Patterned magnetic nanowires are extremely well suited for data storage and logic devices. They offer non-volatile storage, fast switching times, efficient operation and a bistable magnetic configuration that are convenient for representing digital information. Key to this is the high level of control that is possible over the position and behaviour of domain walls (DWs) in magnetic nanowires. Magnetic random access memory based on the propagation of DWs in nanowires has been released commercially, while more dynamic shift register memory and logic circuits have been demonstrated. Here, we discuss the present standing of this technology as well as reviewing some of the basic DW effects that have been observed and the underlying physics of DW motion. We also discuss the future direction of magnetic nanowire technology to look at possible developments, hurdles to overcome and what nanowire devices may appear in the future, both in classical information technology and beyond into quantum computation and biology.
We present numerical evidence from atomistic calculations that the coercivity of high-performance NdFeB-sintered-magnets (<20% of the theoretical Stoner–Wolfarth-limit) can be explained by a distorted region of Nd2Fe14B at grain boundaries, which has a reduced local magnetic anisotropy. We show that depending on the boundary composition of fcc-NdO and hcp-Nd2O3, the thickness of this region of reduced anisotropy varies between 0.4 for fcc and 1.6 nm for the hcp phase. For NdO, the distortions are mostly confined in the fcc-NdO-phase but equally distributes in both the hcp-Nd2O3 and Nd2Fe14B. The experimentally measured coercivity of 1.25 T can be understood when taking this distortion and magnetostatic effects into account.
Aim: To explore the factor structure, reliability, and potential usefulness of a patient safety climate questionnaire in UK health care. Setting: Four acute hospital trusts and nine primary care trusts in England. Methods: The questionnaire used was the 27 item Teamwork and Safety Climate Survey. Thirty three healthcare staff commented on the wording and relevance. The questionnaire was then sent to 3650 staff within the 13 NHS trusts, seeking to achieve at least 600 responses as the basis for the factor analysis. 1307 questionnaires were returned (36% response). Factor analyses and reliability analyses were carried out on 897 responses from staff involved in direct patient care, to explore how consistently the questions measured the underlying constructs of safety climate and teamwork. Results: Some questionnaire items related to multiple factors or did not relate strongly to any factor. Five items were discarded. Two teamwork factors were derived from the remaining 11 teamwork items and three safety climate factors were derived from the remaining 11 safety items. Internal consistency reliabilities were satisfactory to good (Cronbach's alpha >0.69 for all five factors). Conclusions: This is one of the few studies to undertake a detailed evaluation of a patient safety climate questionnaire in UK health care and possibly the first to do so in primary as well as secondary care. The results indicate that a 22 item version of this safety climate questionnaire is useable as a research instrument in both settings, but also demonstrates a more general need for thorough validation of safety climate questionnaires before widespread usage.A s health care comes to be seen as a potentially high risk environment, there is increasing pressure to assess the safety culture of healthcare organisations. Some authors promote the use of semi-structured or qualitative approaches to assessing culture, 1 while others suggest that culture can be assessed using a questionnaire approach. There is a real debate over how effectively culture can be assessed using climate questionnaires. As described by Denison, 4 culture refers to the ''deep structure of organisations'' (values, beliefs and behaviours) and is traditionally assessed through interviews or observation, whereas climate mainly concerns individuals' perceptions of their work environment (policies, practices and procedures) at a particular point in time [5][6][7][8] and is amenable to measurement by questionnaire.9 Despite this debate, safety climate questionnaires have been used to assess safety culture in many safety critical industries such as nuclear power, aviation 10 and petrochemicals.11 Some questionnaires for use in health care have been derived from work in other industries such as aviation 12 or have included several items validated in other settings-for example, the armed forces.13 Most of the available healthcare safety climate questionnaires have been developed in the United States.It has been suggested that safety climate questionnaire data may be used as an indicat...
Background Paediatric fever is a common cause of emergency department (ED) attendance. A lack of prompt and definitive diagnostics makes it difficult to distinguish viral from potentially life-threatening bacterial causes, necessitating a cautious approach. This may result in extended periods of observation, additional radiography, and the precautionary use of antibiotics (ABs) prior to evidence of bacterial foci. This study examines resource use, service costs, and health outcomes. Methods We studied an all-year prospective, comprehensive, and representative cohort of 6518 febrile children (aged < 16 years), attending Alder Hey Children’s Hospital, an NHS-affiliated paediatric care provider in the North West of England, over a 1-year period. Performing a time-driven and activity-based micro-costing, we estimated the economic impact of managing paediatric febrile illness, with focus on nurse/clinician time, investigations, radiography, and inpatient stay. Using bootstrapped generalised linear modelling (GLM, gamma, log), we identified the patient and healthcare provider characteristics associated with increased resource use, applying retrospective case-note identification to determine rates of potentially avoidable AB prescribing. Results Infants aged less than 3 months incurred significantly higher resource use than any other age group, at £1000.28 [95% CI £82.39–£2993.37] per child, ( p < 0.001), while lesser experienced doctors exhibited 3.2-fold [95% CI 2.0–5.1-fold] higher resource use than consultants ( p < 0.001). Approximately 32.4% of febrile children received antibiotics, and 7.1% were diagnosed with bacterial infections. Children with viral illnesses for whom antibiotic prescription was potentially avoidable incurred 9.9-fold [95% CI 6.5–13.2-fold] cost increases compared to those not receiving antibiotics, equal to an additional £1352.10 per child, predominantly resulting from a 53.9-h increase in observation and inpatient stay (57.1 vs. 3.2 h). Bootstrapped GLM suggested that infants aged below 3 months and those prompting a respiratory rate ‘red flag’, treatment by lesser experienced doctors, and Manchester Triage System (MTS) yellow or higher were statistically significant predictors of higher resource use in 100% of bootstrap simulations. Conclusion The economic impact of diagnostic uncertainty when managing paediatric febrile illness is significant, and the precautionary use of antibiotics is strongly associated with increased costs. The use of ED resources is highest among infants (aged less than 3 months) and those infants managed by lesser experienced doctors, independent of clinical severity. Diagnostic advances which could increase confidence to withhold antibiotics may yield considerable efficiency gains in these groups, where the perceived risks of failing to identify potentially life-threatening bacterial infections are greatest. ...
We propose a method of pinning and propagating domain walls in artificial multiferroic nanowires using electrically induced surface acoustic waves. Using finite-element micromagnetic simulations and 1D semi-analytical modelling, we demonstrate how a pair of interdigitated acoustic transducers can remotely induce an array of attractive domain wall pinning sites by forming a standing stress/strain wave along a nanowire's length. Shifts in the frequencies of the surface acoustic waves allow multiple domain walls to be synchronously transported at speeds up to 50 ms À1 . Our study lays the foundation for energy-efficient domain wall devices that exploit the low propagation losses of surface acoustic waves to precisely manipulate large numbers of data bits. V C 2015 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4932057] Domain walls (DWs) in magnetic nanowires 1 have great technological potential through the development of "racetrack" memory devices. 2 In these devices, DWs separate magnetically bi-stable domains, the orientations of which represent binary data. Synchronously moving the DWs transports data along the nanowires, thus facilitating read/write operations.A major challenge in the development of racetrack memory has been finding efficient methods of transporting DWs. Although DWs in soft-ferromagnetic nanowires can be propagated at modest applied fields $10 Oe, 3 neighbouring DWs travel in opposite directions, making synchronous data transport impossible unless complex "ratcheted" nanowires 4,5 or field pulses with intricate spatial 6 or temporal profiles 7 are employed. Moving DWs via spin-torque effects is a more attractive approach, since neighbouring DWs travel uni-directionally. However, current-induced DW transport is inefficient and unreliable in soft ferromagnetic systems, 8,9 with complex multilayer nanowires exploiting spin-orbit effects [10][11][12] or containing antiferromagnetically coupled layers 13 being required to obtain fast and reliable DW motion at typical experimental current densities.Previously, we have shown that artificial multiferroic systems, where magnetostrictive nanowires are coupled to electrically contacted piezoelectric layers, offer alternative routes to obtaining synchronous DW motion. 14 In this approach, electrically induced strains in the piezoelectric layer produce local variations in the nanowire's magnetic anisotropy by the Villari effect. These can then be utilized to both pin and synchronously propagate DWs. The approach is attractive because it is voltage rather current driven, and thus is expected to be power efficient. Furthermore, in contrast to both field-and current-induced approaches, where interactions are impulse-based, in the multiferroic approach DWs are constantly confined within a stress-induced potential well, offering precise control of the DWs' positioning. However, the necessity of fabricating arrays of electrical contacts makes for complex device designs when compared to the simple, two-terminal configurations required for current-induced motion...
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