Intrinsic Velocity Research Articles

Resting coronary velocity and myocardial performance in women with impaired coronary flow reserve: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study

BackgroundWomen with evidence of ischemia and no obstructive coronary arteries (INOCA) often have coronary microvascular dysfunction (CMD) indicated by impaired coronary flow reserve (CFR) to adenosine. Low CFR is associated with an adverse prognosis, including incident heart failure. Because the CFR calculation relies on the baseline intrinsic coronary vasomotor flow velocity, a major determinate of CFR and the degree of variation in baseline flow alone may be an important contributor to risk of adverse outcomes in women with CMD. A better understanding of baseline blood flow in the setting of low CFR and its association with myocardial performance would be helpful. MethodsWe evaluated 74 women who underwent invasive coronary reactivity testing in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study and had impaired CFR (<2.32). We assessed the relationship between coronary artery baseline average peak velocity (bAPV) at rest and cardiac magnetic resonance imaging measures of left ventricular (LV) structure and function. ResultsWhen stratified as low (<22 cm/s) versus high (≥22 cm/s) bAPV, there were no differences in cardiovascular risk factors, coronary plaque burden, or LV structure. However, low bAPV was associated with higher LV end-diastolic filling pressure (P = 0.04), lower LV ejection fraction (P = 0.001), and differences in late systolic and diastolic strain rates (P = 0.01 to 0.05). ConclusionsIn women with impaired CFR, low resting coronary flow velocity is associated with more adverse myocardial performance, which may contribute to risk for adverse outcomes and particularly heart failure in women with CMD.

Intrinsic foot joints adapt a stabilized-resistive configuration during the stance phase

BackgroundThis study evaluated the 3D angle between the joint moment and the joint angular velocity vectors at the intrinsic foot joints, and investigated if these joints are predominantly driven or stabilized during gait.MethodsThe participants were 20 asymptomatic subjects. A four-segment kinetic foot model was used to calculate and estimate intrinsic foot joint moments, powers and angular velocities during gait. 3D angles between the joint moment and the joint angular velocity vectors were calculated for the intrinsic foot joints defined as follows: ankle joint motion described between the foot and the shank for the one-segment foot model (hereafter referred as Ankle), and between the calcaneus and the shank for the multi-segment foot model (hereafter referred as Shank-Calcaneus); joint motion described between calcaneus and midfoot segments (hereafter referred as Chopart joint); joint motion described between midfoot and metatarsus segments (hereafter referred as Lisfranc joint); joint motion described between first phalanx and first metatarsal (hereafter referred as First Metatarso-Phalangeal joint). When the vectors were approximately aligned, the moment was considered to result in propulsion (3D angle <60o) or resistance (3D angle >120o) at the joint. When the vectors are approximately orthogonal (3D angle close to 90°), the moment was considered to stabilize the joint.ResultsThe results showed that the four intrinsic joints of the foot are never fully propelling, resisting or being stabilized, but are instead subject to a combination of stabilization with propulsion or resistance during the majority of the stance phase of gait. However, the results also show that during pre-swing all four the joints are subject to moments that result purely in propulsion. At heel off, the propulsive configuration appears for the Lisfranc joint first at terminal stance, then for the other foot joints at pre-swing in the following order: Ankle, Chopart joint and First Metatarso-Phalangeal joint.ConclusionsIntrinsic foot joints adopt a stabilized-resistive configuration during the majority of the stance phase, with the exception of pre-swing during which all joints were found to adopt a propulsive configuration. The notion of stabilization, resistance and propulsion should be further investigated in subjects with foot and ankle disorders.

Numerical analysis of wave-induced current within the inhomogeneous coral reef using a refined SPH model

The effects of reef permeability on the spatial distributions of wave-induced current inside and outside the inhomogeneous coral reef body are investigated using an improved weakly compressible smoothed particle hydrodynamic (WCSPH) mixture model. The governing equations are formulated based on the two-phase mixture theory without considering the solid phase motion in terms of the intrinsic velocity and fluid density. The developed WCSPH mixture model is firstly validated by comparing the predicted results with the corresponding available data for Darcy seepage flow in a U-tube with permeable soil, wave damping over a permeable seabed and wave transformation over a permeable reef. The validated model is then applied to study the spatial distributions of wave-induced current inside and outside the permeable reef body with different porosity and porous layer thickness. Finally, a parametric study is carried out to investigate the effects of different porosity distribution types on wave-induced currents.

Segregation of Sn on migrating interfaces of ferrite recrystallisation: quantification through APT measurements and comparison with the solute drag theory

Solute atoms play an important role in grain boundary migration phenomena, which are critical for understanding the microstructural evolution in metals. Here we investigate the segregation of Sn at migrating boundaries during recrystallisation in a ferritic Fe-Si-Sn alloy using atom probe tomography. Experimental evidence demonstrated a solute depletion zone ahead of the moving interface. The behaviour of Sn was rationalized with the Cahn solute drag theory. A difference in segregation between two investigated migrating interfaces was observed and could be explained by a variation in either binding energy, intrinsic velocity of each interface or in driving force.

Comparisons Between the Field Lines Using an Accelerating and a Constant Solar Wind model

Magnetic field line mapping between the Sun and the Earth is important to trace the nonthermal particles. We generalize a recently developed mapping approach (B stepping) where this approach allows us to map the magnetic field lines by stepping along the local magnetic field direction. We employ an advanced solar wind model which includes acceleration, angular momentum conservation, and intrinsic non-radial velocities and magnetic fields at the inner boundary / source surface. We map the field lines using Wind spacecraft data for two solar rotation periods: one near a solar minimum between CR2118 and CR2119 and other CR1992 near a solar maximum. Maps using the accelerating solar wind model are compared with the maps using a constant solar wind model. On a broad scale, maps using two solar wind models for the same solar rotation periods are very similar. However, in a small scale, there are significant differences, e.g. differences are evident in connectivities, paths, and winding angles. In addition, field lines using the accelerating solar wind model are more azimuthally oriented for during the solar maximum. These differences demonstrate the significance of inclusion of the accelerating radial speed profile, intrinsic azimuthal velocity and magnetic field components.

Mapping Magnetic Field Lines for an Accelerating Solar Wind

Mapping of magnetic field lines is important for studies of the solar wind and the sources and propagation of energetic particles between the Sun and observers. A recently developed mapping approach is generalised to use a more advanced solar wind model that includes the effects of solar wind acceleration, non-radial intrinsic magnetic fields and flows at the source surface/inner boundary, and conservation of angular momentum. The field lines are mapped by stepping along local magnetic field $\bm{B}$ and via a Runge-Kutta algorithm, leading to essentially identical maps. The new model's maps for Carrington rotation CR 1895 near solar minimum (19 April to 15 May 1995) and a solar rotation between CR 2145 and CR 2146 near solar maximum (14 January to 9 February 2014) are compared with the published maps for a constant solar wind model. The two maps are very similar on a large scale near both solar minimum and solar maximum, meaning that the field line orientations, winding angles, and connectivity generally agree very well. However, close inspection shows that the field lines have notable small-scale structural differences. An interpretation is that inclusion of the acceleration and intrinsic azimuthal velocity has significant effects on the local structure of the magnetic field lines. Interestingly, the field lines are more azimuthal for the accelerating solar wind model for both intervals. In addition, predictions for the pitch angle distributions (PADs) for suprathermal electrons agree at the $90$ -- $95\%$ level with observations for both solar wind models for both intervals.

Towards sub-kpc scale kinematics of molecular and ionized gas of star-forming galaxies at z ∼ 1

We compare the molecular and ionized gas kinematics of two strongly lensed galaxies at z ∼ 1 that lie on the main sequence at this redshift. The observations were made with ALMA and MUSE, respectively. We derive the CO and [O II] rotation curves and dispersion profiles of these two galaxies. We find a difference between the observed molecular and ionized gas rotation curves for one of the two galaxies, the Cosmic Snake, for which we obtain a spatial resolution of a few hundred parsec along the major axis. The rotation curve of the molecular gas is steeper than the rotation curve of the ionized gas. In the second galaxy, A521, the molecular and ionized gas rotation curves are consistent, but the spatial resolution is only a few kiloparsec on the major axis. Using simulations, we investigate the effect of the thickness of the gas disk and effective radius on the observed rotation curves and find that a more extended and thicker disk smoothens the curve. We also find that the presence of a strongly inclined (&gt; 70°) thick disk (&gt; 1 kpc) can smoothen the rotation curve because it degrades the spatial resolution along the line of sight. By building a model using a stellar disk and two gas disks, we reproduce the rotation curves of the Cosmic Snake with a molecular gas disk that is more massive and more radially and vertically concentrated than the ionized gas disk. Finally, we also obtain an intrinsic velocity dispersion in the Cosmic Snake of 18.5 ± 7 km s−1 and 19.5 ± 6 km s−1 for the molecular and ionized gas, respectively, which is consistent with a molecular disk with a smaller and thinner disk. For A521, the intrinsic velocity dispersion values are 11 ± 8 km s−1 and 54 ± 11 km s−1, with a higher value for the ionized gas. This could indicate that the ionized gas disk is thicker and more turbulent in this galaxy. These results highlight the diversity of the kinematics of galaxies at z ∼ 1 and the different spatial distribution of the molecular and ionized gas disks. It suggests the presence of thick ionized gas disks at this epoch and that the formation of the molecular gas is limited to the midplane and center of the galaxy in some objects.

Evaluation of the propensity of strain burst in brittle granite based on post-peak energy analysis

The increasing demand for resources and depletion of near ground mineral resources caused deeper mining operations under high-stress rock mass conditions. As a result of this, strain burst, which is the sudden release of stored strain energy in the surrounding rock mass, has become more prevalent and created a considerable threat to workers and construction equipment. It is, therefore, imperative to understand how strain burst mechanism and stored excess strain energy are affected due to the high confinement in deep underground conditions. For this purpose, post-peak energy distributions for brittle rocks were investigated using a newly developed energy calculation method associated with acoustic emission (AE). A series of quasi-static uniaxial and triaxial compression tests controlled by the circumferential expansion were conducted. Snap-back behaviour known as Class-II behaviour associated with energy evolution and the material response under self-sustaining failure were analysed on granites under a wide range of confining pressures (0–60 MPa). The experimental results underline that the energy evolution characteristics are strongly linked to confinement. Stored elastic strain energy (dUE), energy consumed by dominating cohesion weakening (dΦCW) and energy dissipated during mobilisation of frictional failure (dΦFM) showed a rising trend as the confining pressure was increased. An intrinsic ejection velocity was proposed to express the propensity of strain burst that was purely determined by the excess strain energy released from Class II rock.

Cosmology from the Chinese Space Station Optical Survey (CSS-OS)

Abstract The Chinese Space Station Optical Survey (CSS-OS) is a planned full sky survey operated by the Chinese Space Station Telescope (CSST). It can simultaneously perform the photometric imaging and spectroscopic slitless surveys, and will probe weak and strong gravitational lensing, galaxy clustering, individual galaxies and galaxy clusters, active galactic nucleus, and so on. It aims to explore the properties of dark matter and dark energy and other important cosmological problems. In this work, we focus on two main CSS-OS scientific goals, i.e., the weak gravitational lensing (WL) and galaxy clustering surveys. We generate the mock CSS-OS data based on the observational COSMOS and zCOSMOS catalogs. We investigate the constraints on the cosmological parameters from the CSS-OS using the Markov Chain Monte Carlo method. The intrinsic alignments, galaxy bias, velocity dispersion, and systematics from instrumental effects in the CSST WL and galaxy clustering surveys are also included, and their impacts on the constraint results are discussed. We find that the CSS-OS can improve the constraints on the cosmological parameters by a factor of a few (even one order of magnitude in the optimistic case), compared to the current WL and galaxy clustering surveys. The constraints can be further enhanced when performing joint analysis with the WL, galaxy clustering, and galaxy–galaxy lensing data. Therefore, the CSS-OS is expected to be a powerful survey for exploring the universe. Since some assumptions may be still optimistic and simple, it is possible that the results from the real survey could be worse. We will study these issues in detail with the help of simulations in the future.

Electronic properties and carrier transport properties of low-dimensional aluminium doped silicene nanostructure

Abstract Unlike graphene which requires redesigned fabrication technique, silicene is predicted to be compatible with the silicon wafer technology. However, similar to graphene, the gapless properties of silicene hinder its application as field-effect transistors (FETs). By employing nearest neighbour tight-binding (NNTB) approach and Landuaer-Buttiker formalism, the analytical equations for electronic band structure , density of states (DOS), intrinsic carrier concentration, intrinsic velocity and ideal ballistic I–V characteristics have been derived. The simulated results using MATLAB show that a band gap of 0 . 78 e V has been induced in uniformly doped silicene with aluminium (AlSi3NW) in the zigzag direction. The device performance metrics extracted from the current-voltage (I–V) characteristics are subthreshold swing of 60 m V / d e c a d e and threshold voltage of 0.65 V under ideal conditions at room temperature. The results indicate that AlSi3NW device possesses good channel control and effective switching behaviour. The proposed model demonstrates that AlSi3 NW is a potential candidate for future nanoelectronic applications.

Using Project Loon Superpressure Balloon Observations to Investigate the Inertial Peak in the Intrinsic Wind Spectrum in the Midlatitude Stratosphere

AbstractLocation information from superpressure balloons flown by Project Loon provide an unprecedented opportunity to analyze wind fields in the midlatitude stratosphere. Horizontal velocity spectra from the balloons' quasi‐intrinsic frame of reference show clear evidence of a persistent peak in the intrinsic wind spectrum around the inertial frequency. In the Southern Hemisphere midlatitudes, peak‐to‐peak amplitudes of horizontal velocity perturbations (on the order of 20 m/s) are larger than those seen in previous superpressure balloon campaigns in polar regions and similar to those observed in vertical soundings in the midlatitudes. A rotary spectral analysis shows that near‐circular anticyclonic rotation of horizontal wind perturbations around the inertial frequency dominate at most times and locations. The strongest anticyclonic rotation is more common in balloon flight segments with weak zonal winds and during the austral summer. Flight segments with strong eastward zonal velocities during austral winter and spring are more likely to have mixed cyclonic and anticyclonic power around the inertial frequency. These results confirm previous model and radiosonde observations of the peak in horizontal kinetic energy at the inertial frequency and demonstrate they are associated with increased anticyclonic wave power indicative of near‐inertial oscillations or inertia‐gravity waves. Flight segments with mixed cyclonic and anticyclonic power around the inertial frequency display a continuum of wave power from planetary to gravity wave scales. These results help explain the divergence of actual and modeled balloon trajectories in previous studies and provide a baseline against which reanalysis or meteorological model realizations of the intrinsic velocity field can be assessed.

Evidence for Asymmetry in the Velocity Distribution of the Interstellar Neutral Helium Flow Observed by IBEX and Ulysses

Abstract We use observations from the Interstellar Boundary Explorer (IBEX) and Ulysses to explore the possibility that the interstellar neutral helium flowing through the inner solar system possesses an intrinsic non-Maxwellian velocity distribution. In fitting the IBEX and Ulysses data, we experiment with both a kappa distribution and a bi-Maxwellian, instead of the usual Maxwellian assumption. The kappa distribution does not improve the quality of fit to either the IBEX or Ulysses data, and we find lower limits to the kappa parameter of κ &gt; 12.1 and κ &gt; 6.0 from the IBEX and Ulysses analyses, respectively. In contrast, we do find evidence that a bi-Maxwellian improves fit quality. For IBEX, there is a clear preferred bi-Maxwellian solution with T ⊥/T ∥ = 0.62 ± 0.11 oriented about an axis direction with ecliptic coordinates (λ axis, b axis) = (57.°2 ± 8.°9, −1.°6 ± 5.°9). The Ulysses data provide support for this result, albeit with lower statistical significance. The axis direction is close to the interstellar medium (ISM) flow direction, in a heliocentric rest frame, and is therefore unlikely to be indicative of velocity distribution asymmetries intrinsic to the ISM. It is far more likely that these results indicate the presence of asymmetries induced by interactions in the outer heliosphere.

The Evolution and Origin of Ionized Gas Velocity Dispersion from z ∼ 2.6 to z ∼ 0.6 with KMOS3D ∗

Abstract We present the 0.6 &lt; z &lt; 2.6 evolution of the ionized gas velocity dispersion in 175 star-forming disk galaxies based on data from the full integral field spectroscopic survey. In a forward-modeling Bayesian framework including instrumental effects and beam-smearing, we fit simultaneously the observed galaxy velocity and velocity dispersion along the kinematic major axis to derive the intrinsic velocity dispersion σ 0. We find a reduction of the average intrinsic velocity dispersion of disk galaxies as a function of cosmic time, from σ 0 ∼ 45 km s−1 at z ∼ 2.3 to σ 0 ∼ 30 km s−1 at z ∼ 0.9. There is substantial intrinsic scatter ( ) around the best-fit σ 0–z relation beyond what can be accounted for from the typical measurement uncertainties (δσ 0 ≈ 12 km s−1), independent of other identifiable galaxy parameters. This potentially suggests a dynamic mechanism such as minor mergers or variation in accretion being responsible for the scatter. Putting our data into the broader literature context, we find that ionized and atomic+molecular velocity dispersions evolve similarly with redshift, with the ionized gas dispersion being ∼10–15 km s−1 higher on average. We investigate the physical driver of the on average elevated velocity dispersions at higher redshift and find that our galaxies are at most marginally Toomre-stable, suggesting that their turbulent velocities are powered by gravitational instabilities, while stellar feedback as a driver alone is insufficient. This picture is supported through comparison with a state-of-the-art analytical model of galaxy evolution.

Myocardial Stiffness by Intrinsic Cardiac Elastography in Patients with Amyloidosis: Comparison with Chamber Stiffness and Global Longitudinal Strain

The aim of this study was to test the hypothesis that intrinsic cardiac elastography can detect diastolic tissue abnormalities produced by cardiac amyloid infiltration and that measurements may have incremental value beyond traditional echocardiographic measures. The specific aims were (1) to evaluate the relationship between left ventricular myocardial stiffness (by elastography) and measures of diastolic chamber stiffness and systolic strain in patients with amyloidosis and (2) to compare their prognostic potential. We prospectively studied 67 patients with amyloidosis (cardiac amyloidosis, n=48; noncardiac amyloidosis, n=19) and 40 normal subjects. Patients underwent comprehensive echocardiography including measurement of left ventricular global longitudinal strain (GLS) by speckle-tracking. Intrinsic velocity propagation of myocardial stretch (iVP), a direct measure of myocardial elasticity, was quantified using intrinsic cardiac elastography. Chamber stiffness was evaluated from the end-diastolic pressure-volume relationships (P=αVβ). The major end point at follow-up was the composite of death, cardiac hospitalization, worsening heart failure, and stroke. The iVP of myocardial stretch was highest in patients with cardiac amyloidosis compared with those with noncardiac amyloidosis and normal subjects (3.2±1.0, 1.8±0.4, and 1.6±0.2m/sec, respectively; P<.0001) and correlated with chamber stiffness, function, and structure (β coefficient, operating chamber stiffness, GLS, wall thickness; P≤.001 for all). At follow-up (median, 2.6years), measures of left ventricular and myocardial stiffness, GLS, diastolic dysfunction grade, and N-terminal pro-brain natriuretic peptide were associated with excess events. At multivariate analysis, iVP of myocardial stretch remained an independent predictor of adverse events, incremental to GLS and N-terminal pro-brain natriuretic peptide. Measurements by cardiac elastography correlate with functional and structural derangements produced by cardiac amyloid infiltration but provide unique information that is incremental to conventional echocardiography.

What drives the velocity dispersion of ionized gas in star-forming galaxies?

Abstract We analyse the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation rates (SFRs), SFR surface densities ($\rm {\Sigma _{SFR}}$), stellar masses, and stellar mass surface densities ($\rm {\Sigma _{*}}$). By combining with high z galaxies, we found that there is a good correlation between the velocity dispersion and the SFR as well as $\rm {\Sigma _{SFR}}$. But the correlation between the velocity dispersion and the stellar mass as well as $\rm {\Sigma _{*}}$ is moderate. By comparing our results with predictions of theoretical models, we found that the energy feedback from star formation processes alone and the gravitational instability alone cannot fully explain simultaneously the observed velocity–dispersion/SFR and velocity–dispersion/$\rm {\Sigma _{SFR}}$ relationships.

Depth-Dependent Geoacoustic Inferences With Dispersion at the New England Mud Patch via Reflection Coefficient Inversion

Depth-dependent geoacoustic properties are inferred from wide-angle frequency-domain reflection-coefficient data at two sites with different mud-layer thicknesses on the New England Mud Patch. A trans-dimensional Bayesian inversion is employed to estimate geoacoustic properties and uncertainties from these data using the viscous grain shearing sediment model and spherical-wave reflection-coefficient predictions. Results near the thick-mud (SWAMI) site show a nearly uniform sound velocity over the upper approximately 9.2 m, followed by a transition layer with velocity increasing nonlinearly by $\sim$ 280 m/s over 1.8 m. At the thin-sediment (VC31-2) site, the velocity profile exhibits a similar transition layer. Estimates of intrinsic velocity and attenuation dispersion are also obtained. Over the measurement band of about 400–1300 Hz, the velocity in the fine-grained sediments (mud) at both sites varies by only a few meters per second, i.e., velocity is nearly independent of frequency. The attenuation of the fine-grained sediments at both sites follows a nearly linear frequency dependence. The geoacoustic inferences compare reasonably closely with independent measurements including core measurements, chirp-reflection data, and angle of intromission data.

A Second Galaxy Missing Dark Matter in the NGC 1052 Group

Abstract The ultra-diffuse galaxy NGC1052-DF2 has a very low velocity dispersion, indicating that it has little or no dark matter. Here we report the discovery of a second galaxy in this class, residing in the same group. NGC1052-DF4 closely resembles NGC1052-DF2 in terms of its size, surface brightness, and morphology; has a similar distance of ; and also has a population of luminous globular clusters extending out to from the center of the galaxy. Accurate radial velocities of the diffuse galaxy light and seven of the globular clusters were obtained with the Low Resolution Imaging Spectrograph on the Keck I telescope. The velocity of the diffuse light is identical to the median velocity of the clusters, , and close to the central velocity of the NGC 1052 group. The rms spread of the globular cluster velocities is very small at . Taking observational uncertainties into account we determine an intrinsic velocity dispersion of , consistent with the expected value from the stars alone ( ) and lower than expected from a standard NFW halo ( ). We conclude that NGC1052-DF2 is not an isolated case but that a class of such objects exists. The origin of these large, faint galaxies with an excess of luminous globular clusters and an apparent lack of dark matter is, at present, not understood.

Origin of a Massive Hyper-runaway Subgiant Star LAMOST-HVS1: Implication fromGaiaand Follow-up Spectroscopy

We report that LAMOST-HVS1 is a massive hyper-runaway subgiant star with mass of 8.3 Msun and super-Solar metallicity, ejected from the inner stellar disk of the Milky Way $\sim$ 33 Myr ago with the intrinsic ejection velocity of $568^{+19}_{-17}$ km/s (corrected for the streaming motion of the disk), based on the proper motion data from Gaia Data Release 2 (DR2) and high-resolution spectroscopy. The extremely large ejection velocity indicates that this star was not ejected by the supernova explosion of the binary companion. Rather, it was probably ejected by a 3- or 4-body dynamical interaction with more massive objects in a high-density environment. Such a high-density environment may be attained at the core region of a young massive cluster with mass of $\gtrsim 10^4$ Msun. The ejection agent that took part in the ejection of LAMOST-HVS1 may well be an intermediate mass black hole ($\gtrsim$ 100 Msun), a very massive star ($\gtrsim$ 100 Msun), or multiple ordinary massive stars ($\gtrsim$ 30 Msun). Based on the flight time and the ejection location of LAMOST-HVS1, we argue that its ejection agent or its natal star cluster is currently located near the Norma spiral arm. The natal star cluster of LAMOST-HVS1 may be an undiscovered young massive cluster near the Norma spiral arm.

Enhanced electroosmotic flow and ion selectivity in a channel patterned with periodically arranged polyelectrolyte-filled grooves

An enhanced electroosmotic flow through a surface-modulated microchannel is considered. The microchannel is modulated by periodically arranged rectangular grooves filled with polyelectrolyte materials. The flat surface of the walls is maintained at a constant charge density. A nonlinear model based on the Poisson–Nernst–Planck equations coupled with the Darcy–Brinkman–Forchheimer equation in the polyelectrolyte region and Navier–Stokes equations in the clear fluid region is adopted. Going beyond the widely employed Debye–Huckel linearization, we adopt numerical methods to elucidate the effect of pertinent parameters on electroosmosis in the patterned channel. The patterned microchannel results in an enhancement in the average EOF by creating an intrinsic velocity slip at the polyelectrolyte–liquid interface. An analytical solution of the EOF for a limiting case in which the groove width is much higher than the channel height is obtained based on the Debye–Huckel approximation. This analytical solution is in good agreement with the present numerical model when a low charge density and a thin Debye layer are considered. We have also established an analogy between the EOF in a polyelectrolyte-filled grooved-channel with the EOF in which the grooves are replaced by the charged slipping planes.

Asymmetric jet production in the active galactic nucleus of NGC 1052

Context. Few active galactic nuclei (AGN) reveal double-sided jet systems. However, these systems are crucial to understand basic physical properties of extragalactic jets. Aims. We address the questions whether jets in AGN are symmetric in nature, how well they are collimated on small scales, and how they evolve with time. Methods. We monitored the sub-parsec scale morphology of NGC 1052 with the Very Long Baseline Array at 43 GHz from 2005 to 2009. Results. A detailed study of 29 epochs show a remarkable asymmetry between both jets. A kinematic analysis of the outflows reveals higher apparent velocities for the eastern (approaching) jet as compared to the western (receding) jet, i.e., βej = 0.529 ± 0.038 and βwj = 0.343 ± 0.037, respectively. Contradictory to previous studies, we find higher flux densities for the western jet as compared to the eastern. The distribution of brightness temperature and jet width features well-collimated jets up to 1 mas distance to the dynamic center and a nearly conical outflow further outward. By combining flux density ratios and velocities of the jet flows, we were unable to find a combination of intrinsic velocities and inclination angles of the jets that is consistent for all four years of observation; this contradicts findings for symmetrically evolving jets. Spectral index maps between quasi-simultaneous 22 GHz and 43 GHz observations support the existence of an optically thick absorber covering the innermost ≃1.6 mas around the 43 GHz central feature and an optically thin jet emission with a spectral index of ≤−1. Conclusions. Our results fit into a picture in which we expect larger internal energy and/or magnetic flux in the western jet and higher kinetic energy in the eastern jet. Previous observations at lower frequencies have found slower velocities of the moving jet features as compared to this work. Considering the different velocities in different areas, we suggest a spine-sheath structure with a faster inner layer and slower outer layer.