1,175 research outputs found
A low-loss, broadband antenna for efficient photon collection from a coherent spin in diamond
We report the creation of a low-loss, broadband optical antenna giving highly
directed output from a coherent single spin in the solid-state. The device, the
first solid-state realization of a dielectric antenna, is engineered for
individual nitrogen vacancy (NV) electronic spins in diamond. We demonstrate a
directionality close to 10. The photonic structure preserves the high spin
coherence of single crystal diamond (T2>100us). The single photon count rate
approaches a MHz facilitating efficient spin readout. We thus demonstrate a key
enabling technology for quantum applications such as high-sensitivity
magnetometry and long-distance spin entanglement.Comment: 5 pages, 4 figures and supplementary information (5 pages, 8
figures). Comments welcome. Further information under
http://www.quantum-sensing.physik.unibas.c
In-vitro and in-vivo evaluation of the antistaphylococcal activity of S-5556, a new 16-membered macrolide
During recent years, a resurgence of interest in the macrolides had led to the discovery of new derivatives of erythromycin with improved antibacterial activity and pharmacokinetic properties. In this study the in-vitro and in-vivo antistaphylococcal activity of S-5556, a 16-membered macrolide, was evaluated. In vitro, S-5556 was slightly less active than erythromycin against methicillin-susceptible Staphylococcus aureus. In contrast, it had superior activity for methicillin-resistant S. aureus (MRSA); several of these strains with inducible resistance to the macrolides-lincosamides-streptogramins group were susceptible to S-5556 whereas erythromycin was inactive. The combination of S-5556 with oxatillin was synergic for most MRSA strains tested. In vivo, a single prophylactic dose of S-5556 prevented 75%-100% of the cases of acute staphylococcal subcutaneous foreign body infection in a guinea pig-model. In a rat-model of chronic implant infection due to a methicillin- and erythromycin-resistant S. aureus strain, S-5556 significantly decreased the bacteria] concentration around the foreign material, however resistant mutants emerge
Detection of Pneumocystis jirovecii by Two Staining Methods and Two Quantitative PCR Assays
Abstract : Background: : Pneumocystis jirovecii is an opportunistic pathogen that causes pneumonia, particularly in immunodeficient hosts. Materials and Methods: : We retrospectively compared the results obtained by two staining methods (toluidine blue and calcofluor white) and two quantitative (q) real time PCR assays for the detection of P. jirovecii in bronchoalveolar lavage (BAL) specimens. For the qPCR assays, we used newly selected probes and primers targeting the Kex-1 gene, which codes for a serine endoprotease, and compared the results to those from the published assay targeting the ÎČ-tubulin gene. Results: : A total of 1,843 BAL specimens were analyzed microscopically in parallel, and 74 (4.0%) were found to be positive with both stains, 23 (1.2%) were positive only with the toluidine blue stain, and six (0.3%) only with the calcofluor stain (p = 0.003). Of these, a selection of 186 consecutive BAL fluid samples were tested by qPCR using the respective different primer pairs. 21 of the 186 samples (11.3%) were microscopically positive with both stains as well as qPCR positive after 18-31 cycles (corresponding to 5.24 Ă 106 copies/ml to 640 copies/ml of native BAL) using the Kex-1 primer pair and between 21-33 cycles using the ÎČ-tubulin assay. A good correlation between semi-quantitative microscopy and the number of PCR cycles needed for a positive signal was noted. Of the remaining 165 samples, 153 (82%) were both microscopically and PCR negative (PCR with the two sets of primers); the remaining 12 samples (7%) were Kex-1-based PCR positive (from cycles 33 to 41, corresponding to 160 copies/ml of BAL or less) but microscopically negative. Of these latter samples, ten (6%) were also positive (from cycles 34 to 38) with the primers targeting the ÎČ-tubulin gene. Taking microscopy as a reference, the sensitivity of qPCR targeting the Kex-1 gene was 100%, and the specificity was 92.4%. Conclusion: : The sensitive qPCR analysis proved to be a rapid and reliable method to detect P. jirovecii in BA
Comparative in-vitro activity of new quinolones against clinical isolates and resistant mutants
The in-vitro activity of five new fluoroquinolones, WIN 57273, sparfloxacin, flerox-acin, temafloxacin and tiprofloxacin was determined against 543 recent clinical isolates and eight quinolone resistant strains derived by mutation and their five parent strains. WIN 57273 was the most active compound against Gram-positive bacteria, sparfloxacin had a broad spectrum which was similar to that of cipro-floxacin. Ciprofloxacin showed the greatest activity against Gram-negative bacteria. Temafloxacin showing some activity against Gram-positive organisms and Acinetobacter spp. Fleroxacin was the least active compound studied. Compared to wild type parent strains, the mutated strains produced the following results. In Enterobacter cloacae OmpF deficiency increased the MICs of all quinolones by 8-32-fold. In Pseudomonas aeruginosa OmpF deficiency had a limited effect, Omp D2 deficiency combined with an increased lipopolysaccharide content produced greater resistance, i.e. 4-16-fold; mutations in gyrase were associated with variously increased MICs, depending on the strain and compound teste
Real-space probing of the local magnetic response of thin-film superconductors using single spin magnetometry
We report on direct, real-space imaging of the stray magnetic field above a
micro-scale disc of a thin film of the high-temperature superconductor
YBaCuO (YBCO) using scanning single spin magnetometry. Our
experiments yield a direct measurement of the sample's local London penetration
depth and allow for a quantitative reconstruction of the supercurrents flowing
in the sample as a result of Meissner screening. These results show the
potential of scanning single spin magnetometry for studies of the nanoscale
magnetic properties of thin-film superconductors, which could be readily
extended to elevated temperatures or magnetic fields.Comment: 6 pages, 4 figure
Chronic central neuropeptide Y infusion in normal rats: status of the hypothalamo-pituitary-adrenal axis, and vagal mediation of hyperinsulinaemia
Summary: Neuropeptide Y in the hypothalamus is a potent physiological stimulator of feeding, and may contribute to the characteristic metabolic defects of obesity when hypothalamic levels remain chronically elevated. Since corticosterone and insulin are important regulators of fuel metabolism, the longitudinal effects of chronic (6 days) intracerebroventricular infusion of neuropeptide Y in normal rats on the hypothalamo-pituitary-adrenal axis and on insulin secretion were studied. Neuropeptide Y-infused rats were either allowed to eat ad libitum, or were pair-fed with normophagic control rats. Neuropeptide Y increased the basal plasma concentrations of adrenocorticotropic hormone and corticosterone during the first 2 days of its intracerebroventricular infusion and increased cold stress-induced plasma adrenocorticotropic hormone concentrations. After 4-6 days of central neuropeptide Y infusion, however, basal plasma adrenocorticotropic hormone and corticosterone concentrations were no different from control values (except in ad libitum-fed rats in which corticosteronaemia remained elevated), they were unaffected by the stress of cold exposure, and the hypothalamic content of corticotropin-releasing factor immunoreactivity was significantly decreased. A state of hyperinsulinaemia was present throughout the 6 days of intracerebroventricular neuropeptide Y infusion, being more marked in the ad libitum-fed than in the pair-fed group. The proportions of insulin, proinsulin, and conversion intermediates in plasma and pancreas were unchanged. Hyperinsulinaemia of the pair-fed neuropeptide Y-infused rats was accompanied by muscle insulin resistance and white adipose tissue insulin hyperresponsiveness, as assessed by the in vivo uptake of 2-deoxyglucose. Finally, bilateral subdiaphragmatic vagotomy prevented both the basal and the marked glucose-induced hyperinsulinaemia of animals chronically infused with neuropeptide Y, demonstrating that central neuropeptide Y-induced hyperinsulinaemia is mediated by the parasympathetic nervous syste
A role for suppressed thermogenesis favoring catch-up fat in the pathophysiology of catch-up growth
Catch-up growth is a risk factor for later obesity, type 2
diabetes, and cardiovascular diseases. We show here
that after growth arrest by semistarvation, rats refed
the same amount of a low-fat diet as controls show 1)
lower energy expenditure due to diminished thermogenesis
that favors accelerated fat deposition or catch-up
fat and 2) normal glucose tolerance but higher plasma
insulin after a glucose load at a time point when their
body fat and plasma free fatty acids (FFAs) have not
exceeded those of controls. Isocaloric refeeding on a
high-fat diet resulted in even lower energy expenditure
and thermogenesis and increased fat deposition and
led to even higher plasma insulin and elevated plasma
glucose after a glucose load. Stepwise regression analysis
showed that plasma insulin and insulin-to-glucose
ratio after the glucose load are predicted by variations
in efficiency of energy use (i.e., in thermogenesis)
rather than by the absolute amount of body fat or
plasma FFAs. These studies suggest that suppression of
thermogenesis per se may have a primary role in the
development of hyperinsulinemia and insulin resistance
during catch-up growth and underscore a role for suppressed
thermogenesis directed specifically at catch-up
fat in the link between catch-up growth and chronic
metabolic diseases
Microplastics on the menu: Plastics pollute Indonesian Manta Ray and Whale Shark feeding grounds
The implications of plastic pollution, including microplastics, on marine ecosystems and species are increasingly seen as an environmental disaster. Yet few reports focus on filter-feeding megafauna in regions heavily impacted by plastic pollution, such as Indonesia in the Coral Triangle, a global marine biodiversity hotspot. Here, we evaluate plastic abundance and characterize debris from feeding grounds for manta rays Mobula alfredi and whale sharks Rhincodon typus in three coastal locations in Indonesia: Nusa Penida Marine Protected Area, Komodo National Park, and Pantai Bentar, East Java. A 200 ÎŒm plankton net was used to sample the top 0.5 m of the water column (âtrawl surveyâ) and floating plastics were assessed along âŒ440 m long transects (âvisual surveyâ) during the Indonesian north-west (wet) and south-east (dry) monsoon seasons during 2016â2018. Microplastics were identified visually, measured and categorized from trawl samples, and larger floating plastics were counted and categorized visually from boats. Plastic abundance ranged widely from 0.04 to 0.90 pieces mâ3 (trawl survey) and 210 to 40,844 pieces kmâ2 (visual survey). Results from linear models showed significant seasonal and location differences in estimated plastic abundance for trawl and visual surveys in Nusa Penida and Komodo. Plastic abundance was up to ⌠44 times higher in the wet than the dry season, with the largest seasonal effect observed in Nusa Penida. Overall, small pieces â50% combined) were the most prevalent plastics. Theoretical plastic ingestion rates were calculated using estimated filtration volumes of manta rays and whale sharks and the mean plastic abundance in their feeding grounds. Upper plastic ingestion estimates for manta rays were âŒ63 and 25 pieces hâ1 for Nusa Penida and Komodo locations, respectively, and âŒ137 pieces hâ1 for whale sharks in Java. Analysis of manta ray egested material confirmed plastic ingestion, the consequences of which might include exposure to toxic plastic additives and adhered persistent organic pollutants. Communicating this information to communities who stand to benefit from healthy megafauna populations might help local governments as they work toward reducing plastics in the marine environment
- âŠ