Repulsive Features Research Articles

THE RUSSIAN FOLK “EGYPTOLOGY”

The paper deals with Russian folk legends about “pharaohs” - mythical creatures with a human torso and a fish tail, who inhabited the water element. The legends reflected the oldest layer of folk knowledge about the ancient Egyptian history. These ideas go back to the biblical story about Pharaoh's army that drowned in the Red Sea during the exodus of the Jews from Egypt. In Old Russia, the title “Pharaoh” became a symbol of a proud and wicked ruler. The legend about the mythical water people was first recorded by Vasily Poznyakov, who travelled to Egypt in 1558. At the end of the 16th century, his story was used by Trifon Korobeynikov, who was on a pilgrimage to the East. Thanks to this work, “pharaohs” and “pharaonic women” were formed as negative characters of the Christian legend and in the 18th - 19th centuries were firmly incorporated into Russian folklore, while the image of the mythical people itself received an eschatological sound. Images of these creatures became one of the motifs of folk decorative art in Nizhny Novgorod province and neighboring counties of Kostroma province. It had a negative meaning, which derived from the “negativity” of the Old Testament character of the same name and was projected onto one of the repulsive features of the local character.

Electrostatic Repulsive Features of Free-Standing Titanium Dioxide Nanotube-Based Membranes in Biofiltration Applications.

This study presents the electrostatic repulsive features of electrochemically fabricated titanium dioxide nanotube (NT)-based membranes with different surface nanomorphologies in cross-flow biofiltration applications while maintaining a creatinine clearance above 90%. Although membranes exhibit antifouling behavior, their blood protein rejection can still be improved. Due to the electrostatically negative charge of the hexafluorotitanate moiety, the fabricated biocompatible, superhydrophilic, free-standing, and amorphous ceramic nanomembranes showed that about 20% of negatively charged 66 kDa blood albumin was rejected by the membrane with ∼100 nm pores. As the nanomorphology of the membrane was shifted from NTs to nanowires by varying fabrication parameters, pure water flux and bovine serum albumin (BSA) rejection performance were reduced, and the membrane did not lose its antifouling behavior. Herein, nanomembranes with different surface nanomorphologies were fabricated by a multi-step anodic oxidation process and characterized by scanning electron microscopy, atomic force microscopy, water contact angle analysis, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The membrane performance of samples was measured in 3D printed polyethylene terephthalate glycol flow cells replicating implantable artificial kidney models to determine their blood toxin removal and protein loss features. In collected urine mimicking samples, creatinine clearances and BSA rejections were measured by the spectrophotometric Jaffe method and high-performance liquid chromatography.

Aggregation behavior of nanoparticles: Revisiting the phase diagram of colloids.

Surface functionalization of metal nanoparticles (NPs), e.g., using peptides and proteins, has recently attracted a considerable attention in the field of design of therapeutics and diagnostics. The possibility of diverse functionalization allows them to selectively interact with proteins, while the metal core ensures solubility, making them tunable therapeutic agents against diseases due to mis-folding or aggregation. On the other hand, their action is limited by possible self-aggregation, which could be, however, prevented based on the full understanding of their phase diagram as a function of the environmental variables (temperature, ionic strength of the solution, concentration) and intrinsic characteristics (size, charge, amount, and type of functional groups). A common modeling strategy to study the phase behavior is to represent the NPs as spheres interacting via effective potentials implicitly accounting for the solvation effects. Their size put the NPs into the class of colloids, albeit with particularly complex interactions including both attractive and repulsive features, and a consequently complex phase diagram. In this work, we review the studies exploring the phases of these systems starting from those with only attractive or repulsive interactions, displaying a simpler disperse-clustered-aggregated transitions. The phase diagram is here interpreted focusing on the universal aspects, i.e., those dependent on the general feature of the potentials, and available data are organized in a parametric phase diagram. We then consider the potentials with competing attractive short range well and average-long-range repulsive tail, better representing the NPs. Through the proper combination of the attractive only and repulsive only potentials, we are able to interpret the appearance of novel phases, characterized by aggregates with different structural characteristics. We identify the essential parameters that stabilize the disperse phase potentially useful to optimize NP therapeutic activity and indicate how to tune the phase behavior by changing environmental conditions or the NP chemical–physical properties.

Synchronization in phase-coupled oscillator with attractive–repulsive frequencies

We investigate the synchronization behavior of a simple but quite useful mode of emergent collective behavior in ensembles of interacting dynamical elements, the Kuramoto model with attractive–repulsive frequencies features. Here, we derive a series of phase-locked (PL) states and identify the significant synchronization transition points analytically with exact boundary conditions. A detailed stability study of the model is also presented, as well as the bifurcation of the PL states set. Extremely, we show that these frequencies do not influence the stability of the system model, while the synchronization ability is considerably changed.

Circular motion of test particles around wormhole represented by exponential metric

The motion of photons, neutral and charged particles around wormhole described by exponential metric which is the solution of the Einstein-scalar field equations has been studied. It is also proven that the wormhole solution is a special case of the well-known JNW spacetime and that the scalar field corresponds to the phantom field which has the anti-gravitating repulsive feature. It is also shown that the characteristic radii, namely, innermost stable circular orbit (ISCO), marginally bound orbit (MBO) and photon sphere in the spacetime described by exponential metric are less than that obtained in the Schwarzschild spacetime. However, the size of the shadow of the wormhole is greater than the shadow of the Schwarzschild black hole. The energy efficiency in the spacetime described by exponential metric is relatively large than that in the Schwarzschild spacetime. Later it is assumed that the wormhole is embedded in the asymptotically uniform magnetic field which behaves similar to the dipole-like field near the origin. The dynamical motion of charged particles around the wormhole described by exponential metric implanted in the asymptotically uniform magnetic field has been studied assuming that charged particles are acted by gravitational and Lorentz forces, simultaneously. It is shown that the ISCO position for charged particle will be always less than that of neutral particle.

On a class of repulsive mixture models

Finite or infinite mixture models are routinely used in Bayesian statistical practice for tasks such as clustering or density estimation. Such models are very attractive due to their flexibility and tractability. However, a common problem in fitting these or other discrete models to data is that they tend to produce a large number of overlapping clusters. Some attention has been given in the statistical literature to models that include a repulsive feature, i.e., that encourage separation of mixture components. We study here a method that has been shown to achieve this goal without sacrificing flexibility or model fit. The model is a special case of Gibbs measures, with a parameter that controls the level of repulsion that allows construction of d-dimensional probability densities whose coordinates tend to repel each other. This approach was successfully used for density regression in Quinlan et al. (J Stat Comput Simul 88(15):2931–2947, 2018). We detail some of the global properties of the repulsive family of distributions and offer some further insight by means of a small simulation study.

Manipulation of bistability through the coupling strength in cavity magnon polaritons

Benefiting from the latest experiment of non-linearity in cavity magnon polaritons due to the magnetocrystalline anisotropy in the yttrium iron garnet (YIG) crystal, we theoretically propose a cavity magnonics model that can be used to study the bistable behaviors by changing the coupling strength, which presents the rich and interesting phenomena. In the case of resonance, the critical driving powers of the upper and lower polariton modes have the smaller values for the larger coupling strength but the larger values for the smaller coupling strength. In addition, the upper and lower polariton modes show the repulsive and attractive features, respectively, when the derivative of the coupling strength with respect to the position of the YIG sphere changes from positive to negative. Especially, the bistability of the lower polariton mode disappears when the driving power is strong enough. Our research broadens the means of manipulation of non-linearity in cavity magnon system, which provides a promising application for cavity spintronics and information processing.

Density regression using repulsive distributions

ABSTRACTFlexible regression is a traditional motivation for the development of non-parametric Bayesian models. A popular approach for this involves a joint model for responses and covariates, from which the desired result arises by conditioning on the covariates. Many such models involve the convolution of a continuous kernel with some discrete random probability measure defined as an infinite mixture of i.i.d. atoms. Following this strategy, we propose a flexible model that involves the concept of repulsion between atoms. We show that this results in a more parsimonious representation of the regression than the i.i.d. counterpart. The key aspect is that repulsion discourages mixture components that are near each other, thus favouring parsimony. We show that the conditional model retains the repulsive features, thus facilitating interpretation of the resulting flexible regression, and with little or no sacrifice of model fit compared to the infinite mixture case. We show the utility of the methodology by way of a small simulation study and an application to a well-known data set.

Evaluating the potential energy landscape over single molecules at room temperature with lateral force microscopy

One of the challenges of AFM, in contrast to STM, is that the measured signal includes both long-range and short-range components. The most accurate method for removing long-range components is to measure both on and off an adsorbate and to subtract the difference. This on-off method is challenging at room temperature due to thermal drift. By moving to a non-contact scheme in which the lateral component of the force interaction is probed, the measurement is dominated by short-range interactions. We use frequency-modulation lateral force microscopy to measure individual PTCDA molecules adsorbed on Ag/Si(111)-(3×3). By fitting the data to a model potential, we can extract the depth and width of the potential. When the tip is closer to the sample, a repulsive feature can be observed in the data.

Universal relations and normal phase of an ultracold Fermi gas with coexistings- andp-wave interactions

We study the universal relations and normal-phase thermodynamics of a two-component ultracold Fermi gas with coexisting $s$- and $p$-wave interactions. Due to the orthogonality of two-body wave functions of different scattering channels, the universal thermodynamic relations of the system appear to be direct summations of contributions from each partial-wave scattering channel. These universal relations are dictated by a set of contacts, which can be associated with either $s$- or $p$-wave interactions. Interestingly, due to the interplay of $s$- and $p$-wave interactions on the many-body level, the contacts, and hence all the relevant thermodynamic quantities, behave differently from those with only $s$- or $p$-wave interactions. These are manifest in our numerical calculations based on second-order virial expansions for $^{40}\mathrm{K}$ atoms under typical experimental parameters. A particularly interesting finding is that, due to the coexistence of $s$- and $p$-wave scatterings, the interaction energy of the repulsive branch features abrupt changes across the $p$-wave resonances. Our results can be readily checked experimentally for $^{40}\mathrm{K}$ atoms near the $198\phantom{\rule{0.28em}{0ex}}\mathrm{G}\phantom{\rule{4pt}{0ex}}p$-wave Feshbach resonance, where multiple partial-wave scatterings naturally coexist.

Conformal cylindrically symmetric spacetimes in modified gravity

We investigate cylindrically symmetric spacetimes in the context of [Formula: see text] gravity. We firstly attain conformal symmetry of the cylindrically symmetric spacetime. We obtain solutions to use features of the conformal symmetry, field equations and their solutions for cylindrically symmetric spacetime filled with various cosmic matters such as vacuum state, perfect fluid, anisotropic fluid, massive scalar field and their combinations. With the vacuum state solutions, we show that source of the spacetime curvature is considered as Casimir effect. Casimir force for given spacetime is found using Wald’s axiomatic analysis. We expose that the Casimir force for Boulware, Hartle–Hawking and Unruh vacuum states could have attractive, repulsive and ineffective features. In the perfect fluid state, we show that matter form of the perfect fluid in given spacetime must only be dark energy. Also, we offer that potential of massive and massless scalar field are developed as an exact solution from the modified field equations. All solutions of field equations for vacuum case, perfect fluid and scalar field give a special [Formula: see text] function convenient to [Formula: see text]-CDM model. In addition to these solutions, we introduce conformal cylindrical symmetric solutions in the cases of different [Formula: see text] models. Finally, geometrical and physical results of the solutions are discussed.

Theoretical studies on the spectroscopic properties of methyl mercaptan (CH3SH)

The properties of the ground and low-lying excited states of methyl mercaptan (CH3SH) are studied by using quantum chemistry methods. The geometric parameters and energies of the ground state and the triplet excited state are calculated in this work. It is shown that the calculated geometries of the ground and triplet state are stable and the triplet state potential energy surface has the repulsive feature. The calculated vertical excitation energies and vertical ionization potentials of methyl mercaptan are in best agreement with the experimental values. In addition, the vertical electron affinity and the adiabatic electron affinity of the CH3SH molecule are also calculated.

Auxiliary-field quantum Monte Carlo simulations of neutron matter in chiral effective field theory.

We present variational Monte Carlo calculations of the neutron matter equation of state using chiral nuclear forces. The ground-state wave function of neutron matter, containing nonperturbative many-body correlations, is obtained from auxiliary-field quantum Monte Carlo simulations of up to about 340 neutrons interacting on a 10(3) discretized lattice. The evolution Hamiltonian is chosen to be attractive and spin independent in order to avoid the fermion sign problem and is constructed to best reproduce broad features of the chiral nuclear force. This is facilitated by choosing a lattice spacing of 1.5 fm, corresponding to a momentum-space cutoff of Λ=414 MeV/c, a resolution scale at which strongly repulsive features of nuclear two-body forces are suppressed. Differences between the evolution potential and the full chiral nuclear interaction (Entem and Machleidt Λ=414 MeV [L. Coraggio et al., Phys. Rev. C 87, 014322 (2013).

Auxiliary-field quantum Monte Carlo simulations of neutron matter in chiral effective field theory

We present variational Monte Carlo calculations of the neutron matter equation of state using chiral nuclear interactions. The ground-state wavefunction of neutron matter, containing nonperturbative many-body correlations, is obtained from auxiliary-field quantum Monte Carlo simulations of up to about 340 neutrons interacting on a 10 discretized lattice. The evolution Hamiltonian is chosen to be attractive and spin-independent in order to avoid the fermion sign problem and is constructed to best reproduce broad features of chiral nuclear forces. This is facilitated by choosing a lattice spacing of 1.5 fm, corresponding to a momentum-space cutoff of 414 MeV/c, a resolution scale at which strongly repulsive features of nuclear two-body forces are suppressed. Differences between the evolution potential and the full chiral nuclear interaction are then treated perturbatively. Our results for the equation of state are compared to previous quantum Monte Carlo simulations which employed chiral two-body forces at next-to-next-to-leading order (N2LO). In addition we include the effects of three-body forces at N2LO, which provide important repulsion at densities higher than 0.02 fm, as well as two-body forces at N3LO.

“The Mesmeric Power”: Sarah Grand and the Novel of the Female Orator

The “feminist trilogy” novels of the English New Woman author Sarah Grand culminate, after a long and tortuous course, in a vision of the female public speaker, described by the narrator as “one of the first swallows of the woman’s summer” (Beth Book 527). Surprisingly, Grand’s works have not yet been placed into conversation with other novels portraying female orators. Her trilogy directly intervenes in this strain of fiction, which unfolds approximately from the 1848 Seneca Falls Convention to the propaganda novels of the militant suffragette era. By her own account, Grand’s first novel portrays a heroine typifying “not a perfect, but a transitional state . . . , a state which may have its repulsive features” (Ideala 5). By the trilogy’s final entry, Grand reframes a pejoratively cast “mesmeric power” for charismatic speech in the far more positive terms of what she calls “genius.” In the process, she successfully transforms the female public speaker from a curious anomaly to the harbinger of feminist triumph. In this essay, I consider the roughly half-century lineage of the novel of the female orator, which includes contributions by Nathaniel Hawthorne and George Eliot, followed by even more explicit treatments in Henry James, Grand, and Elizabeth Robins. What emerges from this consideration is a view of a contested strain of the nineteenth-century novel, within which the female orator was the object of satire and scrutiny before her successful emergence in the suffragette novel. Across the nineteenth century, iterations of this figure are alternately condemned or apotheosized through the use of the rhetoric of the mesmeric and the supernatural. The story of what I call the novel of the female orator—there was never a discrete genre for the female orator—begins with Nathaniel Hawthorne’s The Blithedale Romance (1852), and ends with the sudden evaporation of the suffragette novel at the outset of the First World War. Its development is intertwined with the “debate about female publicity” (Harman 2), chronicled in such studies as Barbara Leah Harman’s The Feminine Political Novel in Victorian England. Harman argues that the

Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2

Molecular dynamics simulations have been performed to study the potential of mean force (PMF) between passivated gold nanoparticles (NPs) in supercritical CO(2) (scCO(2)). The nanoparticle model consists of a 140 atom gold nanocore and a surface self-assembled monolayer, in which two kinds of fluorinated alkanethiols were considered. The molecular origin of the thermodynamics interaction and the solvation effect has been comprehensively studied. The simulation results demonstrate that increasing the solvent density and ligand length can enhance the repulsive feature of the free energy between the passivated Au nanoparticles in scCO(2), which is in good agreement with previous experimental results. The interaction forces between the two passivated NPs have been decomposed to reveal various contributions to the free energy. It was revealed that the interaction between capping ligands and the interaction between the capping ligands and scCO(2) solvent molecules cooperatively determine the total PMF. A thermodynamic entropy-energy analysis for each PMF contribution was used to explain the density dependence of PMF in scCO(2) fluid. Our simulation study is expected to provide a novel microscopic understanding of the effect of scCO(2) solvent on the interaction between passivated Au nanoparticles, which is helpful to the dispersion and preparation of functional metal nanoparticles in supercritical fluids.

An anti-Schwarzshild solution: Wormholes and scalar-tensor solutions

We investigate a static solution with an hyperbolic nature, characterised by a pseudo-spherical foliation of space. This space-time metric can be perceived as an anti-Schwarzschild solution, and exhibits repulsive features. It belongs to the class of static vacuum solutions termed "a degenerate static solution of class A" (see [1]). In the present work we review its fundamental features, discuss the existence of generalised wormholes, and derive its extension to scalar-tensor gravity theories in general.

Darwin and Religion: Correcting the Caricatures

Much has been written on the subject of Darwinism and religion, but rather less on the development of Darwin’s own thinking on religious matters and how it changed over time. What were his religious, or anti-religious, beliefs? Did he believe that his theory of evolution by natural selection was incompatible with belief in a Creator? Was it his revolutionary science that turned him into an agnostic? If not, what other considerations affected his judgment? The aim of this paper is to illuminate these questions and, in so doing, to correct some popular caricatures that frequently appear when the two words ‘science’ and ‘religion’ are juxtaposed. Darwin himself reflected deeply on the theological problem of suffering and justified his naturalism on the ground that it made the deity less directly responsible for the more repulsive features of creation. The deism that he espoused at the time of writing his Origin of Species also left its mark in his conviction that it would be demeaning to the deity to suggest that its purposes could not be achieved through natural causes. The diversity of the religious responses also corrects a common misperception that there was almost unanimous hostility from religious interests.

The impact of nanoscale chemical features on micron-scale adhesion: Crossover from heterogeneity-dominated to mean-field behavior

This work explores the impact of nanoscale surface heterogeneity, small relative to the effective contact area between two surfaces, on pairwise colloid-scale interactions. Polycation-based positive patches, of order 10 nm in diameter, arranged randomly and lying flat on otherwise negative substrates, were used to create surfaces whose competing attractive and repulsive features determined the net interactions with opposing surfaces. Lab experiments and simulations of the adhesion of gently flowing dilute negative microparticles varied particle size (0.5–2 μm), ionic strength ( κ −1 = 1–12 nm) and the density of heterogeneity on the collectors. Limiting behaviors from heterogeneity-controlled at high ionic strength to mean-field-like interactions at low ionic strength are reported. When heterogeneities are important, pairwise interactions are more attractive than predicted by average surface properties (e.g. per DLVO), and an adhesion threshold, describing the minimum average density of cationic features needed for single particle capture (adhesion), depends strongly on Debye length. In the opposite limit, the threshold becomes insensitive to the Debye length, and the average surface character approximates the interactions. An analytical treatment, reduced to a simple scaling argument predicts a −1/2 power-law dependence of the adhesion threshold on Debye length and particle size. A slightly stronger particle size dependence in experiments and simulations results from hydrodynamic contributions along with slight scaling differences in electrostatic, van der Waals, and hydrodynamic forces. An analogy to biological ligands is made for the heterogeneity-dominated limit: it is discovered, for this particular system, that engagement of as few as 20–100 cationic patches dictates particle adhesion (with details depending on flow, particle size, and ionic strength), similar to reports for selectin-mediated rolling of white blood cells during the inflammatory pathway. Also discovered is a heterogeneity-dependent crossover in the effect of ionic strength on particle capture, where added salt promotes particle adhesion in most cases but stabilizes the particles when the heterogeneity becomes relatively dense.

Olfactory experience modifies the effect of odour on feeding behaviour in a goal-related manner

Natural food odours elicit different behavioural responses in snails. The tentacle carries an olfactory organ, and it either protracts toward a stimulating carrot odour or retraces in a startle-like fashion away from a cucumber odour. The tentacle retraction to cucumber was still present after the snails were fed cucumber during inter-trial periods. Also, snails without any food experience displayed a longer latency to the first bite of cucumber than of carrot and rejected cucumber more often. After tasting these foods, the latency to carrot was not affected while the latency to and number of rejections of cucumber decreased. These results suggest that initial repulsive features of food odour can be only partially compensated by olfactory learning and feeding experience. In the present study, we demonstrated that an invertebrate can be repulsed or attracted by the same natural odour at the same time and that these behavioural responses are likely aimed at achieving different physiologically relevant goals.