997 resultados para Back trajectory


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The first part of the paper explores some of the reasons why contemporary border studies understate the full significance of state borders and their global primacy. It is argued that this failing is rooted in a much wider lack of historical reflexivity-a reluctance to acknowledge the historical positioning (the 'where and when') of contemporary border studies themselves. This reluctance encourages a form of pseudohistory, or 'epochal thinking', which disfigures perspective on the present. Among the consequences are (a) exaggerated claims of the novelty of contemporary border change, propped up by poorly substantiated benchmarks in the past; (b) an incapacity to recognise the 'past in the present' as in the various historical deposits of state formation processes; and (c) a failure to recognise the distinctiveness of contemporary state borders and how they differ from other borders in their complexity and globality. The second part of the paper argues for a recalibration of border studies aimed at balancing their spatial emphases with a much greater, and more critical, historical sensitivity. It insists that 'boundedness', and state boundedness in particular, is a variable that must be understood historically. This is illustrated by arguing that a better analysis of contemporary border change means rethinking the crude periodisation which distinguishes the age of empire from the age of nation-states and, in turn, from some putative contemporary era 'beyond nation-states' and their borders.

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Respiratory viruses are among the most important causes of morbidity and mortality worldwide. From a vaccine viewpoint, such viruses may be divided into two principle groups-those where infection results in long-term immunity and whose continued survival requires constant mutation, and those where infection induces incomplete immunity and repeated infections are common, even with little or no mutation. Influenza virus and respiratory syncytial virus (RSV) typify the former and latter groups, respectively. Importantly, successful vaccines have been developed against influenza virus. However, this is not the case for RSV, despite many decades of research and several vaccine approaches. Similar to natural infection, the principle limitation of candidate RSV vaccines in humans is limited immunogenicity, characterised in part by short-term RSV-specific adaptive immunity. The specific reasons why natural RSV infection is insufficiently immunogenic in humans are unknown but circumvention of innate and adaptive immune responses are likely causes. Fundamental questions concerning RSV/host interactions remain to be addressed at both the innate and adaptive immune levels in humans in order to elucidate mechanisms of immune response circumvention. Taking the necessary steps back to generate such knowledge will provide the means to leap forward in our quest for a successful RSV vaccine. Recent developments relating to some of these questions are discussed. (C) 2007 Elsevier B.V. All rights reserved.

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In the present work, by investigating the influence of source/drain (S/D) extension region engineering (also known as gate-underlap architecture) in planar Double Gate (DG) SOI MOSFETs, we offer new design insights to achieve high tolerance to gate misalignment/oversize in nanoscale devices for ultra-low-voltage (ULV) analog/rf applications. Our results show that (i) misaligned gate-underlap devices perform significantly better than DC devices with abrupt source/drain junctions with identical misalignment, (ii) misaligned gate underlap performance (with S/D optimization) exceeds perfectly aligned DG devices with abrupt S/D regions and (iii) 25% back gate misalignment can be tolerated without any significant degradation in cut-off frequency (f(T)) and intrinsic voltage gain (A(VO)). Gate-underlap DG devices designed with spacer-to-straggle ratio lying within the range 2.5 to 3.0 show best tolerance to misaligned/oversize back gate and indeed are better than self-aligned DG MOSFETs with non-underlap (abrupt) S/D regions. Impact of gate length and silicon film thickness scaling is also discussed. These results are very significant as the tolerable limit of misaligned/oversized back gate is considerably extended and the stringent process control requirements to achieve self-alignment can be relaxed for nanoscale planar ULV DG MOSFETs operating in weak-inversion region. The present work provides new opportunities for realizing future ULV analog/rf design with nanoscale gate-underlap DG MOSFETs. (C) 2008 Elsevier Ltd. All rights reserved.

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Objectives: To evaluate the feasibility of a randomized-controlled trial (RCT) investigating the effects of adding auricular acupuncture (AA) to exercise for participants with chronic low-back pain (CLBP). Methods: Participants with CLBP were recruited from primary care and a university population and were randomly allocated (n=51) to 1 of 2 groups: (1) "Exercise Alone (E)"-12-week program consisting of 6 weeks of supervised exercise followed by 6 weeks unsupervised exercise (n=27); or (2) "Exercise and AA (EAA)"-12-week exercise program and AA (n=24). Outcome measures were recorded at baseline, week 8, week 13, and 6 months. The primary outcome measure was the Oswestry Disability Questionnaire. Results: Participants in the EAA group demonstrated a greater mean improvement of 10.7% points (95% confidence interval, -15.3,-5.7) (effect size=1.20) in the Oswestry Disability Questionnaire at 6 months compared with 6.7% points (95% confidence interval, -11.4,-1.9) in the E group (effect size=0.58). There was also a trend towards a greater mean improvement in quality of life, LBP intensity and bothersomeness, and fear-avoidance beliefs in the EAA group. The dropout rate for this trial was lower than anticipated (15% at 6 mo), adherence with exercise was similar (72% E; 65% EAA). Adverse effects for AA ranged from 1% to 14% of participants. Discussion: Findings of this study showed that a main RCT is feasible and that 56 participants per group would need to be recruited, using multiple recruitment approaches. AA was safe and demonstrated additional benefits when combined with exercise for people with CLBP, which requires confirmation in a fully powered RCT.

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BACKGROUND: Current evidence supports the use of exercise-based treatment for chronic low back pain that encourages the patient to assume an active role in their recovery. Walking has been shown it to be an acceptable type of exercise with a low risk of injury. However, it is not known whether structured physical activity programmes are any more effective than giving advice to remain active.

METHODS/DESIGN: The proposed study will test the feasibility of using a pedometer-driven walking programme, as an adjunct to a standard education and advice session in participants with chronic low back pain. Fifty adult participants will be recruited via a number of different sources. Baseline outcome measures including self reported function; objective physical activity levels; fear-avoidance beliefs and health-related quality of life will be recorded. Eligible participants will be randomly allocated under strict, double blind conditions to one of two treatments groups. Participants in group A will receive a single education and advice session with a physiotherapist based on the content of the 'Back Book'. Participants in group B will receive the same education and advice session. In addition, they will also receive a graded pedometer-driven walking programme prescribed by the physiotherapist. Follow up outcomes will be recorded by the same researcher, who will remain blinded to group allocation, at eight weeks and six months post randomisation. A qualitative exploration of participants' perception of walking will also be examined by use of focus groups at the end of the intervention. As a feasibility study, treatment effects will be represented by point estimates and confidence intervals. The assessment of participant satisfaction will be tabulated, as will adherence levels and any recorded difficulties or adverse events experienced by the participants or therapists. This information will be used to modify the planned interventions to be used in a larger randomised controlled trial.

DISCUSSION: This paper describes the rationale and design of a study which will test the feasibility of using a structured, pedometer-driven walking programme in participants with chronic low back pain.

TRIAL REGISTRATION: [ISRCTN67030896].

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We examine problems resulting from the narrow empirical focus associated with evidence-based nursing, including the deleterious influence of vested interests, disattention to patients’ experiences, underestimation of the importance of social processes, lack of an individualized research perspective, marginalization of other forms of knowledge, and the undermining of patients’ autonomy. Addressing each problem in turn, we argue that inclusion of patients at all stages of evidence-based practice can counter or ameliorate these problems. While we concede that patient involvement is not a complete solution to the problem of empiricism, it is the most effective means available to defend nursing values.

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The Wing-Kristofferson (WK) model of movement timing emphasises the separation of central timer and motor processes. Several studies of repetitive timing have shown that increase in variability at longer intervals is attributable to timer processes; however, relatively little is known about the way motor aspects of timing are affected by task movement constraints. In the present study, we examined timing variability in finger tapping with differences in interval to assess central timer effects, and with differences in movement amplitude to assess motor implementation effects. Then, we investigated whether effects of motor timing observed at the point of response (flexion offset/tap) are also evident in extension, which would suggest that both phases are subject to timing control. Eleven participants performed bimanual simultaneous tapping, at two target intervals (400, 600 ms) with the index finger of each hand performing movements of equal (3 or 6 cm) or unequal amplitude (left hand 3, right hand 6 cm and vice versa). As expected, timer variability increased with the mean interval but showed only small, non-systematic effects with changes in movement amplitude. Motor implementation variability was greater in unequal amplitude conditions. The same pattern of motor variability was observed both at flexion and extension phases of movement. These results suggest that intervals are generated by a central timer, triggering a series of events at the motor output level including flexion and the following extension, which are explicitly represented in the timing system.

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The Wing-Kristofferson movement timing model (A. M. Wing & A. B. Kristofferson, 1973a, 1973b) distinguishes central timer and motor implementation processes. Previous studies have shown that increases in interresponse interval (IRI) variability with mean IRI are due to central timer processes, not motor implementation. The authors examine whether this is true with IRI duration changes in binary rhythm production. Ten participants provided IRI and movement data in bimanual synchronous tapping under equal (isochronous) and alternating (rhythm) interval conditions. Movement trajectory changes were observed with IRI duration (300, 500, or 833 ms) and for 500-ms IRIs produced in rhythm contexts (300/500 ms, 500/833 ms). However, application of the Wing-Kristofferson model showed that duration and context effects on IRI variability were attributable largely to timer processes with relatively little effect on motor processes.