To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The refraction effect at small incidence angles was investigated for solid Al2O3 disks of varying surface roughness, and Al2O3 and LaB6 powder layers of varying thickness and roughness using pseudo parallel beam optics. For the disks the peak shift Δ2θ correlated approximately inversely with ζmax, the maximum slope of a sinusoidal model of the surface roughness. For a disk polished with 3θm diamond, Δ2θ exceeded that predicted by the James equation. For the powder layers Δ2θ was very small for the thinnest layers. For thicker, rougher layers Δ2θ was larger and was probably due to displacement error from the 0.4° divergence of the Soller slit used and specular reflection of the diffracted beam from the Soller slit leaves.
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.
Although most hospitals report very high levels of hand hygiene compliance (HHC), the accuracy of these overtly observed rates is questionable due to the Hawthorne effect and other sources of bias. In the study, we aimed (1) to compare HHC rates estimated using the standard audit method of overt observation by a known observer and a new audit method that employed a rapid (<15 minutes) “secret shopper” method and (2) to pilot test a novel feedback tool.
Quality improvement project using a quasi-experimental stepped-wedge design.
This study was conducted in 5 acute-care hospitals (17 wards, 5 intensive care units) in the Midwestern United States.
Sites recruited a hand hygiene observer from outside the acute-care units to rapidly and covertly observe entry and exit HHC during the study period, October 2016–September 2017. After 3 months of observations, sites received a monthly feedback tool that communicated HHC information from the new audit method.
The absolute difference in HHC estimates between the standard and new audit methods was ~30%. No significant differences in HHC were detected between the baseline and feedback phases (OR, 0.92; 95% CI, 0.84–1.01), but the standard audit method had significantly higher estimates than the new audit method (OR, 9.83; 95% CI, 8.82–10.95).
HHC estimates obtained using the new audit method were substantially lower than estimates obtained using the standard audit method, suggesting that the rapid, secret-shopper method is less subject to bias. Providing feedback using HHC from the new audit method did not seem to impact HHC behaviors.
In-spiraling supermassive black holes should emit gravitational waves, which would produce characteristic distortions in the time of arrival residuals from millisecond pulsars. Multiple national and regional consortia have constructed pulsar timing arrays by precise timing of different sets of millisecond pulsars. An essential aspect of precision timing is the transfer of the times of arrival to a (quasi-)inertial frame, conventionally the solar system barycenter. The barycenter is determined from the knowledge of the planetary masses and orbits, which has been refined over the past 50 years by multiple spacecraft. Within the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), uncertainties on the solar system barycenter are emerging as an important element of the NANOGrav noise budget. We describe what is known about the solar system barycenter, touch upon how uncertainties in it affect gravitational wave studies with pulsar timing arrays, and consider future trends in spacecraft navigation.
To describe the use of antimicrobial stewardship policies and to investigate factors associated with implementation in a national sample of acute care hospitals.
Infection Control Directors from acute care hospitals participating in the National Healthcare Safety Network (NHSN).
An online survey was conducted in the Fall of 2011. A subset of hospitals also provided access to their 2011 NHSN annual survey data.
Responses were received from 1,015 hospitals (30% response rate). The majority of hospitals (64%) reported the presence of a policy; use of antibiograms and antimicrobial restriction policies were most frequently utilized (83% and 65%, respectively). Respondents from larger, urban, teaching hospitals and those that are part of a system that shares resources were more likely to report a policy in place (P<.01). Hospitals located in California were more likely to have policy in place than in hospitals located in other states (P=.014).
This study provides a snapshot of the implementation of antimicrobial stewardship policies in place in U.S. hospitals and suggests that statewide efforts in California are achieving their intended effect. Further research is needed to identify factors that foster the adoption of these policies.
We used UV-to-IR archival data to investigate the nature of the giant spiral galaxy, NGC 6872, 65 Mpc away. It belongs to the southern Pavo group and is interacting with a small lenticular galaxy, IC4970. GALEX UV images show a very large part of the galaxy not seen before, making it one of the largest spiral galaxies known, with a physical size greater than 150 kpc. The SED of 17 regions (10 kpc of diameter) across the two arms show a remarkable spatial distribution, as if they were mirror images with respect to their stellar population. However, the last 40 kpc of the northeastern arm are much bluer than any other region of the southwestern one. There is a strong spatial correlation between the NUV luminosity and the distance to the nucleus. The UV data supports the scenario of an interaction at 130 Myr which triggered star formation all over the disk of NGC 6872. The tip of the northeastern arm resembles a tidal dwarf galaxy in the process of formation.
GaAs crystal presents some interesting perspectives for resonant biosensors due to its piezoelectric and good mechanical properties and the opportunity to bio-functionalize the surface. Moreover, GaAs can be micromachined by wet etching in several solutions, which constitutes a batch and low-cost process of fabrication. The lateral field excitation (LFE) is used to generate bulk acoustic waves. The main advantage of LFE is the possibility to measure in liquid media, moreover reduced aging and increased frequency stability are also ensured. In this study, an analytical modelization is used to determine the orientations of the vibrating membrane and the electric field that give satisfactory metrological performances. Electrical performances are discussed as a function of geometrical parameters. A simulation based on a Finite Element Modelization is performed in order to optimize the design of the resonant structure. The microfabrication process of the structure is presented. The choice of etchants is discussed in terms of etching rates and surface textures. Several steps of the fabrication of the sensing area structure are shown and characterized. Finally, the active area is fabricated according to the theoretical and experimental results of this study.
Hydrogenated amorphous (a-Si:H) and microcrystalline (µc-Si:H) silicon films are indispensable materials for large area electronic devices like solar cells, image sensors and thin film transistors (TFTs). The interest of the µc-Si:H films arise from the fact that they combine the high optical absorption of a-Si:H and the electrical transport properties close to those of crystalline silicon. In this work we show the correlation between substrate deposition temperature, crystallinity and electrical properties of a-Si:H and µc-Si:H films. The films were prepared by a conventional PECVD (13.56 MHz) RF system from PH3/SiH4/H2 gas mixtures in the temperature range of 100 to 250°C. While phosphorus doped (n) a-Si:H are deposited yielding conductivity values no better than 10−2 S/cm, (n) µc-Si:H layers deposited at substrate temperature of 250°C show conductivity values higher than 101 S/cm, crystalline fraction up to 80% and Hall mobility of about 0.9 cm2. V−1.s−1. It was observed that a change in the dark conductivity behavior occurs around 140°C, with a large increase in the conductivity values. A corresponding increase is not seen in the average grain size and in the crystalline volume fraction, which shows an almost linear increase with the deposition temperature. This stronger influence of the temperature in the electrical characteristics of the µc-Si:H films may be related to the phosphorus activation, which occurs in higher degree at higher deposition temperatures. The correlation among Raman spectroscopy, Hall effect and AC conductivity measurements (frequency range 6 Hz to 13 MHz) shows that the crystalline phase dominates the electrical transport mechanism in µc-Si:H films. Preliminary results of AC measurements indicate that the electrical resistivity of each phase of this material can be determined.
We present angle-resolved photoemission measurements for ultrathin In films on Si(111). Depending on the coverage, this system self-organizes into a metallic monolayer with either 4×1 or √7×√3 symmetry relative to the substrate. Electronically, they behave like ideal one- and two-dimensional electron gases (1DEG and 2DEG), respectively. The 4×1 system has atomic chains of In whose energy bands disperse only parallel to the chains, while for the √7×√3 system, the dominant reciprocal space features (in both diffraction and bandstructure) resemble a pseudo-square lattice with only weaker secondary features relating to the √7×√3 periodicity. In both materials the electrons show coupling to the structure. The 1DEG couples strongly to phonons of momentum 2kF, leading to an 8×“2” Peierls-like insulating ground state. The 2DEG appears to be partially stabilized by electron gap formation at the √7×√3 zone boundary.
The behaviour of thin liquid films is known to be dominated by surface
tension forces. We show that the crystallization of thin liquid films
requires that two wetting angle conditions be simultaneously satisfied: (i)
relating to the liquid–vapour interface and (ii) relating to the
crystal–liquid interface. The balance between capillary pressure and thermal
gradient forces shows that the equilibrium freezing point of thin films is
actually depressed below the bulk freezing point. The magnitude of the
effect is 1°K in an 800 Å thick film. These observations suggest that
small–scale thickness fluctuations may be responsible for the initiation of
sub–grain boundaries in the growth of crystalline silicon films.