Cross Field Research Articles

Computing cross fields A PDE approach based on the Ginzburg-Landau theory

Cross fields are auxiliary in the generation of quadrangular meshes. A method to generate cross fields on surface manifolds is presented in this paper. Algebraic topology constraints on quadrangular meshes are first discussed. The duality between quadrangular meshes and cross fields is then outlined, and a generalization to cross fields of the Poincaré-Hopf theorem is proposed, which highlights some fundamental and important topological constraints on cross fields. A finite element formulation for the computation of cross fields is then presented, which is based on Ginzburg-Landau equations and makes use of edge-based Crouzeix-Raviart interpolation functions. It is first presented in the planar case, and then extended to a general surface manifold. Finally, application examples are solved and discussed.

Ficus hispida Bark Extract Prevents Nociception, Inflammation, and CNS Stimulation in Experimental Animal Model.

Background. Ficus hispida is traditionally used in the ailment of pain, inflammation, and neurological disorders. The present study set out to evaluate the in vivo antinociceptive, anti-inflammatory, and sedative activity of the ethanol extract of Ficus hispida bark (EFHB). Methods. The antinociceptive activity of EFHB was evaluated by using acetic acid induced writhing, formalin, hot plate, and tail immersion methods in Swiss albino mice. Its anti-inflammatory activity was assessed by using carrageenan and histamine induced rat paw oedema test in Wister rats. The central stimulating activity was studied by using pentobarbital induced hypnosis, hole cross, and open field tests in Swiss albino mice. Results. EFHB demonstrated antinociceptive activity both centrally and peripherally. It showed 62.24% of writhing inhibition. It significantly inhibited licking responses in early (59.29%) and late phase (71.61%). It increased the reaction time to the thermal stimulus in both hot plate and tail immersion. It inhibited the inflammation to the extent of 59.49%. A substantial increase in duration of sleep up to 60.80 min and decrease of locomotion up to 21.70 at 400 mg/kg were also observed. Conclusion. We found significant dose dependent antinociceptive, anti-inflammatory, and sedative properties of EFHB in experimental animal models.

Conceptualizing the EU in Traditional Legal Research: How to Deal with Differentiated Integration after Pringle?

Following a period of increasing internationalization and globalization how should traditional legal scholars and students of EU law approach the process of European integration from a methodological perspective? This essay, located in the cross field between theory- building and legal practice, identifies a preliminary answer to this particular question by refining the legal dimension of Multi-level governance (MLG). This framework was originally introduced in political science by Gary Marks et al. in the early 1990’s to describe, and not explain, the functioning of the EU. In order to bridge the inherent gap between academic disciplines the article constructs a theoretical space along three axes (i.e. sovereignty, decision- making and arenas) where the EU is understood as both a political system and a legal system. Based on a comparative method, the paper then applies the MLG framework to a hard legal case, namely the European Stability Mechanism (ESM) that has given rise to a number of constitutional and substantive law issues addressed by the CJEU in C-370/12, Pringle. This includes the uneasy relationship between the ESM and the No-bail out clause in art. 125 TFEU. On this basis, it is concluded that MLG not only describes some factual characteristics of the EU but also provides a particularly useful analytic tool when confronted with differentiated integration in legal research.

Density dependence of SOL power width in ASDEX upgrade L-Mode

Understanding the heat transport in the scrape-off layer (SOL) and the divertor region is essential for the design of large fusion devices such as ITER and DEMO. Current scalings for the power fall-off length λq in H-Mode [1] are available only for the outer divertor target at low densities with low recycling divertor conditions. For the divertor power spreading S only an empirical scaling for ASDEX Upgrade L-Mode is available based on global plasma parameters [2]. Modelling using SOLPS shows a dependence of S on the divertor electron temperature [3]. A more detailed analysis of the heat transport forming λq and S is presented for ASDEX Upgrade L-Mode discharges in hydrogen (H), deuterium (D) and helium (He). For low densities the power fall-off length λq,o on the outer divertor target in H and D is described by the same parametric dependencies as the H-Mode scaling [1] but with a larger absolute size of the power fall-off length in L-Mode.The divertor power spreading S is studied using the local divertor measurements of the target electron temperature Te,tar and density ne,tar. It is found that the competition of the diffusive transport parallel and perpendicular to the magnetic field forming S∝χ⊥/χ∥ is dominated by the temperature dependence of parallel electron conduction. For high divertor temperatures the ion gyro radius has a significant contribution to S, resulting in a minimum of S at ∼30 eV.A recent study [4] with an open divertor configuration found an asymmetry of the power fall-off length between inner and outer target with a smaller power fall-off length λq,i on the inner divertor target. Measurements with a closed divertor configuration find a similar asymmetry for low recycling divertor conditions. It is found, in the experiment, that the in/out asymmetry λq,i/λq,o is strongly increasing with increasing density. Most notably the heat flux density at the inner divertor target is reducing with increasing λq,i whilst the total power onto each divertor target stays constant. It is found that λq,o exhibits no significant density dependence for hydrogen and deuterium but increases with about the square root of the electron density for helium. The difference between H,D and He could be due to the different recycling behaviour in the divertor. These findings may help current modelling attempts to parametrize the density dependence of the widening of the power channel and thus allow for detailed comparison to both divertor effects like recycling or increased upstream SOL cross field transport.

Edge rotation from momentum transport by neutrals

Due to their high cross field mobility, neutral atoms can have a strong effect on transport even at the low relative densities found inside the separatrix. We use a charge-exchange dominated model for the neutrals, coupled to neoclassical ions, to calculate momentum transport when it is dominated by the neutrals. We can then calculate self-consistently the radial electric field and predict the intrinsic rotation in an otherwise torque-free plasma. Using a numerical solver for the ion distribution to allow arbitrary collisionality, we investigate the effects of inverse aspect ratio and elongation on plasma rotation. We also calculate the rotation of a trace carbon impurity, to facilitate future comparison to experiments using charge exchange recombination spectroscopy diagnostics.

Activities of the sinus node pacemaking during the simulated atrial reentry

Numerous studies implicated the relationship between the sinus node dysfunction (SND) and atrial arrhythmias, but the pacemaker activities of sinoatrial node (SAN) during the atrial reentry before the formation of structural and electrophysiological remodeling in SAN were not well investigated. In the present study, a gradient two-dimensional model including SAN and atrium was built to reflect heterogeneities of the SAN. The reentrant wave was induced by the cross field method in the atrium. The simulation demonstrated a suppressed SAN spontaneous firing by the invading reentry and a 4:1 entrance block into the SAN at a reentrant cycle length of 80 ms. When the retrograde electrical excitation from atrium captured the SAN cell, the maximum diastolic potential of its action potential was found to become more negative with increased upstroke velocity. At the same time, the amplitudes of If, ICaL and IKs were enlarged. Besides, the interactions of the atrium and SAN presented a block of the sinus firing from exiting to the atrium while protecting the central SAN from the effects of the invading reentry. These findings suggested a link between SND and atrial reentry, and therefore were helpful in explaining the role of atrial arrhythmias in SND.

High magnetic field test of bismuth Hall sensors for ITER steady state magnetic diagnostic.

Performance of bismuth Hall sensors developed for the ITER steady state magnetic diagnostic was investigated for high magnetic fields in the range ±7 T. Response of the sensors to the magnetic field was found to be nonlinear particularly within the range ±1 T. Significant contribution of the planar Hall effect to the sensors output voltage causing undesirable cross field sensitivity was identified. It was demonstrated that this effect can be minimized by the optimization of the sensor geometry and alignment with the magnetic field and by the application of "current-spinning technique."

Advances in theoretical study on transition-metal-catalyzed C−H activation

Transition-metal-catalyzed C–H activation represents one of most attractive research fields in modern organic chemistry while theoretical studies have become a popular and effective tool for elucidating mechanism nowadays. The recent achievements in the cross field of the two orientations are reviewed in this article. The first part introduced the advances in theoretical study on transition-metal-catalyzed C–H activation. The elegant work reported mainly in and after 2013, classified according to the mechanisms of C–H activation, were covered. The second part provided an analysis on the distribution of quantum-chemical methods, solvation models and basis sets in the collected theoretical studies.

Towards an automatic isogeometric analysis suitable trivariate models generation—Application to geometric parametric analysis

This paper presents an effective method to automatically construct trivariate tensor-product spline models of complicated geometry and arbitrary topology. Our method takes as input a solid model defined by its triangulated boundary surface. Using cuboid decomposition, an initial polycube approximating the input boundary mesh is built. This polycube serves as the parametric domain of the tensor-product spline representation required for isogeometric analysis. The polycube’s nodes and arcs decompose the input model’s boundary into quadrilateral patches, and these patches form hexahedral domains. Using aligned global parameterization, the nodes are re-positioned and the arcs are re-routed across the surface in a way to achieve low overall patch distortion, and alignment to principal curvature directions and sharp features. The optimization process is based on one of the main contributions of this paper: a novel way to design cross fields with topological (i.e., imposed singularities) and geometrical (i.e., imposed directions) constraints by solving only sparse linear systems. Based on the optimized polycube and parameterization, compatible B-spline boundary surfaces are reconstructed. Finally, the interior volumetric parameterization is computed using Coon’s interpolation. In the context of parametric studies based on geometrical parameters, this method can be used to compute the morphing required for reduced order modeling. For different parametric instances with the same topology but different geometries, this method allows to have the same representation: i.e., meshes (or parameterizations) with the same topology. The efficiency and the robustness of the proposed approach are illustrated by several examples.

Tracing Field‐Coherent Quad Layouts

AbstractGiven a cross field over a triangulated surface we present a practical and robust method to compute a field aligned coarse quad layout over the surface. The method works directly on a triangle mesh without requiring any parametrization and it is based on a new technique for tracing field‐coherent geodesic paths directly on a triangle mesh, and on a new relaxed formulation of a binary LP problem, which allows us to extract both conforming quad layouts and coarser layouts containing t‐junctions. Our method is easy to implement, very robust, and, being directly based on the input cross field, it is able to generate better aligned layouts, even with complicated fields containing many singularities. We show results on a number of datasets and comparisons with state‐of‐the‐art methods.

Direct measurement of the plasma loss width in an optimized, high ionization fraction, magnetic multi-dipole ring cusp

The loss width of plasma in the WiPAL multi-dipole magnetic ring cusp [Cooper et al., Phys. Plasmas 21, 13505 (2014); Forest et al., J. Plasma Phys. 81, 345810501 (2015)] has been directly measured using a novel array of probes embedded in the insulating plasma limiters. The large plasma volume (∼10 m3), small loss area associated with strong rare earth permanent magnets (Bo∼2.23 kG at face), and large heating power (≤200 kW) produces a broad range of electron temperatures (2<Te<15 eV), ion temperatures (0.03<Ti<2 eV), plasma densities (3×1010<ne<2×1012 cm−3), and ionization fractions (0.05<ne/(ne+nn)<1), in both argon and helium, all of which were accurately measured. This plasma regime, accessible with high magnetic fields, differs from previous devices: the cusp loss width is much larger than the Debye length and electron gyroradius and comparable to the collision length. Plasma parameters measured at the surface of ceramic limiter tiles covering the magnets and along radial chords in the cusp magnetic field indicate that electron density and temperature are nearly constant on magnetic field lines and that the mirror forces play little role in confining the plasma other than to constrict the loss area. Particle balance modeling is used to determine the cross field diffusion coefficient base on the measured losses to the limiters. The experimentally determined cross field diffusion coefficient (which determines the cusp loss width) is consistent with ambipolar diffusion across five orders of magnitude. The ambipolar diffusion across a given field line is set primarily by the electron-neutral collisions in the region where the magnetic field is the weakest, even though these plasmas can have ionization fractions near 1.

Influence of energetic ions on neoclassical tearing modes

In addition to their effect on the linear stability of tearing modes, energetic particles can influence the nonlinear evolution of a magnetic island through an uncompensated cross field current due to the effect of charge separation when the orbit width of an energetic particle is much larger than the island width. The corresponding return parallel current may compensate the loss of bootstrap current in the magnetic island. This nonlinear effect depends on the island’s propagation frequency (the rotation frequency of the island relative to the plasma), the density gradient of energetic ions and magnetic shear. If the island’s propagation frequency is positive, the effect of the uncompensated current plays a stable role on neoclassical tearing modes. When the magnetic shear is sufficiently small, this effect becomes significant and can partially cancel or even overcome the destabilizing effect of the perturbed bootstrap current. In ITER this provides a possibility of using energetic ions to suppress the neoclassical tearing mode for the steady state and hybrid scenarios with weak magnetic shear.

Barley plants over-expressing the NAC transcription factor gene HvNAC005 show stunting and delay in development combined with early senescence.

The plant-specific NAC transcription factors have attracted particular attention because of their involvement in stress responses, senescence, and nutrient remobilization. The HvNAC005 gene of barley encodes a protein belonging to subgroup NAC-a6 of the NAC family. This study shows that HvNAC005 is associated with developmental senescence. It was significantly up-regulated following ABA treatment, supported by ABA-responsive elements in its promoter, but it was not up-regulated during dark-induced senescence. The C-termini of proteins closely related to HvNAC005 showed overall high divergence but also contained conserved short motifs. A serine- and leucine-containing central motif was essential for transcriptional activity of the HvNAC005 C-terminus in yeast. Over-expression of HvNAC005 in barley resulted in a strong phenotype with delayed development combined with precocious senescence. The over-expressing plants showed up-regulation of genes involved with secondary metabolism, hormone metabolism, stress, signalling, development, and transport. Up-regulation of senescence markers and hormone metabolism and signalling genes supports a role of HvNAC005 in the cross field of different hormone and signalling pathways. Binding of HvNAC005 to promoter sequences of putative target genes containing the T[G/A]CGT core motif was shown by direct protein-DNA interactions of HvNAC005 with promoters for two of the up-regulated genes. In conclusion, HvNAC005 was shown to be a strong positive regulator of senescence and so is an obvious target for the fine-tuning of gene expression in future attempts to improve nutrient remobilization related to the senescence process in barley.

Antioxidant, Antinociceptive and CNS Activities of Viscum orientale and High Sensitive Quantification of Bioactive Polyphenols by UPLC.

Viscum orientale Willd. (Loranthaceae) has long been used in traditional medicine to treat pain, neuropharmacological disorders and various forms of tumor but not yet been reported. The aim of this study is to rationalize the traditional medicinal use of this plant by evaluating the methanol extract of V. orientale leaves (MEVOL) for anti-nociceptive, CNS depressant and antioxidant activities and to quantify the bioactive polyphenols present in this plant. Five polyphenolic compounds namely gallic acid, vanillic acid, caffeic acid, ellagic acid, and quercetin (17.54, 8.99, 99.61, 4523.31, and 100.15 mg/100 g of dry weight, respectively) have been identified in MEVOL using Ultra Performance Liquid Chromatography. Qualitative antioxidant activity determined by Thin Layer Chromatography indicated the presence of antioxidants. In quantitative antioxidant test using 2,2-diphenyl 1-picrylhydrazyl, MEVOL exhibited strong free antioxidant activity in a dose dependant manner (IC50 = 6.63 μg/ml) compared with ascorbic acid (IC50 = 1.91 μg/ml) and butylatedhydroxyanisole (IC50 = 2.27 μg/ml) controls. Total phenolic content determined using Folin Ciocaltu reagent was found to be 73.4 mg gallic acid equivalent/g of extract, while flavonoid content estimated using aluminum chloride colorimetric method was 170.7 mg quercetin equivalent/g of extract. Anti-nociceptive activity of MEVOL measured using acetic acid and formalin induced pain models in mice was significant (p < 0.001). MEVOL showed 65.6 and 88.8% writhing inhibition at 300 and 500 mg/kg body weight, respectively, comparing with standard diclofenac-Na (75.2% inhibition) at 25 mg/kg body weight in acetic acid induced pain model. In formalin induced pain model, paw licking was inhibited 45.93 and 56.4% in early phase and 55.66 and 72.64% in late phase at 300 and 500 mg/kg body weight, respectively, while diclofenac-Na inhibited 60.47 and 61.32% in early and late phase at 10 mg/kg body weight, respectively. In neuropharmacological activity test, overall behavioral test significantly reinforced CNS depressant activity. Spontaneous motor activities were reduced (p < 0.05) in both hole cross and open field tests compared with diazepam. Antioxidant activity of MEVOL is likely due to the phenolic and flavonoid compounds present within the leaf tissues. This study reveals significant in vivo anti-nociceptive and CNS depressant activities which justifies traditional medicinal applications of V. orientale.

Preparing underprepared students for higher education and beyond: the development and implementation of an integrated project

ABSTRACTA current problem faced in South Africa is that university graduates are weak and underprepared for the work environment. The purpose of this study was to assist students in bridging the aforementioned gap and to ease the transition from theory to practice. The aim of the study was to critically analyse the development and implementation of the integrated project. This study targeted first-year (Extended Curriculum Programme) students, who had been identified as being underprepared for higher education. The factors that initiated the design and development of the integrated project were the South African Qualifications Authority, Critical Cross Field Outcomes and the University of Technology's National Diploma in Cost and Management Accounting exit level outcome, which promote lifelong learning. The integrated project was an authentic assessment which required students to transfer their theoretical knowledge obtained in the classroom to assist small businesses within the community. Academics should be encouraged to use authentic problems in the designing of assessments which will promote student-centredness and lifelong learning. With the continuous engagement of an integrated project, these first-year underprepared students will be better equipped to adjust and excel in the work environment.

Directional Field Synthesis, Design, and Processing

AbstractDirection fields and vector fields play an increasingly important role in computer graphics and geometry processing. The synthesis of directional fields on surfaces, or other spatial domains, is a fundamental step in numerous applications, such as mesh generation, deformation, texture mapping, and many more. The wide range of applications resulted in definitions for many types of directional fields: from vector and tensor fields, over line and cross fields, to frame and vector‐set fields. Depending on the application at hand, researchers have used various notions of objectives and constraints to synthesize such fields. These notions are defined in terms of fairness, feature alignment, symmetry, or field topology, to mention just a few. To facilitate these objectives, various representations, discretizations, and optimization strategies have been developed. These choices come with varying strengths and weaknesses. This report provides a systematic overview of directional field synthesis for graphics applications, the challenges it poses, and the methods developed in recent years to address these challenges.

Development and Integration of an SSR-Based Molecular Identity Database into Sugarcane Breeding Program

Sugarcane breeding is very difficult and it takes 12 to 14 years to develop a new cultivar for commercial production. This is because sugarcane varieties are highly polyploid, inter-specific hybrids with 100 to 130 chromosomes that may vary across geographical areas. Other obstacles/constraints include the small size of flowers that may not synchronize but may self-pollinate, difficulty in distinguishing hybrids from self progenies, extreme (G × E) interactive effect, and potential variety mis-identification during vegetative propagation and varietal exchange. To help cane breeders circumvent these constraints, a simple sequence repeats (SSR)-based molecular identity database has been developed at the United States Department of Agriculture-Agricultural Research Service, Sugarcane Research Unit in Houma, LA. Since 2005, approximately 2000 molecular identities have been constructed for clones of sugarcane and related Saccharum species that cover geographical areas including Argentina, Australia, Bangladesh, China, Colombia, India, Mexico, Pakistan, South Africa, Thailand, USA (Louisiana, Florida, Texas, and Hawaii), and Venezuela. The molecular identity database is updated annually and has been utilized to: (1) provide molecular descriptors to newly registered cultivars; (2) identify in a timely fashion any mislabeled or unidentifiable clones from cross parents and field evaluation plots; (3) develop de novo clones of energy cane with S. spontaneum cytoplasm; (4) provide clone-specific fingerprint information for assessing cross quality and paternity of polycross; (5) determine genetic relatedness of parental clones; (6) select F1 hybrids from (elite × wild) or (wild × elite) crosses; and (7) investigate the inheritance of SSR markers in sugarcane. The integration of the molecular identity database into the sugarcane breeding program may improve the overall efficacy of cultivar development and commercialization.

Temperature dynamics and velocity scaling laws for interchange driven, warm ion plasma filaments

The influence of electron and ion temperature dynamics on the radial convection of isolated structures in magnetically confined plasmas is investigated by means of numerical simulations. It is demonstrated that the maximum radial velocity of these plasma blobs roughly follows the inertial velocity scaling, which is proportional to the ion acoustic speed times the square root of the filament particle density times the sum of the electron and ion temperature perturbations. Only for small blobs the cross field convection does not follow this scaling. The influence of finite Larmor radius effects on the cross-field blob convection is shown not to depend strongly on the dynamical ion temperature field. The blob dynamics of constant finite and dynamical ion temperature blobs is similar. When the blob size is on the order of 10 times the ion Larmor radius the blobs stay coherent and decelerate slowly compared to larger blobs which dissipate faster due to fragmentation and turbulent mixing.

From participatory design and ontological ethics, towards an approach to constructive ethics

This paper explores, analyses and discusses the potential of applying Danish theologian and philosopher K. E. Løgstrup's ontological approach to ethics, when planning and conducting participatory design activities. By doing so, ethical considerations, will transform from being a summative evaluation perspective typically included at the end of a design process, to becoming a more formative and constructive perspective which influences the entire process. The approach presented in this paper will support on-going research within the field of Value Sensitive Design with theoretically based principles. These are principles that practitioners may consider when planning e.g. workshops in order to ensure that the activities facilitate both the design process and establish an ethical foundation for the design process. In addition to the theoretical contribution of the paper, the notion of constructive ethics is exemplified in practice by on-going research in the cross field between persuasive design and learning, carried out in collaboration with the Danish Military. Previous research has suggested that both participatory design and ethics may be essential to persuasive design in theory and in practice. However, considering the impact interactive technologies have on users in general, the principles exemplified through this case are relevant in a much broader perspective and to many other design traditions.

Feature-aligned Surface Parameterization Using Secondary Laplace Operator and Loop Subdivision

Surface parameterization is of great importance for many applications such as quadrangulation, texture mapping and surface fitting. An important issue for surface parameterization is how to align parametric lines with feature directions. To address this issue, in this paper we first utilize Loop subdivision basis functions and isogeometric analysis (IGA) to calculate eigenfunctions of the secondary Laplace operator (SLO) on triangle meshes. Eigenfunctions are then used for centroidal Voronoi tessellation (CVT) based surface segmentation, and boundaries of the segmented regions are extracted as feature lines which contain concave creases and convex ridges. Along each feature line, adjacent triangles are defined as guidance triangles to parameterize the surface using a constrained cross field method, where feature lines are preserved and aligned to parametric lines. Several examples are presented in the end to verify the robustness of our algorithm.