Single and double slit scattering of wave packets

The scattering of wave packets from a single slit and a double slit with the Schr\"odinger equation, is studied numerically and theoretically. The phenomenon of diffraction of wave packets in space and time in the backward region, previously found for barriers and wells, is encountered here also. A new phenomenon of forward diffraction that occurs only for packets thiner than the slit, or slits, is calculated numerically as well as, in a theoretical approximation to the problem. This diffraction occurs at the opposite end of the usual diffraction phenomena with monochromatic waves.Comment: Latex format, 35 pages, 15 eps (some colored) figure

CNN model for studying dynamics and travelling wave solutions of FitzHugh-Nagumo equation

AbstractIn this paper, a cellular neural network (CNN) model of FitzHugh–Nagumo equation is introduced. Dynamical behavior of this model is investigated using harmonic balance method. For the CNN model of FitzHugh–Nagumo equation, propagation of solitary waves have been proved

Metric-scalar gravity with torsion and the measurability of the non-minimal coupling

The "measurability" of the non-minimal coupling is discussed by considering the correction to the Newtonian static potential in the semi-classical approach. The coefficient of the "gravitational Darwin term" (GDT) gets redefined by the non-minimal torsion-scalar couplings. Based on a similar analysis of the GDT in the effective field theory approach to non-minimal scalar we conclude that for reasonable values of the couplings the correction is very small.Comment: 10 pages, LaTex. Accepted for publication in Mod. Phys. Lett.

Positron scattering from formic acid

We report on measurements of total cross sections for positron scattering from the fundamental molecule formic acid (HCOOH). In this case, the energy range of our experimental work is 0.3-50.2 eV. Our interpretation of these data was somewhat complicated by the fact that at room temperature, formic acid vapor consists of about 95% monomer and 5% dimer forms, so that the present cross sections represent an average for that ensemble. To assist us in interpreting the data, rigorous Schwinger multichannel level calculations for positron elastic scattering from the formic acid monomer were also undertaken. These calculations, incorporating an accurate model for the target polarization, are found to be in good qualitative agreement with our measured data, particularly when allowance is made for the target beam mixture (monomer versus dimer) in the experiment

Note on the role of friction-induced momentum conservation in the collisional drift wave instability

The collisional drift wave instability is reexamined taking into account the ion response in the direction parallel to the magnetic field lines, which appears due to friction with electrons and which can not be omitted in view of the momentum conservation. A modified instability threshold is obtained. In plasmas with dominant electron collisions with neutrals, the instability threshold is shifted towards higher frequencies, compared to the case of dominant electron collisions with ions. The difference between the two cases vanishes when the ion sound response is negligible, i.e., when the instability threshold disappears, and both ions and neutrals react to the electron friction in the same manner.Comment: 12 pages, 1 figur

PEEK Retainers without CAD-CAM: Simple Solutions for Everyday Challenges

Background: The need to perform occasional or continuous MRI exams and the interference with metal orthodontic appliances might be important and take a primary role during retention since the retention period is significantly longer than orthodontic treatment. Several non-metallic materials were proposed as potential alternatives to perform fixed retainers in orthodontics, but they showed internal limits. Methods: Polyetheretherketone (PEEK) was used in the present clinical report as a fixed orthodontic retainer in the lower arch in order to perform an appliance with mechanical properties comparable to metallic ones but with a higher biocompatibility material and without the need for removal in case of an MRI exam. The retainer wire was handmade in the studio and then shaped to fit the arch. Results: PEEK showed a good capability for constructing a lingual fixed retainer compared to other aesthetic non-metallic and metallic materials. Conclusions: To the best of our knowledge, this study proposes how to easily build a retainer in PEEK and provides a clinical example of how this material can be beneficial

Histological Analysis of Oral Tissue Grafting: A Focus on Donor Site Selection

The science of dental tissue grafting is evolving, with an increased understanding of factors influencing graft behavior. Despite the widespread clinical use of soft tissue grafts, the histological characteristics of different gingival harvesting sites are still underexplored. This study aimed to fill this gap by analyzing 50 tissue samples harvested from 25 patients across three sites: the hard palate, maxillary tuberosity, and palatal rugae. Each sample underwent thorough histological and histomorphometric analysis. Conventional statistical analysis was performed using SPSS, while predictive modeling was conducted with RapidMiner Studio. The study identified significant histological differences among the graft sites, with notable variations in total graft height, epithelial height, and interdigitation perimeter. These findings underscore the importance of donor site selection in influencing graft success. Pair plots and principal component analysis (PCA) further highlighted the distinct histological features of each tissue type. The random forest classifier identified total graft height, epithelial height, and perimeter as the most influential factors in predicting graft site behavior. This study offers valuable insights into the histological characteristics of soft tissue grafts, potentially leading to more predictable clinical outcomes

Experimental and theoretical cross sections for positron scattering from the pentane isomers

10 págs.; 8 figs.; 3 tabs.Isomerism is ubiquitous in chemistry, physics, and biology. In atomic and molecular physics, in particular, isomer effects are well known in electron-impact phenomena; however, very little is known for positron collisions. Here we report on a set of experimental and theoretical cross sections for low-energy positron scattering from the three structural isomers of pentane: normal-pentane, isopentane, and neopentane. Total cross sections for positron scattering from normal-pentane and isopentane were measured at the University of Trento at incident energies between 0.1 and 50 eV. Calculations of the total cross sections, integral cross sections for elastic scattering, positronium formation, and electronic excitations plus direct ionization, as well as elastic differential cross sections were computed for all three isomers between 1 and 1000 eV using the independent atom model with screening corrected additivity rule. No definitive evidence of a significant isomer effect in positron scattering from the pentane isomers appears to be present. ©2016 AIP Publishing LLCG.G. and F.B. would like to acknowledge the Spanish Ministerio de Economía y Productividad (Project No. FIS2012-31230) and the European Science Foundation (COST Action Grants Nos. MP1002–Nano-IBCT and MC1301-CELINA) for financial support. Finally, L.C. thanks the Japan Society for the Promotion of Science for his fellowship.Peer Reviewe