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We examined Clostridioides difficile infection (CDI) prevention practices and their relationship with hospital-onset healthcare facility-associated CDI rates (CDI rates) in Veterans Affairs (VA) acute-care facilities.
From January 2017 to February 2017, we conducted an electronic survey of CDI prevention practices and hospital characteristics in the VA. We linked survey data with CDI rate data for the period January 2015 to December 2016. We stratified facilities according to whether their overall CDI rate per 10,000 bed days of care was above or below the national VA mean CDI rate. We examined whether specific CDI prevention practices were associated with an increased risk of a CDI rate above the national VA mean CDI rate.
All 126 facilities responded (100% response rate). Since implementing CDI prevention practices in July 2012, 60 of 123 facilities (49%) reported a decrease in CDI rates; 22 of 123 facilities (18%) reported an increase, and 41 of 123 (33%) reported no change. Facilities reporting an increase in the CDI rate (vs those reporting a decrease) after implementing prevention practices were 2.54 times more likely to have CDI rates that were above the national mean CDI rate. Whether a facility’s CDI rates were above or below the national mean CDI rate was not associated with self-reported cleaning practices, duration of contact precautions, availability of private rooms, or certification of infection preventionists in infection prevention.
We found considerable variation in CDI rates. We were unable to identify which particular CDI prevention practices (i.e., bundle components) were associated with lower CDI rates.
The aim of the present study is to use the syndemic framework to investigate the risk of contracting HIV in the US population. Cross-sectional analyses are from The National Health and Nutrition Examination Survey. We extracted and aggregated data on HIV antibody test, socio-demographic characteristics, alcohol use, drug use, depression, sexual behaviours and sexually transmitted diseases from cycle 2009–2010 to 2015–2016. We carried out weighted regression among young adults (20–39 years) and adults (40–59 years) separately. In total, 5230 men and 5794 women aged 20–59 years were included in the present analyses. In total, 0.8% men and 0.2% women were tested HIV-positive. Each increasing HIV risk behaviour was associated with elevated odds of being tested HIV-positive (1.15, 95% CI 1.15–1.15) among young adults and adults (1.61, 95% CI 1.61–1.61). Multi-faceted, community-based interventions are urgently required to reduce the incidence of HIV in the USA.
Chapter 6 presents a discussion of instabilities in coordinate systems other than Cartesian. In this context, the Taylor problem, Görtler vortices, pipe flow, the rotating disk problem, the trailing vortex and the round jet are all presented. In each case the linearized disturbance equations are derived.
The instability of geophysical flows are covered in Chapter 7. From the class of geophysical flows, there are three classes that are distinct and that illustrate the salient properties when viewed from the basis of perturbations. These cases include the effects of density variations and rotation. The cases considered in this chapter are stratified flow, rotation (Rossby waves) and the Ekman layer.
Chapter 4 addresses the important topic of spatial instability for spatially evolving flows, such as shear layers, jets and wakes. The chapter starts out with a derivation of Gaster’s transformation that allows spatial growth rates to be computed from temporal growth rates. The chapter also presents a dicussion of absolute and convective instabilites, and of wavepackets. It concludes with a discussion of dicrete and continuous spectra.
Chapter 8 addresses the intial value problem, x, where the effect of initial conditions are sought within the linear disturbance regime. Laplace transforms, moving coordinates and numerical approaches are all discussed. Examples of the latter include channel flows and the Blasius boundary layer. The chapter concludes with an in-depth discussion of optimizing the initial conditions for subcritical Reynolds numbers to obtain the maximum energy as a function of time. The concept of algebraically instability is discussed within this context, such that when the normalized energy density is greater than one, the flow is said to be algebraically unstable.
Chapter 13 addresses issues associated with experimental techniques for investigating hydrodynamic instabilties. These issues include the experimental facility, model configuration and instrumentation, all of which impact our understanding of hydrodynamic instabilities.
Chapter 12 summarizes techniques of flow control and optimization. The reader is introduced into both passive and active flow control. Techniques such as flexible boundaries, wave induced forcing, feed-forward and feedback control and optimal control theory are all discussed in some detail.
Chapter 1 introduces the basic concepts of hydrodynamic stability theory. The chapter begins with a discussion of the classical experiments of Reynolds, and moves the reader quickly through other examples of instability found in nature. The basic equations of motion and their linearization are then introduced, which sets the up the foundation for the rest of the book.
Chapter 11 introduces the reader to the world of direct numerical simulations. Temporal and spatial formulations are covered along with boundary and initial conditions. Time-marching methods and spatial discretization methods are also discussed. A variety of applications are then presented.
Chapter 5 examines the role of compressibility on the instability of boundary layers and mixing layers. For the compressible mixing layer, a thorough discussion of the mean flow, compressible Rayleigh equation and neutral stability curves is presented. In the discussion of invisicd distrubances, the compressible vortex sheet is also discussed. For the compressible boundary layer, the viscous stability equations are derived, followed by the neutral stability boundaries.