Miracle-dz/UniFAR-FTUs huggingface dataset:
A note on “critical roughness height” and “transitional roughness”

An unrigorous but plausible analysis suggests that the concept of a critical roughness height, below which roughness does not affect a turbulent wall flow, is erroneous. The Oseen approximation implies that the effect of roughness on the additive constant in the logarithmic law of the wall should vary as the square of the roughness Reynolds number (specifically the roughness height in “wall units”). This is an important point in determining whether surfaces used in experiments at high unit Reynolds number can be regarded as hydraulically smooth. Attention is also called to the qualitative difference between Nikuradse’s measurements of friction factor in pipe flow with uniform-size sand-grain roughness in the “transitional” range of Reynolds number and the data correlation in the Moody chart of 1944; the latter was derived from tests on miscellaneous real-life rough surfaces in the 1930s. Nearly all textbooks on elementary fluid dynamics present, but practically none discuss, this difference. Nikuradse’s m.
Pyroelectric response mechanism of barium strontium titanate ceramics in dielectric bolometer mode: The underlying essence of the enhancing effect of direct current bias field

Pyroelectric response mechanism of Ba0.70Sr0. 30TiO3 ceramics under dielectric bolometer (DB) mode was investigated by dielectric and pyroelectric properties measurement. The variations of total, intrinsic, and induced pyroelectric coefficients (ptot, pint, pind) with temperatures and bias fields were analyzed. pint plays the dominant role to ptot through most of the temperature range and pind will be slightly higher than pint above T0. The essence of the enhancing effect of DC bias field on pyroelectric coefficient can be attributed to the high value of pint. This mechanism is useful for the pyroelectric materials (DB mode) applications.
Synergistic mitigation of the Rayleigh–Taylor instability in Z-pinch implosions by sheared axial flow and finite Larmor radius effect

The synergistic stabilizing effect of sheared axial flow (SAF) and finite Larmor radius (FLR) on the Rayleigh–Taylor instability in Z-pinch implosions is considered by means of the magnetohydrodynamic (MHD) equations. The SAF is introduced into the MHD equations in a conventional way and the FLR is introduced in the same way as used by Roberts and Taylor [Phys. Rev. Lett. 8, 197 (1962)]. Therefore, the linearized MHD equations include both SAF and FLR effects. The results indicate that in the whole wavenumber region the synergistic effect of FLR and SAF can mitigate the Rayleigh–Taylor instability; at low flow velocity the synergistic effect of FLR and the SAF is slightly (∼10%) stronger than the mitigation effect of FLR alone and remarkably stronger than the mitigation effect of the SAF alone; at higher flow velocities in the large wavenumber region (for normalized wavenumber κ>2.4) the synergistic effect of FLR and the SAF is remarkably stronger than the mitigation effect due to either one of the two, r.
Numerical Modeling of the Dynamics and Microphysics of Warm Cumulus Convection

Abstract Two cumulus cloud models in two space dimensions are presented; one is a bulk physical model without microphysics and the other includes the microphysical processes such as nucleation, diffusional growth of cloud droplets, stochastic coalescence, and fallout of raindrops. Some numerical aspects of the models are discussed; in particular, a method is described which allows long time steps to be used for the calculation of condensation in regions of relatively old droplet populations. The bulk-physical and microphysical models are compared for a non-precipitation case. The numerical results revealed that the inclusion of microphysics had little effect on the whole cloud dynamics, a result which considerably differs from that of Arnason and Greenfield. The microphysical model produced hi-modal spectra of droplets through the interaction of a mid-level nucleation region, which corresponds to the base of an upper intense thermal, and the vertical advection and diffusion of existing droplets from a low.
Immunomodulatory Effects of Mesenchymal Stem Cell-Derived Extracellular Vesicles in Allergic Airway Disease

Mesenchymal stem cells (MSCs) have been reported as promising candidates for the treatment of various diseases, especially allergic diseases, as they have the capacity to differentiate into various cells. However, MSCs itself have several limitations such as creating a risk of aneuploidy, difficulty in handling them, immune rejection, and tumorigenicity, so interest in the extracellular vesicles (EVs) released from MSCs are increasing, and many studies have been reported. Previous studies have shown that extracellular vesicles (EVs) produced by MSCs are as effective as the MSCs themselves in suppression of allergic airway inflammation through the suppression of Th2 cytokine production and the induction of regulatory T cells (Treg) expansion. EVs are one of the substances secreted by paracrine induction from MSCs, and because it exerts its effect by delivering contents such as mRNA, microRNA, and proteins to the receptor cell, it can reduce the problems or risks related to stem cell therapy. This article reviews the immunomodulatory properties of MSCs-derived EVs and their therapeutic implications for allergic airway disease.
Factors Aﬀecting Post Acceptance of E-Learning Platform in times of COVID-19: An Evidence from an Emerging Economy

COVID 19-has changed the landscape and the method to conduct daily tasks since past two years. Considering the restrictions and lockdowns enforced by the government, educational institutes were greatly impacted. It became challenging for the teachers to complete the courses on required schedule and to teach the students. The students suffered due to constant lockdown and the restriction enforced by the government regarding the use of physical spaces. Amidst such time adopting e-learning platform became essential as it can help in completing the curriculum on time and to cover the incurred loss. This study was aimed at analyzing the factors that is PU, PEOU, SE, PE, CM, and PDR and is impact on the adoption of e-learning platform by students and teachers. A survey was conducted forcollection of data for this study. A total of 250 participants constituted the sample size for this research work. The results were analyzed in PLS-SEM software. The results concluded that (PE) , perceived usefulness, perceived daily routine and critical masshad positive relation and significant relationship on the adoption of e-learning platform. Whereas self-efficiency and (PEU) have positive and insignificant relationship on adoption of e-learning platform.
Extended perceptual spaces for pitched and percussive timbres

A series of listening tests attempted to better isolate higher‐order perceptual dimensions of timbre by building on past findings showing that spectral centroid and rise time represent principal acoustic correlates of the primary timbral dimensions. Listeners with varying levels of musical training rated the timbral similarity of three sets of pitched and percussive instrument sounds that were equated for centroid and rise time using signal processing techniques. Multidimensional scaling analyses yielded two‐ and three‐dimensional perceptual spaces for the three stimulus sets. Several aspects of the spectral fine structure of the timbres correlated with the dimensions of these spaces, but the nature of the acoustic correlate varied somewhat depending on the stimulus set in which the timbre was presented. The results suggest that additional perceptual dimensions of timbre exist, but that their precise acoustic correlates are context dependent and therefore less perceptually ‘‘primary’’ than centroid and ri.
Photoconductivity and optical properties of silicon coated by thin TiO2 film in situ doped by Au nanoparticles

Light trapping enhancement by plasmonic‐active metal nanoparticles (NPs) is believed to be a promising approach to increase silicon‐based solar cell efficiency. Therefore, we investigated TiO2 films in situ doped by Au NPs (TiO2:AuNPs) deposited by spin coating on a silicon substrate. Photoconductivity and optical properties of the TiO2:AuNPs/Si structures were studied in comparison with those of TiO2/Si reference samples. We found that an introduction of the 40–50 nm diameter AuNPs into the antireflective TiO2 layer deteriorates the antireflection properties and decreases the external yield of photogeneration of charge carriers. This is due to an increase of the layer reflection in the red‐IR part of the spectrum, and due to the parasitic absorption of light by AuNPs in the blue‐green part. Charge carrier recombination effect at the TiO2:AuNPs/Si interface is also found to decrease the external yield. We conclude that the TiO2:AuNPs layers could potentially be applied on the rear but not on the front side of Si solar cells.
Tip clearance effects in a turbine rotor : Part I : Pressure field and loss

This paper presents an experimental investigation of the effects of the tip clearance flow in an axial turbine rotor. The effects investigated include the distribution and the development of the pressure, the loss, the velocity, and the turbulence fields. Theseflow fields were measured using the techniques of static pressure taps, rapid response pressure probes, rotating five-hole probes, and Laser Doppler Velocimeter. Part I of this paper covers the loss development through the passage, and the pressure distribution within the passage, on the blade surfaces, on the blade tip, and on the casing wall. Regions with both the lowest pressure and the highest loss indicate the inception and the trace of the tip leakage vortex. The suction effect of the vortex slightly increases the blade loading near the tip clearance region. The relative motion between the turbine blades and the casing wall results in a complicated pressure field in the tip region. The fluid near the casing wall experiences a considerable pressure difference across the tip. The highest total pressure drop and the highest total pressure loss were both observed in the region of the tip leakage vortex, where the loss is nearly twice as high as that near the passage vortex region. However, the passage vortex produces more losses than the tip leakage vortex in total. The development of the loss in turbine rotor is similar to that observed in cascades. Part II of this paper covers the velocity and the turbulence fields.
Depth and latitude dependence of solar rotation

A 15-day time series of spatially resolved full-disk Doppler observations is used to measure the dependence of p-mode oscillation frequencies on the mode azimuthal order m. This dependence may be used to infer the depth and latitude variation of the solar rotation. The results are consistent with solar models that have approximately the surface latitudinal differential rotation within the convection zone, but no latitudinal differential rotation in the radiative interior. The data do not make it possible to distinguish between models for which the angular rotation rate within the convection zone is a function of latitude alone, and those for which it is constant on cylindrical surfaces. Weak evidence for a pole-equator asymmetry in the sound speed is found. 18 references.
The influence of Coulomb centers located in HfO2/SiO2 gate stacks on the effective electron mobility

In this paper, we present an experimental and theoretical study on the reduction in electron mobility in metal-oxide-semiconductor field-effect transistors (MOSFETs) with a TiN/HfO2/SiO2 gate stack. Through low temperature mobility measurements down to 100 K, it is shown that the scattering mechanism responsible for the mobility degradation in MOSFETs with gate stack integrating HfO2 material is weakly dependent on temperature. Furthermore, the effect of vicinity of HfO2 is demonstrated through two SiO2 interfacial layers (ILs) of thicknesses 1 and 2 nm showing that the electron mobility is further reduced by decreasing the IL thickness. Both of these observations lead us to identify the remote-Coulomb scattering (RCS) as being the main factor limiting low-field mobility. In order to investigate more deeply the effect of Coulomb centers located in the gate stack, we have developed and used a RCS-limited mobility model. This model includes image charge, inversion layer quantization with upper subbands, a f.
Collective stabilisation of multi-agent dynamical systems with single agent control

This paper studies the stability and performance of a multi-agent system composed of identical linear time-invariant dynamic agents, when only a single agent in the system is controlled by an exogenous single-input–single-output controller. It is shown that a wide class of multi-agent systems can be collectively stabilised by controlling any single agent. The tracking performance of such a closed-loop system, however, has a fundamental limitation. It is also shown that generically not only the output of controlled agent but either the sum or average of all agent outputs can be used for an exogenous controller. An example is presented to illustrate theoretical results developed in this study.
A HIGH-RESOLUTION MASS MAP OF GALAXY CLUSTER SUBSTRUCTURE: LensPerfect ANALYSIS OF A1689

We present a strong lensing (SL) mass model of A1689 which resolves substructures an estimated 25 kpc across within the central ∼400 kpc diameter. We achieve this resolution by perfectly reproducing the observed (strongly lensed) input positions of 168 multiple images of 55 knots residing within 135 images of 42 galaxies. Our model makes no assumptions about light tracing mass, yet we reproduce the brightest visible structures with some slight deviations. A1689 remains one of the strongest known lenses on the sky, with an Einstein radius of RE = 47. ″0 ± 1. ″2 (143+3−4 kpc) for a lensed source at zs = 2. We find that a single Navarro–Frenk–White (NFW) or Sérsic profile yields a good fit simultaneously (with only slight tension) to both our SL mass model and published weak lensing (WL) measurements at larger radius (out to the virial radius). According to this NFW fit, A1689 has a mass of Mvir = 2.0+0.5−0.3 × 1015 M☉ h−170 (M200 = 1.8+0.4−0.3 × 1015 M☉ h−170) within the virial radius rvir = 3.0 ± 0.2 Mpc h−170 (r200 = 2.4+0.1−0.2 Mpc h−170), and a central concentration cvir = 11.5+1.5−1.4 (c200 = 9.2 ± 1.2). Our SL model prefers slightly higher concentrations than previous SL models, bringing our SL + WL constraints in line with other recent derivations. Our results support those of previous studies which find A1689 has either an anomalously large concentration or significant extra mass along the line of sight (perhaps in part due to triaxiality). If clusters are generally found to have higher concentrations than realized in simulations, this could indicate that they formed earlier, perhaps as a result of early dark energy.
Mechanical and electrical properties of carbon‐nanotube‐reinforced Cu–Ti alloy matrix composites

It is known that there is a very weak bonding between carbon nanotube (CNT) and pure copper matrix since copper is known to be naturally nonwetting with CNT. In this study, the titanium is applied as a matrix‐alloying element and the CNT‐reinforced copper–titanium (Cu–Ti) alloy composites (Cu–Ti/CNT) are fabricated by a powder metallurgical method. The results show that Cu–Ti/CNT composites evidently exhibit enhanced interfacial bonding and yield strength while retaining the electronic conductivity of Cu/CNT composites. Improvements in interfacial bonding and mechanical properties of the composites are attributed to the formation of a thin transition layer of TiC at the interface between CNTs and Cu–Ti matrix.
An Elliptic Curve Based Multi-Signature Scheme For Wireless Network

In this paper we propose a design of multi-signature scheme for wireless networks and it isbased on an improved elliptic curve digital signature algorithm. Wireless communicationsperform better with the elliptic curve cryptosystem because of their efficiency regardingspeed, low bandwidth and high security. Multi-Signature is the special purpose signaturein which multiple signer jointly sign a message or messages. Security of the scheme relieson elliptic curve discrete logarithm problem (ECDLP). Our scheme is more secure and hasimproved efficiency of computation than with the existing schemes.
Effect of combined particle-phase diffusivity and viscosity on the compressible boundary layer of a particulate suspension over a flat plate

Boundary layer flow and heat transfer of pure and contaminated fluids have been an attractive research area for many investigators for many years due to its direct application in the aerospace, automotive, petroleum, geothermal, and many other industries. Here, a mathematical dilute fluid-particle suspension model governing steady, laminar, compressible, boundary layer flow and heat transfer over a semi-infinite flat plate based on the Eulerian or continuum approach is developed. The model accounts for both particulate viscous and diffusive effects. Both the fluid and the particle phases are assumed to have general power-law viscosity-temperature relations. For the case of finite particle-phase viscosity, a general boundary condition borrowed from rarefied gas dynamics is used for the particle phase at the surface. Uniform and nonuniform particle-phase slip coefficients are investigated. Numerical solution of the governing equations is obtained by an implicit, iterative, tridiagonal finite difference method. Graphical results for the displacement thicknesses and skin-friction coefficients of both phases as well as the wall heat transfer are presented for various parametric conditions.
The Utility of Perirenal Fat in Determining the Risk of Onset and Progression of Diabetic Kidney Disease

Background Perirenal fat (PRF) has multiple effects on the kidney through its physical structure and adipocytokine-secreting ability. The present study explored the relationship between PRF thickness and the onset and progression of albuminuria in patients with diabetes. Methods In the cross-sectional analysis, we screened 959 patients from 8764 subjects with type 2 diabetes mellitus (T2DM) who met the inclusion criteria and measured their perirenal fat thickness (PFT) using color Doppler ultrasound. A group of laboratory indexes were included in the analysis models. In a longitudinal study, a total of 218 patients with a baseline UACR <30 mg/g were included in the follow-up study. Results In a cross-sectional analysis, patients with diabetes and higher PFT presented with higher albuminuria. Multiple logistic regression analysis indicated that PFT was an independent risk factor for the degree of albuminuria in patients with T2DM (odds ratio = 4.186, 95%CI: 2.290–7.653, P < 0.001). In a longitudinal study, 218 albuminuria-free patients with T2DM at the baseline were followed up for a mean of 12.3 months. Based on the cutoff value from the ROC diagnostic test in the cross-sectional study, patients were divided into two groups: higher PFT (H-PFT) and lower PFT (L-PFT). Kaplan–Meier survival curve analysis showed that H-PFT was associated with a higher incidence of albuminuria than L-PFT (log-rank test, χ2 = 4.522, P = 0.033). Cox regression analysis showed that PFT was a risk factor for the earlier onset of albuminuria (hazard ratio 2.83, 95% CI: 1.34–4.88, P < 0.001). Conclusions PRF evaluated by color Doppler ultrasound is an easy and reliable tool for predicting the onset and progression of albuminuria in patients with T2DM.
Evidence for long period Alfvén waves in the inner solar system

Magnetic field and plasma data of Helios 1 and 2 between 0.3 and 1 AU have been used to investigate the Alfvenic character of the solar wind fluctuations with periods above 1 hour. Clear evidence for the existence of very long period Alfvenic waves, up to about 15 hours (in the spacecraft frame) close to the sun, has been obtained. The observations at different heliocentric distances suggest that the longest wavelengths are removed from the Alfvenic regime leaving the sun. 19 references.
Distributions of Tree Comparison Metrics—Some New Results

Measures of dissimilarity (metrics) for comparing trees are important tools in the quantitative analysis of evolutionary trees, but many of their properties are incompletely known. The present paper reports formulae for the distributions of three classes of tree comparison metrics: the partition (or symmetric difference) metric, the quartet metric (which compares subsets of four taxa), and a metric based on path-length differences between pairs of taxa. The properties studied include the mean and variance for several underlying distributions of trees, the range, the effect of the number of taxa, and methods of calculation. Three basic theorems and their proofs are reported, one for each class of tree comparison metric
On the Sensitivity of Bayes Factors to the Prior Distributions

The Bayes factoris a Bayesian statistician's tool for model selection. Bayes factors can be highly sensitive to the prior distributions used for the parameters of the models under consideration. We discuss an approach for studying the sensitivity of the Bayes factor to the prior distributions for the parameters in the models being compared. The approach is found to be extremely useful for nested models; it has a graphical flavor making it more attractive than other common approaches to sensitivity analysis for Bayes factors.
NGC 7097: THE ACTIVE GALACTIC NUCLEUS AND ITS MIRROR, REVEALED BY PRINCIPAL COMPONENT ANALYSIS TOMOGRAPHY

Three-dimensional spectroscopy techniques are becoming more and more popular, producing an increasing number of large data cubes. The challenge of extracting information from these cubes requires the development of new techniques for data processing and analysis. We apply the recently developed technique of principal component analysis (PCA) tomography to a data cube from the center of the elliptical galaxy NGC 7097 and show that this technique is effective in decomposing the data into physically interpretable information. We find that the first five principal components of our data are associated with distinct physical characteristics. In particular, we detect a low-ionization nuclear-emitting region (LINER) with a weak broad component in the Balmer lines. Two images of the LINER are present in our data, one seen through a disk of gas and dust, and the other after scattering by free electrons and/or dust particles in the ionization cone. Furthermore, we extract the spectrum of the LINER, decontaminated from stellar and extended nebular emission, using only the technique of PCA tomography. We anticipate that the scattered image has polarized light due to its scattered nature.
Heisenberg Fields which Vanish on Domains of Momentum Space

If a local Heisenberg field vanishes, or where appropriate has an infinite zero, on one of the momentum space domains A, p2 = —a2; B, 0 ≤ p2 M2, then the field is a generalized free field. Counter examples show that this conclusion cannot be drawn if the field vanishes on the momentum space domains D, 0 ≤ M12 < p2 < M22, p ≠ 0; or E, p = 0. It follows that if two fields in the same Borchers class are equal on one of the domains A, B, or C, then the fields differ at most by a generalized free field in their Borchers class.