Magnetic properties of metallic fine particle systems

A study of the magnetic properties of metallic fine particle systems in the form of magnetic fluids has been made. The fluids were prepared utilising the organometallic decomposition route (detailed separately by N. Mason, Ph.D. thesis, Durham University 1986) and single metal systems containing Fe, Co and Ni were prepared from new precursors. The properties of the first hydrocarbon based mixed metal particle systems are also reported. For systems prepared with Fe precursors it is thought that the fine particles are not in the α-Fe phase but may be amorphous and/or consist of iron carbides. Co and Ni systems result in particles with bulk-metal like structures although Co usually forms in the f.c.c. phase. The h.c.p. is also observed. The mixed metal systems were of FeCo and Ni(_3)Fe and a tendency to form the superlattice or ordered structures was observed. In both cases Fe has been lost to the particles and this is thought to be due to the formation of volatile iron compounds during preparation and/or surfactant complexes. Narrow size distributions have been obtained in all cases with mean particle diameters in the range 4-10 nm and standard deviations of between 0.8 and 1.9. The form of the size distribution has been found to be Gaussian. A study of the anisotropy of the particles using torque and magnetisation measurements has found uniaxial anisotropy with the first anisotropy constant of the order lO(^5)Jmֿ(^3).The values observed are too large to be ascribed solely to shape anisotropy. Low temperature magnetisation measurements have revealed the existence of a paramagnetic component in the fluids. Loss of magnetisation has occurred in all systems and is thought to be due to oxidation of the metal

Piracy, File Sharing … And Legal Fig Leaves

Peer to Peer (P2P) platforms have been very effective in allowing the transmissionof large, bandwidth-intensive files (such as music and video) over the internet. Many such platformsare open source, and have been established by various operators as systems for the unauthoriseddistribution of copyright protected content.In addition to civil (and often criminal) liability faced bypersons establishing P2P platforms for the unlawful distribution of content, an end-user whodownloads copyright protected content from an unauthorised site risks civil action by the copyrightowner for breach of copyright by making an unauthorised copy of the file.The paper will look at thesignificant growth in P2P file sharing and its role as a medium for copyright piracy. The paper willexamine: how P2P file sharing facilitates internet piracy; the effect of case law; legislative changeswhich have taken place in an attempt to deter illegal distribution of copyright material through P2Pplatforms.; the effectiveness of strategies adopted by rights holders in an attempt to reduceunauthorised file sharing and ; protection measures available both for copyright owners seeking toavoid having their work illegally copied , and also third parties (such as ISPs and content hosts) whomay unknowingly become involved in the distribution of such material

Food Policy Councils: Lessons Learned

As the food and financial crises bring fresh urgency to concerns over hunger, food access, public health, labor and economic development -- citizens and governments are beginning to connect these issues back to the food system as a whole. Councils are springing up across North America to "connect the dots"1 between the growing number of neighborhood food initiatives and communities forging policies for just, healthy food systems. Food Policy Councils act as both forums for food issues and platforms for coordinated action. The first Food Policy Council started in 1982 in Knoxville, Tennessee. Since then Food Policy Councils have been established at state, local and regional levels across the county. Some have remarkable success stories. Others have failed, disbanded, or spun-off into other service and non-profit organizations.What lessons can be taken from North America's three-decade experiment in formulating local food policy? Food Policy Councils: Lessons Learned is an assessment based on an extensive literature review and testimony from 48 individual interviews with the people most involved in Food Policy Councils

The influence of a six-week, high-intensity games intervention on the pulmonary oxygen uptake kinetics in prepubertal obese and normal-weight children

Background: The pulmonary oxygen uptake ( O2) response is deleteriously influenced by obesity in pre-pubertal children, as evidenced by a slower phase II response. To date, no studies have investigated the ability of an exercise intervention to ameliorate this. Objectives: To investigate the influence of a six week, high-intensity games orientated intervention on the O2 kinetic response of pre-pubertal obese (OB) and normal-weight (NW) children during heavy intensity exercise. Methods: Thirteen NW and fifteen OB children participated in a twice-weekly exercise intervention involving repeated bouts of 6-minutes of high-intensity, games-orientated exercises followed by 2 minutes of recovery. Sixteen NW and 11 OB children served as a control group. At baseline and post-intervention, each participant completed a graded-exercise test to volitional exhaustion and constant work rate heavy intensity exercise.Results: Post intervention, OB children demonstrated a reduced phase II τ (Pre: 30±8 cf. Post: 24±7 s), MRT (Pre: 50±10 cf. Post: 38±9 s) and phase II amplitude (Pre: 1.51±0.30 cf. Post: 1.34±0.27 l∙min-1). No changes were evident in the NW children. Conclusions: The present findings demonstrate that a six-week, high-intensity intervention can have a significant positive impact on the dynamic O2 response of obese pre-pubertal children

Perceived Exertion Relationships in Adults and Children

The ratings of perceived exertion are commonly employed within both a clinical and exercise setting to quantify, monitor and evaluate an individual’s exercise tolerance and level of exertion. Recent advances in the area of perceived exertion have led to novel applications in the use of the ratings of perceived exertion scale as a means of predicting an individual’s maximal functional capacity (VO2max) for exercise (Eston, Lamb, Parfitt, & King, 2005; Eston, Faulkner, Mason, & Parfitt, 2006; Eston, Lambrick, Sheppard, & Parfitt, 2008; Faulkner, Parfitt, & Eston, 2007). Yet the utility of such procedures with low-fit individuals or children has received little or no research attention. As such, one aim of this thesis was to assess the efficacy of the ratings of perceived exertion in predicting the VO2max of low-fit men and women, and healthy children. It is often presumed that like adults, a child’s perception of exertion rises linearly with increases in exercise intensity, despite a limited amount research suggesting otherwise. Moreover, there is a lack of empirical evidence to suggest that children regulate their power output during a closed-loop exercise task in order to complete a given distance in the fastest time possible. Therefore, a further aim of this thesis was to explore the nature of the perceptual responses of young children across differing modes of exercise, and to examine whether children employ pacing strategies during running. In relation to this latter aim, it was of particular interest to explore pacing in relation to the ratings of perceived exertion during running, as the ratings of perceived exertion have been proposed as a key component of such a regulatory system during exercise (Tucker, 2009). This thesis comprises a qualitative review of relevant literature, and six study chapters which were borne out of five empirical studies. The findings of studies 1 and 2 (chapters 3 & 4, respectively) support the utility of the ratings of perceived exertion to estimate VO2max in low-fit men and women, during cycle ergometry exercise. Importantly, this has been shown from a single exercise test at a low-moderate exercise intensity, during either a step-incremental (study 1) or ramp-incremental (study 2) protocol. Studies 3 and 4 (chapters 5 & 6, respectively) provide evidence to suggest that a child’s perception of exertion may rise linearly or curvilinearly in relation to increasing work, during either cycle ergometry or treadmill exercise. These studies support the utility of a unique, curvilinear, paediatric ratings of perceived exertion scale in obtaining accurate exertional responses from young children, across differing modes of exercise. In contrast to studies 1 and 2, study 5 (chapter 7) suggests that the novel means of predicting maximal functional capacity from submaximal ratings of perceived exertion in adults is inaccurate with young children. This was particularly evident in the low intraclass correlation coefficients and wide limits of agreement obtained between measured- and predicted VO2max, for both cycle ergometry and treadmill exercise. Study 6 (chapter 8) demonstrated that young children employ pacing strategies during an 800 m run, similar to adults, and that this improves with trial familiarisation. Moreover, the presence of other competitors has a detrimental effect on performance, particularly for girls

A randomized controlled trial to assess the central hemodynamic response to exercise in patients with transient ischaemic attack and minor stroke

Early exercise engagement elicits meaningful changes in peripheral blood pressure in patients diagnosed with transient ischaemic attack (TIA) or minor stroke. However, central hemodynamic markers may provide clinicians with important diagnostic and prognostic information beyond that provided by peripheral blood pressure readings. The purpose of this single-centre, randomized, parallel-group clinical trial was to determine the effect of a 12-week aerobic exercise intervention on central and peripheral hemodynamic variables in patients with TIA or minor stroke. In this study, 47 participants (66±10 years) completed a baseline assessment, which involved the measurement of central and peripheral hemodynamic parameters, undertaken in the morning, in a fasted state. Participants were randomized to either a 12-week exercise or control group on completion of the baseline assessment. An identical follow-up assessment was completed post intervention. Central hemodynamic variables were assessed using an oscillometric device at both assessments. Analysis of covariance demonstrated a significant interaction for central and peripheral blood pressure and augmentation index (all P<0.05; ηp2.09–.11), with the exercise group presenting lower values than the control group post intervention (118±17 vs 132±28 mm Hg for central blood pressure; 125±19 vs 138±28 mm Hg for peripheral blood pressure; 104±49 vs 115±67% for augmentation index). The present study demonstrates that participation in an exercise program soon after stroke/TIA diagnosis may elicit significant beneficial changes to a patient's central systolic blood pressure and augmentation index. This may positively impact upon the treatment strategies implemented by clinicians in the care of patients with TIA and minor stroke

The efficacy of a discontinuous graded exercise test in measuring peak oxygen uptake in children aged 8 to 10 years

As children’s natural activity patterns are highly intermittent in nature, and characterised by rapid changes from rest to vigorous physical activity, discontinuous exercise tests may be considered ecologically valid for this population group. This study compared the peak physiological responses from a discontinuous and continuous graded exercise test (GXT_D, GXT_C, respectively) during treadmill exercise in children. Twenty-one healthy children (9.6 ± 0.6 y) completed GXT_D and GXT_C in a randomised order, separated by 72-hours. Following each GXT, and after a 15-minute recovery, participants completed a verification test at 105% of the velocity attained at peak oxygen consumption (VO2peak). There were no differences in VO2peak (55.3 ± 8.2 cf. 54.4 ± 7.6 mL·kg-1·min-1) or maximal heart rate (202 ± 10 cf. 204 ± 8 b·min-1) between GXT_C and GXT_D, respectively (P>.05). Peak running speed (10.7 ± 0.9 cf. 12.1 ± 1.3 km·h-1) and respiratory exchange ratio (1.04 ± 0.05 cf. 0.92 ± 0.05) were however different between tests (P.05), VO2peak (53.3 ± 7.3 mL·kg-1·min-1) and heart rate (197 ± 13 b·min-1) were significantly lower in the GXT_D verification test (P<.05). In conclusion, a discontinuous GXT is an accurate measure of VO2peak in children aged 8 to 10 years and may be a valid alternative to a continuous GXT, despite its longer duration

Effect of an acute dose of omega-3 fish oil following exercise-induced muscle damage

Purpose The purpose of this double-blind, placebo-controlled study was to examine the effect of two fish oil supplements, one high in EPA (750 mg EPA, 50 mg DHA) and one low in EPA (150 mg EPA, 100 mg DHA), taken acutely as a recovery strategy following EIMD. Methods Twenty-seven physically active males (26 ± 4 year, 1.77 ± 0.07 m, 80 ± 10 kg) completed 100 plyometric drop jumps to induce muscle damage. Perceptual (perceived soreness) and functional (isokinetic muscle strength at 60° and 180° s−1, squat jump performance and countermovement jump performance) indices of EIMD were recorded before, and 1, 24, 48, 72, and 96h after the damaging protocol. Immediately after the damaging protocol, volunteers ingested either a placebo (Con), a low-EPA fish oil (Low EPA) or a high-EPA fish oil (High EPA) at a dose of 1 g per 10 kg body mass. Results A significant group main effect was observed for squat jump, with the High EPA group performing better than Con and Low EPA groups (average performance decrement, 2.1, 8.3 and 9.8%, respectively), and similar findings were observed for countermovement jump performance, (average performance decrement, 1.7, 6.8 and 6.8%, respectively, p = 0.07). Significant time, but no interaction main effects were observed for all functional and perceptual indices measured, although large effect sizes demonstrate a possible ameliorating effect of high dose of EPA fish supplementation (effect sizes ≥0.14). Conclusion This study indicates that an acute dose of high-EPA fish oil may ameliorate the functional changes following EIMD

Correction:Physical activity and mental health experiences of people living with long term conditions during COVID-19 pandemic: A qualitative study

Notice of republication This article was republished on March 14 th, 2024, to correct the author list and add Danielle Lambrick and James Faulkner as the third and fourth authors respectively. Please download this article again to view the correct version. The originally published, uncorrected article and the republished, corrected articles are provided here for reference. (PLoS ONE (2023) 18: 7 (e0285785) DOI: 10.1371/journal.pone.0285785)</p

True-to-size surface mapping with neutral helium atoms

Three-dimensional mapping of microscopic surface structures is important in many applications of technology and research, including areas as diverse as microfluidics, MEMS and geoscience. How- ever on the nanoscale, using established techniques for such imaging can be extremely challenging. Scanning helium microscopy (SHeM) is a new technique that uses neutral helium atoms as a probe, enabling completely non-destructive imaging. The technique is broadly applicable and ideal for many otherwise difficult to image materials such as insulators, ultra-thin nano-coatings and biological sam- ples. Here we present a method for implementation and operation of a stereo helium microscope, by applying the photometric stereo method of surface reconstruction to helium microscopy. Four detectors around the sample are typically required, but we show how sample rotation can be used to perform stereo reconstruction with a single detector instrument, or to improve the quality of the reconstructed surface by increasing the number of independent measurements. We examine the quality of the reconstructed surface and show that for low aspect ratio good absolute height is recovered. For features with height/width ∼ 1 the shape of the surface is still recovered well (8% error) despite multiple scattering and masking of the helium beam by surface topography. Therefore it is possible to perform accurate reconstruction of the shape of nanoscale structures with a height to width ratio of at least unity.SM Lambrick acknowledges funding from Mathworks Lt