Singularity-Free Electrodynamics for Point Charges and Dipoles: Classical Model for Electron Self-Energy and Spin

It is shown how point charges and point dipoles with finite self-energies can be accomodated into classical electrodynamics. The key idea is the introduction of constitutive relations for the electromagnetic vacuum, which actually mirrors the physical reality of vacuum polarization. Our results reduce to conventional electrodynamics for scales large compared to the classical electron radius $r_0\approx 2.8\times10^{-13}$ cm. A classical simulation for a structureless electron is proposed, with the appropriate values of mass, spin and magnetic moment.Comment: 3 page

Antibiotic resistance peculiarities of S. aureus isolates, obtained from nasal and throat mucosa of outpatients, Chernivtsi city

The purpose of this study was to determine the specificity of sensitivity to antibiotics of S. aureus strains isolated from nasal mucous membranes and tonsils, as well as to identify the factors of antibiotic resistance. Materials and methods. The pure culture method was used to study smears of the palatine tonsils, the nose and the secret of the external auditory canal of 561, 56 and 15 cultures, respectively. Identification of isolated cultures was carried out according to morphological, tinctorial, physiological and biochemical characteristics. The sensitivity of S. aureus strains to antibiotics was studied and analyzed, 211 of which were isolated from the mucous of the palatine tonsils and 18 - from the nasal mucous. All the isolated strains of S. aureus were determined for the presence of antibiotic resistance factors (FA) -ß-lactamases (BL) and penicillin-binding protein (PВPs). Results. High percentage of strains resistant to ß-lactam antibiotics and macrolides was found in both groups of studied cultures. However, the number of resistant forms to these antibiotics was higher among nasal strains. At the same time, none of the resistant strain to aminoglycosides, fluoroquinolones, lincosamides, tetracyclines, and vancomycin was detected among them. 9.57 % of the strains isolated from the tonsillar mucosa were resistant to the last one. BL and PВPs antibiotic resistance factors of isolated S. aureus strains were more frequent among nasal isolates (BL – 83.3 %, PВPs – 66.7 %) than in strains isolated from the palatine tonsils (BL – 66.3 %, PВPs – 38.6 %), P < 0.05. Sensitivity to antibiotics of S. aureus strains having both FA simultaneously (30 strains) and strains having none of them (26 strains) turned out to be different. Among the strains having both FA, 100 % were resistant to penicillin, 93.3 % to oxacillin, and 36.7 % to vancomycin. Whereas there were 3.9 %, 0.0 %, and 7.7 % strains without FA resistant to these antibiotics, respectively. Resistance to azithromycin was greater in the group of strains with FA: 26.7 % versus 7.7 % in the group without FA. The strains of both groups were highly sensitive with an insignificant difference to other studied antibiotics (aminoglycosides, fluoroquinolones, macrolides, lincosamides and tetracyclines). Conclusions. S. aureus strains isolated from the mucous membranes of the nose and tonsils differ in sensitivity to antibiotics and the presence of FA. The nasal strains of S. aureus are more likely to be resistant to ß-lactam antibiotics and macrolides. Vancomycin resistant strains of S. aureus are significantly more common among strains with FA

Absorption and birefringence study for reduced optical losses in diamond with high NV concentration

The use of diamond color centers such as the nitrogen-vacancy (NV) center is increasingly enabling quantum sensing and computing applications. Novel concepts like cavity coupling and readout, laser threshold magnetometry and multi-pass geometries allow significantly improved sensitivity and performance via increased signals and strong light fields. Enabling material properties for these techniques and their further improvements are low optical material losses via optical absorption of signal light and low birefringence. Here we study systematically the behavior of absorption around 700 nm and birefringence with increasing nitrogen- and NV-doping, as well as their behavior during NV creation via diamond growth, electron beam irradiation and annealing treatments. Absorption correlates with increased nitrogen-doping yet substitutional nitrogen does not seem to be the direct absorber. Birefringence reduces with increasing nitrogen doping. We identify multiple crystal defect concentrations via absorption spectroscopy and their changes during the material processing steps and thus identify potential causes of absorption and birefringence as well as strategies to fabricate CVD diamonds with high NV density yet low absorption and low birefringence.Comment: Accepted by Philosophical Transactions A (DOI: 10.1098/rsta.2022.0314

Atomic Supersymmetry, Rydberg Wave Packets, and Radial Squeezed States

We study radial wave packets produced by short-pulsed laser fields acting on Rydberg atoms, using analytical tools from supersymmetry-based quantum-defect theory. We begin with a time-dependent perturbative calculation for alkali-metal atoms, incorporating the atomic-excitation process. This provides insight into the general wave packet behavior and demonstrates agreement with conventional theory. We then obtain an alternative analytical description of a radial wave packet as a member of a particular family of squeezed states, which we call radial squeezed states. By construction, these have close to minimum uncertainty in the radial coordinates during the first pass through the outer apsidal point. The properties of radial squeezed states are investigated, and they are shown to provide a description of certain aspects of Rydberg atoms excited by short-pulsed laser fields. We derive expressions for the time evolution and the autocorrelation of the radial squeezed states, and we study numerically and analytically their behavior in several alkali-metal atoms. Full and fractional revivals are observed. Comparisons show agreement with other theoretical results and with experiment.Comment: published in Physical Review

Boundary dynamics and multiple reflection expansion for Robin boundary conditions

In the presence of a boundary interaction, Neumann boundary conditions should be modified to contain a function S of the boundary fields: (\nabla_N +S)\phi =0. Information on quantum boundary dynamics is then encoded in the $S$-dependent part of the effective action. In the present paper we extend the multiple reflection expansion method to the Robin boundary conditions mentioned above, and calculate the heat kernel and the effective action (i) for constant S, (ii) to the order S^2 with an arbitrary number of tangential derivatives. Some applications to symmetry breaking effects, tachyon condensation and brane world are briefly discussed.Comment: latex, 22 pages, no figure

Why are Prices Sticky? Evidence from Business Survey Data

This paper offers new insights on the price setting behaviour of German retail firms using a novel dataset that consists of a large panel of monthly business surveys from 1991-2006. The firm-level data allows matching changes in firms' prices to several other firm-characteristics. Moreover, information on price expectations allow analyzing the determinants of price updating. Using univariate and bivariate ordered probit specifications, empirical menu cost models are estimated relating the probability of price adjustment and price updating, respectively, to both time- and state- dependent variables. First, results suggest an important role for state-dependence; changes in the macroeconomic and institutional environment as well as firm-specific factors are significantly related to the timing of price adjustment. These findings imply that price setting models should endogenize the timing of price adjustment in order to generate realistic predictions concerning the transmission of monetary policy. Second, an analysis of price expectations yields similar results providing evidence in favour of state-dependent sticky plan models. Third, intermediate input cost changes are among the most important determinants of price adjustment suggesting that pricing models should explicitly incorporate price setting at different production stages. However, the results show that adjustment to input cost changes takes time indicating "additional stickiness" at the last stage of processing

Treatment decisions and employment of breast cancer patients: Results of a population‐based survey

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142258/1/cncr30959.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142258/2/cncr30959_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142258/3/cncr30959-sup-0001-suppinfo1.pd