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To investigate an outbreak of Burkholderia cepacia complex and describe the measures that revealed the source.
A 629-bed, tertiary-care, pediatric hospital in Houston, Texas.
Pediatric patients without cystic fibrosis (CF) hospitalized in the pediatric and cardiovascular intensive care units.
We investigated an outbreak of B. cepacia complex from February through July 2016. Isolates were evaluated for molecular relatedness with repetitive extragenic palindromic polymerase chain reaction (rep-PCR); specific species identification and genotyping were performed at an independent laboratory. The investigation included a detailed review of all cases, direct observation of clinical practices, and respiratory surveillance cultures. Environmental and product cultures were performed at an accredited reference environmental microbiology laboratory.
Overall, 18 respiratory tract cultures, 5 blood cultures, 4 urine cultures, and 3 stool cultures were positive in 24 patients. Among the 24 patients, 17 had symptomatic infections and 7 were colonized. The median age of the patients was 22.5 months (range, 2–148 months). Rep-PCR typing showed that 21 of 24 cases represented the same strain, which was identified as a novel species within the B. cepacia complex. Product cultures of liquid docusate were positive with an identical strain of B. cepacia complex. Local and state health departments, as well as the CDC and FDA, were notified, prompting a multistate investigation.
Our investigation revealed an outbreak of a unique strain of B. cepacia complex isolated in clinical specimens from non-CF pediatric patients and from liquid docusate. This resulted in a national alert and voluntary recall by the manufacturer.
Better understanding of the functional biology of early angiosperms may clarify ecological factors surrounding their origin and early radiation. Phylogenetic studies identify Amborella, Nymphaeales (water lilies), Austrobaileyales, and Chloranthaceae as extant lineages that branched before the radiation of core angiosperms. Among living plants, these lineages may represent the best models for the ecology and physiology of early angiosperms. Here we combine phylogenetic reconstruction with new data on the morphology and ecophysiology of these plants to infer early angiosperm function. With few exceptions, Amborella, Austrobaileyales, and Chloranthaceae share ecophysiological traits associated with shady, disturbed, and wet habitats. These features include low and easily light-saturated photosynthetic rates, leaf anatomy related to the capture of understory light, small seed size, and clonal reproduction. Some Chloranthaceae, however, possess higher photosynthetic capacities and seedlings that recruit in canopy gaps and other sunny, disturbed habitats, which may have allowed Cretaceous Chloranthaceae to expand into more diverse environments. In contrast, water lilies possess ecophysiological features linked to aquatic, sunny habitats, such as absence of a vascular cambium, ventilating stems and roots, and floating leaves tuned for high photosynthetic rates in full sun. Nymphaeales may represent an early radiation into such aquatic environments. We hypothesize that the earliest angiosperms were woody plants that grew in dimly lit, disturbed forest understory habitats and/or shady streamside settings. This ecology may have restricted the diversity of pre-Aptian angiosperms and living basal lineages. The vegetative flexibility that evolved in the understory, however, may have been a key factor in their diversification in other habitats. Our inferences based on living plants are consistent with many aspects of the Early Cretaceous fossil record and can be tested with further study of the anatomy, chemistry, and sedimentological context of Early Cretaceous angiosperm fossils.
Excavations at Çatalhöyük have been ongoing for over 20 years and have involved multi-national teams, a diverse range of archaeological specialists and a vast archive of records. The task of marshalling this data so that it can be useful not only at the post-excavation stage, but also while making decisions in the field, is challenging. Here, members of the team reflect on the use of digital technology on-site to promote a reflexive engagement with the archaeology. They explore how digital data in a fieldwork context can break down communication barriers between specialists, foster an inclusive approach to the excavation process and facilitate reflexive engagement with recording and interpretation.
Variation in human cognitive ability is of consequence to a large number of health and social outcomes and is substantially heritable. Genetic linkage, genome-wide association, and copy number variant studies have investigated the contribution of genetic variation to individual differences in normal cognitive ability, but little research has considered the role of rare genetic variants. Exome sequencing studies have already met with success in discovering novel trait-gene associations for other complex traits. Here, we use exome sequencing to investigate the effects of rare variants on general cognitive ability. Unrelated Scottish individuals were selected for high scores on a general component of intelligence (g). The frequency of rare genetic variants (in n = 146) was compared with those from Scottish controls (total n = 486) who scored in the lower to middle range of the g distribution or on a proxy measure of g. Biological pathway analysis highlighted enrichment of the mitochondrial inner membrane component and apical part of cell gene ontology terms. Global burden analysis showed a greater total number of rare variants carried by high g cases versus controls, which is inconsistent with a mutation load hypothesis whereby mutations negatively affect g. The general finding of greater non-synonymous (vs. synonymous) variant effects is in line with evolutionary hypotheses for g. Given that this first sequencing study of high g was small, promising results were found, suggesting that the study of rare variants in larger samples would be worthwhile.
The future of centimetre and metre-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from a few hundred MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is a technology demonstrator aimed in the mid-frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phased-array feed systems on parabolic reflectors. The large field-of-view makes ASKAP an unprecedented synoptic telescope that will make substantial advances in SKA key science. ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of two sites selected by the international community as a potential location for the SKA. In this paper, we outline an ambitious science program for ASKAP, examining key science such as understanding the evolution, formation and population of galaxies including our own, understanding the magnetic Universe, revealing the transient radio sky and searching for gravitational waves.
Significant research effort is regularly applied to the goal of reducing the size of radio-frequency antennas while maintaining the entire set of positive attributes of proven but relatively large antennas. Such parameters as frequency response (multiple or single), bandwidth, and complexity of the antenna-driver balun structures require iterative optimization. The direct-write processes now available have enabled the insertion of reactive-loading elements as integral parts of the antenna structure, especially into new conformal designs. These reactive-loading elements were used in conjunction with modern design techniques to achieve antenna devices that were reduced in size to as much as half that of traditional counterparts. The performances of the miniaturized antennas constructed by direct-write methods were evaluated and compared to those of traditional antenna structures.
While information for the medical aspects of disaster surge is increasingly available, there is little guidance for health care facilities on how to manage the psychological aspects of large-scale disasters that might involve a surge of psychological casualties. In addition, no models are available to guide the development of training curricula to address these needs. This article describes 2 conceptual frameworks to guide hospitals and clinics in managing such consequences. One framework was developed to understand the antecedents of psychological effects or “psychological triggers” (restricted movement, limited resources, limited information, trauma exposure, and perceived personal or family risk) that cause the emotional, behavioral, and cognitive reactions following large-scale disasters. Another framework, adapted from the Donabedian quality of care model, was developed to guide appropriate disaster response by health care facilities in addressing the consequences of reactions to psychological triggers. This framework specifies structural components (internal organizational structure and chain of command, resources and infrastructure, and knowledge and skills) that should be in place before an event to minimize consequences. The framework also specifies process components (coordination with external organizations, risk assessment and monitoring, psychological support, and communication and information sharing) to support evidence-informed interventions.
(Disaster Med Public Health Preparedness. 2011;5:73-80)
A highly sensitive x-ray fluorescence (XRF) technique has been developed for the determination of low metal concentrations in the etch resistant layer of surface-imaged photoresists. The samples may be analyzed quickly and the method is applicable to a wide variety of surfaceimaging processes. For each metal of interest the XRF spectrometer is easily calibrated using polymer films containing known concentrations of a metal-containing reagent. Examples of the application of this technique to the analysis of Ti, Si and Zr-containing films are described.
a-Si:H solar cells were irradiated with 1.00 MeV proton fluences in the range of 1.00E14 to 1.2 5E15 cm-2. Annealing of the short-circuit current density was studied at 0, 22, 50, 100 and 150 °C. Annealing times ranged from an hour to several days. The measurements confirmed that annealing occurs at O °C and the initial characteristics of the cells are restored by annealing at 200 °C. It is proposed that the degradation in the short-circuit current density with irradiation is due to carrier recombination through the fraction of D° states bounded by the guasi-Fermi energies. The time dependence of the rate of annealing in the short-circuit current density appears to be consistent with the interpretation that there is dispersive transport mechanism which leads to the annealing of the irradiation induced defects.
During the past few years we have been studying several of the physical processes relevant to the production of spherical shells for inertial confinement fusion targets, both in a microgravity environment and in a containerless environment. The work has led to the development of several experimental facilities. Those which are most unique are described here, and fall into three categories as follows: 1. Ones which provide an induced low- or microgravity containerless environment, such as a vertical drag-free wind tunnel, two differing low-pressure and/or high-temperature drop towers for processing metallic or metallic-glass specimens, and a neutral buoyancy tank, 2. Ones providing containerless processing capability, such as a focusing radiator and an electrostatic levitator and 3. Ones providing extended microgravity and containerless capabilities, such as the KC-135 aircraft and the Space Processing Application Rockets. The physical processes which we have been studying include, but are not limited to, those which establish the shell sphericity, concentricity, surface topology, material properties, coatings, heating and cooling requirements and the effects of gravity on fusion pellet fabrication processes.
Mercuric iodide (HgI2) is a semiconductor that has shown great promise for use in roomtemperature high-resolution x-ray and gamma-ray spectrometers. Its widespread usage has been limited, however, by low yield and long-term reliability problems. The processing of this material is still in its infancy compared to silicon, so research efforts continue to pursue the root causes of device failures. Two likely sources of performance limitations are impurities and poor contacts. Significant efforts have been expended in developing and using various purification schemes. However, quantitative chemical analyses have shown that several metallic impurities still exist at the high ppb level. In addition, it has not yet been definitively determined which impurities are most problematic and at what level they have a detrimental effect. Leakage currents and currentvoltage measurements have been used to study the movement of mobile impurity-related defect centers in the bulk mercuric iodide. In particular, this method has been used to quantify the drift of metallic impurities, such as Ag and Cu, which are known to or believed to degrade HgI2 detectors. Four-point-probe sheet resistance measurements have been used to study the stability of contacts and the formation of reaction layers. In particular, such measurements have revealed that the Pd contacts currently used for the highest quality detectors are not as stable as previously thought, as the films of Pd react with the HgI2 to form the amalgam PdHg.
Periodically loaded line phase shifter circuits using voltage tunable BaSrTiO3 (BST) parallel plate capacitors have been demonstrated at X-band. The first such phase shifter circuit was capable of 100° of phase shift with an insertion loss of 7.6 dB at 10 GHz. Subsequently, the monolithic fabrication procedure was refined resulting in an improved phase shifter circuit with 200° of phase shift and an insertion loss of 6.2 dB at 10 GHz. In addition to promising loss performance (32°/dB) at 10 GHz, the circuits reported here have several desirable features such as moderate control voltages (20 V), room temperature operation, and compatibility with monolithic fabrication techniques.
For p-type ion implanted SiC, temperatures in excess of 1600 °C are required to activate the dopant atoms and to reduce the crystal damage inherent in the implantation process. At these high temperatures, however, macrosteps (periodic welts) develop on the SiC surface. In this work, we investigate the use of a graphite mask as an anneal cap to eliminate the formation of macrosteps. N-type 4H- and 6H-SiC epilayers, both ion implanted with low energy (keV) Boron (B) schedules at 600 °C, and 6H-SiC substrates, ion implanted with Aluminum (Al), were annealed using a Graphite mask as a cap. The anneals were done at 1660 °C for 20 and 40 minutes. Atomic force microscopy (AFM), capacitance-voltage (C-V) and secondary ion mass spectrometry (SIMS) measurements were then taken to investigate the effects of the anneal on the surface morphology and the substitutional activation of the samples. It is shown that, by using the Graphite cap for the 1660 °C anneals, neither polytype developed macrosteps for any of the dopant elements or anneal times. The substitutional activation of Boron in 6H-SiC was about 15%.
We report the growth and structural properties of InSb and InSb:N quantum dots on InAs and GaAs substrates. Strain induced, self-assembled quantum dots are grown using solid-source molecular beam epitaxy. For improved growth control, we developed a growth technique similar to atomic layer epitaxial methods. InSb and InSb:N multiple quantum dots formed on both InAs and GaAs. We explain the formation of multiple quantum dots by the anisotropic distribution of strain energy within the quantum dot, the long adatom lifetime during atomic layer epitaxy, and the low bond energy of InSb. Nitrogen incorporation during formation of quantum dots changes surface energy barrier and causes anisotropic distribution of strain energy, results in formation of closely coupled multiple quantum dots in <110> orientation. We obtained mid infrared luminescence around 3.6 μm from InNSb QDs grown on InAs substrate, where it exhibits relatively low efficiencies of nitrogen incorporation compared to the quantum well structure.