To save 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 saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
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 saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved 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.
Evidence-based central-line–associated bloodstream infection (CLABSI) prevention guidelines recommend the use of an antiseptic scrub to disinfect needleless connectors before device access. Guideline noncompliance may render disinfection ineffective. The goal of this study was to observe needleless-connector disinfection practices and to identify perceived facilitators and barriers to best practices of needleless-connector access.
Methods:
A human factors mixed-methods study involving nursing focus groups of perceived barriers and facilitators and clinical observations of compliance with instructions and protocols for use of 3.15% chlorhexidine gluconate/70% isopropyl alcohol (CHG/IPA) and 70% isopropyl alcohol (IPA) antisepsis products for central venous access device (CVAD) needleless-connector disinfection was conducted in intensive care units (ICUs) at 2 academic medical centers.
Results:
Access to the antiseptic product and lesser workload were identified as best-practice facilitators. Barriers were the time required per needleless-connector access and knowledge deficits. Of the 48 observed access events, 77% resulted in needleless-connector disinfection. The observed mean needleless-connector scrubbing times when using IPA were substantially below the recommended time. Drying time after product use was negligible.
Conclusions:
Lack of access to the disinfection product, emergency situations, and high workload were barriers to needleless-connector disinfection. Observed scrubbing and drying times were shorter than recommended, especially for IPA wipes. These needleless-connector disinfection deficits may increase the risk of CLABSI. Ongoing education and periodic competency evaluation of needleless-connector disinfection, improvement of supply management, and staffing workload are required to imbed and sustain best practices. Further study involving a larger sample size in diverse patient populations is warranted.
In the Basilicata region, located in southern Italy and known for hosting among the first occurrences of the Acheulean culture in southwestern Europe, the Lower Paleolithic site of Loreto at Venosa is located less than a kilometer from the emblematic site of Notarchirico and less than 25 km from Cimitero di Atella. The Loreto site has not been studied as thoroughly as the two other sites and, although geological investigations have been carried out in the Venosa basin, no direct numerical dating has ever been published for the three archaeological levels brought to light during the excavation campaigns. We present a multi-method geochronological approach combining ESR/U-series, ESR, and 40Ar/39Ar permitting to refine the age of the most ancient archaeological level (A) of the Loreto site. These data allow us to propose an MIS 13 age for this level, in accordance with previous hypotheses based on geological and paleontological data. We also propose a technical review of the lithic tools preserved in the collection of the National Archaeological Museum of Venosa to integrate Loreto in the evolution scheme of the European Acheulean techno-complex emergence and diffusion.
Frequency-modulated continuous-wave radar systems profit from increasing the absolute bandwidths of the generated frequency chirps to improve range resolution. As the relative bandwidth of SiGe-voltage-controlled oscillators (VCOs) is limited to about 80%, increasing the center frequency fundamentally or via frequency multiplication is the most direct way to increase that absolute bandwidth. However, as some applications require penetration depth, which dramatically decreases with frequency, other solutions are necessary. Therefore, state-of-the-art concepts rely on the down-conversion of generated frequency chirps via two separately stabilized frequency sources. This article implements a novel architecture, offering relative bandwidths of >100% within a single phase-locked loop (PLL). Therefore, two VCOs at different center frequencies are fed into a down-conversion mixer, whose output is directly stabilized via that PLL with one loop filter generating both tuning voltages. Those circuit blocks can be summarized as one equivalent VCO, offering a higher relative bandwidth and a significantly more linear tuning curve. Thereby, a solution to limited relative bandwidths with high VCO gain variation of single VCO synthesizers is offered while substantially reducing the hardware and implementation effort compared to the state-of-the-art.
The distribution of stress generated by a turbulent flow matters for many natural phenomena, of which rivers are a prime example. Here, we use dimensional analysis to derive a linear, second-order ordinary differential equation for the distribution of stress across a straight, open channel, with an arbitrary cross-sectional shape. We show that this equation is a generic first-order correction to the shallow-water theory in a channel of large aspect ratio. It has two adjustable parameters – the dimensionless diffusion parameter, $\chi$, and a local-shape parameter, $\alpha$. By assuming that the momentum is carried across the stream primarily by eddies and recirculation cells with a size comparable to the flow depth, we estimate $\chi$ to be of the order of the inverse square root of the friction coefficient, $\chi \sim C_f^{-1/2}$, and predict that $\alpha$ vanishes when the flow is highly turbulent. We examine the properties of this equation in detail and confirm its applicability by comparing it with flume experiments and field measurements from the literature. This theory can be a basis for finding the equilibrium shape of turbulent rivers that carry sediment.
In a thoughtful commentary in this journal a decade ago, Michael Rutter reviewed 25 years of progress in the field before concluding that developmental psychopathology (DP) initiated a paradigm shift in clinical science. This deduction requires that DP itself be a paradigm. According to Thomas Kuhn, canonical paradigms in the physical sciences serve unifying functions by consolidating scientists’ thinking and scholarship around single, closed sets of discipline-defining epistemological assumptions and methods. Paradigm shifts replace these assumptions and methods with a new field-defining framework. In contrast, the social sciences are multiparadigmatic, with thinking and scholarship unified locally around open sets of epistemological assumptions and methods with varying degrees of inter-, intra-, and subdisciplinary reach. DP challenges few if any of these local paradigms. Instead, DP serves an essential pluralizing function, and is therefore better construed as a metaparadigm. Seen in this way, DP holds tremendous untapped potential to move the field from zero-sum thinking and scholarship to positive-sum science and epistemological pluralism. This integrative vision, which furthers Dante Cicchetti’s legacy of interdisciplinarity, requires broad commitment among scientists to reject zero-sum scholarship in which portending theories, useful principles, and effective interventions are jettisoned based on confirmation bias, errors in logic, and ideology.
Using thermal convection in liquid metal, we show that strong spatial confinement not only delays the onset Rayleigh number $Ra_c$ of Rayleigh–Bénard instability but also postpones the various flow-state transitions. The $Ra_c$ and the transition to fully developed turbulence Rayleigh number $Ra_f$ depend on the aspect ratio $\varGamma$ with $Ra_c\sim \varGamma ^{-4.05}$ and $Ra_f\sim \varGamma ^{-3.01}$, implying that the stabilization effects caused by the strong spatial confinement are weaker on the transition to fully developed turbulence when compared with that on the onset. When the flow state is characterized by the supercritical Rayleigh number $Ra/Ra_{c}$ ($Ra$ is the Rayleigh number), our study shows that the transition to fully developed turbulence in strongly confined geometries is advanced. For example, while the flow becomes fully developed turbulence at $Ra\approx 200Ra_c$ in a $\varGamma =1$ cell, the same transition in a $\varGamma =1/20$ cell only requires $Ra\approx 3Ra_c$. Direct numerical simulation and linear stability analysis show that in the strongly confined regime, multiple vertically stacked roll structures appear just above the onset of convection. With an increase of the driving strength, the flow switches between different-roll states stochastically, resulting in no well-defined large-scale coherent flow. Owing to this new mechanism that only exists in systems with $\varGamma <1$, the flow becomes turbulent in a much earlier stage. These findings shed new light on how turbulence is generated in strongly confined geometries.
The acoustic response of a five-bladed rotor to an axisymmetric turbulent boundary layer at the tail end of a body of revolution (BOR) is investigated numerically to elucidate the physical sources of acoustics, particularly the role of coherent structures in sound generation. The BOR is at a length-based Reynolds number of $1.9 \times 10^6$ and free-stream Mach number of 0.059. Two rotor advance ratios, $1.44$ and $1.13$, are considered. The turbulent boundary layer on the nose and midsection of the BOR is computed using wall-modelled large-eddy simulation, whereas that in the acoustically important tail-cone section is wall-resolved. The radiated acoustic field is calculated using the Ffowcs Williams–Hawkings equation. The computed flow statistics and sound pressure spectra agree well with the experimental measurements at Virginia Tech. In addition to broadband turbulence-ingestion noise, spectral humps near multiples of the blade-passing frequency and accompanying valleys are captured. They are shown to be caused by correlated blade unsteady-loading dipole sources and their constructive and destructive interference as a result of successive blades cutting through the same coherent structures. The latter undergo rapid growth in the decelerating tail-cone boundary layer before their interaction with the rotor. The acoustic radiation is dominated by the outer region of the blade owing to a combination of larger blade chord-length, inflow turbulence intensity and blade speed. The numerical results also correctly predict the effect of the rotor advance ratio on the acoustic field. A mixed free-stream/convection Mach-number scaling successfully collapses the sound pressure spectra at the two advance ratios.
The straightening–unstraightening correspondence of Grothendieck–Lurie provides an equivalence between cocartesian fibrations between $(\infty, 1)$-categories and diagrams of $(\infty, 1)$-categories. We provide an alternative proof of this correspondence, as well as an extension of straightening–unstraightening to all higher categorical dimensions. This is based on an explicit combinatorial result relating two types of fibrations between double categories, which can be applied inductively to construct the straightening of a cocartesian fibration between higher categories.
The present study aimed to explore the perspectives of older adults and health providers on cardiac rehabilitation care provided virtually during COVID-19. A qualitative exploratory methodology was used. Semi-structured interviews were conducted with 15 older adults and 6 healthcare providers. Five themes emerged from the data: (1) Lack of emotional intimacy when receiving virtual care, (2) Inadequacy of virtual platforms, (3) Saving time with virtual care, (4) Virtual care facilitated accessibility, and (5) Loss of connections with patients and colleagues. Given that virtual care continues to be implemented, and in some instances touted as an optimal option for the delivery of cardiac rehabilitation, it is critical to address the needs of older adults living with cardiovascular disease and their healthcare providers. This is particularly crucial related to issues accessing and using technology, as well as older adults’ need to build trust and emotional connection with their providers.
We describe Pericelis nivea sp. nov. from sunken wood collected 330 m deep, off the coast of Owase, Japan. This is the first record of Pericelis from the bathyal zone. Unlike other congeners, P. nivea sp. nov. is characterized by the absence of eyespots. We provide a partial sequence of the mitochondrial cytochrome c oxidase subunit I gene as a DNA barcode for the new species. Phylogenetic analyses based on concatenated sequences of nuclear 18S and 28S ribosomal DNA showed that P. nivea sp. nov. was nested in the clade of Pericelis with high support; however, the relationship between P. nivea sp. nov. and other Pericelis species was unclear.