2,806 research outputs found
Determination of antimicrobial susceptibility patterns of Nocardia spp. from clinical specimens by Etest
ABSTRACTSusceptibilities to 11 antimicrobial agents were determined by Etest for 93 Nocardia isolates from clinical specimens and 15 type strains belonging to different Nocardia spp. All isolates were susceptible to trimethoprim-sulphamethoxazole, amikacin and linezolid, but susceptibilities of the various Nocardia spp. to β-lactams, aminoglycosides, ciprofloxacin and clarithromycin varied markedly. Overall, there was a good correlation between the drug resistance patterns and the species identification established by conventional phenotypic tests and 16S rDNA sequencing. Among the different species encountered, Nocardia farcinica and Nocardia brasiliensis displayed the most multiresistant profiles, with resistance to imipenem occurring mainly among isolates of N. brasiliensis and Nocardia abscessus. The species variability in susceptibility profiles and the numerous recent taxonomic changes means that in-vitro susceptibility tests may be a complementary tool for the identification of Nocardia isolates from human clinical specimens. Further studies on a larger number of species from more diverse geographical sources, including species that are found less commonly among clinical isolates, are required to validate and extend the results
Lifetime measurements of Triaxial Strongly Deformed bands in Tm
With the Doppler Shift Attenuation Method, quadrupole transition moments,
, were determined for the two recently proposed Triaxial Strongly Deformed
(TSD) bands in Tm. The measured moments indicate that the
deformation of these bands is larger than that of the yrast, signature
partners. However, the measured values are smaller than those predicted by
theory. This observation appears to be valid for TSD bands in several nuclei of
the regionComment: 8 pages, 5 figures. Submitted to Physical Review
Electronic structure of triangular, hexagonal and round graphene flakes near the Fermi level
The electronic shell structure of triangular, hexagonal and round graphene
quantum dots (flakes) near the Fermi level has been studied using a
tight-binding method. The results show that close to the Fermi level the shell
structure of a triangular flake is that of free massless particles, and that
triangles with an armchair edge show an additional sequence of levels ("ghost
states"). These levels result from the graphene band structure and the plane
wave solution of the wave equation, and they are absent for triangles with an
zigzag edge. All zigzag triangles exhibit a prominent edge state at the Fermi
level, and few low-energy conduction electron states occur both in triangular
and hexagonal flakes due to symmetry reasons. Armchair triangles can be used as
building blocks for other types of flakes that support the ghost states. Edge
roughness has only a small effect on the level structure of the triangular
flakes, but the effect is considerably enhanced in the other types of flakes.
In round flakes, the states near the Fermi level depend strongly on the flake
radius, and they are always localized on the zigzag parts of the edge
Chemical characterisation of atmospheric aerosols during a 2007 summer field campaign at Brasschaat, Belgium : sources and source processes of biogenic secondary organic aerosol
Measurements of organic marker compounds and inorganic species were performed on PM2.5 aerosols from a Belgian forest site that is severely impacted by urban pollution ("De Inslag", Brasschaat, Belgium) during a 2007 summer period within the framework of the "Formation mechanisms, marker compounds, and source apportionment for biogenic atmospheric aerosols (BIOSOL)" project. The measured organic species included (i) low-molecular weight (MW) dicarboxylic acids (LMW DCAs), (ii) methanesulfonate (MSA), (iii) terpenoic acids originating from the oxidation of alpha-pinene, beta-pinene, d-limonene and Delta(3)-carene, and (iv) organosulfates related to secondary organic aerosol from the oxidation of isoprene and alpha-pinene. The organic tracers explained, on average, 5.3% of the organic carbon (OC), of which 0.7% was due to MSA, 3.4% to LMW DCAs, 0.6% to organosulfates, and 0.6% to terpenoic acids. The highest atmospheric concentrations of most species were observed during the first five days of the campaign, which were characterised by maximum day-time temperatures >22 degrees C. Most of the terpenoic acids and the organosulfates peaked during day-time, consistent with their local photochemical origin. High concentrations of 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) and low concentrations of cis-pinonic acid were noted during the first five days of the campaign, indicative of an aged biogenic aerosol. Several correlations between organic species were very high (r>0.85), high (0.70.7) and showed an Arrhenius-type relationship, consistent with their formation through OH radical chemistry
Identifying Overlapping and Hierarchical Thematic Structures in Networks of Scholarly Papers: A Comparison of Three Approaches
We implemented three recently proposed approaches to the identification of
overlapping and hierarchical substructures in graphs and applied the
corresponding algorithms to a network of 492 information-science papers coupled
via their cited sources. The thematic substructures obtained and overlaps
produced by the three hierarchical cluster algorithms were compared to a
content-based categorisation, which we based on the interpretation of titles
and keywords. We defined sets of papers dealing with three topics located on
different levels of aggregation: h-index, webometrics, and bibliometrics. We
identified these topics with branches in the dendrograms produced by the three
cluster algorithms and compared the overlapping topics they detected with one
another and with the three pre-defined paper sets. We discuss the advantages
and drawbacks of applying the three approaches to paper networks in research
fields.Comment: 18 pages, 9 figure
Characterization of heterogeneity and spatial distribution of phases in complex solid dispersions by thermal analysis by structural characterization and X-ray micro computed tomography
Purpose: This study investigated the effect of drug-excipient miscibility on the heterogeneity and spatial distribution of phase separation in pharmaceutical solid dispersions at a micron-scale using two novel and complementary characterization techniques, thermal analysis by structural characterization (TASC) and X-ray micro-computed tomography (XCT) in conjunction with conventional characterization methods. Method: Complex dispersions containing felodipine, TPGS, PEG and PEO were prepared using hot melt extrusion-injection moulding. The phase separation behavior of the samples was characterized using TASC and XCT in conjunction with conventional thermal, microscopic and spectroscopic techniques. The in vitro drug release study was performed to demonstrate the impact of phase separation on dissolution of the dispersions. Results: The conventional characterization results indicated the phase separating nature of the carrier materials in the patches and the presence of crystalline drug in the patches with the highest drug loading (30% w/w). TASC and XCT where used to provide insight into the spatial configuration of the separate phases. TASC enabled assessment of the increased heterogeneity of the dispersions with increasing the drug loading. XCT allowed the visualization of the accumulation of phase separated (crystalline) drug clusters at the interface of air pockets in the patches with highest drug loading which led to poor dissolution performance. Semi-quantitative assessment of the phase separated drug clusters in the patches were attempted using XCT. Conclusion: TASC and XμCT can provide unique information regarding the phase separation behavior of solid dispersions which can be closely associated with important product quality indicators such as heterogeneity and microstructure
Octupole transitions in the 208Pb region
The 208Pb region is characterised by the existence of collective octupole states.
Here we populated such states in 208Pb + 208Pb deep-inelastic reactions. γ-ray angular
distribution measurements were used to infer the octupole character of several E3 transitions.
The octupole character of the 2318 keV 17− → 14+ in 208Pb, 2485 keV 19/2
− → 13/2
+ in
207Pb, 2419 keV 15/2
− → 9/2
+ in 209Pb and 2465 keV 17/2
+ → 11/2
− in 207Tl transitions was
demonstrated for the first time. In addition, shell model calculations were performed using two
different sets of two-body matrix elements. Their predictions were compared with emphasis on
collective octupole states.This work is supported by the Science and Technology Facilities Council
(STFC), UK, US Department of Energy, Office of Nuclear Physics, under Contract No. DEAC02-06CH11357
and DE-FG02-94ER40834, NSF grant PHY-1404442
Evidence for particle-hole excitations in the triaxial strongly-deformed well of ^{163}Tm
Two interacting, strongly-deformed triaxial (TSD) bands have been identified
in the Z = 69 nucleus ^{163}Tm. This is the first time that interacting TSD
bands have been observed in an element other than the Z = 71 Lu nuclei, where
wobbling bands have been previously identified. The observed TSD bands in
^{163}Tm appear to be associated with particle-hole excitations, rather than
wobbling. Tilted-Axis Cranking (TAC) calculations reproduce all experimental
observables of these bands reasonably well and also provide an explanation for
the presence of wobbling bands in the Lu nuclei, and their absence in the Tm
isotopes.Comment: 13 pages, 7 figure
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