4,164 research outputs found
An explicit model for the adiabatic evolution of quantum observables driven by 1D shape resonances
This paper is concerned with a linearized version of the transport problem
where the Schr\"{o}dinger-Poisson operator is replaced by a non-autonomous
Hamiltonian, slowly varying in time. We consider an explicitly solvable model
where a semiclassical island is described by a flat potential barrier, while a
time dependent 'delta' interaction is used as a model for a single quantum
well. Introducing, in addition to the complex deformation, a further
modification formed by artificial interface conditions, we give a reduced
equation for the adiabatic evolution of the sheet density of charges
accumulating around the interaction point.Comment: latex; 26 page
Asymptotic Analysis of a Schrödinger-Poisson System with Quantum Wells and Macroscopic Nonlinearities in Dimension 1
2000 Mathematics Subject Classification: 35Q02, 35Q05, 35Q10, 35B40.We consider the stationary one dimensional Schrödinger-Poisson system on a bounded interval with a background potential describing a quantum well. Using a partition function which forces the particles to remain in the quantum well, the limit h®0 in the nonlinear system leads to a uniquely solved nonlinear problem with concentrated particle density. It allows to conclude about the convergence of the solution
An improved transient algorithm for the simulation of a resonant tunneling diode
40 pagesA fast algorithm is proposed for the simulation of the transient evolution of a resonant tunneling diode by a multiscale approach. The problem is modeled by the time-dependent Schrödinger-Poisson system. By decomposing the wave function into a non resonant part and a resonant part, the fast algorithm is designed by combining standard finite difference method for the Schrödinger-Poisson equation with proper time-dependent and/or nonlinear transmission boundary condition. In addition, with a suitable interpolation of the non resonant one, an accurate and fast algorithm is presented for the computation of the resonant part via the projection method. With this two scale decomposition, the new numerical method can save the computational time significantly
Effect of repeated use on topographical features of protaper next endodontic rotary file
Background: The purpose of this study was to evaluate themorphological alterations of the ProTaper next rotary file (PTN)under scanning electron microscopy (SEM).Materials and Methods: A total of 18 simulated root canals wereallocated to three groups. Six new sets of PTN instruments were used3 times. A #10 K-file was inserted into the working length, followedby ProGlider to create a glide path. Ensuring the manufacturersinstructions with 99% ethyl alcohol for irrigation, all canals wereprepared. Files were photographed in the same position before andafter three canals preparations using a high-resolution SEM.Result: A metal strip appeared on one X1 instrument surfacepreoperatively. Microcrack defects were observed on two X2 filespostoperatively, and the blunt cutting edge was observed on threeX1 files before and after use and one file fractured.Conclusion: Small number of changes appeared on PTN surfaces,yet same PTN file can be used safely 3 times to prepare multi-rootedteeth within the same patient
The crystal structure of Pneumolysin at 2.0 Å resolution reveals the molecular packing of the pre-pore complex
Pneumolysin is a cholesterol-dependent cytolysin (CDC) and virulence factor of Streptococcus pneumoniae. It kills cells by forming pores assembled from oligomeric rings in cholesterol-containing membranes. Cryo-EM has revealed the structures of the membrane-surface bound pre-pore and inserted-pore oligomers, however the molecular contacts that mediate these oligomers are unknown because high-resolution information is not available. Here we have determined the crystal structure of full-length pneumolysin at 1.98 Å resolution. In the structure, crystal contacts demonstrate the likely interactions that enable polymerisation on the cell membrane and the molecular packing of the pre-pore complex. The hemolytic activity is abrogated in mutants that disrupt these intermolecular contacts, highlighting their importance during pore formation. An additional crystal structure of the membrane-binding domain alone suggests that changes in the conformation of a tryptophan rich-loop at the base of the toxin promote monomer-monomer interactions upon membrane binding by creating new contacts. Notably, residues at the interface are conserved in other members of the CDC family, suggesting a common mechanism for pore and pre-pore assembly
Hybrid of Eddy Current Probe Based on Permanent Magnet and GMR Sensor
The eddy current testing (ECT) is used to inspect a material to determine its properties without destroying its utility. The applications include detection of flaws in aircrafts, pipeline, etc. An ECT is a weak sensitivity to a subsurface defect. Applications of giant magnetic sensors (GMR) are increasingly applied to the measurement of weak magnetic fields related to the currents they cause. In this paper, GMR sensor with magnet bar (permanent) is utilized. The proposed probe system is utilized to study the impact of the width and depth defect on the signal of eddy current testing. The maximum depth of flaw in a mild steel can be revealed by using this probe. The graph of the difference between the peak amplitude and the penetration depth of each slot of a different width of the two bands of mild steel shows the increase of the signal for each slot and flat above 3mm. The experimental result proves the inability of a PMGMR probe to detect a defect at a depth of 3mm on a surface defect
Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector
A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV
Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector
A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino
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