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To identify potential participants for clinical trials, electronic health records (EHRs) are searched at potential sites. As an alternative, we investigated using medical devices used for real-time diagnostic decisions for trial enrollment.
To project cohorts for a trial in acute coronary syndromes (ACS), we used electrocardiograph-based algorithms that identify ACS or ST elevation myocardial infarction (STEMI) that prompt clinicians to offer patients trial enrollment. We searched six hospitals’ electrocardiograph systems for electrocardiograms (ECGs) meeting the planned trial’s enrollment criterion: ECGs with STEMI or > 75% probability of ACS by the acute cardiac ischemia time-insensitive predictive instrument (ACI-TIPI). We revised the ACI-TIPI regression to require only data directly from the electrocardiograph, the e-ACI-TIPI using the same data used for the original ACI-TIPI (development set n = 3,453; test set n = 2,315). We also tested both on data from emergency department electrocardiographs from across the US (n = 8,556). We then used ACI-TIPI and e-ACI-TIPI to identify potential cohorts for the ACS trial and compared performance to cohorts from EHR data at the hospitals.
Receiver-operating characteristic (ROC) curve areas on the test set were excellent, 0.89 for ACI-TIPI and 0.84 for the e-ACI-TIPI, as was calibration. On the national electrocardiographic database, ROC areas were 0.78 and 0.69, respectively, and with very good calibration. When tested for detection of patients with > 75% ACS probability, both electrocardiograph-based methods identified eligible patients well, and better than did EHRs.
Using data from medical devices such as electrocardiographs may provide accurate projections of available cohorts for clinical trials.
Various medications and devices are available for facilitation of emergent endotracheal intubations (EETIs). The objective of this study was to survey which medications and devices are being utilized for intubation by Canadian physicians.
A clinical scenario-based survey was developed to determine which medications physicians would administer to facilitate EETI, their first choice of intubation device, and backup strategy should their first choice fail. The survey was distributed to Canadian emergency medicine (EM) and intensive care unit (ICU) physicians using web-based and postal methods. Physicians were asked questions based on three scenarios (trauma; pneumonia; heart failure) and responded using a 5-point scale ranging from “always” to “never” to capture usual practice.
The survey response rate was 50.2% (882/1,758). Most physicians indicated a Macintosh blade with direct laryngoscopy would “always/often” be their first choice of intubation device in the three scenarios (mean 85% [79%-89%]) followed by video laryngoscopy (mean 37% [30%-49%]). The most common backup device chosen was an extraglottic device (mean 59% [56%-60%]). The medications most physicians would “always/often” administer were fentanyl (mean 45% [42%-51%]) and etomidate (mean 38% [25%-50%]). EM physicians were more likely than ICU physicians to paralyze patients for EETI (adjusted odds ratio 3.40; 95% CI 2.90-4.00).
Most EM and ICU physicians utilize direct laryngoscopy with a Macintosh blade as a primary device for EETI and an extraglottic device as a backup strategy. This survey highlights variation in Canadian practice patterns for some aspects of intubation in critically ill patients.
Influenza A (H1N1) pdm09 became the predominant circulating strain in the United States during the 2013–2014 influenza season. Little is known about the epidemiology of severe influenza during this season.
A retrospective cohort study of severely ill patients with influenza infection in intensive care units in 33 US hospitals from September 1, 2013, through April 1, 2014, was conducted to determine risk factors for mortality present on intensive care unit admission and to describe patient characteristics, spectrum of disease, management, and outcomes.
A total of 444 adults and 63 children were admitted to an intensive care unit in a study hospital; 93 adults (20.9%) and 4 children (6.3%) died. By logistic regression analysis, the following factors were significantly associated with mortality among adult patients: older age (>65 years, odds ratio, 3.1 [95% CI, 1.4–6.9], P=.006 and 50–64 years, 2.5 [1.3–4.9], P=.007; reference age 18–49 years), male sex (1.9 [1.1–3.3], P=.031), history of malignant tumor with chemotherapy administered within the prior 6 months (12.1 [3.9–37.0], P<.001), and a higher Sequential Organ Failure Assessment score (for each increase by 1 in score, 1.3 [1.2–1.4], P<.001).
Risk factors for death among US patients with severe influenza during the 2013–2014 season, when influenza A (H1N1) pdm09 was the predominant circulating strain type, shifted in the first postpandemic season in which it predominated toward those of a more typical epidemic influenza season.
Infect. Control Hosp. Epidemiol. 2015;36(11):1251–1260
A small proportion of pediatric sport- and recreation-related injuries are serious enough to be considered “major trauma.” However, the immediate and long-term consequences in cases of pediatric major trauma are significant and potentially life-threatening. The objective of this study was to describe the incidence and outcomes of pediatric major traumas related to sport and recreational activities in Nova Scotia.
This study was a retrospective case series. Data on major pediatric traumas related to sport and recreational activities on a provincial scope were extracted from the Nova Scotia Trauma Program Registry between 2000 and 2013. We evaluated frequency, type, severity, and outcomes of major traumas. Outcomes assessed included length of hospital stay, admission to a special care unit (SCU), and mortality.
Overall, 107 children aged three to 18 years sustained a major trauma (mean age 12.5 [SD 3.8]; 84% male). Most injuries were blunt traumas (97%). The greatest proportion were from cycling (59, 53%), followed by hockey (8, 7%), skateboarding (7, 7%) and skiing (7, 7%). The Nova Scotia Pediatric Trauma Team was activated in 27% of cases. Mean in-hospital length of stay was five days (SD 5.6), and nearly half (49%) of patients required SCU admission. Severe traumatic brain injury occurred in 52% of cases, and mortality in five cases.
Over a 13-year period, the highest incidence of pediatric major trauma related to sport and recreational activities was from cycling, followed by hockey. Severe traumatic brain injury occurred in over half of pediatric major trauma patients.
Optical absorption efficiency, an important metric for sensing, radiometric and energy harvesting applications, has been studied theoretically and experimentally in porous, ordered nanostructures, including multi-walled- (MW) carbon nanotubes (CNTs) and single-walled- (SW) CNTs. We have characterized the absorption efficiencies in the 350 nm -7000 nm wavelength range of vertically aligned MWCNT arrays with high site densities synthesized directly on metallic substrates using a plasma-enhanced (PE)- chemical vapor deposition (CVD) process. Our ultra-thin absorbers exhibit a reflectance as low as ∼ 0.02 % (100 X lower than the benchmark). Such high efficiency absorbers are particularly attractive for radiometry, as well as energy harnessing applications. This work increases the portfolio of materials that can be integrated with such absorbers due to the potential for reduced synthesis temperatures arising from a plasma process. Optical modeling calculations were conducted that enabled a determination of the extinction coefficient in the films.
In the twenty-five years since the original publication of these two Volumes, there have been numerous developments in string theory. The curious twists and turns that marked its pre-1987 evolution have continued apace, and current research makes contact with a wide range of areas of mathematics and physics. In the following we will mention briefly some of these developments and then explain why we believe that these volumes are still useful.
Major insights into the non-perturbative structure of string theory followed from the discovery of non-perturbative duality symmetries of super-string theory. This led to the realization that the myriad of apparently distinct superstring theories that arise in ten or fewer dimensions actually are different perturbative approximations to the same underlying theory, which has come to be known as M-theory. Furthermore, M-theory has eleven-dimensional supergravity as another semiclassical limit. The understanding of these interconnections was aided by the simultaneous discovery of the properties of a family of dynamical objects called p-branes, which are extended objects that fill p spatial dimensions, as opposed to the 1 dimension of the string. p-branes can be viewed as solitons that are generalizations of the magnetic monopoles of conventional quantum field theory and the black holes of general relativity. Indeed, these discoveries have stimulated impressive advances in understanding the quantum and thermodynamic properties of large classes of black holes.
An important outcome of these considerations has been striking progress in understanding the nonperturbative structure of the quantum field theories that arise from string theory in various limits.
The particle spectrum of a string theory consists of a finite number of massless states and an infinite tower of massive excitations at a mass scale characterized by a fundamental parameter – the string tension or Regge slope. As has been explained in previous chapters, this parameter must be of order the Planck mass (1019 GeV) in order that the graviton interact with the usual Newtonian strength. If one wishes to give a phenomenological description of the consequences of string theory for lowenergy physics, it should not be necessary to describe explicitly what the massive states are doing. It is natural, instead, to formulate an effective action based entirely on fields that correspond to massless, or at least very light, degrees of freedom only. Such a description turns out to be useful not only for a phenomenological analysis, but even as a framework for addressing certain theoretical issues, such as the occurrence of anomalies.
The infinite set of point-particle fields that arise in string theory consists of a finite number of massless fields, which we collectively represent for the moment by ϕ0, and an infinite number of heavy fields collectively represented by ϕH In principle, it must be possible to describe string theory by a classical action S(ϕ0 ϕH (or, at the quantum level, a quantum effective action) governing these fields. At present, we do not have really satisfactory ways to formulate and understand the exact classical action S(ϕ0, ϕH).
In the first eleven chapters of this book we have attempted to introduce the reader to string theory as it is presently understood. Our focus now shifts to making contact with more familiar physics. In this chapter we develop some concepts in differential geometry that are useful in understanding general relativity and Yang-Mills theory even in four dimensions, but which are of particular utility in ten-dimensional physics. Our treatment in this chapter is comparatively elementary and aims mostly to develop the minimum material we require in chapters 13 and 14. In chapter 13, we will discuss supergravity theory in ten dimensions, which at least in perturbation theory is the low-energy limit of ten-dimensional superstring theory. In chapter 14, we will discuss some of the important ideas that arise in compactification from ten to four dimensions. The concluding chapters of this book, chapters 15 and 16, are devoted to more specialized mathematical background and more speculative ideas about compactification.
Spinors In General Relativity
A good place to start our discussion is to think about the coupling of spinors to a gravitational field. This problem is of great importance in string theories in which both fermions and gravity are present, and this alone would justify its consideration here. In addition, thinking about the coupling of spinors to a gravitational field forces us to examine issues whose analogs for Yang-Mills theory we will wish to consider later. The question of coupling spinors to general relativity was considered briefly in chapter 4, in connection with a discussion of two-dimensional supergravity, but here we will be more extensive.
Since superstring theories are necessarily ten-dimensional theories, any discussion of phenomenology must begin with a discussion of how apparent four-dimensional physics is related to underlying ten-dimensional physics. The present chapter is devoted to this question. We will carry out the discussion in the context of field theory, but with an emphasis on properties that depend only on qualitative assumptions, not numerical details, and so can remain valid in string theory. What we will try to accomplish in this chapter is not to develop detailed models of compactification but to set the stage and introduce some of the essential concepts.
Wave Operators in Ten Dimensions
Most of the preceding chapters have been devoted to string propagation in ten-dimensional flat Minkowski space M10, but henceforth we will consider ten-dimensional space-time to be some more general ten manifold M. We take M to be of the form M4 × K, where M4 is four-dimensional Minkowski space and K is a compact six manifold which is, unfortunately, as yet unknown. More precisely, we take the vacuum state to be a product M4 × K; it must have this form if we wish to maintain four-dimensional Poincaré invariance. Of course, physical fluctuations will not necessarily respect the product form of the vacuum configuration, but as in so many other areas of physics, understanding the ground state is the key to understanding the low-energy excitations.