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Laboratory identification of carbapenem-resistant Enterobacteriaceae (CRE) is a key step in controlling its spread. Our survey showed that most Veterans Affairs laboratories follow VA guidelines for initial CRE identification, whereas 55.0% use PCR to confirm carbapenemase production. Most respondents were knowledgeable about CRE guidelines. Barriers included staffing, training, and financial resources.
Shunt-related adverse events are frequent in infants after modified Blalock–Taussig despite use of acetylsalicylic acid prophylaxis. A higher incidence of acetylsalicylic acid-resistance and sub-therapeutic acetylsalicylic acid levels has been reported in infants. We evaluated whether using high-dose acetylsalicylic acid can decrease shunt-related adverse events in infants after modified Blalock–Taussig.
In this single-centre retrospective cohort study, we included infants ⩽1-year-old who underwent modified Blalock–Taussig placement and received acetylsalicylic acid in the ICU. We defined acetylsalicylic acid treatment groups as standard dose (⩽7 mg/kg/day) and high dose (⩾8 mg/kg/day) based on the initiating dose.
There were 34 infants in each group. Both groups were similar in age, gender, cardiac defect type, ICU length of stay, and time interval to second stage or definitive repair. Shunt interventions (18 versus 32%, p=0.16), shunt thrombosis (14 versus 17%, p=0.74), and mortality (9 versus 12%, p=0.65) were not significantly different between groups. On multiple logistic regression analysis, single-ventricle morphology (odds ratio 5.2, 95% confidence interval of 1.2–23, p=0.03) and post-operative red blood cells transfusion ⩾24 hours [odds ratio 15, confidence interval of (3–71), p<0.01] were associated with shunt-related adverse events. High-dose acetylsalicylic acid treatment [odds ratio 2.6, confidence interval of (0.7–10), p=0.16] was not associated with decrease in these events.
High-dose acetylsalicylic acid may not be sufficient in reducing shunt-related adverse events in infants after modified Blalock–Taussig. Post-operative red blood cells transfusion may be a modifiable risk factor for these events. A randomised trial is needed to determine appropriate acetylsalicylic acid dosing in infants with modified Blalock–Taussig.
We use experimental methods to investigate subsidy incidence, the transfer of subsidy payments from intended recipients to other economic agents, in privately negotiated spot markets. Our results show that market outcomes in treatments with a subsidy given to either buyers or sellers are significantly different from both a no-subsidy treatment and the competitive prediction of a 50% subsidy incidence. The disparity in incidence across treatments relative to predicted levels suggests that incidence equivalence does not hold in this market setting. Moreover, we find no statistical difference in market outcomes when benefits are framed as a “subsidy” versus a schedule shift.
We consider the stability of nonlinear travelling waves in a class of activator-inhibitor systems. The eigenvalue equation arising from linearizing about the wave is seen to preserve the manifold of Lagrangian planes for a nonstandard symplectic form. This allows us to define a Maslov index for the wave corresponding to the spatial evolution of the unstable bundle. We formulate the Evans function for the eigenvalue problem and show that the parity of the Maslov index determines the sign of the derivative of the Evans function at the origin. The connection between the Evans function and the Maslov index is established by a ‘detection form,’ which identifies conjugate points for the curve of Lagrangian planes.
Subcritical fronts are shown to exist in a quintic version of the well-known complex Ginzburg–Landau equation, which has a subcritical pitchfork as well as a supercritical saddle-node bifurcation. The fronts connect a finite amplitude plane wave state to a stable zero solution. The unstable manifold at finite amplitude and stable manifold of vanishing amplitude solutions are shown to intersect transversely on an invariant zero-wavenumber manifold with parameters set to be real. By the persistence of transverse intersection, frontal connections exist for a continuum of nearly real fronts parametrised by appropriate variables that exhibit some interesting changes in dimension.
Strained Si- and SiGe-based heterostructure metal-oxide-semiconductor field-effect transistors (MOSFETs) grown on relaxed SiGe virtual substrates exhibit dramatic electron and hole mobility enhancements over bulk Si, making them promising candidates for next generation complementary MOSFET (CMOS) devices. The most heavily investigated heterostructures consist of single strained Si layers grown upon relaxed SiGe substrates. While this configuration offers significant performance gains for both n- and p-MOSFETs, the enhanced hole mobility remains much lower than the enhanced electron mobility. By contrast, a combination of buried compressively strained Si1−yGey layers and tensile strained Si surface layers grown on relaxed Si1−xGex (x < y), hereafter referred to as dual channel heterostructures, offers nearly symmetric electron and hole mobilities without compromising n-MOSFET device performance. To investigate these heterostructures, we study the effects of alloy scattering on channel mobility in long channel MOSFETs. By using the combination of a buried Si0.2Ge0.8 channel and a strained Si surface channel grown on a relaxed Si0.5Ge0.5 virtual substrate, we have achieved nearly symmetric electron and hole mobility in the same heterostructure. By employing different virtual substrate compositions, we can decouple the effects of strain and alloy scattering in both tensile strained surface channels and compressively strained buried channels. We show that significant hole mobility enhancements can be achieved in dual channel heterostructures, even for buried channel compositions where alloy scattering is expected to be most severe. Furthermore, we show that alloy scattering in tensile strained SiGe surface channels impacts electrons much more severely than holes. Taken together, these results demonstrate that dual channel heterostructures can offer symmetric carrier mobilities and provide excellent performance gains for CMOS applications.
The preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole coated YBa2Cu3O7-δ microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layer. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa2Cu3O7-δ film, the oxidized (conductive) polymer depresses Tc by up to 15K. Thus, a new type of molecular switch for controlling superconductivity is demonstrated.
Several series of amorphous silicon nitride thin films have been grown by plasma-enhanced chemical vapour deposition, where the ratio of ammonia and silane feed gases was held constant for each series while the deposition temperature was varied from 160 °C to 550 °C, and all other deposition conditions were held constant. Photothermal Deflection Spectroscopy measurements were used to determine the Urbach slope E0 and the defect density ND. It is found that ND is determined by E0 for most of these samples, suggesting that defect equilibration occurs in a-SiNx:H for x up to at least 0.6. The growth temperature at which the disorder is minimised increases to higher values with increasing x, which is explained in terms of a hydrogen-mediated bond equilibration reaction. Fourier Transform Infra Red spectroscopy measurements were performed to determine the changes in hydrogen bonding with growth temperature. The results suggest that a second bond equilibration reaction also occurs at the growing surface, but that equilibrium cannot be reached at higher temperatures because of hydrogen evolution from Si-H bonds.
We have been developing a new approach to layered hybrid (inorganic/organic) photovoltaic materials for fabrication by Roll-to-Roll (R2R) manufacturing. In this report, we combine the low cost and processability of organic electrically conducting polymers with the efficiency of dye sensitized titanium dioxide, semi-conductor quantum dots (CdSe) self-assembled on layered clay materials (Laponite) onto indium tin oxide coated flexible substrate polyethylene terephthalate (PET) substrates. We have shown electron transfer, guest-guest and host-guest interactions, charge separation, spectral line broadening, and quenching of fluorescence signals which indicate electronic coupling of the dye [Ru(bpy)3]2+ on a CdSe nanocrystal and titanium dioxide nanoparticles. Scanning electron microscopy and atomic force microscopy demonstrate successful nanoparticle formation and thin film self-assembly, as well as surface morphology and polymer thickness.
We demonstrate how data mining techniques can be applied to complex combinatorial data sets and how data from multiple sources can be aggregated via the developed scientific data management system. An example is shown for the case of aggregated combinatorial data for the study of composition, processing, structure, and property relationships of transparent conducting oxides by applying data mining techniques such as principal component analysis. Data mappings of mined results are shown to effectively enable visualization of data trends, identification of anomalies in Fourier transform infrared spectroscopy patterns, and scientifically interesting libraries and spectral regions.