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Children with CHD and acquired heart disease have unique, high-risk physiology. They may have a higher risk of adverse tracheal-intubation-associated events, as compared with children with non-cardiac disease.
Materials and methods
We sought to evaluate the occurrence of adverse tracheal-intubation-associated events in children with cardiac disease compared to children with non-cardiac disease. A retrospective analysis of tracheal intubations from 38 international paediatric ICUs was performed using the National Emergency Airway Registry for Children (NEAR4KIDS) quality improvement registry. The primary outcome was the occurrence of any tracheal-intubation-associated event. Secondary outcomes included the occurrence of severe tracheal-intubation-associated events, multiple intubation attempts, and oxygen desaturation.
A total of 8851 intubations were reported between July, 2012 and March, 2016. Cardiac patients were younger, more likely to have haemodynamic instability, and less likely to have respiratory failure as an indication. The overall frequency of tracheal-intubation-associated events was not different (cardiac: 17% versus non-cardiac: 16%, p=0.13), nor was the rate of severe tracheal-intubation-associated events (cardiac: 7% versus non-cardiac: 6%, p=0.11). Tracheal-intubation-associated cardiac arrest occurred more often in cardiac patients (2.80 versus 1.28%; p<0.001), even after adjusting for patient and provider differences (adjusted odds ratio 1.79; p=0.03). Multiple intubation attempts occurred less often in cardiac patients (p=0.04), and oxygen desaturations occurred more often, even after excluding patients with cyanotic heart disease.
The overall incidence of adverse tracheal-intubation-associated events in cardiac patients was not different from that in non-cardiac patients. However, the presence of a cardiac diagnosis was associated with a higher occurrence of both tracheal-intubation-associated cardiac arrest and oxygen desaturation.
Duncan Fairgrieve, Senior Fellow in Comparative Law at the British Institute of International and Comparative Law, London,
Geraint Howells, Dean and Chair Professor of Commercial Law, City University of Hong Kong,
Peter Møgelvang-Hansen, Professor of Commercial Law at the Copenhagen Business School, Denmark,
Gert Straetmans, Full Professor of European Economic, Consumer and Commercial Law, University of Antwerp, Belgium,
Dimitri Verhoeven, Researcher, Faculty of Law, University of Antwerp, Belgium,
Piotr MacHnikowski, Professor of Civil Law and head of the Civil Law and Private International Law Department at the University of Wrocław, Poland,
André Janssen, Visiting Professor at the City University Hong Kong, China,
Reiner Schulze, Professor of German and European Civil Law, University of Münster, Germany
From a historical perspective, product liability was traditionally seen in many jurisdictions as merely a concrete illustration of the law of obligations to a specific factual matrix, involving the causing of damage by a product. It was only when the mass manufacture of consumer goods started to occur that sufficient impetus was generated towards the identification of an autonomous area of law. It was only then that practitioners and scholars commenced specialisation in the sphere of product liability. The US was of course at the vanguard of developments, and a word will thus be said of the evolution in the US, as a background to the European context. Professor David Owen records in his leading US treatise on the topic that the consequence of the spread of industrialisation in the 19th century was that by 1900, products ‘cases began to appear with some frequency’. There then followed iconic cases such as MacPherson v Buick Motor Co or Greenman v Yuba Power Products Inc, which ushered in the modern era of US products liability, accompanied by the various Restatements, with Owen noting that the strict liability rule enshrined in §402A of the Restatement (Second) of Torts resulted in the ‘the doctrine of strict products liability in tort, together with a miscellany of secondary principles spread like wildfire around the nation’.
The development of product liability in Europe as a distinctive area of the law occurred much later than in the US. It was not until relatively late in the 20th century, after the occurrence of mass product disasters in Europe, and the realisation that traditional responses of the law were inadequate to deal with such situations, that there was a movement towards products liability as raising distinct legal issues, for which a tailor-made regime for compensation was potentially required. It should be noted that comparative law played a role in this process in certain European jurisdictions, with Gerhard Wagner describing for instance how in Germany ‘product liability was imported from the US, both with regard to the legal problem and its solution’.
Comprehension of predicates and reflexives was examined in children who stutter (CWS) and children who do not stutter (CWNS) who were between 9 years, 7 months and 10 years, 2 months. Demands on working memory and manual reaction time were also assessed in two experiments that employed a four-choice picture-selection sentence comprehension task. CWS were less accurate than CWNS on the attachment of predicates. For reflexives, there was no between-group difference in accuracy, but there was a difference in speed. The two constructions induced processing at different points on a speed–accuracy continuum with CWS sacrificing accuracy to respond fast with predicates, while they maintained accuracy of reflexives by responding slower relative to CWNS. Predicates made more demands on language than nonspeech motor reaction time, whereas the reverse was the case with reflexives for CWS compared to CWNS.
A rare subclass of Type Ia supernovae (SNe Ia) shows evidence of strong interaction with a hydrogen-rich circumstellar medium (CSM); these objects are referred to as SNe Ia-CSM. PTF11kx began life as a SN Ia, but after a month it began to show indications of significant interaction with its CSM. This well-studied object solidified the connection between SNe Ia-CSM and more typical SNe Ia, despite their spectral similarity to Type IIn SNe (which likely come from massive star progenitors, as opposed to the white dwarf progenitors for the SNe Ia-CSM). The spectra of all ~20 known SNe Ia-CSM are dominated by Hα emission (with widths of ~2000 km s−1) and exhibit large Hα/Hβ intensity ratios; moreover, they have an almost complete lack of He I emission (see left panel of Figure 1). They also show possible evidence of dust formation through a decrease in the red wing of Hα 75–100 days past maximum brightness. The absolute magnitudes of SNe Ia-CSM are found to be -21.3 mag ≤ MR ≤ −19 mag (see right panel of Figure 1), and they also show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM imply that these objects come from a relatively young stellar population.
An enormous effort is underway worldwide to attempt to detect gravitational waves. If successful, this will open a new frontier in astronomy. An essential portion of this effort is being carried out in Australia by the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA), with research teams working at the Australia National University, University of Western Australia, and University of Adelaide involving scientists and students representing many more institutions and nations. ACIGA is developing ultrastable high-power continuous-wave lasers for the next generation interferometric gravity wave detectors; researching the problems associated with high optical power in resonant cavities; opening frontiers in advanced interferometry configurations, quantum optics, and signal extraction; and is the world's leader in high-performance vibration isolation and suspension design. ACIGA has also been active in theoretical research and modelling of potential astronomical gravitational wave sources, and in developing data analysis detection algorithms. ACIGA has opened a research facility north of Perth, Western Australia, which will be the culmination of these efforts. This paper briefly reviews ACIGA's research activities and the prospects for gravitational wave astronomy in the southern hemisphere.
A log-coffin excavated in the early nineteenth century proved to be well enough preserved in the early twenty-first century for the full armoury of modern scientific investigation to give its occupants and contents new identity, new origins and a new date. In many ways the interpretation is much the same as before: a local big man buried looking out to sea. Modern analytical techniques can create a person more real, more human and more securely anchored in history. This research team shows how.
We study the axisymmetric stretching of a thin sheet of viscous fluid driven by a centrifugal body force. Time-dependent simulations show that the sheet radius R(t) tends to infinity in finite time. As time t approaches the critical time t*, the sheet becomes partitioned into a very thin central region and a relatively thick rim. A net momentum and mass balance in the rim leads to a prediction for the sheet radius near the singularity that agrees with the numerical simulations. By asymptotically matching the dynamics of the sheet with the rim, we find that the thickness h in the central region is described by a similarity solution of the second kind, with h ∝ (t* − t)α where the exponent α satisfies a nonlinear eigenvalue problem. Finally, for non-zero surface tension, we find that the exponent increases rapidly to infinity at a critical value of the rotational Bond number B = 1/4. For B > 1/4, surface tension defeats the centrifugal force, causing the sheet to retract rather than to stretch, with the limiting behaviour described by a similarity solution of the first kind.
Paul Thompson’s monograph on William Butterfield set out to challenge the bizarre misconceptions which had previously warped appreciation of his work. These included Sir John Summerson’s accusation of ‘purposeful sadism’, Ian Nairn’s view of him as an ‘unexpected Heathcliff, and Henry-Russell Hitchcock’s description of him as uncivilized, ‘a man who never wrote a book or an article’ and who rarely travelled. Mendacious anecdotes suggested a puritanical and antisocial character, lacking in humanity. Thompson effectively refuted such absurdities, but Butterfield’s letters — very few of which have been published, even in part — provide fascinating evidence of his character. They reveal his humour and his affection for old friends, and his strongly held, but eminently sensible, religious views, as well as his pragmatic and conscientious practice of architecture. This evidence bears out and adds much useful detail to Thompson’s depiction of the man, refining our understanding of him and allowing his personality to come to the fore.
In Chapters 1–5, we have provided an elementary exposition of the basic concepts in classical solid mechanics, namely linear elasticity, elastostatics, elastodynamics, models for thin structures and nonlinear elasticity. In each case, we have focused on practical examples that highlight the most interesting modelling and mathematical issues.
In Chapter 6, our aim was to show how formal perturbation methods, widely used in fluid dynamics, can be applied to many problems in solid mechanics involving bodies that are thin or slender. Although the remainder of the book does not rely on this chapter, we firmly believe that the techniques demonstrated there form an invaluable component of any applied mathematician's armoury.
Finally, in Chapters 7–9, we have given necessarily brief introductions to some of the important physical situations where classical solid mechanics fails, and the elementary theories from Chapters 1–5 must be re-examined. Inevitably, the mathematical problems involved here become more challenging, and we have therefore limited our attention to idealised models that clearly illustrate the fundamental concepts.
The diversity and open-endedness of the topics described in Chapter 9 reflect the fact that we have not done justice to many scientific ideas in theoretical solid mechanics. Fracture, plasticity and viscoelasticity, for example, are subjects of enormous practical importance, and there are many texts describing both the practical and the mathematical aspects in much greater detail than the contents of Chapters 7–9.
In Chapter 4, we derived various approximate models for thin or slender elastic configurations such as rods and plates. These models were obtained using net force and moment balances combined with ad hoc constitutive relations, for example between the bending moments and the curvatures. In this chapter, we show how such models may be derived systematically from the underlying continuum equations and boundary conditions. We concentrate on a few canonical models for plates, beams, rods and shells. Each of these models is important in its own right, and their derivation illustrates the tools that are widely useful for analysing more general thin structures.
The basic idea is to exploit the slenderness of the geometry so as to simplify the equations of elasticity asymptotically. This process is made systematic by first non-dimensionalising the equations, so that all the variables are dimensionless and of order one. This highlights the small slenderness parameter ε = h/L, where h is a typical thickness and L a typical length of the elastic body. A simplified system of equations is then obtained by carefully taking the limit ε → 0. Typically, the solution is sought as an asymptotic expansion in powers of the small parameter ε, and the techniques demonstrated here fall within the general theories of asymptotic expansions and perturbation methods. Kevorkian & Cole (1981), Hinch (1991) and Bender & Orszag (1978) provide very good general expositions of these methods.
This chapter concerns steady state problems in linear elasticity. This topic may appear to be the simplest in the whole of solid mechanics, but we will find that it offers many interesting mathematical challenges. Moreover, the material presented in this chapter will provide crucial underpinning to the more general theories of later chapters.
We will begin by listing some very simple explicit solutions which give valuable intuition concerning the role of the elastic moduli introduced in Chapter 1. Our first application of practical importance is elastic torsion, which concerns the twisting of an elastic bar. This leads to a class of exact solutions of the Navier equation in terms of solutions of Laplace's equation in two dimensions. However, as distinct from the use of Laplace's equation in, say, hydrodynamics or electromagnetism, the dependent variable is the displacement, which has a direct physical interpretation, rather than a potential, which does not. This means we have to be especially careful to ensure that the solution is single-valued in situations involving multiply-connected bars.
These remarks remain important when we move on to another class of two-dimensional problems called plane strain problems. These have even more general practical relevance but involve the biharmonic equation. This equation, which will be seen to be ubiquitous in linear elastostatics, poses significant extra difficulties as compared to Laplace's equation. In particular, we will find that it is much more difficult to construct explicit solutions using, for example, the method of separation of variables.
This chapter concerns simple unsteady problems in linear elasticity. As noted in Section 1.10, the unsteady Navier equation (1.7.8) bears some similarity to the familiar scalar wave equation governing small transverse displacements of an elastic string or membrane. We therefore start by reviewing the main properties of this equation and some useful solution techniques. This allows us to introduce, in a simple context, important concepts such as normal modes, plane waves and characteristics that underpin most problems in linear elastodynamics.
In contrast with the classical scalar wave equation, the Navier equation is a vector wave equation, and this introduces many interesting new properties. The first that we will encounter is that the Navier equation in an infinite medium supports two distinct kinds of plane waves which propagate at two different speeds. These are known as P-waves and S-waves, and correspond to compressional and shearing oscillations of the medium respectively. Considered individually, both P- and S-waves behave very much like waves as modelled by the scalar wave equation (1.10.9). In practice, though, they very rarely exist in isolation since any boundaries present inevitably convert P-waves into S-waves and vice versa. We will illustrate this phenomenon of mode conversion in Section 3.2.5 by considering the reflection of waves at a plane boundary.
In two-dimensional and axisymmetric problems, we found in Chapter 2 that the steady Navier equation may be transformed into a single biharmonic equation by introducing a suitable stress function. In Sections 3.3 and 3.4 we will find that the same approach often works even for unsteady problems, and pays dividends when we come to analyse normal modes in cylinders and spheres.
The world around us, natural or man-made, is built and held together by solid materials. Understanding their behaviour is the task of solid mechanics, which is in turn applied to many areas, from earthquake mechanics to industry, construction to biomechanics. The variety of materials (metals, rocks, glasses, sand, flesh and bone) and their properties (porosity, viscosity, elasticity, plasticity) is reflected by the concepts and techniques needed to understand them: a rich mixture of mathematics, physics and experiment. These are all combined in this unique book, based on years of experience in research and teaching. Starting from the simplest situations, models of increasing sophistication are derived and applied. The emphasis is on problem-solving and building intuition, rather than a technical presentation of theory. The text is complemented by over 100 carefully-chosen exercises, making this an ideal companion for students taking advanced courses, or those undertaking research in this or related disciplines.