Epidemiology of child pedestrian casualty rates: can we assume spatial independence?

Child pedestrian injuries are often investigated by means of ecological studies, yet are clearly part of a complex spatial phenomena. Spatial dependence within such ecological analyses have rarely been assessed, yet the validity of basic statistical techniques rely on a number of independence assumptions. Recent work from Canada has highlighted the potential for modelling spatial dependence within data that was aggregated in terms of the number of road casualties who were resident in a given geographical area. Other jurisdictions aggregate data in terms of the number of casualties in the geographical area in which the collision took place. This paper contrasts child pedestrian casualty data from Devon County UK, which has been aggregated by both methods. A simple ecological model, with minimally useful covaraties relating to measures of child deprivation, provides evidence that data aggregated in terms of the casualty's home location cannot be assumed to be spatially independent and that for analysis of these data to be valid there must be some accounting for spatial auto-correlation within the model structure. Conversely, data aggregated in terms of the collision location (as is usual in the UK) was found to be spatially independent. Whilst the spatial model is clearly more complex it provided a superior fit to that seen with either collision aggregated or non-spatial models. Of more importance, the ecological level association between deprivation and casualty rate is much lower once the spatial structure is accounted for, highlighting the importance using appropriately structured models.     

Houston,we've had a problem: when do we override rules?

As important as rules are in health care, the authors explain why it is sometimes necessary to deviate from them to maximize patient outcomes. They then provide a framework for documenting, discussing, and teaching the importance of making exceptions and changing rules.     

Geoengineering: could we or should we make it work?

Schemes to modify large-scale environment systems or control climate have been proposed for over 50 years to (i) increase temperatures in high latitudes, (ii) increase precipitation, (iii) decrease sea ice, (iv) create irrigation opportunities, or (v) offset potential global warming by injecting iron in the oceans or sea-salt aerosol in the marine boundary layer or spreading dust in the stratosphere to reflect away an amount of solar energy equivalent to the amount of heat trapped by increased greenhouse gases from human activities. These and other proposed geoengineering schemes are briefly reviewed. Recent schemes to intentionally modify climate have been proposed as either cheaper methods to counteract inadvertent climatic modifications than conventional mitigation techniques such as carbon taxes or pollutant emissions regulations or as a counter to rising emissions as governments delay policy action. Whereas proponents argue cost-effectiveness or the need to be prepared if mitigation and adaptation policies are not strong enough or enacted quickly enough to avoid the worst widespread impacts, critics point to the uncertainty that (i) any geoengineering scheme would work as planned or (ii) that the many centuries of international political stability and cooperation needed for the continuous maintenance of such schemes to offset century-long inadvertent effects is socially feasible. Moreover, the potential exists for transboundary conflicts should negative climatic events occur during geoengineering activities.     

‘When can we apply LEFM principles to elastic softening materials?’

The paper focusses on the determination of R, the size of the fully developed softening zone associated with a semi-infinite crack in a remotely loaded infinite elastic softening solid. R is a characteristic length for a material, and is important in that if R is less than an appropriate characteristic dimension of a structure, then LEFM principles can be used to describe the structure's failure. With p _c and _c being respectively the maximum stress and displacement within the softening zone, then provided the softening is not particularly pronounced, i.e. the area under the stress (p)-displacement (v) curve is % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaacaaeaacq% GH+aGpaiaawoWaaiaabccacaqGWaGaaeOlaiaabkdacaqG1aGaamiC% aSGaam4yaOGaeqiTdq2ccaWGJbaaaa!3FB5!\[\widetilde > {\text{ 0}}{\text{.25}}pc\delta c\], it is shown that R 0.4E _0c/P _c and R is relatively insensitive to the precise p-v softening behaviour (E ₀ = E/(1 – v ²) where E is Young's modulus and is Poisson's ratio. However, when the area under the curve is % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaacaaeaacq% GH8aapaiaawoWaaiaabccacaqGWaGaaeOlaiaabkdacaqG1aGaamiC% aSGaam4yaOGaeqiTdq2ccaWGJbaaaa!3FB1!\[\widetilde < {\text{ 0}}{\text{.25}}pc\delta c\], then R increases above this 0.4E _0c/P _c value. For this case, and provided most of the area under the p-v curve is not associated with the tail in the softening law, a more appropriate expression for R is R 0.1E ₀ ² / ₀ ² /K ² , with K ² /E ₀ being the area under the p-v curve and K being the stress intensity associated with the full development of a softening zone.     

What can we learn about North Dakota's youngest drivers from their crashes?

For North Dakota teens, three of every four deaths are from motor vehicle crashes. Injury crash records for teen drivers were studied to gain insight regarding driver, vehicle, and road factors for public safety policy and program discussions. Results show 14-year-old drivers are three times more likely to die or be disabled in an injury crash than 17-year-old drivers, and that male drivers are 30% less likely to incur severe injury. As expected, seat belt use is a critical factor in severe injury avoidance. The likelihood for death or disablement is 165% greater for unbelted teen drivers than for those who are properly belted. In addition, rural and gravel roads pose a risk. Teens are six times more likely to be severely injured in crashes on rural roads than on urban roads. Findings suggest that an increased licensing age and seat belt emphasis may reduce teen traffic injuries in the state. In addition, more information on exposure should be attained to better understand rural and gravel road as risks.     

"Safety in Numbers" re-examined: can we make valid or practical inferences from available evidence?

“Safety in Numbers”(SIN), a recent concept in transportation research, policy and planning, has emerged as a causal inference from the non-linear statistical association between estimates of the numbers of walkers or bicyclists in an area and the rate or number of traffic collisions experienced by pedestrians or cyclists. Proponents of SIN argue that greater numbers of walkers or cyclists modify the hazardous behaviors of motor vehicle drivers thus creating safer conditions. This paper critically examines the research on the non-linear association as an adequate empirical basis for this causal interpretation. Given the paucity of evidence supporting a specific mechanism for the SIN effect, alternative plausible explanations of the non-linear association behind SIN, and a potential for unintended consequences from its policy application, the authors call for caution in the use of SIN in transportation policy and planning dialogue and decision-making.     

Abrupt climate change: can society cope?

Consideration of abrupt climate change has generally been incorporated neither in analyses of climate-change impacts nor in the design of climate adaptation strategies. Yet the possibility of abrupt climate change triggered by human perturbation of the climate system is used to support the position of both those who urge stronger and earlier mitigative action than is currently being contemplated and those who argue that the unknowns in the Earth system are too large to justify such early action. This paper explores the question of abrupt climate change in terms of its potential implications for society, focusing on the UK and northwest Europe in particular. The nature of abrupt climate change and the different ways in which it has been defined and perceived are examined. Using the example of the collapse of the thermohaline circulation (THC), the suggested implications for society of abrupt climate change are reviewed; previous work has been largely speculative and has generally considered the implications only from economic and ecological perspectives. Some observations about the implications from a more social and behavioural science perspective are made. If abrupt climate change simply implies changes in the occurrence or intensity of extreme weather events, or an accelerated unidirectional change in climate, the design of adaptation to climate change can proceed within the existing paradigm, with appropriate adjustments. Limits to adaptation in some sectors or regions may be reached, and the costs of appropriate adaptive behaviour may be large, but strategy can develop on the basis of a predicted long-term unidirectional change in climate. It would be more challenging, however, if abrupt climate change implied a directional change in climate, as, for example, may well occur in northwest Europe following a collapse of the THC. There are two fundamental problems for society associated with such an outcome: first, the future changes in climate currently being anticipated and prepared for may reverse and, second, the probability of such a scenario occurring remains fundamentally unknown. The implications of both problems for climate policy and for decision making have not been researched. It is premature to argue therefore that abrupt climate change - in the sense referred to here - imposes unacceptable costs on society or the world economy, represents a catastrophic impact of climate change or constitutes a dangerous change in climate that should be avoided at all reasonable cost. We conclude by examining the implications of this contention for future research and policy formation.     

Understanding the market for remanufactured products: what can we learn from online trading and Web search sites?

Notwithstanding the interest it elicits from academics and practitioners, relatively little is known about the market for remanufactured products. Research, still in its infancy, has focused almost entirely on what affects willingness to pay, and our understanding of other key marketing questions, such as what drives search intensity for remanufactured products and the number of remanufactured products on offer, is limited. This paper fills this knowledge gap. Focusing on the online market for remanufactured electrical and electronic products, we empirically test whether product-specific and market-specific determinants affect search intensity and number of remanufactured products on offer, that is number of listings. We use as inputs online search traffic, product-specific data collected from various other online sources and relevant eBay listing data. Our analysis supports the hypotheses that search intensity for remanufactured products is associated with search intensity for price and elapsed time since the launch of new counterpart products. Number of remanufactured products listed is associated with number of listings for new counterparts and two product-specific characteristics: presence of moving parts and whether the product is used for personal hygiene. We discuss several implications of our findings for remanufacturers and policy-makers as well as directions for future research.     

Unbalanced lines: where are we now?

Unbalanced unpaced serial production lines have been the subject of continued interest over the last half a century. Research into these systems taking a diversity of approaches has given rise to a variety of insights which may be of increasing relevance in a context of fast-changing production and flexibility needs. By mapping the major conclusions reached in the area of unpaced asynchronous unbalanced lines over time and from diverse sources, this review identifies some possible future avenues of research that can usefully advance knowledge in this domain.     

Graphene annealing: how clean can it be?

Surface contamination by polymer residues has long been a critical problem in probing graphene's intrinsic properties and in using graphene for unique applications in surface chemistry, biotechnology, and ultrahigh speed electronics. Poly(methyl methacrylate) (PMMA) is a macromolecule commonly used for graphene transfer and device processing, leaving a thin layer of residue to be empirically cleaned by annealing. Here we report on a systematic study of PMMA decomposition on graphene and of its impact on graphene's intrinsic properties using transmission electron microscopy (TEM) in combination with Raman spectroscopy. TEM images revealed that the physisorbed PMMA proceeds in two steps of weight loss in annealing and cannot be removed entirely at a graphene susceptible temperature before breaking. Raman analysis shows a remarkable blue-shift of the 2D mode after annealing, implying an anneal-induced band structure modulation in graphene with defects. Calculations using density functional theory show that local rehybridization of carbons from sp(2) to sp(3) on graphene defects may occur in the random scission of polymer chains and account for the blue-shift of the Raman 2D mode.     

Why can't we find a better biological indicator of dose?

The three general principles of the International Commission on Radiological Protection (ICRP) are: justification, optimisation (ALARA) and dose limitation. The principle application of optimisation (ALARA) for occupational exposures of workers or the public to external radiation is reliant on low doses being assessed accurately, which could be achieved using biological dosimetry. Although cytogenetic analyses for dicentrics and translocations are the most useful techniques for biological dosimetry, these were initially developed for and have been applied to middle and high range dose exposures; the range where deterministic injury is possible. Application of these techniques for biomonitoring or screening of relatively large groups of low exposed people is possible but limited as chromosome analysis is time-consuming and requires highly skilled personnel. In addition, some technical considerations constrain dose estimation in the low dose range. This paper considers the advantages of cytogenetic techniques for biodosimetry and also highlights their limitation at low doses. However, optimisation of low dose assessment could be obtained by improvement in the technique perhaps in combination with other approaches that consider variations in individual sensitivity. Developments in modern molecular biology have brought new approaches into prospect but so far they are not routinely applicable. The potential use and throughput of these new technologies is discussed.     

Slamming of ships: where are we now?

Literature published on the problem of ship slamming in waves is reviewed from the point of view of someone working at a ship research institute. Such an institute is confronted with rather practical questions regarding the acceptability of certain design parameters such as the acceptable amount of bow flare angle for use at sea. The importance of these questions is illustrated by noting that actual slamming or the presumed danger of slamming is the main reason for ship operators to reduce speed or to change heading. The review shows that such questions cannot yet be answered. The problem of the local effect of the impact is very complicated owing to the importance of air inclusions, bubbles in the water, compressibility of water and cavitation effects. Only a computational method properly including all these effects will give an accurate answer; also model tests will not be capable of doing this, if only because the methods to extrapolate the results of models to full scale are not yet developed. The problem of the global response of the ship to a wave impact is closer to being solved. A two-stage approach is proposed, consisting of a computational fluid dynamics method for individual impacts and an approximate method to be included in long-term simulations. However, to arrive at a realistic long-term distribution, one has to account for the seamanship of the captain; avoiding the worst conditions or adapting the ship speed and course has a large effect on the actual extremes. Research on this topic has hardly begun.     

Towards sensor array materials: can failure be delayed?

Further to prior development in enhancing structural health using smart materials, an innovative class of materials characterized by the ability to feel senses like humans, i.e. ‘nervous materials’, is discussed. Designed at all scales, these materials will enhance personnel and public safety, and secure greater reliability of products. Materials may fail suddenly, but any system wishes that failure is known in good time and delayed until safe conditions are reached. Nervous materials are expected to be the solution to this statement. This new class of materials is based on the novel concept of materials capable of feeling multiple structural and external stimuli, e.g. stress, force, pressure and temperature, while feeding information back to a controller for appropriate real-time action. The strain–stress state is developed in real time with the identified and characterized source of stimulus, with optimized time response to retrieve initial specified conditions, e.g. shape and strength. Sensors are volumetrically embedded and distributed, emulating the human nervous system. Immediate applications are in aircraft, cars, nuclear energy and robotics. Such materials will reduce maintenance costs, detect initial failures and delay them with self-healing. This article reviews the common aspects and challenges surrounding this new class of materials with types of sensors to be embedded seamlessly or inherently, including appropriate embedding manufacturing techniques with modeling and simulation methods.     

Historic and current strategies in bone tissue engineering: Do we have a hope in Hench?

Professors Larry Hench and Julia Polak formed the Tissue Engineering and Regenerative Medicine Centre (TERM) at Imperial College London to foster collaborations between biologists and materials scientists. Early work at the center elucidated the biomolecular interactions between primary human osteoblasts and 45S5 Bioglass . As research efforts expanded, the team discovered that the dissolution products of both 45S5 Bioglass and 58S sol-gel bioactive glasses had osteoblastic stimulatory properties. To address the shortage of appropriate cells for bone tissue engineering applications, TERM scientists also demonstrated the differentiation of embryonic stem (ES) cells to osteoblasts when treated with the dissolution products of bioactive glasses. They also found that the soluble factors ascorbic acid, beta -glycerophosphate, and dexamethasone preferentially differentiated ES cells to osteoblasts, and their combination with the dissolution products of bioactive glasses stimulated differentiation even further. Taken together, these results demonstrate the suitability of bioactive glasses as scaffolds for bone tissue engineering as they not only provide an osteoconductive and osteoproductive substrate, but also actively stimulate cells to express appropriate osteoblastic phenotypes. Professor Hench's vision to pioneer regenerative medicine research continues with the aim of developing novel therapeutics to treat musculoskeletal disability.     

Portable and wearable dialysis: where are we now?

Although dialysis is a life-saving treatment for patients with acute and chronic kidney disease, mortality remains high, with the survival of patients treated by regular hemodialysis similar to that of some solid organ tumors. Recent reports have suggested that a major increase in the dose of dialysis, delivered by frequent nocturnal dialysis, may improve survival. Unfortunately, only a minority of centers can offer this type of therapy, and only to a minority of their patients. Thus, to improve access to dialysis as well as increase the delivered dose of dialysis, a major change in the current paradigm of dialysis delivery is required. For many years, the "holy grail" of dialysis has been to develop a wearable or portable system, allowing patients to be treated while performing their normal activities of daily living. It is only recently with the advances in technology that such dialysis devices have been possible. Prototype devices for both hemodialysis and peritoneal dialysis have been studied with favorable results. Typically, these have been short-term studies, and longer term trials are eagerly awaited, to determine whether the current generation of wearable continuous dialysis devices cannot only remove waste products of metabolism and control volume but also maintain acid-base and electrolyte homeostasis and actually improve outcomes. In addition, a novel generation of dialysis devices based on nanotechnologies are being developed. Hopefully, these wearable continuous devices will be available as an option for routine clinical practice in the not-too-distant future.     

Raising the bar: can increased statutory penalties deter drink-drivers?

The rate of road accidents per 100,000 vehicles registered was examined before and after the statutory penalties for drink-driving offences were doubled in New South Wales (NSW), Australia. Interrupted time-series analyses found significant increases in three non-fatal accident series after the implementation of the new penalties. The observed increase in the rate of single-vehicle night-time accidents, the accident category most likely to be alcohol-related, was not expected and runs contrary to the anticipated deterrent effect of the new laws. The failure of this policy to have an impact on aggregate-level road accident rates is discussed.     

The forgotten component of the quality triad: can we still learn something from "structure"?

BACKGROUND: Quality assessment was founded on structural measures, such as accreditation status of facilities, credentialing of providers, and type of provider. Recent efforts in measures development have focused on processes and outcomes because research has suggested that structural measures are not strong markers of the quality of care at the health plan or provider levels. Nevertheless, the literature on the quality of health care contains a number of examples illustrating the potential application of structural measures to the assessment of quality. The continued development of measures of structure-which would at least measure aspects of the physical environment, working conditions, organizational culture, and provider satisfaction--may be helpful because generalizing from studies of process and outcome requires specification of the conditions under which these linkages are found. A ROAD MAP FOR MEASURES DEVELOPMENT: The Leapfrog Group of large purchasers has promoted the application of three patient safety "leaps" that are, in essence, structural measures: the use of computerized physician order entry, the selective referral of patients to high-volume providers for certain procedures, and the availability of board-certified critical care specialists in intensive care units. Structural measures, like process and outcomes measures, face the same challenges of standardization, reliability, validity, and portability. Field testing of potential measures will be required to examine the feasibility and added value of these measures in real-world settings. CONCLUSION: Research to date suggests that a new cadre of structural measures of health care quality, which have largely been overlooked in the recent measures development boom, have the potential to fill in important gaps in our ability to assess quality.