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Determining infectious cross-transmission events in healthcare settings involves manual surveillance of case clusters by infection control personnel, followed by strain typing of clinical/environmental isolates suspected in said clusters. Recent advances in genomic sequencing and cloud computing now allow for the rapid molecular typing of infecting isolates.
To facilitate rapid recognition of transmission clusters, we aimed to assess infection control surveillance using whole-genome sequencing (WGS) of microbial pathogens to identify cross-transmission events for epidemiologic review.
Clinical isolates of Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, and Klebsiella pneumoniae were obtained prospectively at an academic medical center, from September 1, 2016, to September 30, 2017. Isolate genomes were sequenced, followed by single-nucleotide variant analysis; a cloud-computing platform was used for whole-genome sequence analysis and cluster identification.
Most strains of the 4 studied pathogens were unrelated, and 34 potential transmission clusters were present. The characteristics of the potential clusters were complex and likely not identifiable by traditional surveillance alone. Notably, only 1 cluster had been suspected by routine manual surveillance.
Our work supports the assertion that integration of genomic and clinical epidemiologic data can augment infection control surveillance for both the identification of cross-transmission events and the inclusion of missed and exclusion of misidentified outbreaks (ie, false alarms). The integration of clinical data is essential to prioritize suspect clusters for investigation, and for existing infections, a timely review of both the clinical and WGS results can hold promise to reduce HAIs. A richer understanding of cross-transmission events within healthcare settings will require the expansion of current surveillance approaches.
Dynamic surficial changes and changes in the position of the firn line and the areal extent of Hofsjökull ice cap, Iceland, were studied through analysis of a time series (1973–98) of synthetic-aperture radar (SAR) and Landsat data. A digital elevation model of Hofsjökull, which was constructed using SAR interferometry, was used to plot the SAR backscatter coefficient (σ°) vs elevation and air temperature along transects across the ice cap. Seasonal and daily σ° patterns are caused by freezing or thawing of the ice-cap surface, and abrupt changes in σ° are noted when the air temperature ranges from ∼−5° to 0°C. Late-summer 1997 σ° (SAR) and reflectance (Landsat) boundaries agree and appear to be coincident with the firn line and a SAR σ° boundary that can be seen in the January 1998 SAR image. In January 1994 through 1998, the elevation of this σ° boundary on the ice cap was quite stable, ranging from 1000 to 1300 m, while the equilibrium-line altitude, as measured on the ground, varied considerably. Thus the equilibrium line may be obscured by firn from previous years. Techniques are established to measure long-term changes in the elevation of the firn line and changes in the position of the ice margin.
New observations show that RR Lyrae stars in the metal-rich globular clusters NGC 6388 and NGC 6441 have unusually long periods, which indicate that the horizontal branches of these clusters are unusually bright for their metallicities, as predicted by Sweigart & Catelan (1998).
Autobiographical memory involves the recall of personal facts (semantic memory) and re-experiencing of specific personal events (episodic memory). Although impairments in autobiographical memory have been found in adults with unilateral temporal lobe epilepsy (TLE) and attributed to compromised hippocampal integrity, it is not yet known whether this occurs in children with TLE. In the current study, 21 children with TLE and 24 healthy controls of comparable age, sex, and socioeconomic status were administered the Children's Autobiographical Interview. Compared to controls, children with TLE recalled fewer episodic details, but only when no retrieval prompts were provided. There was no difference between the groups for semantic autobiographic details. Interestingly, the number of episodic details recalled increased significantly from 6 to 16 years of age in healthy control children, but not in children with TLE. Exploratory analyses revealed that, within the group of children with TLE, epilepsy factors, including presence or absence of structural hippocampal abnormalities, did not relate to the richness of episodic recall. Our results provide first evidence of autobiographical episodic memory deficits in children with TLE. (JINS, 2013, 19, 1–12)
Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
Multiple salmonellosis outbreaks have been linked to contaminated tomatoes. We investigated a multistate outbreak of Salmonella Typhimurium infections among 190 cases. For hypothesis generation, review of patients' food histories from four restaurant-associated clusters in four states revealed that large tomatoes were the only common food consumed by patients. Two case-control studies were conducted to identify food exposures associated with infections. In a study conducted in nine states illness was significantly associated with eating raw, large, round tomatoes in a restaurant [matched odds ratio (mOR) 3·1, 95% confidence interval (CI) 1·3–7·3]. In a Minnesota study, illness was associated with tomatoes eaten at a restaurant (OR 6·3, mid-P 95% CI 1·05–50·4, P=0·046). State, local and federal regulatory officials traced the source of tomatoes to Ohio tomato fields, a growing area not previously identified in past tomato-associated outbreaks. Because tomatoes are commonly eaten raw, prevention of tomato contamination should include interventions on the farm, during packing, and at restaurants.
The Niah Caves in Sarawak, Borneo, have captured evidence for people and economies of 8000 and 4000 years ago. Although not continuous on this site, these open two windows on to life at the cultural turning point, broadly equivalent to the transition from Mesolithic to Neolithic. They have much in common, inferring that the occupants, perhaps belonging to an older maritime dispersal, had a choosy appetite for the Neolithic package.
We report photoluminescence, linear absorption and femto-second transient bleaching spectra for a colloidal solution of indium phosphide (InP) quantum dots at ambient temperatures. The photoluminescence quantum yield is shown to depend not only upon the size of the quantum dots, with larger dots exhibiting higher quantum yields, but also upon the excitation wavelength. At short wavelengths, photoluminescence excitation spectra deviate markedly from the absorption spectra indicating that an efficient non-radiative deactivation pathway becomes prominent at these higher photon energies. We interpret this observation in terms of an inefficient relaxation mechanism between the second excited state and the lowest energy excited state from which the emission emanates. The results are consistent with the existence of a phonon bottleneck.
One of the most challenging areas of materials research is the imaging of technologically relevant materials with microscopic and atomic-scale resolution. As part of the development of these methods, near-surface atoms in single crystals were imaged using core-level photoelectron holograms. The angle-dependent electron diffraction patterns that constitute an electron hologram were two-dimensionally transformed to create a three dimensional, realspace image of the neighboring scattering atoms. We have made use of a multiplewavenumber, phased-summing method to improve the atom imaging capabilities of experimental photoelectron holography using the Cu(001) and Pt(111) prototype systems. These studies are performed to evaluate the potential of holographic atom imaging methods as structural probes of unknown materials.
Planar wavcguides were made from a linear epoxy copolymer of bisphcnol-A
diglycidyl ether and amino-nitro-tolanc. The refractive indices, ni-M and
n-E, and the clectrooptic coeflicients, r33 and r13,
of the poled nonlinear optical polymcr films were determined by measurements
of the wavcguide modes of these films at a wavelength of 632.8nm, and the
results arc reported for both electrode and corona poling. The ratio of the
second order susceptibilities was found to exceed significantly the
theoretically expected value of 3. Restricted motion of the nonlinear
chromophorcs during poling provides a possible explanation of this
Uranium and its fission product Tc in aerobic environment will be in the forms of UO22+ and TcO4−. Reduced forms of tetravalent U and Tc are sparingly soluble. As determined by transmission electron microscopy, the reduction of uranyl acetate by immobilized cells of Desulfovibrio desuifuricans results in the production of black uraninite nanocrystals precipitated outside the cell. Some nanocrystals are associated with outer membranes of the cell as revealed from cross sections of these metabolic active sulfate-reducing bacteria. The nanocrystals have an average diameter of 5 nm and have anhedral shape. The reduction of Re7+ by cells of Desulfovibrio desulfuricans is fast in the media containing H2 electron donor, and slow in the media containing lactic acid. It is proposed that cytochrome in these cells has an important role in the reduction of uranyl and Re7+ that is a chemical analogue for one uranium fission product Tc7+ through transferring electron from molecular hydrogen or lactic acid to the oxyions of UO22+ and ReO4-.
It had already been shown with a single virulent strain (A42) of Fusobacterium necrophorum that suspension of the fusobacteria in sub-lethal doses of broth cultures of other bacteria reduced the minimum infective dose (> 106 organisms) for mice by subcutaneous inoculation, sometimes to < 10 organisms. The present study extended the known range of bacteria with strong infectivity-enhancing properties to include Bacillus cereus, Klebsiella oxytoca and Staphylococcus aureus; and of those with weaker effect to include Bacillus subtilis, ‘Bacteroides melaninogenicus’, Clostridium sporogenes, Pasteurella haemolytica, and Proteus mirabilis.
The study also showed that five further virulent strains of F. necrophorum closely resembled A42 in respect of striking susceptibility to infectivity enhancement by Escherichia coli, Actinomyces (Corynebacterium) pyogenes and S. aureus. One further strain (A6) of F. necrophorum resembled A42 in respect of strong infectivity enhancement by A. pyogenes, S. aureus, B. cereus and K. oxytoca but differed from it and the other five strains in being only slightly affected by E. coli.
This work was a necessary prelude to the development of a method, based on infectivity enhancement, for the detection and isolation of F. necrophorum present in small numbers in heavily contaminated material such as faeces.
The isolation of Fusobacterium necrophorum present in small numbers in heavily contaminated material such as faeces or soil is hampered by the lack of an efficient selective medium and by the high minimum infective dose of the organism. A sensitive method for the detection and isolation of faecal strains of F. necrophorum type A was based on the subcutaneous injection of faeces, suspended (5% w/v) in broth culture of Actinomyces (Corynebacterium) pyogenes or Staphylococcus aureus to increase fusobacterial infectivity, into mice pretreated with clostridial antitoxins. When necrobacillosis developed F. necrophorum was identified microscopically in tissue from the advancing edge of the lesion and isolated on a partly selective medium.
The enhancement of fusobacterial infectivity produced by A. pyogenes and by S. aureus was high, but the latter was slightly the more efficient, enabling as few as 80 F. necrophorum organisms/g of faeces to be detected.
Use of the method showed that 3 of 16 wallabies had F. necrophorum in their faeces at the time of examination. Numerous epidemiological applications are suggested.
This article reports on the latest experiments in the series of
Richtmyer–Meshkov instability (RMI) shock-tube experiments.
Previous work described a double-bump experiment that evidenced some
degree of unrepeatability. The present work features an enlarged
perturbation introduced to improve repeatability. In common with the
previous work, the experiments were conducted at shock Mach number 1.26
(70 kPa overpressure), using the Atomic Weapons Establishment 200
× 100 mm shock tube with a three-zone test cell arrangement of
air/sulphur hexafluoride/air. The sulphur hexafluoride gas
(SF6) was chosen for its high density (5.1 relative to air)
providing an Atwood number of 0.67. Gas separation was by means of
microfilm membranes, supported by fine wire meshes. A double-bump
perturbation of two-dimensional geometry was superimposed on the
downstream membrane representing a 0.6% addition to the dense gas
volume. Visualization of the turbulent gas mixing was by laser sheet
illumination of the seeded SF6 gas using a copper vapor
laser pulsing at 12.5 kHz. Mie scattered light was recorded using a
35-mm rotating drum camera to capture a sequence of 50 images per
experiment. Sample experimental results shown alongside corresponding
three-dimensional hydrocode calculations highlight the problems in both
analysis and comparison caused by multiple scattering arising from the
necessary use of a high seeding concentration. Included is a
demonstration of the effectiveness of introducing into the hydrocode a
Monte Carlo-based simulation of the multiple scattering process. The
results so derived yield greatly improved qualitative agreement with
the experimental images. Quantitative analysis took the form of
deriving relative intensity data from line-outs through experimental
images and their code equivalents. A comparison revealed substantial
agreement on major features.
This article reports the first Richtmyer–Meshkov instability
experiments using an improved version of the Atomic Weapons
Establishment convergent shock tube. These investigate the
shock-induced turbulent mixing across the interfaces of an
air/dense gas/air region. Multipoint ignition of a detonatable
gas mixture produces a cylindrically convergent shock that travels into
a test cell containing the dense gas region. The mixing process is
imaged with shadowgraphy. Sample results are presented from an
unperturbed experiment and one with a notch perturbation imposed on one
of the dense gas interfaces. The unperturbed experiment shows the
mixing across the dense gas boundaries and the motion of the bulk dense
gas region. Imposition of the notch perturbation produces a
mushroom-shaped air void penetrating the dense gas region.
Three-dimensional simulations performed using the AWE TURMOIL3D code
are presented and compared with the sample experimental results. A very
good agreement is demonstrated. Conducting these first turbulent mixing
experiments has highlighted a number of areas for future development of
the convergent shock-tube facility; these are also presented.
In field populations of Lucilia cuprina (Wiedemann) in Australia, there was a very low percentage of mating in females that, on the evidence of their stage of ovarian development, had not yet consumed protein-rich material. Virtually all females whose oocytes had reached early vitellogenesis had mated. Thus, most females of this anautogenous species had mated soon after their ovarian development had proceeded beyond the resting stage at which development ceases in females that have not consumed protein. The relationship between mated status and ovarian development of hand-caught females did not differ from that for females which had been allowed to remain for more than 1 h with sexually active males in the collection chamber of traps. Thus mating occurred rarely, if at all, in the trap chambers, which suggests that females in the field mate soon after first becoming sexually receptive. This, together with knowledge that females of this species do not remate readily, indicates that the operational sex ratio in L. cuprina is heavily male-biased.