Energy Asymmetry Research Articles

Systematic of alpha decay half-lives: role of quantization condition

Using the semiclassical WKB method and considering the WKB quantization condition, the alpha decay half-lives of 420 alpha emitters were calculated with eight forms of the proximity and Woods–Saxon type potentials. The effect of quantization condition on the nuclear potential, effective potential, assault frequency, tunneling probability, alpha decay half-life, and root mean square deviation between theory and the experiment were investigated. Significant differences between calculated half-lives with and without inclusion of the quantization condition were observed specially for proximity potentials. By including the quantization, the Woods–Saxon potential was found as the best potential for even–even, even–odd, odd–even, odd–odd, and all alpha emitters. The quantization condition normalized the nuclear potentials. Therefore, by considering this condition, the thirteen forms of the prox77 potential with different sets of the surface energy and surface asymmetry constants gave the same results. This result was justified with two sets of parameters.

Band engineering of non-hexagonal 2D tetragonal-silicene sheet and nanoribbons: A theoretical approach

We report combined first-principle and tight-binding (TB) calculation to investigate the mechanical and electronic properties of non-hexagonal two-dimensional (2D) tetragonal-silicene (TS) sheet and nanoribbons (NRs). The results obtained by the TB method are consistent with the density functional theory (DFT) results. The elastic constants of the TS sheet are comparable to silicene. The existence of two Dirac cones is observed at different k→ points in the irreducible Brillouin Zone. A spin-orbit bandgap larger than silicene is observed in TS. The criteria for the stability and robustness of the Dirac Cones on the TB parameters are extensively investigated. Both the Dirac points are robust and stable under a wide range of hopping parameters. The degeneracy of the Dirac cones can be removed by introducing asymmetry in the on-site energy. Comparing the DFT and TB band structures, the values of the TB hopping parameters are estimated. The electronic properties of the TSNRs show a strong dependence on the width and the edge states. The symmetric armchair TSNRs show a width dependent multiple Dirac cones in the Brillouin zone. The number of Dirac cones of the NR is found to be dependent on the TB hopping parameters as well. On the other hand, asymmetric armchair TSNRs are semiconducting. The tuning of the bandgap for asymmetric armchair TSNRs by modulating the TB hopping parameters is also explored. Zigzag TSNR behaves as a degenerate semiconductor with the presence of Dirac cones just below and above EF. We subsequently expect that these theoretical findings will give a better comprehension of Dirac materials and their NRs with its potential application in nano-electronics.

Structure-Elasticity Relationship of Potassium Silicate Glasses from Brillouin Light Scattering Spectroscopy and Molecular Dynamics Simulations.

Brillouin light scattering (BLS) spectroscopy and molecular dynamic (MD) simulations allowed the identification of a relationship between the elastic properties and the structure of K-containing glasses of formula (K2O)x-(SiO2)1-x, having different K2O concentrations. Excellent agreement was observed between experimental data and simulations. The peculiar elastic properties observed for these potassium silicate glasses have been extensively discussed in terms of structural and energetic features of the materials. Elastic properties were shown to be strongly dependent on the asymmetry of potential energy in the K-BO interactions and the K-NBO interactions. A low K2O content (below 10-15% K2O) appeared to be in favor of K+-BO interactions and high asymmetry of potential energy, whereas a high K2O content (from 10 to 15% K2O) was in favor of K+-NBO interactions with lower asymmetry. Our results suggest a possible explanation to the observed anomalous dependence of elastic properties of potassium silicate glasses with K2O amount.

CL-IoT: cross-layer Internet of Things protocol for intelligent manufacturing of smart farming

Internet of Things (IoT) for Intelligent Manufacturing of Smart Farming gained significant attention from researchers to automate various farming applications called Smart Farming (SF). The sensors and actuators deployed across the farm using which farmers receive periodic farm information related to temperature, soil moisture, light intensity, and water used, etc. The clustering-based methods are proven energy-efficient solutions for Wireless Sensor Networks (WSNs). However, by considering long-distance communications and scalable networks of IoT enabled SF; the present clustering solutions cannot be feasible and having higher delay and latency for various SF applications. To focus on requirements SF applications, an efficient and scalable protocol for remote monitoring and decision making of farms in rural regions called CL-IoT protocol proposed. A cross-layer-based clustering and routing algorithms have designed to reduce network communication delay, latency, and energy consumption. The cross-layer-based optimal Cluster Head (CH) selection solution proposed to overcome the energy asymmetry problem in WSN. The parameters of different layers like a physical, medium access control (MAC), and network layer of each sensor used to evaluate and select optimal CH and efficient data transmission. The nature-inspired algorithm proposed with a novel probabilistic decision rule functions as a fitness function to discover the optimal route for data transmission. The performance of the CL-IoT protocol analyzed using NS2 by considering the energy-efficiency, computational-efficiency, and QoS-efficiency factors. Compared to state-of-art IoT-based farming methods, the CL-IoT reduces energy consumption, communication overhead, and end-to-end delay up to a certain extent and maximizes the network throughput.

Introducing noisi: a Python tool for ambient noise cross-correlation modeling and noise source inversion

Abstract. We introduce the open-source tool noisi for the forward and inverse modeling of ambient seismic cross-correlations with spatially varying source spectra. It utilizes pre-computed databases of Green's functions to represent seismic wave propagation between ambient seismic sources and seismic receivers, which can be obtained from existing repositories or imported from the output of wave propagation solvers. The tool was built with the aim of studying ambient seismic sources while accounting for realistic wave propagation effects. Furthermore, it may be used to guide the interpretation of ambient seismic auto- and cross-correlations, which have become preeminent seismological observables, in light of nonuniform ambient seismic sources. Written in the Python language, it is accessible for both usage and further development and efficient enough to conduct ambient seismic source inversions for realistic scenarios. Here, we introduce the concept and implementation of the tool, compare its model output to cross-correlations computed with SPECFEM3D_globe, and demonstrate its capabilities on selected use cases: a comparison of observed cross-correlations of the Earth's hum to a forward model based on hum sources from oceanographic models and a synthetic noise source inversion using full waveforms and signal energy asymmetry.

Giant Dzyaloshinskii-Moriya interaction in epitaxial Co/Fe bilayers with C2v symmetry

Dzyaloshinskii-Moriya interaction (DMI) is an antisymmetric fundamental magnetic exchange interaction, which is responsible for the formation of exotic topological spin textures in chiral magnets. Here by investigating the DMI-induced energy asymmetry of the magnon dispersion relation, we quantify the atomistic DMI vectors in two atomic layers made of Fe and Co epitaxially grown on W(110). We provide direct experimental evidence that in layered ferromagnets this fundamental interaction can be tailored via quantum engineering of the lattice symmetry, direct intra- and interlayer DMI coupling. We report on a giant DMI in epitaxial Co/Fe bilayers grown on W(110), exhibiting ${C}_{2v}$ symmetry. Our results pave the way for tailoring DMI on the atomic length scales with the perspective of designing desired topological spin textures.

Very Long Baseline Astrometry of PSR J1012+5307 and its Implications on Alternative Theories of Gravity

Abstract PSR J1012+5307, a millisecond pulsar in orbit with a helium white dwarf (WD), has been timed with high precision for about 25 yr. One of the main objectives of this long-term timing is to use the large asymmetry in gravitational binding energy between the neutron star and the WD to test gravitational theories. Such tests, however, will be eventually limited by the accuracy of the distance to the pulsar. Here, we present very long baseline interferometry (VLBI) astrometry results spanning approximately 2.5 yr for PSR J1012+5307, obtained with the Very Long Baseline Array as part of the project. These provide the first proper motion and absolute position for PSR J1012+5307 measured in a quasi-inertial reference frame. From the VLBI results, we measure a distance of kpc (all the estimates presented in the abstract are at 68% confidence) for PSR J1012+5307, which is the most precise obtained to date. Using the new distance, we improve the uncertainty of measurements of the unmodeled contributions to orbital period decay, which, combined with three other pulsars, places new constraints on the coupling constant for dipole gravitational radiation and the fractional time derivative of Newton’s gravitational constant in the local universe. As the uncertainties of the observed decays of orbital period for the four leading pulsar-WD systems become negligible in ≈10 yr, the uncertainties for and κ D will be improved to ≤1.5 × 10−13 yr−1 and ≤1.0 × 10−4, respectively, predominantly limited by the distance uncertainties.

Measuring the top energy asymmetry at the LHC: QCD and SMEFT interpretations

The energy asymmetry in top-antitop-jet production is an observable of the top charge asymmetry designed for the LHC. We perform a realistic analysis in the boosted kinematic regime, including effects of the parton shower, hadronization and expected experimental uncertainties. Our predictions at particle level show that the energy asymmetry in the Standard Model can be measured with a significance of 3σ during Run 3, and with more than 5σ significance at the HL-LHC. Beyond the Standard Model the energy asymmetry is a sensitive probe of new physics with couplings to top quarks. In the framework of the Standard Model Effective Field Theory, we show that the sensitivity of the energy asymmetry to effective four-quark interactions is higher or comparable to other top observables and resolves blind directions in current LHC fits. We suggest to include the energy asymmetry as an important observable in global searches for new physics in the top sector.

Межполушарная асимметрия и церебральный энергообмен у молодых людей Арктической зоны Российской Федерации в сезоны с нарушенной фотопериодикой

Межполушарная асимметрия и церебральный энергообмен у молодых людей Арктической зоны Российской Федерации в сезоны с нарушенной фотопериодикой

One-proton knockout from C16 at around 240 MeV/nucleon

The cross section for one-proton knockout from $^{16}\mathrm{C}$ with a large neutron-proton separation energy asymmetry on a carbon target has been measured at an intermediate beam energy of around 240 MeV/nucleon. The measured cross section is compared to the predictions based on the eikonal reaction model with shell-model structure inputs. The beam-energy dependence of the reduction on the extracted spectroscopic strength for strongly bound nucleon removal is derived from combining the existing intermediate-energy data with the present measurement. The deduced reduction factor ${R}_{s}$, defined as the ratio of the measured and theoretical cross sections, for the strongly bound nucleon removal at around 240 MeV/nucleon is consistent with the systematics observed from knockout reactions induced by light nuclear targets at intermediate energies of around 80 MeV/nucleon.

An ocean wind-wave climatology for the Southern Brazilian Shelf. Part II: Variability in space and time

Previously validated model results were used to characterize the wave climate over the Southern Brazilian Shelf (SBS). The low mean significant wave height over the western South Atlantic shelves was shown together with examples of cyclone-induced extreme wave fields and other typical wave conditions. The mean offshore spectra showed a bimodal shape with a predominance of S/SSW and ENE/E waves with distinctive interannual rising periods in wave energy density. Along-shelf wave energy gradients were seen near the coast with higher energy located off capes and coastal projections and energy minima between them. A considerable drop in wave energy suggests the 40 m depth as the mean wave base and consequently the lower limit of the SBS shoreface. The upper shoreface mean wave energy density varied abruptly along the shelf in response to differences in bottom declivities. The large and shallow shoreface was responsible for an intense refraction of the waves and hence very small angles of attack. Additionally, it was shown the sheltering effect caused by capes and coastal projections and a remarkable north/south energy asymmetry between them, caused by a windowing on the wave propagation to the shore. Altogether, it was possible to state that bottom friction plays a major role in wave differentiation along the SBS shoreface, thus suggesting that shelf morphology might indeed be more important to generate wave variability than the offshore wave variation itself.

Instantaneous Segmental Energy Symmetry Index as Gait Compensation Indicator in Asymmetrical Walking

Purpose: Human body constantly adapts to optimise the energy expenditure. A better understanding of the mechanical energetic costs in lower extremities helps identify the compensatory mechanism adopted in asymmetrical gait. This paper proposes the use of instantaneous segmental energy and normalised symmetry index (SInorm) to examine asymmetrical gait. This approach can provide better overview of gait quality allowing identification of change in segmental energy during different gait phases and contribution of each segment in compensating abnormal walking. Method: An experimental study was carried out to validate this method. Twenty healthy subjects were recruited. Asymmetrical gait was simulated by restricting knee motion during walking using a knee brace. Mechanical energy was determined for each segment of the left and right limbs. Normalised Symmetry Index (SInorm) was then calculated to examine bilateral differences in segmental energy during stance phase and swing phase. Statistical analysis using ANOVA and Tukey-Kramer multiple comparison test to identify asymmetry of the segmental energy (p-value < 0.05). Result: Significant asymmetry of segmental energy occurred during swing phase. Greater asymmetry was observed in kinetic energy than in potential energy. The affected limb segments produced lower kinetic energy than the normal limb. At asymmetrical state, potential energy of the affected limb’s foot and thigh were lower than that of the normal segments while the inverse was true for thigh segment. Conclusion: These results suggested that in asymmetrical gait, a form of compensatory mechanism is adopted to walk. This can be observed in the change of instantaneous segmental energy during walking.

Solid-State 17O NMR Study of Carboxylic Acid Dimers: Simultaneously Accessing Spectral Properties of Low- and High-Energy Tautomers.

We report a solid-state 17O NMR study of several crystalline carboxylic acids. We found that, while each of these compounds forms discrete hydrogen-bonded dimers in the crystal lattice, their solid-state 17O magic-angle spinning (MAS) NMR spectra display quite different features and different temperature dependencies. We showed that experimentally observed 17O NMR spectral behaviors can be explained as being due to thermal averaging between the two tautomers that are produced as a result of concerted double-hydrogen hopping dynamics within each dimer. In general, the two tautomers have different energies due to intramolecular interactions and crystal packing. From an analysis of variable-temperature 17O MAS NMR spectra, energy asymmetry between the two tautomers was experimentally determined for each of the carboxylic acid compounds studied. The same data analysis also offers an opportunity to simultaneously assess 17O NMR parameters in both low- and high-energy tautomers. We concluded that the periodic plane-wave density functional theory (DFT) calculations can produce reliable 17O NMR parameters (chemical shift and quadrupolar coupling tensors) for both tautomers. The same periodic DFT calculations have also produced reasonable energy asymmetry values for the studied carboxylic acid dimers. We have also observed substantial H/D isotope shifts in solid-state 17O NMR.

Symmetry of deterministic ratchets.

We consider the overdamped motion of a Brownian particle in an unbiased force field described by a periodic function of coordinate and time. A compact analytical representation has been obtained for the average particle velocity as a series in the inverse friction coefficient, from which follows a simple and clear proof of hidden symmetries of ratchets, reflecting the symmetry of summation indices of the applied force harmonics relative to their numbering from left to right and from right to left. We revealed the conditions under which (i) the ratchet effect is absent; (ii) the ratchet average velocity is an even or odd functional of the applied force, whose dependences on spatial and temporal variables are characterized by periodic functions of the main types of symmetries: shift, symmetric, and antisymmetric, and universal, which combines all three types. These conditions have been specified for forces with those dependences of a multiplicative (or additive-multiplicative) and additive structure describing two main ratchet types, pulsating and forced ratchets. We found the fundamental difference in dependences of the average velocity of pulsating and forced ratchets on parameters of spatial and temporal asymmetry of potential energy of a particle for systems in which the spatial and temporal dependence is described by a sawtooth potential and a deterministic dichotomous process, respectively. In particular, it is shown that a pulsating ratchet with a multiplicative structure of its potential energy cannot move directionally if the energy is of the universal symmetry type in time; this restriction is removed in the inertial regime, but only if the coordinate dependence of the energy does not belong to either symmetric or antisymmetric functions.

Changes of MJO propagation characteristics under global warming

The change of Madden–Julian Oscillation (MJO) propagation and periodicity characteristics under global warming is investigated using two selected CMIP5 models. It is found that the MJO period tends to be shorter, while its eastward propagation tends to be accelerated. Meanwhile the main MJO activity center shifts eastward toward the central equatorial Pacific. Two factors are possibly responsible for the increased eastward phase speed of the MJO. The first is attributed to the increase of atmospheric static stability that accelerates equatorial Kelvin wave speed. The second is attributed to the increase of zonal asymmetry of MJO-scale moist static energy (MSE) tendency, which is contributed to the combined effect of anomalous circulation and mean MSE gradient. A theoretical framework is constructed to understand the relative role of anomalous heating and mean static stability changes in determining MJO-scale circulation change. It is found that their effect is phase dependent. During the initial warming phase the circulation change is primarily controlled by the heating change, whereas during the later warming phase it is primarily controlled by the static stability change. The eastward shift of the main MJO activity center is possibly caused by the occurrence of an El Nino-like mean SST change and associated vertical overturning circulation change in the tropical Pacific.

Blue shift in the interband optical transitions of gated monolayer black phosphorus

The anisotropic frequency-dependent optical conductivity of single-layer puckered phosphorene is studied, and also its dependence on the electrostatic gating of the top and bottom sublayers. The effective Hamiltonian within the k→⋅p→ approximation is used to obtain the electronic band structure from which the interband optical transitions are evaluated using the Kubo formula. Inherent asymmetry in the dispersion energy of carriers along the armchair and zigzag edges gives rise to anisotropic optical features. The bandgap increases with gate voltage resulting in absorption at higher optical energies along the armchair edge, which is the so-called blue shift, while along the zigzag edge such a shift is not significant. The temperature and exciton effects on the interband response are concisely discussed. These results provide new insights which render phosphorene attractive for optoelectronic devices.

Staggered potential and magnetic field tunable electronic switch in a kagome nanoribbon junction

We propose a possible electronic switch on a two dimensional (2D) kagome lattice by applying a perpendicular inhomogeneous magnetic field and a staggered sublattice potential. By means of the tight-binding lattice model and the non-equilibrium Green’s function method, we calculate the quantum Hall conductance of the device at zero temperature limit. The numerical results demonstrate that when a staggered lattice potential is considered, the conventional integer Hall effect is changed into discrete fractional conductance peaks, and a finite energy gap can be opened in the system, which may induce a metal-insulator transition and can be designed as a 2D electronic valve. The conductance valve phenomena mainly come from the interplay between the asymmetry energy band induced by the magnetic field and a band gap opened by the staggered potential. The ON(OFF) state of the electron transport is efficiently controlled by the device parameters such as the magnetic field, the staggered lattice potential and the Fermi level. Our findings might be useful for designing efficient current valves in 2D nano-electronic devices.

Temperature dependent study of neutron-rich thermally fissile 244−262Th and 246−264U nuclei within E-TRMF model

We have studied the fission parameters of hot neutron-rich thermally fissile T244−262h and U246−264 nuclei within the temperature dependent effective field theory motivated relativistic mean field (E-TRMF) formalism by using the recently developed FSUGarnet and IOPB-I parameter sets. The results obtained by these two forces are compared with the results of the well known and widely accepted NL3 parameter set. The excitation energy E⁎, shell correction energy δEshell, single particle energy for neutrons and protons ϵn,p, level density parameter a, neutron skin thickness ΔR, two neutron separation energy S2n, and asymmetry energy coefficient asym of these neutron-rich thermally fissile nuclei are calculated at finite temperature. The dependency of level density parameter and other observables on the temperature and the force parameters (interaction Lagrangian) are discussed.

Asymmetry in energy versus spin transport in certain interacting disordered systems

We study energy transport in XXZ spin chains driven to nonequilibrium configurations by thermal reservoirs of different temperatures at the boundaries. We discuss the transition between diffusive and subdiffusive transport regimes in sectors of zero and finite magnetization at high temperature. At large anisotropies we find that diffusive energy transport prevails over a large range of disorder strengths, which is in contrast to spin transport that is subdiffusive in the same regime for weak disorder strengths. However, when finite magnetization is induced, both energy and spin currents decay as a function of system size with the same exponent. Based on this, we conclude that diffusion of energy is much more pervasive than that of magnetization in these disordered spin-1/2 systems, and occurs across a significant range of the interaction-disorder parameter phase-space; we suggest this is due to conservation laws present in the clean XXZ limit.

Translocation of non-interacting heteropolymer protein chains in terms of single helical propensity and size

In this work we present an analytical framework to calculate the average translocation time τ required for an ideal proteinogenic polypeptide chain to cross over a small pore on a membrane. Translocation is considered to proceed as a chain of non-interacting amino acid residues of sequence {Xj} diffuses through the pore against an energy barrier Δℱ, set by chain entropy and unfolding-folding energetics. We analyze the effect of sequence heterogeneity on the dynamics of translocation by means of helical propensity of amino acid residues. In our calculations we use sequences of fifteen well-known proteins that are translocated which span two orders of magnitude in size according to the number of residues N. Results show non-symmetric free energy barriers as a consequence of sequence heterogeneity, such asymmetry in energy may be useful in differentiated directions of translocation. For the fifteen polypeptide chains considered we found conditions when sequence heterogeneity has not a significant effect on the time scale of translocation leading to a scaling law τ ∝ Nν, where ν ∼ 1.6 is an exponent that holds for most ground state energies. We also identify conditions when sequence heterogeneity has a great impact on the time scale of translocation, in consequence, no more scaling laws for τ there exist.