Non-monotonic Profiles Research Articles

Antineuroinflammation activity of n-butanol fraction of Marsilea crenata Presl. in microglia HMC3 cell line.

Background Neuroinflammation is one of the main causes of neurodegenerative events. Phytoestrogen is a group compounds that have an estrogen-like structure or function. Phytoestrogen has a high potential to overcome neuroinflammation caused by estrogen deficiency in postmenopausal women. Marsilea crenata Presl. is a plant known to contain phytoestrogens. This research aimed to analyze the activity of an n-butanol fraction of M. crenata leaves in inhibiting the classical pathway activation of microglia HMC3 cell line to M1 polarity, which has proinflammatory characteristics. Methods Microglia HMC3 cell line was cultured in Eagle's minimum essential medium and induced with IFN-γ for 24 h to activate the cell to M1 polarity in 24-well microplates. The n-butanol fraction was added with various doses of 62.5, 125, and 250 ppm and genistein 50 μM as a positive control. The expression of major histocompatibility complex II (MHC II) as a marker was tested using a confocal laser scanning microscope. Results The result of MHC II measurement shows a significant difference in the MHC II expression in the microglia HMC3 cell line between the negative control and all treatment groups at p<0.05, indicating a non-monotonic dose-response profile. Conclusions The best dosage to inhibit MHC II expression was 250 ppm with the value of 200.983 AU. It is then concluded that n-butanol fraction of M. crenata leaves has antineuroinflammation activity due to its phytoestrogens.

Transport of Microplastic Particles in Saturated Porous Media

This study used polystyrene latex colloids as model microplastic particles (MPs) and systematically investigated their retention and transport in glass bead-packed columns. Different pore volumes (PVs) of MP influent suspension were first injected into the columns at different ionic strengths (ISs). The breakthrough curves (BTCs) were obtained by measuring the MP concentrations of the effluents. Column dissection was then implemented to obtain retention profiles (RPs) of the MPs by measuring the concentration of attached MPs at different column depths. The results showed that the variation in the concentrations of retained MPs with depth changed from monotonic to non-monotonic with the increase in the PV of the injected influent suspension and solution IS. The non-monotonic retention was attributed to blocking of MPs and transfer of these colloids among collectors in the down-gradient direction. The BTCs were well simulated by the convection-diffusion equation including two types of first-order kinetic deposition (i.e., reversible and irreversible attachment). However, this model could not well simulate the non-monotonic retention profiles due to the fact that the transfer of colloids among collectors was not considered. The results in this study are critical to developing models to simulate the fate and transport of MPs in porous media such as soil.

The profile of attentional modulation to visual features.

Although it is well established that feature-based attention (FBA) can enhance an attended feature, how it modulates unattended features remains less clear. Previous studies have generally supported either a graded profile as predicted by the feature-similarity gain model or a nonmonotonic profile predicted by the surround suppression model. To reconcile these different views, we systematically measured the attentional profile in three basic feature dimensions—orientation, motion direction, and spatial frequency. In three experiments, we instructed participants to detect a coherent feature signal against noise under attentional or neutral condition. Our results support a nonmonotonic hybrid model of attentional modulation consisting of feature-similarity gain and surround suppression for orientation and motion direction. For spatial frequency, we also found a similar nonmonotonic profile for higher frequencies than the attended frequency, but a lack of attentional modulation for lower frequencies than the attended frequency. The current findings can reconcile the discrepancies in the literature and suggest the hybrid model as a new framework for attentional modulation in feature space. In addition, a computational model incorporating known properties of spatial frequency channels and attentional modulations at the neural level reproduced the asymmetric attentional modulation, thus revealing a connection between surround suppression and the basic neural architecture of an early visual system.

Entropy preserving low dissipative shock capturing with wave-characteristic based sensor for high-order methods

Shock capturing procedures are required to stabilise numerical simulations of gas dynamics problems featuring non-isentropic discontinuities. In the present work, particular attention is focused on the expected non-monotonicity of the entropy profile across shock waves. A peculiar physical property which was not considered so far in the evaluation of shock capturing techniques. In the context of high-order spectral difference methods and using most recent discontinuity sensors based on the decay rate of the modes of the amplitude of characteristic waves, results show how the choice of a physical-based procedure (additional viscosity) returns a better description of shocks compared to approaches relying on the direct addition of a Laplacian term in the solved equations. Various canonical compressible flows are simulated, in one-, two-, and three-dimensional setups, to illustrate the performance and flexibility of the proposed approach. It is shown that the addition of a well-calibrated bulk viscosity is capable of smoothing out discontinuities without an excessive damping of vortical structures, preserving also specific compressible flow physics, as the non-monotonic entropy profiles through the shocks.

A High-Resolution Method to Map Out the γ/γ' Lattice Misfit in Ni-Based Superalloys

Lattice misfit is an essential parameter/property that affects the mechanical behavior of two-phase superalloys. Here we report a new method to use sub-micrometer-focused synchrotron X-ray beam to directly measure the γ/γ′ misfit in Ni-based superalloys. By combining polychromatic X-ray Laue diffraction and monochromatic energy scan, the lattice constants of both phases and the lattice misfit are mapped out at high spatial resolution, which is only limited by the X-ray beam size and scanning step size. We also developed data analysis algorithms to elevate the reliability of peak fitting and the precision and accuracy of lattice constants/misfit measurements. The success of our method is illustrated by uncovering the pronounced variations and non-monotonic profiles of the misfit and phase fractions throughout the heat affected zone in a laser 3D-printed Ni-based superalloy. The nano-hardness distribution in the transition region from the base metal to the cladding layers is empirically correlated with the phase fractions that are reflected by the diffraction peak intensities.

Non-monotonic retention profiles during axi-symmetric colloidal flows

The article studies axi-symmetric suspension and nano-colloidal transport with size-distributed fines in subterranean reservoirs and presents non-monotonic behaviour of the particle retention profiles (RPs). First, we introduce the averaging (upscaling) of the governing system for groundwater with fines over the probabilistic particle-size distribution, and use the analytical model for linear one-dimensional flows to match the laboratory experiments. One set of four tests provides breakthrough curves and post-mortem retention profiles; the results are closely matched. Another test gives retention profiles in three moments; high match was achieved for two moments. In all tests, the number of degrees of freedom of the experimental data array is higher than the number of tuned model parameters; therefore, the close match validates the mathematical model. Subsequently, we develop an upscaling procedure for axisymmetric flow, providing the transport equations for “averaged” particle population. Next, we solve the upscaled equations for suspension injection into a vertical well numerically. It was found out that the radial flows exhibit non-monotonic retention profiles (NRPs). The upscaled equations for axi-symmetric flow allow calculating well injectivity decline during suspension injection and the size of damaged zone, which is important for well stimulation design.

Traveling wave into an unstable state in dissipative oscillator chains

Coupled oscillators can exhibit complex spatiotemporal dynamics. Here, we study the propagation of nonlinear waves into an unstable state in dissipative coupled oscillators. To this, we consider the dissipative Frenkel–Kontorova model, which accounts for a chain of coupled pendulums or Josephson junctions and coupling superconducting quantum interference devices. As a function of the dissipation parameter, the front that links the stable and unstable state is characterized by having a transition from monotonous to non-monotonous profile. In the conservative limit, these traveling nonlinear waves are unstable as a consequence of the energy released in the propagation. Traveling waves into unstable states are peculiar of dissipative coupling systems. When the coupling and the dissipation parameter are increased, the average front speed decreases. Based on an averaging method, we analytically determine the front speed. Numerical simulations show a quite fair agreement with the theoretical predictions. To show that our results are generic, we analyze a chain of coupled logistic equations. This model presents the predicted dynamics, opening the door to investigate a wider class of systems.

Modeling excitability in cerebellar stellate cells: Temporal changes in threshold, latency and frequency of firing

Cerebellar stellate cells are inhibitory molecular interneurons that regulate the firing properties of Purkinje cells, the sole output of cerebellar cortex. Recent evidence suggests that these cells exhibit temporal increase in excitability during whole-cell patch-clamp configuration in a phenomenon termed runup. They also exhibit a non-monotonic first-spike latency profile as a function of the holding potential in response to a fixed step-current. In this study, we use modeling approaches to unravel the dynamics of runup and categorize the firing behavior of cerebellar stellate cells as either type I or type II oscillators. We then extend this analysis to investigate how the non-monotonic latency profile manifests itself during runup. We employ a previously developed, but revised, Hodgkin–Huxley type model to show that stellate cells are indeed type I oscillators possessing a saddle node on an invariant cycle (SNIC) bifurcation. The SNIC in the model acts as a “threshold” for tonic firing and produces a slow region in the phase space called the ghost of the SNIC. The model reveals that (i) the SNIC gets left-shifted during runup with respect to Iapp=Itest in the current-step protocol, and (ii) both the distance from the stable limit cycle along with the slow region produce the non-monotonic latency profile as a function of holding potential. Using the model, we elucidate how latency can be made arbitrarily large for a specific range of holding potentials close to the SNIC during pre-runup (post-runup). We also demonstrate that the model can produce transient single spikes in response to step-currents entirely below ISNIC, and that a pair of dynamic inhibitory and excitatory post-synaptic inputs can robustly evoke action potentials, provided that the magnitude of the inhibition is either low or high but not intermediate. Our results show that the topology of the SNIC is the key to explaining such behaviors.

Formation of nonmonotonic profiles of densities and fluxes of charged particles and ambipolar field reversal in argon dusty plasmas

In the present work, various scenarios of the spatial distributions of argon dusty plasma parameters are considered, focusing on the case of a large density of dust particles. It is shown that in this case a scenario with the inversion of the ambipolar field sign, considered in earlier studies by authors for plasma with heavy negative ions, can be realized. In this case, the ionization inside the dust cloud becomes small in comparison with the volume loss of charges inside the dust cloud, and the lack of charges is compensated by their arrival from the outer peripheral plasma region. This transition is accompanied by the phenomenon of the reversal of the sign of the radial electric field at the boundary of the dust cloud, and the formation of nonmonotonic profiles of the electron density with a shift of the maximum electron density from the center to the periphery. The radial stability of the dust particles cloud is provided by the balance of the increasing dust charge density gradient in the presence of the pushing out ambipolar field.

Explaining non-monotonic retention profiles during flow of size-distributed colloids

Non-monotonic retention profiles (NRP) have been observed in numerous studies of colloidal-nano flows in porous media. For the first time, we explain the phenomenon by distributed particle properties (size, shape, surface charge). We discuss colloidal-nano transport with fines attachment considering stochastically distributed filtration coefficient (particle attachment probability) and the area occupied by particle on the rock surface. The distributed dynamic system allows for exact averaging (upscaling) yielding a novel 3 × 3 system of equations for total concentrations. Besides the traditional equations of particle mass balance and capture-rate, the novel system contains a third independent equation for kinetics of site occupation during particle attachment. Ten laboratory tests exhibiting NRP have been successfully matched by the upscaled system for binary colloids. These laboratory tests with 7-parametric data arrays have been successfully matched by the 5-parameter model, which validates the model. The tuned parameter values belong to their common intervals. The laboratory data tuning was significantly simplified by deriving the exact solution of upscaled equations. These results provide valuable insights for understanding the transport mechanisms and environmental impact in colloidal-nano flows exhibiting NRP. Besides, the upscaled system and the analytical model for 1D transport facilitate interpretation of the laboratory coreflood data and allows for the laboratory-based predictions for 3D colloidal-nano transport at the field scale.

Numerical study on nonlinear growth of m/n = 3/1 double tearing mode in high Lundquist number regime

The nonlinear growth of the m/n = 3/1 double tearing mode (DTM) is numerically investigated in cylinder geometry with non-monotonic radial profiles of the equilibrium safety factor, having two q = 3 surfaces. The formation of plasmoids is found in high Lundquist number regime in such configurations for the first time. During the nonlinear growth of DTM, long and thin Sweet–Parker current sheets are formed near the original inner and outer rational surfaces and become tearing unstable for a large enough Lundquist number, leading to secondary and tertiary magnetic islands which accelerate the magnetic reconnection. The plasmoids also affect the magnetic topology at nonlinear mode saturation. The system can eventually saturate at a quasi-stationary state with small island pairs. The simulation results show that the Lundquist number and the distance between two rational surfaces have important effects on plasmoids formation.

A Zel’dovich–von Neumann–Döring-like detonation wave in a multi-temperature mixture

The detonation wave structure is analysed in a binary mixture undergoing a reversible chemical reaction represented by$A_{r}\rightleftharpoons A_{p}$. It is assumed that the flow satisfies the proper basic assumptions of the Zel’dovich–von Neumann–Döring (ZND) detonation model, namely the flow is one-dimensional and the shock is represented by a jump discontinuity, but the assumption of local thermodynamic equilibrium is disregarded. This allows us to deeply investigate the coupling between the detonation structure of overdriven detonations and its chemical kinetics. The thermodynamic non-equilibrium effects are taken into account in the mathematical description, using the model of a multi-temperature mixture developed within extended thermodynamics, which has been proved to be consistent with a kinetic theory approach. The reaction rate is then enriched with terms that take into account the temperatures of the constituents. The results show that the temperature difference between components within the detonation wave structure, which describes thermodynamic non-equilibrium, is driven by the chemical reaction. Numerical computations confirm the existence of non-monotonic profiles in the reaction zone of overdriven detonations which are sensitive to changes in the activation energy and reaction heat.

Effects of Turbulent Hyporheic Mixing on Reach‐Scale Transport

AbstractTurbulence causes rapid mixing of solutes and fine particles between open channel flow and coarse‐grained streambeds. Turbulent mixing is known to control hyporheic exchange fluxes and the distribution of vertical mixing rates in the streambed, but it is unclear how turbulent mixing ultimately influences mass transport at the reach scale. We used a particle‐tracking model to simulate local‐ and reach‐scale solute transport for a stream with coarse‐grained sediments. Simulations were first used to determine profiles of vertical mixing rates that best described solute concentration profiles measured within a coarse granular bed in flume experiments. These vertical mixing profiles were then used to simulate a pulse solute injection to show the effects of turbulent hyporheic exchange on reach‐scale solute transport. Experimentally measured concentrations were best described by simulations with a nonmonotonic mixing profile, with highest mixing at the sediment–water interface and exponential decay into the bed. Reach‐scale simulations show that this enhanced interfacial mixing couples in‐stream and hyporheic solute transport. Coupling produces an interval of exponential decay in breakthrough curves and delays the onset of power law tailing. High streamwise velocities in the hyporheic zone reduce mass recovery in the water column and cause breakthrough curves to exhibit steeper power law slopes than predictions from mobile‐immobile modeling theory. These results demonstrate that transport models must consider the spatial variability of streamwise velocity and vertical mixing for both the stream and the hyporheic zone, and new analytical theory is needed to describe reach‐scale transport when high streamwise velocities are present in the hyporheic zone.

Methods to Estimate Surface Roughness Length for Offshore Wind Energy

The northeastern coast of the U.S. is projected to expand its offshore wind capacity from the existing 30 MW to over 22 GW in the next decade, yet, only a few wind measurements are available in the region and none at hub height (around 100 m today); thus, extrapolations are needed to estimate wind speed as a function of height. A common method is the log-law, which is based on surface roughness length (z0). No reliable estimates of z0 for the region have been presented in the literature. Here, we fill this knowledge gap using two field campaigns that were conducted in the Nantucket Sound at the Cape Wind (CW) platform: the 2003–2009 “CW Historical”, which collected wind measurements on a meteorological tower at three levels (20, 41, and 60 m AMSL) with sonic and cup/vane anemometers, and the 2013–2014 IMPOWR (Improving the Mapping and Prediction of Offshore Wind Resources), which collected high-frequency wind and flux measurements at 12 m AMSL. We tested three different methods to calculate z0: (1) analytical method, dependent on friction velocity u∗ and a stability function ψ; (2) the Charnock relationship between z0 and u∗; and (3) a statistical method based on wind speed observed at the three levels. The first two methods are physical, whereas the statistical method is purely mathematical. Comparing mean and median of z0, we find that the median is a more robust statistics because the mean varies by over four orders of magnitude across the three methods and the two campaigns. In general, the median z0 exhibits little seasonal variability and a weak dependency on atmospheric stability, which was predominantly unstable (54–67%). With the goal of providing the most accurate estimates of wind speed near the hub height of modern turbines, the statistical method, despite delivering unrealistic z0 values at times, gives the best estimates of 60 m winds, even when the 5 m wind speed from a nearby buoy is used as the reference. The unrealistic z0 values are caused by nonmonotonic wind speed profiles, occurring about 41% of the time, and should not be rejected because they produce realistic fits. Furthermore, the statistical method outperforms the other two even though it does not need any stability information. In summary, if wind speed data from multiple levels are available, as is the case with vertically pointing floating lidar and meteorological towers, the statistical method is recommended, regardless of the seemingly unrealistic z0 values at times. If multilevel wind speeds are not available but advanced sonic anemometry is available at one level, the analytical method is recommended over Charnock’s. Lastly, if a single, constant value of z0 is sought after to characterize the region, we recommend the median from the statistical method, i.e., 6.09×10−3 m, which is typical of rough seas.

Human lifetime entropy in a historical perspective (1750–2014)

This paper uses Shannon’s entropy index to the base 2 to quantify the risk relative to the age at death in terms of bits (i.e. the amount of information revealed by tossing a fair coin). We first provide a simple decomposition of Shannon’s lifetime entropy index that allows us to analyse the determinants of lifetime entropy (in particular its relation with Wiener’s entropy of the event “death at a particular age conditional on survival to that age”) and to study how the risk about the duration of life is resolved as the individual becomes older. Then, using data on 37 countries from the Human Mortality Database, we show that, over the last two centuries, (period) lifetime entropy at birth has exhibited, in all countries, an inverted-U shape pattern with a maximum in the first half of the twentieth century (at 6 bits), and reaches, in the early twenty-first century, 5.6 bits for men and 5.5 bits for women. It is also shown that the entropy age profile shifted from a non-monotonic profile (in the eighteenth and nineteenth centuries) to a strictly decreasing profile (in the twentieth and twenty-first centuries).

Copper-induced non-monotonic dose response in Caco-2 cells.

Copper is an essential dietary micronutrient in humans for proper cell function; however, in excess, it is toxic. The human cell line Caco-2 is popular as an in vitro model for intestinal absorption and toxicology. This study investigated the response of exponentially growing Caco-2 cells to prolonged copper exposure (120h). An unexpected non-monotonic dose-response profile was observed in Caco-2 cells. Exposure to media supplemented with 3.125μM CuSO4 resulted in decreased cell yield vs. untreated. However, toxicity was progressively reduced from 90% at 3.125μM to 60% at 25μM. This effect was documented between 48 and 120h continuous exposure (p < 0.05). This triphasic toxicity curve was observed to be specific to copper in Caco-2 cells, as iron, manganese and zinc displayed monotonic dose-response profiles. Two inorganic copper forms, copper sulphate and copper chloride, were shown to conserve the non-monotonic dose-response curve. The triphasic effect was shown to be specific to Caco-2 cells. These results have implications for research investigating the effect of copper and other micronutrients using Caco-2 cells.

Characterizing droplet breakup rates of shear-thinning dispersed phase in microreactors

A two-phase flow predictive model with the integration of conservative level-set method (LSM) and Carreau-Yasuda constitutive equation was developed herein. The LSM was chosen as a potential interface capturing scheme for elucidating the interfacial phenomena including insight into the mechanism of shear-thinning droplets. In present paper, the dynamics of shear-dependent droplet emergence, growth, detachment and translocation in a Newtonian microsystem were examined via computational fluid dynamics (CFD) analysis. Dilute sodium carboxymethylcellulose (Na-CMC) solution was treated as dispersed phase (70 mPa.s < ηo < 10.2644 Pa.s) whereas the olive oil (68 mPa.s) was designated as continuous phase. Visualisation experiments were carried out and these laboratory data were used to validate the simulation results. Detailed 2D simulations were presented to examine systematically the impact of fluid properties on the droplet breakup rate at predefined flow rate ratio, Q of 0.05. The results yielded an inflection point in the dependence of droplet breakup rate on Na-CMC concentration was found in between the dilute and semi-dilute concentration regimes. This inflection point displays a non-monotonic profile which is mainly caused by the considerable viscosity effect of Na-CMC polymer when its concentration increases above a critical value (C > C*˜0.40 wt%). This striking behaviour highlights the importance of rheological effects in flows with a shear-dependent fluid under various flow conditions. The viscous effect of Na-CMC fluids substantially affects the manipulation over the droplet pinch-off time and production rate. Thus, it necessitate the control of the shear rate by adjusting the flow conditions and aspect ratio of microchannels.

Entanglement in anisotropic expanding spacetime

We study the effect of space anisotropy in the entanglement generated by expanding universe on spin 0 and 1/2 fields. For massive scalar field we find revivals of entanglement entropy vs momentum after decreasing from the maximum at k = 0. In massive Dirac field the effect is a slight distortion of the non-monotonic profile giving rise to the maximum of entanglement entropy at k > 0. More interestingly, massless field of both type can only get entangled through anisotropy, with a maximum of entanglement entropy occurring at k > 0.

A numerical study on reaction-induced radial fingering instability

The dynamics of $A+B\rightarrow C$ fronts is analysed numerically in a radial geometry. We are interested to understand miscible fingering instabilities when the simple chemical reaction changes the viscosity of the fluid locally and a non-monotonic viscosity profile with a global maximum or minimum is formed. We consider viscosity-matched reactants $A$ and $B$ generating a product $C$ having different viscosity than the reactants. Depending on the effect of $C$ on the viscosity relative to the reactants, different viscous fingering (VF) patterns are captured which are in good qualitative agreement with the existing radial experiments. We have found that, for a given chemical reaction rate, an unfavourable viscosity contrast is not always sufficient to trigger the instability. For every fixed Péclet number ($Pe$), these effects of chemical reaction on VF are summarized in the Damköhler number ($Da$) $-$ the log-mobility ratio ($R_{c}$) parameter space that exhibits a stable region separating two unstable regions corresponding to the cases of more and less viscous product. Fixing $Pe$, we determine $Da$-dependent critical log-mobility ratios $R_{c}^{+}$ and $R_{c}^{-}$ such that no VF is observable whenever $R_{c}^{-}\leqslant R_{c}\leqslant R_{c}^{+}$. The effect of geometry is observable on the onset of instability, where we obtain significant differences from existing results in the rectilinear geometry.

Anomalous absorption in ECRH experiments due to the parametric low-threshold excitation of localized UH waves

We describe the theoretical model which interprets the anomalous phenomena, i.e. the generation of backscattering signal observed in the ECRH experiments at TEXTOR, TCV, TJ-II, ASDEX-UG, LHD and FTU, as a consequence of the excitation of the parametric decay instability (PDI) leading to anomalous damping of the pump wave. The PDI power-threshold is shown to be extremely low due to the localization of both or one daughter upper hybrid (UH) waves in presence of a nonmonotonic (hollow) density profile, which is often observed in the ECRH experiments due to the magnetic island or the density pump-out effect. In the case of the extraordinary wave pump the model predicts substantial (up to 25%) anomalous absorption in the electron channel and explains the anomalous ion acceleration by the generation of secondary low frequency waves which directly transfer the pump power to the ion component. The possibility of anomalous absorption of the O-mode pump in the ECRH experiment due to the parametric excitation of trapped UH wave is also discussed and the anomalous absorption rate at the 10% level is predicted.