Radial Densities Research Articles

Comparação dos resultados da densidade capilar peripapilar radial de indivíduos com e sem infecção por Helicobacter pylori

Purpose: To evaluate the radial peripapillary capillary density using optical coherence tomography angiography in patients with and without Helicobacter pylori infection. Methods: This prospective, cross-sectional study comprised 52 patients (52 eyes: Group 1) and 38 patients (38 eyes: Group 2) with and without H. pylori infections, respectively. The radial peripapillary capillary density and retinal nerve fiber layer thickness in 4 equal quadrants and 2 equal hemispheres in the peripapillary region were calculated using optical coherence tomography angiography. The optic nerve head parameters of the patients were also assessed. Results: The groups were similar in terms of age, gender, and the optic nerve head parameters. The radial peripapillary capillary densities in the superior hemisphere and quadrant were significantly lower in Group 1 than in Group 2 (p=0.039 and p=0.028, respectively) and were positively correlated with the superior hemisphere’s retinal nerve fiber layer thickness (p<0.001 and p<0.001, respectively). Similarly, the radial peripapillary capillary densities in the inferior hemisphere and quadrant were also significantly lower in Group 1 compared to Group 2 (p=0.03 and p=0.017, respectively) and were positively correlated with the inferior hemisphere’s retinal nerve fiber layer thickness (p<0.001 and p<0.001, respectively). The retinal nerve fiber layer thickness in the nasal and temporal quadrants were significantly decreased in Group 1 when compared to Group 2 (p=0.013 and p=0.022) and were positively correlated with the corresponding radial peripapillary capillary densities of the 2 quadrants (p=0.002 and p=0.022). Conclusion: The decreased radial peripapillary capillary density in the H. pylori-positive patients suggests that H. pylori may play a role in the etiopathogenesis of glaucoma.

Limiting case of an isoperimetric inequality with radial densities and applications

Limiting case of an isoperimetric inequality with radial densities and applications

Investigation of the Retinal and Optic Disc Microvascularization in Polycystic Ovary Syndrome: An Optical Coherence Tomography Angiography Study

ABSTRACT Purpose To investigate retinal and optic disc microvascular alterations using optical coherence tomography angiography (OCTA) in women with polycystic ovary syndrome (PCOS). Methods Forty-six eyes of 23 patients with PCOS (PCOS group), and 50 eyes of 25 sex and age-matched healthy controls (control group) were included in this cross-sectional study. Foveal retinal thickness, peripapillary retinal nerve fiber layer (RNFL) thickness, vessel density in different sections of the retina and optic disc were analyzed by OCTA. Results The superficial parafoveal vessel densities were significantly lower in PCOS group compared to the control group (53.7 ± 4.0%, and 55.4 ± 2.7%, respectively, p = .02). The deep retinal vessel densities, foveal retinal thicknesses and RNFL thicknesses, whole image of optic disc radial peripapillary capillary densities, foveal avascular zone and flow areas were similar between the groups (p > .05 for all). Conclusion OCTA analysis indicates that patients with PCOS tend to have lower superficial parafoveal vessel densities.

Variational Calculation of Lithium-Like Ions from B+2 to N+4 Using β-Type Roothaan–Hartree–Fock Wavefunction

Within the KaKB, KaLa, and KBLa shells in the position space, the properties of a series of three-electron systems, for instance, B+2, C+3, and N+4 ions, have been studied. This required the partitioning of the two-particle space-spin density and was explicit for the Hartree–Fock description which have been proposed by considering a basis set based on single-zeta B-type orbitals (BTOs). The one- and two-body radial electronic densities R(r1), R(r1, r2), moments ⟨rn1⟩, X-ray form factor F(s), nucleus density R(0), nuclear magnetic shielding constant qd, and the diamagnetic susceptibility бs in the position space are reported. Our results are realized via the Mathematica program and compared with previous theoretical values in the literature.

Research on non-uniform control rod system of PWR

In order to improve the axial power distribution control performance of PWR power control system and simplify the control strategy, three non-uniform power control rod systems based on the novel non-uniform power control rod and their decoupling mode control strategy (mode D) are proposed. The types A, B, and AB non-uniform control rod systems of Qinshan nuclear power plant in China are established by MCNP5. These three non-uniform power control rod systems adopt mode D to control the core power. The radial and axial neutron flux densities of three non-uniform control rod systems at four rod positions are separately calculated. The simulation results show that types A, B, and AB non-uniform control systems adopting the mode D have good power level control performance, and type AB non-uniform control system has the best axial distribution performance. Compared with the other four control strategies, the mode D is simpler.

Evaluation of retinal vascular density and related factors in youth myopia without maculopathy using OCTA

To evaluate the retinal vascular flow density changes of myopic eyes of young adults using optical coherence tomography angiography and the factors affecting these changes. In this cross-sectional study, 90 eyes of 45 participants were analyzed and divided into three groups: mild, moderate, and high myopia (without pathological changes). Macular and radial peripapillary capillary flow densities were measured using optical coherence tomography angiography. Their relationships with the axial length, the spherical equivalent of the refractive error, and age were analyzed using analysis of variance, Pearson’s correlation coefficient, and multivariate linear regression analysis. Superficial and deep macular vascular densities were significantly decreased in the high myopia group compared to the other groups. In the high myopia group, the nasal peripapillary flow density decreased, whereas the flow density inside the disc increased. The axial length negatively correlated with the superficial and deep macular vascular density, but positively correlated with the vascular density inside the disc. The spherical equivalent of the refractive error negatively correlated with the macular vascular density. The retinal vascular density decreased in the high myopia group. Hence, the microvascular network inside the disc may have a compensatory action in the hypoxic setting of high myopia.

Spin density in partially coherent surface-plasmon-polariton vortex fields

We examine the spin angular momentum (SAM) density associated with the recently introduced [Phys. Rev. A 100, 053833 (2019)], partially coherent surface-plasmon-polariton (SPP) vortex fields at a metal-air interface. We show that the vortices appearing in such structured SPP fields induce a SAM density both in the interface plane and in the direction normal to the interface. We find that the radial and azimuthal SAM densities are caused solely by the SPP electric-field correlations. However, besides the intrinsic spin component induced by the complex SPP wave vector, the azimuthal SAM density remarkably carries also a spin component created by the elementary SPPs comprising the partially coherent vortex field. The normal SAM density, on the other hand, arises mainly due to the SPP magnetic-field correlations. Our analysis specifically demonstrates that the state of coherence of the partially coherent SPP vortex field plays an essential role in shaping the SAM density distributions. Our findings can find applications to near-field particle manipulation and in spin-based integrated photonic circuit design.

Ca+ Ions Solvated in Helium Clusters.

We present a combined experimental and theoretical investigation on Ca ions in helium droplets, HeCa. The clusters have been formed in the laboratory by means of electron-impact ionization of Ca-doped helium nanodroplets. Energies and structures of such complexes have been computed using various approaches such as path integral Monte Carlo, diffusion Monte Carlo and basin-hopping methods. The potential energy functions employed in these calculations consist of analytical expressions following an improved Lennard-Jones formula whose parameters are fine-tuned by exploiting ab initio estimations. Ion yields of HeCa -obtained via high-resolution mass spectrometry- generally decrease with N with a more pronounced drop between and , the computed quantum HeCa evaporation energies resembling this behavior. The analysis of the energies and structures reveals that covering Ca with 17 He atoms leads to a cluster with one of the smallest energies per atom. As new atoms are added, they continue to fill the first shell at the expense of reducing its stability, until , which corresponds to the maximum number of atoms in that shell. Behavior of the evaporation energies and radial densities suggests liquid-like cluster structures.

Structural properties of Na atom under impenetrable spatial confinement

The structural properties and radial distributions of the valence electron in different excited levels of Na atom (n = 3–5, l = 0–4; n and l being the principal and orbital angular momentum quantum numbers, respectively) under impenetrable spherical confinement have been studied, where the interaction between the frozen core and the valence electron is mimicked by a model potential available in the literature. The effect of the core on the valence electron has been investigated by estimating the structural properties of Na10+ion under similar confinement. Scaled radial densities at the nucleus and related ratios are presented for a few excited states of the valence electron of Na atom and the corresponding analytic results have been tested numerically.

Formation Dominates Resorption With Increasing Mineralized Density and Time Postfracture in Cortical but Not Trabecular Bone: A Longitudinal HRpQCT Imaging Study in the Distal Radius.

ABSTRACTClinical evaluation of fracture healing is often limited to an assessment of fracture bridging from radiographic images, without consideration for other aspects of bone quality. However, recent advances in HRpQCT offer methods to accurately monitor microstructural bone remodeling throughout the healing process. In this study, local bone formation and resorption were investigated during the first year post fracture in both the fractured (n = 22) and contralateral (n = 19) radii of 34 conservatively treated patients (24 female, 10 male) who presented with a unilateral radius fracture at the Innsbruck University Hospital, Austria. HRpQCT images and clinical metrics were acquired at six time points for each patient. The standard HRpQCT image acquisition was captured for all radii, with additional distal and proximal image acquisitions for the fractured radii. Measured radial bone densities were isolated with a voxel‐based mask and images were rigidly registered to images from the previous imaging session using a pyramid‐based approach. From the registered images, bone formation and resorption volume fractions were quantified for multiple density‐based thresholds and compared between the fractured and contralateral radius and relative to demographics, bone morphometrics, and fracture metrics using regression. Compared with the contralateral radius, both bone formation and resorption were significantly increased in the fractured radius throughout the study for nearly all evaluated thresholds. Higher density cortical bone formation continually increased throughout the duration of the study and was significantly greater than resorption during late‐stage healing in both the fractured and intact regions of the radius. With the small and diverse study population, only weak relationships between fracture remodeling and patient‐specific parameters were unveiled. However this study provides methods for the analysis of local bone remodeling during fracture healing and highlights relevant considerations for future studies, specifically that remodeling postfracture is likely to continue beyond 12‐months postfracture. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Fisher Information of Free-Electron Landau States.

An electron in a constant magnetic field has energy levels, known as the Landau levels. One can obtain the corresponding radial wavefunction of free-electron Landau states in cylindrical polar coordinates. However, this system has not been explored so far in terms of an information-theoretical viewpoint. Here, we focus on Fisher information associated with these Landau states specified by the two quantum numbers. Fisher information provides a useful measure of the electronic structure in quantum systems, such as hydrogen-like atoms and under some potentials. By numerically evaluating the generalized Laguerre polynomials in the radial densities, we report that Fisher information increases linearly with the principal quantum number that specifies energy levels, but decreases monotonically with the azimuthal quantum number m. We also present relative Fisher information of the Landau states against the reference density with , which is proportional to the principal quantum number. We compare it with the case when the lowest Landau level state is set as the reference.

Density functional study of atoms spatially confined inside a hard sphere

AbstractAn atom placed inside a cavity of finite dimension offers many interesting features, and thus has been a topic of great current activity. This work proposes a density functional approach to pursue both ground and excited states of a multi‐electron atom under a spherically impenetrable enclosure. The radial Kohn‐Sham (KS) equation has been solved by invoking a physically motivated work‐function‐based exchange potential, which offers near‐Hartree‐Fock‐quality results. Accurate numerical eigenfunctions and eigenvalues are obtained through a generalized pseudospectral method (GPS) fulfilling the Dirichlet boundary condition. Two correlation functionals, viz., (i) simple, parametrized local Wigner‐type, and (ii) gradient‐ and Laplacian‐dependent non‐local Lee‐Yang‐Parr (LYP) functionals are adopted to analyze the electron correlation effects. Preliminary exploratory results are offered for ground states of He‐isoelectronic series (Z = 2 − 4), as well as Li and Be atom. Several low‐lying singly excited states of He atom are also reported. These are compared with available literature results–which offers excellent agreement. Radial densities as well as expectation values are also provided. The performance of correlation energy functionals are discussed critically. In essence, this presents a simple, accurate scheme for studying atomic systems inside a hard spherical box within the rubric of KS density functional theory.

Addendum: Babic, S., et al. Self-Inductance of the Circular Coils of the Rectangular Cross-Section with the Radial and Azimuthal Current Densities. Physics 2020, 2, 352–367

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Evaluation of the optic nerve head vessel density in patients with limited scleroderma.

Objectives:To investigate the optical coherence tomography angiography (OCTA) parameters of the optic nerve head and peripapillary retina and to assess macular and peripapillary retinal nerve fiber layer (RNFL) thickness by using spectral-domain optical coherence tomography (SD-OCT) in patients with limited scleroderma and to compare these results with those of healthy control subjects.Materials and Methods:42 patients with a confirmed diagnosis of limited scleroderma and 32 age- and sex-matched healthy control subjects were included in the study. OCTA was performed for the radial peripapillary capillary plexus (RPCP) whole image, inside disc, and peripapillary vessel densities in all participants with XR Avanti AngioVue OCTA (Optovue, Fremont, California, USA). OCT images were obtained with Spectralis OCT with eye-tracking dual-beam technology (Heidelberg Engineering GmbH, Heidelberg, Germany), and peripapillary RNFL thickness was evaluated with circle program. The data from the right eyes of all participants were used for statistical analysis.Results:No significant difference was found between the radial RPCP whole image, inside disc, and peripapillary vessel density values or the RNFL parameters of the scleroderma patients when compared with the controls (p > 0.05 for all).Conclusion:Decreased peripapillary vessel density on OCTA, which can be an early sign of glaucoma, could not be observed in scleroderma patients in this study. However, further long-term studies are still needed to identify glaucoma tendency in patients with scleroderma before clinically detectable glaucoma.

Corneal endothelial cell density and microvascular changes of retina and optic disc in autosomal dominant polycystic kidney disease.

Purpose:Vascular endothelial dysfunction in autosomal dominant polycystic kidney disease (ADPKD) may affect the retinal vascular parameters due to structural similarities of kidney and retina. We aimed to evaluate the microvascular changes of retina and optic disc and also corneal endothelial cell density in patients with ADPKD.Methods:Forty-six eyes of 23 patients with ADPKD (Group 1), and 46 eyes of 23 sex- and age-matched healthy controls (Group 2) were included in this cross-sectional study. Demographic and ophthalmic findings of participants were collected. Corneal endothelial cell density (CECD) measurements were obtained by noncontact specular microscopy. Foveal retinal thickness, peripapillary retinal nerve fiber layer (RNFL) thickness, vessel density in different sections of the retina and optic nerve head were analyzed by optical coherence tomography angiography.Results:The mean ages were 41 ± 11 years for Group 1 and 39 ± 10 years for Group 2 (P = 0.313). CECD values were significantly lower in group 1 when compared to group 2 (2653 ± 306 cells/mm2 and 2864 ± 244 cells/mm2, respectively, P < 0.001). The foveal retinal thickness and RNFL thickness were similar, but superior quadrant thickness of RNFL was significantly lower in Group 1 than Group 2 (126 ± 14 μm vs. 135 ± 15 μm, P = 0.003). In Group 1, whole image of optic disc radial peripapillary capillary densities were significantly lower compared to Group 2 (49.4 ± 2.04%, and 50.0 ± 2.2%, respectively, P = 0.043). There was no significant difference regarding superficial, deep retinal vessel densities, foveal avascular zone and flow areas between the groups (P > 0.05 for all).Conclusion:Lower CECD values and decreased superior quadrant RNFL thickness, and microvascular densities of optic disc were revealed in patients with ADPKD. Evaluation of CECD and retinal microvasculature may be helpful in the management of these patients.

The electrostatic origins of specific ion effects: quantifying the Hofmeister series for anions.

Life as we know it is dependent upon water, or more specifically salty water. Without dissolved ions, the interactions between biological molecules are insufficiently complex to support life. This complexity is intimately tied to the variation in properties induced by the presence of different ions. These specific ion effects, widely known as Hofmeister effects, have been known for more than 100 years. They are ubiquitous throughout the chemical, biological and physical sciences. The origin of these effects and their relative strengths is still hotly debated. Here we reconsider the origins of specific ion effects through the lens of Coulomb interactions and establish a foundation for anion effects in aqueous and non-aqueous environments. We show that, for anions, the Hofmeister series can be explained and quantified by consideration of site-specific electrostatic interactions. This can simply be approximated by the radial charge density of the anion, which we have calculated for commonly reported ions. This broadly quantifies previously unpredictable specific ion effects, including those known to influence solution properties, virus activities and reaction rates. Furthermore, in non-aqueous solvents, the relative magnitude of the anion series is dependent on the Lewis acidity of the solvent, as measured by the Gutmann Acceptor Number. Analogous SIEs for cations bear limited correlation with their radial charge density, highlighting a fundamental asymmetry in the origins of specific ion effects for anions and cations, due to competing non-Coulombic phenomena.

Quantization and Structure of Electromagnetic and Gravitational Fields

Following Relativistic Alpha Field Theory (RAFT) here it is started with the solution of the field parameters α and α′ in the combined electromagnetic and gravitational fields. The field parameters α and α′ are described as the functions of the particle charge, particle mass, electrical potential, gravitational potential, gravitational constant, gravitational mass and speed of the light in vacuum. The mentioned parameters are presented by using identity between the constant ratio of Planck mass and Planck length and between gravitational mass and gravitational length. It is shown that the minimal electrical length is limited by the electric charges or by the electrical particle mass. It is also confirmed that the energy conservation constant is valid both in an electromagnetic central symmetric field as well as in a gravitational field. Further, the numerical quantities of the minimal and maximal radial densities for the spherically symmetric particles are also valid in the central symmetric electromagnetic fields, as well as, in the gravitational fields. The quantization of the combination of the central symmetric electromagnetic and gravitational fields is dominant in the region of the minimal length and twice of that length. Therefore, the quantization is applied to the mentioned region, both in central symmetric electrical fields and in the combination of the central symmetric electrical and gravitational fields. It is determined that the minimal distance between two quantum states should be less than 10-35 m. The related minimal transition time can be obtained by using the transition speed equal to the speed of the light in vacuum. Calculation of the energy uncertainty, the shortest transition time, the generic state, the shortest physically possible time and the time effectively spent by the controlled system or control algorithm are presented systematically. The mentioned parameters are calculated both in the case of central symmetric electrical field, as well as, in the combination of the electrical and gravitational fields.

Association of childhood obesity with retinal microvasculature and corneal endothelial cell morphology.

To investigate the optical coherence tomography angiography (OCTA) and specular microscopy (SM) findings in obese children and compare them with healthy ones. In this prospective study, 50 eyes of 25 obese children [body mass index (BMI)≥95th percentile], 36 eyes of 18 control age- and sex- matched healthy subjects (BMI <85th percentile) were included. Demographic features and ophthalmological examination including OCTA measurements as well as SM findings were assessed. Cellular morphology was observed by noncontact SM and results for corneal endothelial cell density (cells/mm2), coefficient of variation of cell size and percentage of hexagonal cells were obtained. The OCTA was performed with 6 × 6mm sections for macula and 4.5 × 4.5mm sections for optic disc in all eyes. Foveal retinal thickness (FRT), retinal nerve fiber layer (RNFL) thickness, vessel density in different sections of retina and optic nerve head were analyzed. All SM parameters, RNFL thickness for average, and all quadrants and optic disc radial peripapillary capillary densities were similar between groups. However, FRT, flow area for choriocapillaris, superficial and deep foveal capillary densities were significantly higher in obese group when compared to controls (242.4±18.2µm vs. 232.1±16.5µm, p=0.024, 2.2±0.1mm2 vs, 2.2±0.0mm2, p=0.042, 22.4±6.9% vs. 15.6±5.5%, p=0.001, and 38.9±7.5% vs. 31.1±8.6 %, p=0.001, respectively). Obese children seem to have higher values of FRT, flow area for choriocapillaris, superficial and deep foveal capillary densities. These results may have significant implications for understanding of how childhood obesity could affect retinal microvasculature.

Design and Analysis of Dual‐Magnet BLDCM for Momentum Wheel

To obtain the larger output torque and the higher stability speed accuracy, a novel dual‐magnet brushless DC motor is proposed, and its structure is introduced. The mathematical model is established by the equivalent surface current method, and the magnetic circuit is analyzed by finite element method. The radial and tangential air gap magnetic flux densities of the dual‐magnet scheme are larger and less than that of the ironless stator and the Halbach array schemes, respectively. The theoretical calculation and simulation results are verified by prototype experiments. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Quantum dots in AA-stacked bilayer graphene

While electrostatic confinement in single-layer graphene and AA-stacked bilayer graphene is precluded by Klein tunneling and the gapless energy spectrum, we theoretically show that a circular domain wall that separates domains of single-layer graphene and AA-stacked bilayer graphene can provide bound states. Solving the Dirac-Weyl equation in the presence of a global mass potential and a local electrostatic potential, we obtain the energy spectrum of these states and the corresponding radial probability densities. Depending on the mass potential profile, regular bound states can exist inside the quantum dot and topological bound states at the domain wall. Controlling the electrostatic potential inside the quantum dot enables the simultaneous presence of both types of states. We find that the number of nodes of the radial wave function of the regular bound states inside the quantum dot is equal to the radial quantum number. The energy spectra of the bound states display anticrossings, reflecting coupling of electron- and holelike states.