The creation of a low energy discrete state in the discrete-state continuum and continuum-continuum interaction

1969 ◽  
Vol 29 (3) ◽  
pp. 128-129 ◽  
Author(s):  
I. Riess
Keyword(s):  
Low Energy ◽  
Discrete State ◽  
The Creation

TOPOLOGICAL CHANGES, CPT AND COMMUTATIVITY OF OPERATOR COUPLING CONSTANTS

1989 ◽  
Vol 04 (05) ◽  
pp. 409-417 ◽  
Author(s):  
P. G. TINYAKOV
Keyword(s):  
Effective Action ◽  
Low Energy ◽  
Coupling Constants ◽  
Planck Length ◽  
Cpt Symmetry ◽  
Different Types ◽  
Suitable Generalization ◽  
The Creation ◽  
Baby Universes ◽  
Topological Changes

We study the low energy effective action that takes into account the creation of baby universes at short (Planck) scales. We derive the restrictions imposed on the general form of the effective action by a suitable generalization of the CPT-symmetry. We find that if the operators creating baby universes of different types commute with each other, the operator coupling constants, present in the effective action, also commute with each other, i.e., they can be diagonalized simultaneously. This result implies that topological changes do not lead to nonlocality at scales large compared to the Planck length.

Thin-flap LASIK with a High-frequency, Low-energy, Small Spot Femtosecond Laser – Effectiveness and Safety

2014 ◽  
Vol 08 (02) ◽  
pp. 99
Author(s):  
Jérôme C Vryghem ◽  
Steven Heireman ◽  
Thibaut Devogelaere ◽  
◽  
◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
High Frequency ◽  
Case Series ◽  
Clinical Results ◽  
Low Energy ◽  
Nominal Thickness ◽  
Small Spot ◽  
Flap Thickness ◽  
The Creation ◽  
High Degree

Objective:To evaluate clinical results of a high-frequency, low-energy, small spot femtosecond laser for the creation of thin corneal flaps in laserin situkeratomileusis (LASIK) used in a comparative case series at a private practice in Brussels, Belgium.Methods:A series of 75 patients selected for LASIK refractive surgery were enrolled for treatment with the Ziemer FEMTO LDV femtosecond laser and received a corneal flap of either 90 μm (59 patients, 103 eyes) or 80 μm (16 patients, 27 eyes) nominal thickness. Prospective evaluation included flap dimensions, intra- and post-operative complications and visual outcomes.Results:Mean flap thickness was 89.03 (standard deviation [SD]: ± 8.26 μm) in the 90 μm group and 81.91 (SD ± 6.80 μm) in the 80 μm group. Mean uncorrected visual was 1.19 ± 0.26 in the 90 μm group and 1.10 ± 0.25 in the 80 μm group. Mean manifest refractive spherical equivalent was –0.12 ± 0.26 D in the 90 μm group and –0.07 ± 0.31 D in the 80 μm group. There was no significant visual loss (≥2 lines loss of best corrected visual acuity) in either group. One flap tear occurred in the 90 μm group (0.97 %) and two pseudo-buttonholes occurred in the 80 μm group (7.41 %). No other clinically relevant complications occurred intra- or post-operatively.Conclusions:The Ziemer LDV femtosecond laser offers a high degree of precision in the creation of 90 and 80 μm flaps for LASIK. Using this device for creating 90 μm flaps can be considered a safe and effective procedure. A higher rate of complications were shown in 80 μm flaps.

scholarly journals Pulsed low-energy stimulation initiates electric turbulence in cardiac tissue

2021 ◽  
Vol 17 (10) ◽  
pp. e1009476
Author(s):  
Rupamanjari Majumder ◽  
Sayedeh Hussaini ◽  
Vladimir S. Zykov ◽  
Stefan Luther ◽  
Eberhard Bodenschatz
Keyword(s):  
Cardiac Tissue ◽  
Chronic Atrial Fibrillation ◽  
Low Energy ◽  
Nonlinear Wave Propagation ◽  
Excitable Systems ◽  
Spatially Extended ◽  
Life Threatening ◽  
The Creation ◽  
Illumination Regime ◽  
Wave Break

Interruptions in nonlinear wave propagation, commonly referred to as wave breaks, are typical of many complex excitable systems. In the heart they lead to lethal rhythm disorders, the so-called arrhythmias, which are one of the main causes of sudden death in the industrialized world. Progress in the treatment and therapy of cardiac arrhythmias requires a detailed understanding of the triggers and dynamics of these wave breaks. In particular, two very important questions are: 1) What determines the potential of a wave break to initiate re-entry? and 2) How do these breaks evolve such that the system is able to maintain spatiotemporally chaotic electrical activity? Here we approach these questions numerically using optogenetics in an in silico model of human atrial tissue that has undergone chronic atrial fibrillation (cAF) remodelling. In the lesser studied sub-threshold illumination régime, we discover a new mechanism of wave break initiation in cardiac tissue that occurs for gentle slopes of the restitution characteristics. This mechanism involves the creation of conduction blocks through a combination of wavefront-waveback interaction, reshaping of the wave profile and heterogeneous recovery from the excitation of the spatially extended medium, leading to the creation of re-excitable windows for sustained re-entry. This finding is an important contribution to cardiac arrhythmia research as it identifies scenarios in which low-energy perturbations to cardiac rhythm can be potentially life-threatening.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

Dissociated Σ=27 boundaries in silicon

1988 ◽  
Vol 46 ◽  
pp. 624-625
Author(s):  
A. Garg ◽  
W.A.T. Clark ◽  
J.P. Hirth
Keyword(s):  
Electron Diffraction ◽  
Local Minimum ◽  
Boundary Energy ◽  
Coincidence Site Lattice ◽  
Boundary Plane ◽  
Low Energy ◽  
Theoretical Understanding ◽  
Site Lattice ◽  
Kikuchi Pattern ◽  
Analysis Techniques

In the last twenty years, a significant amount of work has been done in the theoretical understanding of grain boundaries. The various proposed grain boundary models suggest the existence of coincidence site lattice (CSL) boundaries at specific misorientations where a periodic structure representing a local minimum of energy exists between the two crystals. In general, the boundary energy depends not only upon the density of CSL sites but also upon the boundary plane, so that different facets of the same boundary have different energy. Here we describe TEM observations of the dissociation of a Σ=27 boundary in silicon in order to reduce its surface energy and attain a low energy configuration.The boundary was identified as near CSL Σ=27 {255} having a misorientation of (38.7±0.2)°/[011] by standard Kikuchi pattern, electron diffraction and trace analysis techniques. Although the boundary appeared planar, in the TEM it was found to be dissociated in some regions into a Σ=3 {111} and a Σ=9 {122} boundary, as shown in Fig. 1.

Transfer optics for high spatial resolution electron spectroscopy

1988 ◽  
Vol 46 ◽  
pp. 666-667
Author(s):  
G. G. Hembree ◽  
Luo Chuan Hong ◽  
P.A. Bennett ◽  
J.A. Venables
Keyword(s):  
Magnetic Field ◽  
Scanning Transmission Electron Microscope ◽  
Low Energy ◽  
Objective Lens ◽  
State University ◽  
Arizona State University ◽  
Initial Field ◽  
Resolution Electron ◽  
Scanning Transmission ◽  
Low Energy Electrons

A new field emission scanning transmission electron microscope has been constructed for the NSF HREM facility at Arizona State University. The microscope is to be used for studies of surfaces, and incorporates several surface-related features, including provision for analysis of secondary and Auger electrons; these electrons are collected through the objective lens from either side of the sample, using the parallelizing action of the magnetic field. This collimates all the low energy electrons, which spiral in the high magnetic field. Given an initial field Bi∼1T, and a final (parallelizing) field Bf∼0.01T, all electrons emerge into a cone of semi-angle θf≤6°. The main practical problem in the way of using this well collimated beam of low energy (0-2keV) electrons is that it is travelling along the path of the (100keV) probing electron beam. To collect and analyze them, they must be deflected off the beam path with minimal effect on the probe position.

Performance Evaluation of a Novel Type of Low-Energy Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 354-355
Author(s):  
Bertholdand Senftinger ◽  
Helmut Liebl
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Field Strength ◽  
Numerical Aperture ◽  
Low Energy ◽  
Energy Electron ◽  
High Resolution Imaging ◽  
Lens System ◽  
Resolution Imaging ◽  
Low Energy Electron

During the last few years the investigation of clean and adsorbate-covered solid surfaces as well as thin-film growth and molecular dynamics have given rise to a constant demand for high-resolution imaging microscopy with reflected and diffracted low energy electrons as well as photo-electrons. A recent successful implementation of a UHV low-energy electron microscope by Bauer and Telieps encouraged us to construct such a low energy electron microscope (LEEM) for high-resolution imaging incorporating several novel design features, which is described more detailed elsewhere.The constraint of high field strength at the surface required to keep the aberrations caused by the accelerating field small and high UV photon intensity to get an improved signal-to-noise ratio for photoemission led to the design of a tetrode emission lens system capable of also focusing the UV light at the surface through an integrated Schwarzschild-type objective. Fig. 1 shows an axial section of the emission lens in the LEEM with sample (28) and part of the sample holder (29). The integrated mirror objective (50a, 50b) is used for visual in situ microscopic observation of the sample as well as for UV illumination. The electron optical components and the sample with accelerating field followed by an einzel lens form a tetrode system. In order to keep the field strength high, the sample is separated from the first element of the einzel lens by only 1.6 mm. With a numerical aperture of 0.5 for the Schwarzschild objective the orifice in the first element of the einzel lens has to be about 3.0 mm in diameter. Considering the much smaller distance to the sample one can expect intense distortions of the accelerating field in front of the sample. Because the achievable lateral resolution depends mainly on the quality of the first imaging step, careful investigation of the aberrations caused by the emission lens system had to be done in order to avoid sacrificing high lateral resolution for larger numerical aperture.

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