Meridional trapping and zonal propagation of inertial waves in a rotating fluid shell

AbstractInertial waves propagate in homogeneous rotating fluids, and constitute a challenging and simplified case study for the broader class of inertio-gravity waves, present in all geophysical and astrophysical media, and responsible for energetically costly processes such as diapycnal and angular momentum mixing. However, a complete analytical description and understanding of internal waves in arbitrarily shaped enclosed domains, such as the ocean or a planet liquid core, is still missing. In this work, the inviscid, linear inertial wave field is investigated by means of three-dimensional ray tracing in spherical shell domains, having in mind possible oceanographic applications. Rays are here classically interpreted as representative of energy paths, but in contrast to previous studies, they are now launched with a non-zero initial zonal component allowing for a more realistic, localized forcing and the development of azimuthal inhomogeneities. We find that meridional planes generally act in the shell geometry as attractors for ray trajectories. In addition, the existence of trajectories that are not subject to meridional trapping is here observed for the first time. Their dynamics was not captured by the previous purely meridional studies and unveils a new class of possible solutions for inertial motion in the spherical shell. Both observed behaviours shed some new light on possible mechanisms of energy localization, a key process that still deserves further investigation in our ocean, as well as in other stratified, rotating media.

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Electromagnetic Mathematical Modeling of 3D Supershaped Dielectric Lens Antennas

Mathematical Problems in Engineering ◽

10.1155/2016/8130160 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 14

Author(s):

L. Mescia ◽

P. Bia ◽

D. Caratelli ◽

M. A. Chiapperino ◽

O. Stukach ◽

...

Keyword(s):

Mathematical Modeling ◽

Three Dimensional ◽

Analytical Description ◽

Electromagnetic Analysis ◽

Geometrical Shape ◽

Multiple Reflections ◽

New Class ◽

Lens Antennas ◽

Physical Optic ◽

Dielectric Lens

The electromagnetic analysis of a special class of 3D dielectric lens antennas is described in detail. This new class of lens antennas has a geometrical shape defined by the three-dimensional extension of Gielis’ formula. The analytical description of the lens shape allows the development of a dedicated semianalytical hybrid modeling approach based on geometrical tube tracing and physical optic. In order to increase the accuracy of the model, the multiple reflections occurring within the lens are also taken into account.

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On inertial waves in a rotating fluid sphere

Journal of Fluid Mechanics ◽

10.1017/s0022112001004049 ◽

2001 ◽

Vol 437 ◽

pp. 103-119 ◽

Cited By ~ 72

Author(s):

KEKE ZHANG ◽

PAUL EARNSHAW ◽

XINHAO LIAO ◽

F. H. BUSSE

Keyword(s):

Viscous Dissipation ◽

Special Class ◽

Three Dimensional ◽

Classical Problem ◽

Fluid Sphere ◽

Rotating Fluid ◽

Inertial Waves ◽

Rotating Sphere ◽

First Time ◽

Analytical Expressions

Several new results are obtained for the classical problem of inertial waves in a rotating fluid sphere which was formulated by Poincaré more than a century ago. Explicit general analytical expressions for solutions of the problem are found in a rotating sphere for the first time. It is also discovered that there exists a special class of three-dimensional inertial waves that are nearly geostrophic and always travel slowly in the prograde direction. On the basis of the explicit general expression we are able to show that the internal viscous dissipation of all the inertial waves vanishes identically for a rotating fluid sphere. The result contrasts with the finite values obtained for the internal viscous dissipation for all other cases in which inertial waves have been studied.

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A Peptoid with Extended Shape in Water

10.26434/chemrxiv.7552139 ◽

2019 ◽

Author(s):

Jumpei Morimoto ◽

Yasuhiro Fukuda ◽

Takumu Watanabe ◽

Daisuke Kuroda ◽

Kouhei Tsumoto ◽

...

Keyword(s):

Spectroscopic Analysis ◽

Dimensional Space ◽

Three Dimensional ◽

Biomolecular Recognition ◽

Biological Application ◽

New Class ◽

Proteolytic Resistance ◽

Pharmacokinetic Properties ◽

Optically Pure ◽

Three Dimensional Space

<div> <div> <div> <p>“Peptoids” was proposed, over decades ago, as a term describing analogs of peptides that exhibit better physicochemical and pharmacokinetic properties than peptides. Oligo-(N-substituted glycines) (oligo-NSG) was previously proposed as a peptoid due to its high proteolytic resistance and membrane permeability. However, oligo-NSG is conformationally flexible and is difficult to achieve a defined shape in water. This conformational flexibility is severely limiting biological application of oligo-NSG. Here, we propose oligo-(N-substituted alanines) (oligo-NSA) as a new peptoid that forms a defined shape in water. A synthetic method established in this study enabled the first isolation and conformational study of optically pure oligo-NSA. Computational simulations, crystallographic studies and spectroscopic analysis demonstrated the well-defined extended shape of oligo-NSA realized by backbone steric effects. The new class of peptoid achieves the constrained conformation without any assistance of N-substituents and serves as an ideal scaffold for displaying functional groups in well-defined three-dimensional space, which leads to effective biomolecular recognition. </p> </div> </div> </div>

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The antimicrobial potential of cannabidiol

Communications Biology ◽

10.1038/s42003-020-01530-y ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Mark A. T. Blaskovich ◽

Angela M. Kavanagh ◽

Alysha G. Elliott ◽

Bing Zhang ◽

Soumya Ramu ◽

...

Keyword(s):

Bacterial Infections ◽

Modern Medicine ◽

Gram Negative Bacteria ◽

Gram Negative ◽

New Class ◽

Clostridioides Difficile ◽

Excellent Activity ◽

Induce Resistance ◽

First Time

AbstractAntimicrobial resistance threatens the viability of modern medicine, which is largely dependent on the successful prevention and treatment of bacterial infections. Unfortunately, there are few new therapeutics in the clinical pipeline, particularly for Gram-negative bacteria. We now present a detailed evaluation of the antimicrobial activity of cannabidiol, the main non-psychoactive component of cannabis. We confirm previous reports of Gram-positive activity and expand the breadth of pathogens tested, including highly resistant Staphylococcus aureus, Streptococcus pneumoniae, and Clostridioides difficile. Our results demonstrate that cannabidiol has excellent activity against biofilms, little propensity to induce resistance, and topical in vivo efficacy. Multiple mode-of-action studies point to membrane disruption as cannabidiol’s primary mechanism. More importantly, we now report for the first time that cannabidiol can selectively kill a subset of Gram-negative bacteria that includes the ‘urgent threat’ pathogen Neisseria gonorrhoeae. Structure-activity relationship studies demonstrate the potential to advance cannabidiol analogs as a much-needed new class of antibiotics.

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Cobalt-based magnetic Weyl semimetals with high-thermodynamic stabilities

npj Computational Materials ◽

10.1038/s41524-020-00461-w ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Wei Luo ◽

Yuma Nakamura ◽

Jinseon Park ◽

Mina Yoon

Keyword(s):

Tight Binding ◽

Three Dimensional ◽

Interlayer Coupling ◽

First Principles Calculation ◽

Optimization Approach ◽

Binding Model ◽

Nodal Lines ◽

Weyl Semimetal ◽

Topological Quantum ◽

First Time

AbstractRecent experiments identified Co3Sn2S2 as the first magnetic Weyl semimetal (MWSM). Using first-principles calculation with a global optimization approach, we explore the structural stabilities and topological electronic properties of cobalt (Co)-based shandite and alloys, Co3MM’X2 (M/M’ = Ge, Sn, Pb, X = S, Se, Te), and identify stable structures with different Weyl phases. Using a tight-binding model, for the first time, we reveal that the physical origin of the nodal lines of a Co-based shandite structure is the interlayer coupling between Co atoms in different Kagome layers, while the number of Weyl points and their types are mainly governed by the interaction between Co and the metal atoms, Sn, Ge, and Pb. The Co3SnPbS2 alloy exhibits two distinguished topological phases, depending on the relative positions of the Sn and Pb atoms: a three-dimensional quantum anomalous Hall metal, and a MWSM phase with anomalous Hall conductivity (~1290 Ω−1 cm−1) that is larger than that of Co2Sn2S2. Our work reveals the physical mechanism of the origination of Weyl fermions in Co-based shandite structures and proposes topological quantum states with high thermal stability.

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Shell-crossing in a ΛCDM Universe

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slaa198 ◽

2020 ◽

Vol 501 (1) ◽

pp. L71-L75

Author(s):

Cornelius Rampf ◽

Oliver Hahn

Keyword(s):

Dark Matter ◽

Perturbation Theory ◽

Large Scale ◽

Cold Dark Matter ◽

Three Dimensional ◽

Random Initial Data ◽

Recursion Relations ◽

Indispensable Tool ◽

First Time ◽

Very High

ABSTRACT Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of perturbation theory is shell-crossing, which is the instance when cold-dark-matter trajectories intersect for the first time. We investigate Lagrangian perturbation theory (LPT) at very high orders in the vicinity of the first shell-crossing for random initial data in a realistic three-dimensional Universe. For this, we have numerically implemented the all-order recursion relations for the matter trajectories, from which the convergence of the LPT series at shell-crossing is established. Convergence studies performed at large orders reveal the nature of the convergence-limiting singularities. These singularities are not the well-known density singularities at shell-crossing but occur at later times when LPT already ceased to provide physically meaningful results.

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A novel model for the interpretation of small-angle scattering experiments of self-affine structures

Journal of Applied Crystallography ◽

10.1107/s0021889809048791 ◽

2009 ◽

Vol 43 (1) ◽

pp. 12-16 ◽

Cited By ~ 6

Author(s):

Gerald J. Schneider ◽

D. Göritz

Keyword(s):

Small Angle ◽

Analytical Description ◽

Small Angle Scattering ◽

Filled Rubber ◽

Angle Scattering ◽

Affine Structures ◽

Novel Theory ◽

First Time ◽

Novel Model ◽

Solid Spheres

A novel theory is presented which allows, for the first time, the analytical description of small-angle scattering experiments on anisotropic shaped clusters of nanoparticles. Experimentally, silica-filled rubber which is deformed is used as an example. The silica can be modelled by solid spheres which form clusters. The experiments demonstrate that the clusters become anisotropic as a result of the deformation whereas the spheres are not affected. A comparison of the newly derived model function and the experiments provides, for the first time, microscopic evidence of the inhomogeneous deformation of clusters in the rubbery matrix.

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Imaging the Human Thyroid Using Three-Dimensional Diffuse Optical Tomography: A Preliminary Study

Applied Sciences ◽

10.3390/app11041670 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1670

Author(s):

Tetsuya Mimura ◽

Shinpei Okawa ◽

Hiroshi Kawaguchi ◽

Yukari Tanikawa ◽

Yoko Hoshi

Keyword(s):

Optical Tomography ◽

Tumor Hypoxia ◽

Three Dimensional ◽

Diffuse Optical Tomography ◽

Element Model ◽

Needle Aspiration ◽

Human Thyroid ◽

Tissue Oxygen Saturation ◽

Preliminary Study ◽

First Time

Thyroid cancer is usually diagnosed by ultrasound imaging and fine-needle aspiration biopsy. However, diagnosis of follicular thyroid carcinomas (FTC) is difficult because FTC lacks nuclear atypia and a consensus on histological interpretation. Diffuse optical tomography (DOT) offers the potential to diagnose FTC because it can measure tumor hypoxia, while image reconstruction of the thyroid is still challenging mainly due to the complex anatomical features of the neck. In this study, we attempted to solve this issue by creating a finite element model of the human neck excluding the trachea (a void region). By reconstruction of the absorption coefficients at three wavelengths, 3D tissue oxygen saturation maps of the human thyroid are obtained for the first time by DOT.

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The on-axis magnetic well and Mercier's criterion for arbitrary stellarator geometries

Journal of Plasma Physics ◽

10.1017/s0022377821000465 ◽

2021 ◽

Vol 87 (2) ◽

Author(s):

P. Kim ◽

R. Jorge ◽

W. Dorland

Keyword(s):

Magnetic Field ◽

Original Work ◽

Three Dimensional ◽

Radial Distance ◽

Analytical Form ◽

One Dimensional ◽

Modern Notation ◽

Magnetic Well ◽

First Time ◽

Dimensional Integral

A simplified analytical form of the on-axis magnetic well and Mercier's criterion for interchange instabilities for arbitrary three-dimensional magnetic field geometries is derived. For this purpose, a near-axis expansion based on a direct coordinate approach is used by expressing the toroidal magnetic flux in terms of powers of the radial distance to the magnetic axis. For the first time, the magnetic well and Mercier's criterion are then written as a one-dimensional integral with respect to the axis arclength. When compared with the original work of Mercier, the derivation here is presented using modern notation and in a more streamlined manner that highlights essential steps. Finally, these expressions are verified numerically using several quasisymmetric and non-quasisymmetric stellarator configurations including Wendelstein 7-X.

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Towards an Improved Model of the Galaxy

Highlights of Astronomy ◽

10.1017/s1539299600022280 ◽

1998 ◽

Vol 11 (1) ◽

pp. 570-570

Author(s):

Johan Holmberg ◽

Lennart Lindegren ◽

Chris Flynn

Keyword(s):

Three Dimensional ◽

Direct Determination ◽

Galactic Structure ◽

Open Clusters ◽

Selection Effects ◽

Observational Errors ◽

Red Giant ◽

Improved Model ◽

First Time ◽

Hr Diagram

We use the Hipparcos survey to derive an improved model of the local galactic structure. The availability of parallaxes for all the stars permits direct determination of stellar distributions, eliminating the basic indeterminacy of classical methods based on star counts. Hipparcos gives for the first time a truly three-dimensional view of the solar vicinity, and a complete, homogeneous and highly accurate set of magnitudes and colours. This means that new techniques can be applied in the treatment of the data which place strong constraints on a model that tries to describe the local Galactic structure. Here we investigate how well a static model of low complexitycan describe the Hipparcos observations. The interpretation of the Hipparcos data is complicated by various observational errors and selection effects that are hard to treat correctly. We do not try to correct the data, but instead use a model and subject this model to the same observational errors and selection effects. A model catalogue is created that can be compared with the observed catalogue directly in the observational domain, thereby eliminating the effects from various biases. Many features in the HR diagram are for the first time seen in field stars thanks to Hipparcos, such as the slanted red giant clump, previously seen in rich old open clusters such as Berkeley 18. This and other features ofthe observed HR diagram are well reproduced by the model thanks to the rather detailed modelling of the joint Mv/B — V distribution. Actually, separate distributions were derived for the three different components, disk, thick disk and halo, using the kinematic characteristics of the components to discriminate between them.

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