole second hyperpolarization level is taken into account, demonstrating the importance of the hyperpolarization effects on the low energy positron scattering dynamics. Ramsauer structures were found for both targets, and in the particular case of the F atom, the effect of its quadrupole moment proved to be relevant around the position of the Ramsauer minimum, which was determined together with the scattering length for each of the adopted polarization schemes. A relation of these quantities with the matching radius between the correlation and polarization interactions is also discussed. Agreement between the model potential and ab initio cross sections for the lowest level of target polarization is found for F2. Since there is no previous theoretical or experimental determination of cross sections for these targets, we compared the differential cross sections of F2 with experimental data available for N2 and O2 and found reasonable agreement.

In Situ Monitoring of Layer-by-Layer Assembly Surface Modification of Nanophotonic-Microfluidic Sensor.

An elaboration of the photonic based sensors is the most promising direction in modern analytical chemistry from the point of view of real clinical applications. The highest sensitivity is demonstrated by sensors based on photonic integrated circuits (PICs). This type of sensor has been recently successfully combined with microfluidics, which decreased the analyte volume for analysis down to microliter units. The most significant disadvantage regarding these photonic sensors is low specificity. One of the methods that could be useful for such type of problem is the layer by layer (LBL) assembly. The peculiarity of a PIC based sensor is the ability to precisely control surface modification by using measurements of a minimum resonance position shift. The bovine serum albumin (BSA) and tannic acid (TA) molecules were selected for LBL assembly because on one side they form a stable LBL assembly film based on hydrogen bonds, while the other side of both TA and BSA molecules can be used for conjugation with target molecules. A microring resonator (MRR) and a Mach-Zehnder interferometer (MZI) based on a silicon nitride platform combined with a microfluidic system were elaborated and used for monitoring the LBL film assembly. Obtained results have a good correlation with measurements carried out by atom force microscopy. Thus, the ability of using PIC based sensors for in situ control of surface modification was demonstrated and can be considered in point-of-care (POC) devices that have a very good perspective for both early pathological state diagnosis and evaluation of treatment efficiency.

Negative Ulnar Variance Lessens DRUJ Instability After DRUJ Disruption: A Biomechanical Analysis.

The purpose of this study was to perform a biomechanical investigation on the effect of ulnar variance (UV) on the stability of the distal radioulnar joint (DRUJ) prior to and after DRUJ sectioning. Ten cadaveric forearm specimens were included in the study and baseline UV was assessed radiographically. Radial motion relative to the ulna was evaluated using Intel real sense cameras and a custom developed program. The forearms were dissected, and a radial osteotomy was performed. Using a custom-made plate, radial stability was assessed with an UV of + 4, 0, and -4 mm by measuring the maximum and minimum radial position relative to the ulna during a simulated Shuck test. The volar radioulnar ligaments and triangular fibrocartilage complex (TFCC) were then sectioned, and testing was repeated at each UV state. Sectioning significantly increased radial translation at neutral (P = .008), +4 mm UV (P = .008), and -4 mm UV (P = .018). There were no significant differences in translation between the 3 UV groups with the DRUJ intact (P = .124). The ulnar negative (-4 mm) state had significantly lower translation compared to the positive (+4 mm) (P < .001) and the neutral (0 mm) (P = .026) UV states. There were no significant differences between the positive and neutral UV groups with the DRUJ sectioned. Fixating the radius in -4 mm of ulnar negativity significantly decreased radial translation after sectioning the volar radioulnar ligament and TFCC. Ulnar variance had no effect on stability with an intact DRUJ. Biomechanical Study.

Quantile regression analysis of time-space variation characteristics of tropical cyclones in the west North Pacific basin under global warming

ABSTRACT The enormous economic losses and casualties were caused by tropical cyclones in the southeast coastal areas of China every year. In order to understand the time-space variation characteristics of tropical cyclones (including intensity, minimum central atmosphere pressure, duration, and generation position) in the global and the western North Pacific basin, the monthly and interannual variation characteristics of tropical cyclones from 1949 to 2018 were analyzed by the quantile regression method and least square regression method. The results show that the global climate temperature and the annual maximum wind speed of tropical cyclones have a tendency to increase under different quantiles. While the maximum wind speed of tropical cyclones generated in the WNP basin basically decreases with the increase of years in El Niño, La Niña, and normal years under different quantiles. It is obvious that the interannual variation of the maximum wind speed of tropical cyclones is affected by the ENSO events. Similarly, minimum central atmospheric pressure, duration, and generation position of TCs from 1949 to 2018 are also analyzed in the present study. The results of this study can provide an effective reference for data analysis and trend prediction of tropical cyclones in the western North Pacific basin.

Two-dimensional MgAl2S4 as potential photocatalyst for water splitting and strategies to boost its performance

Exploring novel 2D water-splitting photocatalysts and finding strategies to boost their efficiency are important tasks in nowadays energy industry. Here, employing first-principle calculations, we predicted a novel 2D material, MgAl2S4 monolayer, and studied its potential applications in photocatalytic water splitting. 2D MgAl2S4 is noble-metal-free and possesses great thermal and dynamical stability. The cleavage energy is around 16 meV/Å2 which is even lower than graphene, indicating the high feasibility for experimental fabrications. The band edge positions and the optical absorption spectra indicate the pristine MgAl2S4 monolayer can work as a photocatalyst upon ultraviolet irradiation. Its high electron mobility around 745 cm2v-1s−1 and high conduction band minimum (CBM) position suggest a strong reduction ability. Furthermore, the oxidation ability and light absorbance can be significantly enhanced by a small tensile strain. The complementary marriage of MgAl2S4 and SnSe2 monolayers can form a direct z-scheme heterostructure, which can fully utilize the photocatalytic potential of both components.

Evaluation of the Mid-Latitude Ionospheric trough Using GRACE Data

In this work, statistical analysis of the main ionospheric trough was performed using K-band ranging system (KBR) measurements from the GRACE satellite constellation from 2002 to 2015. The investigated period covers high- and low-solar-activity conditions. The mid-latitude ionospheric trough (MIT) characteristics were investigated for both the northern and southern hemispheres. MIT parameters such as the minimum trough position, trough width and depth, and trough occurrence probability were studied in connection with magnetic local time; geographic distribution; seasons; solar activity; and geomagnetic activity conditions, such as the solar wind plasma speed, interplanetary magnetic field components, and high-resolution geomagnetic indices SYM–H and Hp30.

Advanced separation and classification of ionospheric troughs in midnight conditions

This study uses a novel approach to separate and classify different ionospheric troughs from CHAMP satellite data in the winter midnight ionosphere of the southern hemisphere at high solar activity (2000–2002). The main ionospheric trough (MIT) was separated from the high latitude trough (HLT). The separation was performed through an analysis of troughs in the frame of a model of the diffuse auroral particle precipitation. Two types of HLT were distinguished. In the mid-latitude ionosphere, the MIT was separated from the ring ionospheric trough (RIT), which is formed by the decay processes of the magnetospheric ring current. The separation was performed on the basis of an analysis of the prehistory of all geomagnetic disturbances for the period under study. In addition, a decrease in the electron density, which is superimposed on the MIT and masks its minimum position, is quite often observed at American and Atlantic longitudes near the Polar Circle.

Iterative Pose Estimation for a Planar Object Using Virtual Sphere

This article proposed an iterative pose estimation for the planar object to deal with the pose ambiguity in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Perspective n Points</i> (PnP) problem. Specifically, by utilizing the unit virtual sphere, the PnP pose estimation problem can be performed as a minimization of the error function with three independent transitional parameters, referred to as the coupling position. Then, Levenberg–Marquardt (LM) optimization algorithm is applied to acquire the coupling position of the first local minimum. Furthermore, the coupling position is represented as the two Euler angles and the vector length, which are combined with the planar points to compute the second local minimum approximation as the initialization of the second LM algorithm. Consequently, once the global coupling position in the two local minimum is decided by the lower error, the orientation and position are directly decoupled by using the singular value decomposition. It is shown that the designed pose estimation is able to achieve prescribed performance for locating and distinguishing two local minimum, and meanwhile guarantee the superior computation behavior under the pose ambiguity for the planar object. Finally, numerical simulation and physical experiment are conducted to validate the effectiveness of the proposed method, compared with the state-of-the-art PnP methods.

Analysis of synthetic electron cyclotron emission from the high field side of HL-2M tokamak plasmas.

A synthetic electron cyclotron emission (ECE) diagnostic is used to interpret ECE signals from preset plasma equilibrium profiles, including magnetic field, electron density, and electron temperature. According to the simulation results, the electron temperature (Te) profile covering the harmonic overlap region can be obtained by receiving ECE signals at the high field side (HFS) of the HL-2M plasma. The third harmonic ECE at the low field side (LFS) cannot pass through the second harmonic resonance layer at the HFS unless the optical thickness (τ) of the second harmonic becomes gray (τ ≤ 2). In addition, the impact of the relativistic frequency down-shift has been evaluated and corrected. The measurable range of the HFS ECE has been calculated by scanning different parameters (electron density, temperature, and magnetic field). Higher plasma parameters allow a wider radial range of electron temperature measurements. The minimum inner measurable position can reach R = 120cm (r/a = -0.89) when the product of core temperature (Te0) and density (ne0) is greater than 35 × 1019keVm-3, which is extended by more than 30cm inward compared with that of the LFS measurement. The HFS ECE will greatly improve the diagnostic ability of ECE systems on the HL-2M tokamak.

Vortex induced vibration of a circular cylinder colliding with a rigid wall

The vortex-induced vibration of a circular cylinder near a solid wall exhibits two modes of collision with the wall, namely, ``Impact'' and ``Gracing.'' At the minimum position of the cylinder nearer the wall, the ``Impact'' case corroborates an abrupt change in the velocity gradient with a positive repulsive force magnitude. In contrast, the cylinder embraces the wall and moves away during the ``Gracing'' case, revealing a linear variation of the velocity gradient and nearly-zero repulsive force. The lift signal shows a sudden discontinuity for the ``Impact'' situation while rendering a continuous variation for the ``Gracing.''

Minimum Shareholding Proportion of Equity Funds and Stock Volatility Evidence from a Quasi-Natural Experiment

China’s fund market is getting bigger and bigger. By September 2021, the number of funds in the market had exceeded 8000, with a net value of nearly 24 trillion yuan. Among them, the number of equity funds has doubled compared with 2015, and the net value has increased four times compared with 2015, and it still maintains a rapid growth momentum. Do mutual funds play a role in market stabilization? To demonstrate this issue, we combined the passive trading technique with the positive and negative feedback trading strategies and explained how the minimum position ratio of equity funds affects stock price volatility. Then, using empirical data, we apply the difference-in-differences model to analyze how shifting proportions of the equity funds’ lowest shareholding affects stock volatility. The result shows that the volatility of high-institutional stocks was significantly reduced in comparison with other stocks after 2014. This result is further confirmed in the stocks held by large-scale funds. We used PSM-DID to solve potential endogenous problems and found that the results still support the hypothesis. This evidence supports the point of statement that the equity funds in the Chinese capital market can stabilize the market especially after 2014.

Coexistence of ferroelectric phases in barium titanate single-domain thin films

In about twenty years, the temperature-misfit strain phase diagrams have become valuable tools to describe ferroelectric thin film properties. The background theoretical approach consists in searching for the position of the global minimum of the potential landscape and deducing the thermodynamically stable phase. In temperature-misfit strain phase diagrams, lines separate the stable phase regions, and the analysis of the polarization continuity properties across these lines allows us to determine the order of phase transition. This work revealed additional important information relative to the properties of first order phase transitions; we determined the limit of stability of the metastable phases and plotted the corresponding lines in the traditional temperature-misfit strain diagrams. These one dimensional boundaries are the analog to the superheating and supercooling temperature points in the context of bulk ferroelectric crystal. We highlight two dimensional coexistence regions adjacent to first order thermodynamic transition lines. The location and the shape of these regions are strongly dependent on the set of parameters used to describe the bulk crystal. We illustrate the interest in the revelation of coexistence regions, showing that the corresponding multi-stability properties could be used to design non-binary memory cells by using barium titanate thin films.