Optical spectroscopy of single beryllium acceptors in GaAs/AlGaAs quantum well

We carry out microphotoluminescence measurements of an acceptor-bound exciton (A^0X) recombination in the applied magnetic field with a single impurity resolution. In order to describe the obtained spectra we develop a theoretical model taking into account a quantum well (QW) confinement, an electron-hole and hole-hole exchange interaction. By means of fitting the measured data with the model we are able to study the fine structure of individual acceptors inside the QW. The good agreement between our experiments and the model indicates that we observe single acceptors in a pure two-dimensional environment whose states are unstrained in the QW plain

Asymptotic behaviour of estimators of the parameters of nearly unstable INAR(1) models

A sequence of first-order integer-valued autoregressive type (INAR(1)) processes is investigated, where the autoregressive type coefficients converge to 1. It is shown that the limiting distribution of the joint conditional least squares estimators for this coefficient and for the mean of the innovation is normal. Consequences for sequences of Galton{Watson branching processes with unobservable immigration, where the mean of the offspring distribution converges to 1 (which is the critical value), are discussed

The Gut Commensal Bacteroides thetaiotaomicron Exacerbates Enteric Infection through Modification of the Metabolic Landscape

SummaryThe enteric pathogen enterohemorrhagic Escherichia coli (EHEC) causes severe diarrhea, but the influence of the gut microbiota on EHEC infection is largely unknown. A predominant member of the microbiota, Bacteroides thetaiotaomicron (Bt), is resident at EHEC attachment sites. We show that Bt enhances EHEC virulence gene expression through the transcription factor Cra, which is functionally sensitive to sugar concentrations. This enhanced virulence accompanies increased formation of attaching and effacing (AE) lesions requisite for EHEC colonization. Infection with Citrobacter rodentium, a natural mouse pathogen homologous to EHEC, in Bt-reconstituted mice results in increased gut permeability along with exacerbated host pathology and mortality compared to mice deplete of microflora. Bt modifies the metabolite environment at infection sites, increasing metabolites involved in gluconeogenesis, with stark increases in succinate, which can be sensed by Cra. Our findings suggest that microbiota composition affects disease outcome and may explain links between microbiota composition and disease susceptibility

Resource-efficient low-loss four-channel active demultiplexer for single photons

We report a design and implementation of a resource-efficient spatial demultiplexer which produces 4 indistinguishable photons with efficiency of 39.7% per channel. Our scheme is based on a free-space storage/delay line which accumulates 4 photons and releases them by a controlled polarization rotation using a single Pockels cell.Comment: 8 pages, 7 figure

INVASIVE ASPERGILLOSIS IN AN ADOLESCENT

The article presents the clinical case of invasive aspergillosis in a 15-year-old adolescent with lesions in the spine, ribs and both lungs, and primary immune deficiency which was not diagnosed earlier. In order to diagnose this disease it was necessary to differentiate it from the generalized form of tuberculosis and to perform integral X-ray examination and surgery with consequent morphological and bacteriological examination of the surgical samples

How to: interpret MICs of antifungal compounds according to the revised clinical breakpoints v. 10.0 European committee on antimicrobial susceptibility testing (EUCAST)

BACKGROUND: EUCAST has revised the definition of the susceptibility category "I" from "Intermediate" to "Susceptible, Increased exposure". This implies that "I" can be used where the drug-concentration at the site of infection is high, either because of dose escalation or through other means to ensure efficacy. Consequently, "I" is no longer used as a buffer-zone to prevent technical fact

BASOPHILE ACTIVATION TEST FOR THE DIAGNOSTICS OF FUNGAL SENSITIZATION IN THE PATIENTS WITH CYSTIC FIBROSIS

Aspergillus fumigatus colonization in the patients with cystic fibrosis (CF) may cause sensitization against A. fumigatus and/or allergic bronchopulmonary aspergillosis (ABPA), which significantly worsens the course of underlying disease. At the present time, new diagnostic tests are searched for detection of fungal sensitization in these patients. The aim of this work was to evaluate an opportunity of application of basophile activation test with A. fumigatus allergen in vitro using flow cytometry, aiming for identification of fungal sensitization in the CF patients. The study included 190 patients with CF aged 1 to 37 years. All the patients underwent common allergy screening (skin tests with fungal allergens, determination of serum levels of total IgE and specific IgE for the fungal allergens), and mycological examination (microscopy and culture of respiratory substrates). Computed tomography of the chest was performed upon clinical indications. The basophil activation test with the A. fumigatus allergen was performed in 10 CF patients with ABPA, and 10 CF patients without ABPA, in addition to the standard allergological examination. Frequency of sensitization to A. fumigatus in the patients with cystic fibrosis was 27%, the incidence of allergic bronchopulmonary aspergillosis was 5.7%. The number of eosinophils, total IgE and specific IgE levels in CF patients with ABPA were significantly higher than in CF patients without ABPA. In blood of the ABPA patients we have identified 68.5 (52.5-81.5%) of basophilic leukocytes activated by A. fumigatus allergen, with a stimulation index of 17.07 (10.30-27.70). In appropriate comparison group, the stimulation index did not exceed 1.5 (p = 0.000). Direct positive correlation between the levels of specific IgE to A. fumigatus and the number of basophils activated by A. fumigatus allergens was revealed (r = 0.77; р < 0.05). FVC values and the body mass index in CF patients with ABPA were significantly lower when compared with the patients without fungal sensitization. Introduction of the basophil activation test, along with standard techniques, may enable a more differentiated assessment of ABPA development in CF patients. Timely detection of associations between A. fumigatus sensitization and clinical status of CF patients will facilitate early and effective administration of specific therapy