An efficient finite-difference scheme for computation of electron states in free-standing and core-shell quantum wires

The electron states in axially symmetric quantum wires are computed by means of the effective-mass Schroedinger equation, which is written in cylindrical coordinates phi, rho, and z. We show that a direct discretization of the Schroedinger equation by central finite differences leads to a non-symmetric Hamiltonian matrix. Because diagonalization of such matrices is more complex it is advantageous to transform it in a symmetric form. This can be done by the Liouville-like transformation proposed by Rizea et al. (Comp. Phys. Comm. 179 (2008) 466-478), which replaces the wave function psi(rho) with the function F(rho)=psi(rho)sqrt(rho) and transforms the Hamiltonian accordingly. Even though a symmetric Hamiltonian matrix is produced by this procedure, the computed wave functions are found to be inaccurate near the origin, and the accuracy of the energy levels is not very high. In order to improve on this, we devised a finite-difference scheme which discretizes the Schroedinger equation in the first step, and then applies the Liouville-like transformation to the difference equation. Such a procedure gives a symmetric Hamiltonian matrix, resulting in an accuracy comparable to the one obtained with the finite element method. The superior efficiency of the new finite-difference (FDM) scheme is demonstrated for a few rho-dependent one-dimensional potentials which are usually employed to model the electron states in free-standing and core-shell quantum wires. The new scheme is compared with the other FDM schemes for solving the effective-mass Schroedinger equation, and is found to deliver energy levels with much smaller numerical error for all the analyzed potentials. Moreover, the PT symmetry is invoked to explain similarities and differences between the considered FDM schemes

Helical edge states in silicene and germanene nanorings in perpendicular magnetic field

Due to nonzero intrinsic spin-orbit interaction in buckled honeycomb crystal structures, silicene and germanene exhibit interesting topological properties, and are therefore candidates for the realization of the quantum spin Hall effect. We employ the Kane-Mele model to investigate the electron states in hexagonal silicene and germanene nanorings having either zigzag or armchair edges in the presence of a perpendicular magnetic field. We present results for the energy spectra as function of magnetic field, the electron density of the spin-up and spin-down states in the ring plane, and the calculation of the probability current density. The quantum spin Hall phase is found at the edges between the nontrivial topological phase in silicene and germanene and vacuum. We demonstrate that the helical edge states in zigzag silicene and germanene nanorings can be qualitatively well understood by means of classical magnetic moments. However, this is not the case for comparable-sized armchair nanorings, where the eigenfunctions spread throughout the ring. Finally, we note that the energy spectra of silicene and germanene nanorings are similar and that the differences between the two are mainly related to the difference in magnitude of the spin-orbit coupling.Comment: 17 pages, 10 figure

Hybrid Imaging in Head and Neck Sarcoidosis

To determine the prevalence of head and neck sarcoidosis (HNS) and evaluate the role of hybrid molecular imaging in HNS. Between 2010 and 2018, 222 patients with chronic sarcoidosis and presence of prolonged symptoms of active disease were referred to FDG PET/CT. Active disease was found in 169 patients, and they were all screened for the presence of HNS. All patients underwent MDCT and assessment of the serum ACE level. Follow-up FDG PET/CT examination was done 19.84 ± 8.98 months after the baseline. HNS was present in 38 out of 169 patients. FDG uptake was present in: cervical lymph nodes (38/38), submandibular glands (2/38), cerebrum (2/38), and bone (1/38). The majority of patients had more than two locations of disease. After FDG PET/CT examination, therapy was changed in most patients. Fourteen patients returned to follow-up FDG PET/CT examination in order to assess the therapy response. PET/CT revealed active disease in 12 patients and complete remission in two patients. Follow-up ACE levels had no correlation with follow-up SUVmax level (ρ = −0.18, p = 0.77). FDG PET/CT can be useful in the detection of HNS and in the evaluation of the therapy response. It may replace the use of non-purposive mounds of insufficiently informative laboratory and radiological procedures

Experimental Verification of Inertial Navigation with MEMS for Forensic Investigation of Vehicle Collision

This paper studies whether low-grade inertial sensors can be adequate source of data for the accident characterization and the estimation of vehicle trajectory near crash. Paper presents outcomes of an experiment carried out in accredited safety performance assessment facility in which full-size passenger car was crashed and the recordings of different types of motion sensors were compared to investigate practical level of accuracy of consumer grade sensors versus reference equipment and cameras. Inertial navigation system was developed by combining motion sensors of different dynamic ranges to acquire and process vehicle crash data. Vehicle position was reconstructed in three-dimensional space using strap-down inertial mechanization. Difference between the computed trajectory and the ground-truth position acquired by cameras was on decimeter level within short time window of 750 ms. Experiment findings suggest that inertial sensors of this grade, despite significant stochastic variations and imperfections, can be valuable for estimation of velocity vector change, crash severity, direction of impact force, and for estimation of vehicle trajectory in crash proximity

Functional Geometry of Human Connectomes

Mapping the brain imaging data to networks, where nodes represent anatomical brain regions and edges indicate the occurrence of fiber tracts between them, has enabled an objective graph-theoretic analysis of human connectomes. However, the latent structure on higher-order interactions remains unexplored, where many brain regions act in synergy to perform complex functions. Here we use the simplicial complexes description of human connectome, where the shared simplexes encode higher-order relationships between groups of nodes. We study consensus connectome of 100 female (F-connectome) and of 100 male (M-connectome) subjects that we generated from the Budapest Reference Connectome Server v3.0 based on data from the Human Connectome Project. Our analysis reveals that the functional geometry of the common F&M-connectome coincides with the M-connectome and is characterized by a complex architecture of simplexes to the 14th order, which is built in six anatomical communities, and linked by short cycles. The F-connectome has additional edges that involve different brain regions, thereby increasing the size of simplexes and introducing new cycles. Both connectomes contain characteristic subjacent graphs that make them 3/2-hyperbolic. These results shed new light on the functional architecture of the brain, suggesting that insightful differences among connectomes are hidden in their higher-order connectivity

Constituent quark model for baryons with strong quark-pair correlations and non-leptonic weak transitions of hyperon

We study the roles of quark-pair correlations for baryon properties, in particular on non-leptonic weak decay of hyperons. We construct the quark wave function of baryons by solving the three body problem explicitly with confinement force and the short range attraction for a pair of quarks with their total spin being 0. We show that the existence of the strong quark-quark correlations enhances the non-leptonic transition amplitudes which is consistent with the data, while the baryon masses and radii are kept to the experiment.Comment: 4 pages, 2 figures, talk presented at KEK-Tanashi International Symposium on Physics of Hadrons and Nuclei, Tokyo, Japan, 14-17 Dec. 199

Hyperon Nonleptonic Weak Decays Revisited

We first review the current algebra - PCAC approach to nonleptonic octet baryon 14 weak decay B (\to) (B^{\prime})(\pi) amplitudes. The needed four parameters are independently determined by (\Omega \to \Xi \pi),(\Lambda K) and (\Xi ^{-}\to \Sigma ^{-}\gamma) weak decays in dispersion theory tree order. We also summarize the recent chiral perturbation theory (ChPT) version of the eight independent B (\to) (B^{\prime}\pi) weak (\Delta I) = 1/2 amplitudes containing considerably more than eight low-energy weak constants in one-loop order.Comment: 10 pages, RevTe

Right Heart Remodeling in Patients with End-Stage Alcoholic Liver Cirrhosis: Speckle Tracking Point of View

BACKGROUND: Data regarding cardiac remodeling in patients with alcoholic liver cirrhosis are scarce. We sought to investigate right atrial (RA) and right ventricular (RV) structure, function, and mechanics in patients with alcoholic liver cirrhosis. METHODS: This retrospective cross-sectional investigation included 67 end-stage cirrhotic patients, who were referred for evaluation for liver transplantation and 36 healthy controls. All participants underwent echocardiographic examination including strain analysis, which was performed offline. RESULTS: RV basal diameter and RV thickness were significantly higher in patients with cirrhosis. Conventional parameters of the RV systolic function were similar between the observed groups. Global, endocardial, and epicardial RV longitudinal strains were significantly lower in patients with cirrhosis. Active RA function was significantly higher in cirrhotic patients than in controls. The RA reservoir and conduit strains were significantly lower in cirrhotic patients, while there was no difference in the RA contractile strain. Early diastolic and systolic RA strain rates were significantly lower in cirrhotic patients than in controls, whereas there was no difference in the RA late diastolic strain rate between the two groups. Transaminases and bilirubin correlated negatively with RV global longitudinal strain and RV-free wall strain in patients with end-stage liver cirrhosis. The Model for End-stage Liver Disease (MELD) score, predictor of 3-month mortality, correlated with parameters of RV structure and systolic function, and RA active function in patients with end-stage liver cirrhosis. CONCLUSIONS: RA and RV remodeling is present in patients with end-stage liver cirrhosis even though RV systolic function is preserved. Liver enzymes, bilirubin, and the MELD score correlated with RV and RA remodeling

Influence of feeding on the circadian rhythm of digestive enzymes in cultivated juveniles of the freshwater crayfish Cherax quadricarinatus (Parastacidae)

Se analiza en juveniles en etapa de engorde (7 g) de Cherax quadricarinatus, el ritmo circadiano de los niveles de proteínas totales, la actividad de las proteasas, lipasas y amilasas, y su posible modificación en función del momento de alimentación matutino (8 h) y vespertino (17 h). En general, la actividad de las enzimas digestivas de los juveniles de C. quadricarinatus no mostró un patrón circadiano de secreción, a excepción de las lipasas, donde se observó un incremento de actividad hacia la tarde-noche y disminución hacia las primeras horas de la mañana. Los niveles de proteína total, la actividad de proteinasas y amilasas registradas en la glándula digestiva, permanecieron prácticamente inalterados en todos los experimentos. A pesar de ello, se observó tendencia a que los niveles de actividad de proteinasas disminuyan luego del pulso de alimentación, recuperando los niveles anteriores 3 h después, independientemente del horario de alimentación. En cambio la actividad de amilasa no mostró ninguna tendencia por efecto del horario de alimentación. El estudio de los patrones de secreción de las enzimas digestivas y sus posibles modificaciones, podría ser utilizado como una herramienta para establecer los momentos del día más propicios para la alimentación de los juveniles en cultivo.ABSTRACT. We analyze in juvenile Cherax quadricarinatus fattening stage, the circadian rhythm of total protein levels, activity of proteases, lipases and amylases, and their possible change as a function of morning (8 h) and evening (17 h) feeding. In general, the activity of digestive enzymes of juvenile C. quadricarinatus showed no circadian pattern of secretion of lipases except where there was an increase towards the evening-night and a decrease towards the early hours of the morning. The total protein levels, the activity of proteinases and amylases of juveniles of C. quadricarinatus registered in the midgut gland remained virtually unchanged in all experiments. However, a non-significant tendency to diminish the proteinase activity levels after the feeding pulse was observed, with a return to previous enzymatic levels after 3 h. In contrast, the amylase activity did not show an observable effect by the feeding schedule. The study of the patterns of the digestive enzyme secretion and their possible changes, could be used as a tool to establish the most favorable times of the day for juveniles feeding.Fil: Sacristán, Hernán Javier. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental; Argentina; Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; Argentina;Fil: Franco-Tadic, Luis M.. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Fisiologia de Crustáceos; Argentina;Fil: Lopez, Laura Susana. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental; Argentina; Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; Argentina