Miracle-dz/UniFAR-FTUs huggingface dataset:
Understanding dielectrophoretic trapping of neuronal cells: modelling electric field, electrode-liquid interface and fluid flow

By application of dielectrophoresis neuronal cells can be trapped successfully. Several trapping experiments have been performed using a quadrupole electrode structure at different amplitudes (1, 3, and 5? Vpp) and frequencies (10-50? MHz). Due to the high conductivity of the suspending medium negative dielectrophoretic forces are created. The dielectrophoretic force is determined by the gradient of the electric field. However, the electrode-liquid interfaces are responsible for decreased electric field strengths, and thus decreased field gradients, inside the medium, especially at lower frequencies. Circuit modelling is used to determine the frequency-dependent electric field inside the medium. The creation of an electric field in high conductivity of the medium results in local heating, which in turn induces fluid flow. This flow also drives the neurons and was found to enhance the trapping effect of the dielectrophoretic force. With the use of finite element modelling, this aspect was investigated. The results show that the dielectrophoretic force is dominating just above the substrate. When the upward dielectrophoretic force is large enough to levitate the cells, they may be dragged along with the fluid flow. The result is that more cells may be trapped than expected on the basis of dielectrophoresis alone.
Kelvin-Helmholtz instability in a Hele-Shaw cell

A linear stability analysis is presented for the Kelvin–Helmholtz instability in a Hele-Shaw cell, an analysis based on the Navier–Stokes equation to improve on the previous Euler–Darcy study that Gondret and Rabaud [Phys. Fluids 9, 3267 (1997)] made of their own experiments.
The Boltzmann equation an d the one-fluid hydromagnetic equations in the absence of particle collisions

Starting from the Boltzmann equation for a completely ionized dilute gas with no interparticle collision term but a strong Lorentz force, an attempt is made to obtain one-fluid hydromagnetic equations by expanding in the ion mass to charge ratio. It is shown that the electron degrees of freedom can be replaced by a macroscopic current, but true hydrodynamics still does not result unless some special circumstance suppresses the transport of pressure along magnetic lines of force. If the longitudinal transport of pressure is ignored, a set of self-contained one-fluid hydromagnetic equations can be found even though the pressure is not a scalar.
Generating Intra- and Inter-Class Iris Images by Identity Contrast

Iris recognition is one of the most accurate and reliable biometric technologies. However, due to the high collection costs and privacy of the iris, it is difficult to build a large-scale iris image database for training iris recognition models. This paper proposes a novel iris image generation algorithm which can produce numerous intra- and inter-class iris images. By using contrastive learning, we disentangle identity-related features (e.g., iris texture, left or right eye) and condition-variant features (e.g., pupil size, iris exposure ratio) in the generated images. This disentanglement facilitates identity control over synthetic iris images. Since the iris has the multi-degree-of-freedom (MDOF) topology and high-entropy texture, we specially design the dual-channel input protocol to separate the topology and texture of the iris, so that the generator can infer multi-condition iris images while maintaining the unique texture details. Extensive experiments demonstrate that the proposed approach achieves impressive performance in both image quality and identity representation.
Differential calculus on the space of Steiner minimal trees in Riemannian manifolds

It is proved that the length of a minimal spanning tree, the length of a Steiner minimal tree, and the Steiner ratio regarded as functions of finite subsets of a connected complete Riemannian manifold have directional derivatives in all directions. The derivatives of these functions are calculated and some properties of their critical points are found. In particular, a geometric criterion for a finite set to be critical for the Steiner ratio is found. This criterion imposes essential restrictions on the geometry of the sets for which the Steiner ratio attains its minimum, that is, the sets on which the Steiner ratio of the boundary set is equal to the Steiner ratio of the ambient space.
Propagation in Arbitrarily Magnetized Ferrites Between Two Conducting Parallel Planes

The electromagnetic waves propagating in arbitrarily magnetized homogeneous ferrites between two perfectly conducting parallel planes have been investigated by using the operational calculus method. The discrete propagation constants and the eigenvalues are to be determined from an algebraic equation of the fourth order and a determinantal equation derived from the boundary conditions. The hybrid modes thus found degenerate to the solutions already found for the particular cases of longitudinally and transversely (parallel and perpendicular to boundaries) magnetized ferrite cases.
Inertial particle acceleration statistics in turbulence: Effects of filtering, biased sampling, and flow topology

In this study, we investigate the effect of “biased sampling,” i.e., the clustering of inertial particles in regions of the flow with low vorticity, and “filtering,” i.e., the tendency of inertial particles to attenuate the fluid velocity fluctuations, on the probability density function of inertial particle accelerations. In particular, we find that the concept of “biased filtering” introduced by Ayyalasomayajula et al. [“Modeling inertial particle acceleration statistics in isotropic turbulence,” Phys. Fluids 20, 0945104 (2008)10.1063/1.2976174], in which particles filter stronger acceleration events more than weaker ones, is relevant to the higher order moments of acceleration. Flow topology and its connection to acceleration is explored through invariants of the velocity-gradient, strain-rate, and rotation-rate tensors. A semi-quantitative analysis is performed where we assess the contribution of specific flow topologies to acceleration moments. Our findings show that the contributions of regions of h.
Integrative analysis of the salt stress response in cyanobacteria

Microorganisms evolved specific acclimation strategies to thrive in environments of high or fluctuating salinities. Here, salt acclimation in the model cyanobacterium Synechocystis sp. PCC 6803 was analyzed by integrating transcriptomic, proteomic and metabolomic data. A dynamic reorganization of the transcriptome occurred during the first hours after salt shock, e.g. involving the upregulation of genes to activate compatible solute biochemistry balancing osmotic pressure. The massive accumulation of glucosylglycerol then had a measurable impact on the overall carbon and nitrogen metabolism. In addition, we observed the coordinated induction of putative regulatory RNAs and of several proteins known for their involvement in other stress responses. Overall, salt-induced changes in the proteome and transcriptome showed good correlations, especially among the stably up-regulated proteins and their transcripts. We define an extended salt stimulon comprising proteins directly or indirectly related to compatible solute metabolism, ion and water movements, and a distinct set of regulatory RNAs involved in post-transcriptional regulation. Our comprehensive data set provides the basis for engineering cyanobacterial salt tolerance and to further understand its regulation.
Effect of substrate-induced strain on the structural, electrical, and optical properties of polycrystalline ZnO thin films

The effect of substrate-induced strain in polycrystalline ZnO thin films on different substrate, e.g., GaN epilayer, sapphire (0001), quartz glass, Si(111)∕SiO2, and glass deposited by sol-gel process, has been investigated by x-ray diffraction, scanning electron microscope, electrical resistivity, and photoluminescence measurements. A strong dependence of orientation, crystallite size, and electrical resistivity upon the substrate-induced strain along the c axis has been found. The results of structural and morphological studies indicate that relatively larger tensile strain exists in ZnO deposited on sapphire and glass, while a smaller compressive strain appears in film deposited on GaN and the strain is relaxed in larger crystallite size. The electrical resistivity of the films increases exponentially with increasing strain. The excitonic peak positions are found to shift slightly towards lower energy side with increasing strain. The analysis shows that GaN being a closely lattice-matched substrate pro.
Radiative recombination of complex ions

The rates of radiative capture by atomic systems are computed for the first four ionization stages of the abundant elements C, N, O, Ne, Mg, Si, S, and Ar. A simple prescription is given for calculating the rates for systems in higher ionization stages. Results for capture to atomic helium are also given. In the general case, recent calculations of photoionization cross sections were used to compute capture rates to levels of the ground-state configuration of the recombined species. Captures to other levels of the valence shell and to the higher shells are evaluated by use of hydrogenic formulas but with a correction factor which takes into account the nonhydrogenic nature of these states. This correction factor is due to the incomplete shielding by the inner electrons and represents essentially an effective charge for the recombining ion; it is determined semiempirically from an appropriate weighting of values derived from the observed level structure for each species. In some cases, for the capture to neutral atomic systems, its application increases the resulting computed recombination rate by a significant amount (approx. 50%). Computed recombination rates are tabulated for the four ionization stages at an electron temperature of 10/sup 4/ K and formore » the first stage at 10/sup 2/ K. A convenient procedure is outlined for evaluating the rates at other temperatures in the general neighborhood of these values. 8 tables. « less
NGC 6302: ionized by a very hot star or by a wind?

Lines of very highly ionized silicon recently discovered in the type I planetary nebula NGC 6302 implied a central star temperature of 450,000 K assuming that the high ionization lines were the result of photoionization. This is the highest central star temperature ever reported for a planetary nebula, and the effects of a luminous soft X-ray source on a surrounding nebula have never been examined. New photoionization model calculations assuming a very hot (T-asterisk = 450,000 K) central star are presented. Model calculations which show that such a high central star temperature can reproduce the observed global spectrum of NGC 6302 do not work well in detail. It seems more likely that the very high ionization lines are the result of shock ionization produced by strong winds from the central star. Both the level of ionization and the energetics are consistent with such an origin. Thus the ionization of this nebula may be the result of both collisional (the high-ionization lines) and photoionization (the traditional nebular lines). 21 refs.
Electrification of an elastic sphere by repeated impacts on a metal plate

Impact electrification between an elastic sphere and a metal plate has been studied experimentally. To find out how charge transfers between the contact bodies, the voltage profiles at the impact are measured under various experimental conditions using a digital oscilloscope, and simultaneously the contact deformation of the sphere is visualized with a high-speed camera. The initial charge on the sphere and the transferred charge are obtained from the integrated voltage with respect to the elapsed time of the impact process. The variation of the electrification by repeated impacts is analysed by taking account of the initial charge and charge relaxation with elapsed time. Furthermore, the relationship between the transferred charge and the contact area as a function of the impact velocity is investigated based on the electrification theory and Hertz analysis of elastic contact deformation.
Onsager's pancake approximation for the fluid dynamics of a gas centrifuge

A previously unpublished theory for describing the internal flow in a gas centrifuge is presented. The theory is based on boundary-layer-type arguments on the side walls of the centrifuge with the additional approximation of neglecting radial diffusion of radial momentum. The effects of the top and bottom end caps are incorporated through Ekman-layer solutions. The results are presented in a form amenable to numerical calculations. Some sample calculations are presented for the special case of a centrifuge with a linear temperature profile on the wall and the top and bottom of the centrifuge at the same temperature as the corresponding end of the side wall.
Boundary element solution of the dirichlet-signorini problem by a penalty method

A potential problem with mixed Dirichlet-Signorini boundary condition is reduced to a boundary variational inequality. Penalization yields a nonlinear integral equation in the space{ILM0001]. The stability properties of a Galerkin scheme applied to this equation are considered. Especially their dependence on the penalty parameter is analized. A suitable coupling of meshsize and penalty parameter yields asymptotic error estimates of the whole scheme.
SrI2: a novel scintillator crystal for nuclear isotope identifiers

The growth and scintillating properties of undoped and Eu2+ doped Strontium Iodide indicate excellent potential for gamma ray spectroscopy. Energy resolution at 662 keV was found to be as good as 2.7% at 662 keV. The effect of purification by zone refining was also studied and crystal growth of SrI2 by the Bridgman technique was found to be less subject to cracking compared to the growth of lanthanum halide scintillators.
On the Harris extended family of distributions

A new method for generating new classes of distributions based on the probability-generating function is presented in Aly and Benkherouf [A new family of distributions based on probability generating functions. Sankhya B. 2011;73:70–80]. In particular, they focused their interest to the so-called Harris extended family of distributions. In this paper, we provide several general results regarding the Harris extended models such as the general behaviour of the failure rate function. We also derive a very useful representation for the Harris extended density function as an absolutely convergent power series of the survival function of the baseline distribution. Additionally, some stochastic order relations are established and limiting distributions of sample extremes are also considered for this model. These general results are illustrated in several special Harris extended models. Finally, we discuss estimation of the model parameters by the method of maximum likelihood and provide an application to real data for illustrative purposes.
A new approach to solving stochastic programming problems with recourse

A new numerical approach to the solution of two-stage stochastic linear programming problems is described and evaluated. The approach avoids the solution of the first-stage problem and uses the underlying deterministic problem to generate a sequence of values of the first-stage variables which lead to successive improvements of the objective function towards the optimal policy. The model is evaluated using an example in which randomness is described by two correlated factors. The dynamics of these factors are described by stochastic processes simulated using lattice techniques. In this way, discrete distributions of the random parameters are assembled. The solutions obtained with the new iterative procedure are compared with solutions obtained with a deterministic equivalent linear programming problem. It is concluded that they are almost identical. However, the computational effort required for the new approach is negligible compared with that needed for the deterministic equivalent problem.
Theory and practice of multivariate arma forecasting

We compare univariate and multivariate forecasts based on ARMA models. In theory we cannot do worse by using a multivariate model instead of a univariate one, but we can risk getting no improvement. Conditions for no improvements are discussed as well as cases where large improvements occur. The effect of estimated parameters is examined and found to be small granted that a good method of estimation is used. However, multivariate models could be very sensitive to structural changes. This is illustrated via an example involving monetary data, where the multivariate forecasts perform considerably worse than the univariate ones. This seems to put a limitation on the use of multivariate ARMA forecasting models.
Axisymmetric inertial oscillations of a fluid in a rotating spherical shell

Introduction . This paper is concerned with an interpretation of some experiments on certain axisymmetric inertial oscillations of a rotating fluid in a thick spherical shell. These oscillations are the counterparts to the ones reported by Aldridge and Toomre† (1969) for a full sphere of rotating fluid. A description of the arrangements for both experiments is presented in A & T; some of the measured eigen-frequencies for spherical shells of rotating fluid given by Aldridge (1967) are presented here for comparison with values calculated from a variational principle.
Rotating free-shear flows. I. Linear stability analysis

Using linear stability analysis, the instability characteristics are examined of both planar wakes and mixing layers subjected to rigid‐body rotation with axis of rotation perpendicular to the plane of the ambient flow. In particular, the tendency of rotation to stabilize or destabilize three‐dimensional motions is addressed. In the inviscid limit the results are consistent with the criterion established by Pedley [J. Fluid Mech. 35, 97 (1969)] and Bradshaw [J. Fluid Mech. 36, 177 (1969)]. Cyclonic rotation and strong anticyclonic rotation tend to stabilize three‐dimensional motions, whereas weaker anticyclonic rotation (Ro≳1) acts to destabilize these motions. This latter instability is in the form of streamwise rolls, similar to previous results obtained for boundary layer and channel flows. It is found that this instability is stronger than the coexisting Kelvin–Helmholtz instability for roughly the range 1.5
Northern hemisphere 500-hPa trough merger and fracture : A climatology and case study

Abstract The results of an objective climatology of 500hPa trough merger (defined as the amalgamation of two initially separate vorticity maxima) and trough fracture (defined as the splitting of a single vorticity center into two separate vorticity centers) are presented for the Northern Hemisphere. The data source is the gridded National Meteorological Center (NMC; now the National Centers for Environmental Prediction) analyses available on CD-ROM on the NMC operational octagonal grid (381-km resolution at 60°N) for the period September 1957 to May 1989. A total of 2152 (3053) merger (fracture) events are identified. Merger and fracture events tend to occur preferentially in the band of middle-latitude westerlies. Merger events exhibit a tendency to avoid major mountainous regions and show a somewhat higher frequency of occurrence downstream of these regions. Fracture events cluster somewhat over eastern ocean basins, the southwestern United States, and northwestern Africa while also avoiding major mount.
Zero-one matrices with zero trace.

Introduction* Ryser [5] and Gale [3] have established simple arithmetic conditions that are necessary and sufficient for the existence of a matrix of zeros and ones having prescribed row and column sums. Here we vary the problem slightly and look for conditions under which there will be an n x n matrix of zeros and ones having given row and column sums and zero trace. While it is not difficult to derive such conditions from known feasibility theorems for network flows, they appear not to simplify greatly except under special circumstances. One motivation for considering this problem lies in a graph theoretical interpretation. The existence problem for a directed, loopless graph on n nodes having given local degrees (i.e., for each node two non-negative integers are given, the first specifying the number of issuing arcs, the second the number of entering arcs, and arcs leading from a node to itself are not allowed) is equivalent to that for a zero-one matrix having given row and column sums and zero trace.
A new approach to modelling near-wall turbulence energy and stress dissipation

A new model for the transport equation for the turbulence energy dissipation rate ε and for the anisotropy of the dissipation rate tensor εij, consistent with the near-wall limits, is derived following the term-by-term approach and using results of direct numerical simulations (DNS) for several generic wall-bounded flows. Based on the two-point velocity covariance analysis of Jovanović, Ye & Durst (1995) and reinterpretation of the viscous term, the transport equation is derived in terms of the ‘homogeneous’ part εh of the energy dissipation rate. The algebraic expression for the components of εij was then reformulated in terms of εh, which makes it possible to satisfy the exact wall limits without using any wall-configuration parameters. Each term in the new equation is modelled separately using DNS information. The rational vorticity transport theory of Bernard (1990) was used to close the mean curvature term appearing in the dissipation equation. A priori evaluation of εij, as well as solving the new dissipation equation as a whole using DNS data for quantities other than εij, for flows in a pipe, plane channel, constant-pressure boundary layer, behind a backward-facing step and in an axially rotating pipe, all show good near-wall behaviour of all terms. Computations of the same flows with the full model in conjunction with the low-Reynolds number transport equation for (uiui) All Overbar, using εh instead of ε, agree well with the direct numerical simulations.
Viscosity Solutions of Nonlinear Systems of Degenerated Elliptic Equations of Second Order

In this paper, we discuss the viscosity solutions of Dirichiet problem for weakly coupled systems of fully nonlinear second order degenerated elliptic equations. We prove the existence, uniqueness and continuity of solutions by Perron's method combined with the technique of coupled solutions. Our results generalize those in 9] for the case of general quasi-monotonic systems.
Velocity field analysis in an experimental cavitating mixing layer

The purpose of this experimental study was to analyze a two-dimensional cavitating shear layer. The global aim of this work was to improve understanding and modeling of cavitation phenomena, from a 2D turbulent shear flow to rocket engine turbopomp inducers. This 2D mixing layer flow provided us with a well documented test case to be used for comparisons between behavior with and without cavitation. Similarities and differences enabled us to characterize the effects of cavitation on flow dynamics. The experimental facility enabled us to set up a mixing layer configuration with different cavitation levels. The development of a velocity gradient was observed inside a liquid water flow using PIV–LIF (particle image velocimetry–laser induced fluorescence). Kelvin-Helmholtz instabilities developed at the interface and vaporizations and implosions of cavitating structures inside the vortices were observed. The mixing area grew linearly, showing a constant growth rate, for the range of cavitation levels studied.