642 research outputs found
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
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
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
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
-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
Evidence of a dynamic association between intergroup contact and intercultural competence
Three studies explored the association between intergroup contact and intercultural competence. Study 1 and Study 2 provided evidence of a cross-sectional association between intergroup contact and intercultural competence in which positive contact was associated with increased intercultural competence and negative contact was associated with reductions in this outcome. In Study 3 longitudinal data allowed us to test the possibility of mutual influence between these variables whereby intercultural competence is not only a consequence of intergroup contact, but is also predictive of the quality of future intergroup contact. Results showed that positive contact was longitudinally associated with improvements in intercultural competence, and that higher intercultural competence was associated with a reduction in future negative contact. Findings speak to the importance of taking a dynamic outlook on contact effects. The beneficial consequences of positive contact may be the same variables capable of transforming future contact encounters and reducing the likelihood of negative interactions
Characterising citizenship: race, criminalisation and the extension of internal borders
Citizenship in the UK has in recent times been explicitly framed as a privilege not a right, granted selectively and withdrawn from some. There are several criteria that assist the government in distinguishing those deserving of British citizenship from those undeserving, one of the key ones being ‘character’. The ‘bad character’ criterion can apply for multiple reasons from inconsistencies in immigration paperwork to direct or indirect political associations with a range of disavowed political groups. Although not new, ‘bad character’ has become a principle reason for citizenship refusals in recent years, though has received little academic scrutiny. By bringing together quantitative and qualitative data on citizenship refusals, the article maps the scale of this measure, outlining what it means and to whom it applies. It argues that the ‘bad character’ criterion operates as a racialised exclusionary mechanism that constitutes a new set of amorphous restrictions upon the lives of non-white denizens
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