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Predicting recurrent Clostridium difficile infection (rCDI) remains difficult. METHODS. We employed a retrospective cohort design. Granular electronic medical record (EMR) data had been collected from patients hospitalized at 21 Kaiser Permanente Northern California hospitals. The derivation dataset (2007–2013) included data from 9,386 patients who experienced incident CDI (iCDI) and 1,311 who experienced their first CDI recurrences (rCDI). The validation dataset (2014) included data from 1,865 patients who experienced incident CDI and 144 who experienced rCDI. Using multiple techniques, including machine learning, we evaluated more than 150 potential predictors. Our final analyses evaluated 3 models with varying degrees of complexity and 1 previously published model.
Despite having a large multicenter cohort and access to granular EMR data (eg, vital signs, and laboratory test results), none of the models discriminated well (c statistics, 0.591–0.605), had good calibration, or had good explanatory power.
Our ability to predict rCDI remains limited. Given currently available EMR technology, improvements in prediction will require incorporating new variables because currently available data elements lack adequate explanatory power.
The collective response of electrons in an ultrathin foil target irradiated by an ultraintense (
) laser pulse is investigated experimentally and via 3D particle-in-cell simulations. It is shown that if the target is sufficiently thin that the laser induces significant radiation pressure, but not thin enough to become relativistically transparent to the laser light, the resulting relativistic electron beam is elliptical, with the major axis of the ellipse directed along the laser polarization axis. When the target thickness is decreased such that it becomes relativistically transparent early in the interaction with the laser pulse, diffraction of the transmitted laser light occurs through a so called ‘relativistic plasma aperture’, inducing structure in the spatial-intensity profile of the beam of energetic electrons. It is shown that the electron beam profile can be modified by variation of the target thickness and degree of ellipticity in the laser polarization.
We sought to conduct a major objective of the CAEP Academic Section, an environmental scan of the academic emergency medicine programs across the 17 Canadian medical schools.
We developed an 84-question questionnaire, which was distributed to academic heads. The responses were validated by phone by the lead author to ensure that the questions were answered completely and consistently. Details of pediatric emergency medicine units were excluded from the scan.
At eight of 17 universities, emergency medicine has full departmental status and at two it has no official academic status. Canadian academic emergency medicine is practiced at 46 major teaching hospitals and 13 specialized pediatric hospitals. Another 69 Canadian hospital EDs regularly take clinical clerks and emergency medicine residents. There are 31 full professors of emergency medicine in Canada. Teaching programs are strong with clerkships offered at 16/17 universities, CCFP(EM) programs at 17/17, and RCPSC residency programs at 14/17. Fourteen sites have at least one physician with a Master’s degree in education. There are 55 clinical researchers with salary support at 13 universities. Sixteen sites have published peer-reviewed papers in the past five years, ranging from four to 235 per site. Annual budgets range from $200,000 to $5,900,000.
This comprehensive review of academic activities in emergency medicine across Canada identifies areas of strengths as well as opportunities for improvement. CAEP and the Academic Section hope we can ultimately improve ED patient care by sharing best academic practices and becoming better teachers, educators, and researchers.
We discuss the stellar halos of massive elliptical galaxies, as revealed by our ambitious integral-field spectroscopic survey MASSIVE. We show that metallicity drops smoothly as a function of radius out to ~ 2.5 Re, while the [α/Fe] abundance ratios stay flat. The stars in the outskirts likely formed rapidly (to explain the high ratio of alpha to Fe) but in a relatively shallow potential (to explain the low metallicities). This is consistent with expectations for a two-phase growth of massive galaxies, in which the second phase involves accretion of small satellites. We also show some preliminary study of the gas content of these most MASSIVE galaxies.
A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40°, spanning longitudes 167° through 360°to 79° at b = 0°, plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg2. The brightness temperature sensitivity will be very good, typically σT≃ 1 K at resolution 30 arcsec and 1 km s−1. The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.
We have successfully developed a Seebeck coefficient Standard Reference Material (SRM™), Bi2Te3, that is essential for interlaboratory data comparison and for instrument calibration. Certification measurements were performed using a differential steady-state technique on 10 samples (15 measurements) randomly selected from a batch of 390 bars. The certified Seebeck coefficient values are provided from 10 to 390 K, and they are further supported by transient measurements. The availability of this SRM will validate measurement results, leading to a better understanding of the structure/property relationships and underlying physics of potential high-efficiency thermoelectric materials.
The electrical activation of As implanted Si has been investigated on rapid thermal annealing timescales using sheet resistance, spreading resistance and Hall Effect techniques. For high dose implants (>1015 As cm-2) differential Hall Effect and spreading resistance profiles confirm the existence of a temperature dependent electrical solubility limit. However for low dose implants, annealing schedules chosen such that the electrical solubility limit is not exceeded reveal electrical deactivation which is not accounted for in the clustering theory. Hall Effect measurements performed as a function of temperature have enabled us to reveal directly electrically inactive As which is not observable at room temperature using standard electrical techniques. The results indicate that As atoms in Si introduce deep trapping levels within the bandgap which are responsible forremoving As from the conduction process at room temperature. This temperature activated process is characterized with an activation energy of 0.4eV.
The deposition of polycrystalline silicon in a rapid thermal processor was studied in the temperature range of 600-1100°C using a mixture of silane and argon at reduced pressures. The amorphous-to-polycrystalline transition temperature was determined by X-ray diffraction and UV-visible spectrophotometry to be between 650 and 700°C. The activation energy of the deposition was found to be approximately 1.5 eV in the temperature range of 600 to 800°C, in reasonable agreement with LPCVD and APCVD results. At 800°C and above, the deposition rate depended only weakly on temperature, as is characteristic of mass-transport-fimited processes. The partial pressure of silane was found to affect the deposition rate in both surface-limited and gas-transport-limited depositions. A UV-visible spectrophotometer was used as a reflectometer to measure the surface roughness of the samples, which in general increased with increasing deposition temperature and film thickness. At the lower deposition temperatures, the surfaces were very smooth, as is characteristic of amorphous-silicon films. Furthermore, the ability to change temperature rapidly appears to allow smoother films to be obtained by initially depositing at lower temperatures, and then ramping to a higher temperature to increase the deposition rate.
Rapid thermal nitridation (RTN) of metastable Ti silicide in pure ammonia ambient has been shown to result in the formation of a bilayer TiSi 2'TiN structure. This bilayer structure provides an effective self-aligned diffusion barrier against aluminum spiking. Further, the simultaneous formation of TiN on top of the TiSi2 preserves the low resistivity of the silicide layer upon subsequent high temperature process steps. Rutherford backscatttering spectroscopy, Auger electron spectroscopy and four point probe techniques were used to analyze the stoichiometry of the nitrided layer, and to study the kinetics of the nitridation reaction. The nitridation of the metastable silicide film is a substitutional eaction which begins at the surface of the silicide and progresses by substituting nitrogen atoms for silicon. The nitrogen atoms result from dissociation of ammonia The released silicon atoms then diffuse to the silicide'silicon interface and deposit in an epitaxial manner. The benefits of the proposed metallization scheme are substantiated by electrical characterization of the bilayer structure in comparison with a conventional process.
A study of the oxidation kinetics of lightly doped (100) silicon in dry oxygen has been carried out at different pressures (0.03 atm. to 1.0 atm.) and temperatures (900ºC to 1200ºC) for short times (< 500 seconds). The data can be fit equally well to the parabolic model as it can to the linearparabolic or parallel oxidation models. The activation energy derived from analysis of the parabolic rate constant is 0.94 eVand is the same at 1.0 and 0.1 atmosphere dry O2. It was also found that the parabolic rate constant displayed a linear dependence on the O2 pressure.
Ion-implantation induced amorphization has been used to modify the linearity of response of ultrafast photoconductive switches fabricated on SOS. The extent of amorphization was determined using various materials characterization techniques. TRIM-86 Monte Carlo calculations were used to model the defect densities produced by ion implantation. Linearity of response is critically dependent upon the nature of the semiconductor region under metallic contacts and the character of the response is opposite to that expected from reports in the literature.
The recognition and understanding of the early fossil record on Earth is vital to the success of missions searching for life on other planets. Despite this, the evidence for life on Earth before ~3.0 Ga remains controversial. The discovery of new windows of preservation in the rock record more than 3.0 Ga would therefore be helpful to enhance our understanding of the context for the earliest life on Earth. Here we report one such discovery, a ~3.4 Ga sandstone at the base of the Strelley Pool Formation from the Pilbara of Western Australia, in which micrometre-sized tubular structures preserve putative evidence of biogenicity. Detailed geological mapping and petrography reveals the depositional and early diagenetic history of the host sandstone. We demonstrate that the depositional environment was conducive to life and that sandstone clasts containing putative biological structures can be protected from later metamorphic events, preserving earlier biological signals. We conclude from this that sandstones have an exciting taphonomic potential both on early Earth and beyond.