Anomalous increase in nematic-isotropic transition temperature in dimer molecules induced by magnetic field

We have determined the nematic-isotropic transition temperature as a function of applied magnetic field in three different thermotropic liquid crystalline dimers. These molecules are comprised of two rigid calamitic moieties joined end to end by flexible spacers with odd numbers of methylene groups. They show an unprecedented magnetic field enhancement of nematic order in that the transition temperature is increased by up to 15K when subjected to 22T magnetic field. The increase is conjectured to be caused by a magnetic field-induced decrease of the average bend angle in the aliphatic spacers connecting the rigid mesogenic units of the dimers

Nonstandard electroconvection in a bent-core oxadiazole material

Electroconvection (EC) phenomena have been investigated in the nematic phase of a bent-core oxadiazole material with negative dielectric anisotropy and a frequency dependent conductivity anisotropy. The formation of longitudinal roll (LR) patterns is one of the predominant features observed in the complete frequency and voltage range studied. At voltages much above the LR threshold, various complex patterns such as the "crisscrossed" pattern, bimodal varicose, and turbulence are observed. Unusually, the nonstandard EC (ns-EC) instability in this material, is observed in a regime in which we measure the dielectric and conductivity anisotropies to be negative and positive respectively. A further significant observation is that the EC displays distinct features in the high and low temperature regimes of the nematic phase, supporting an earlier report that EC patterns could distinguish between regions that have been reported as uniaxial and biaxial nematic phases

Persistent global power fluctuations near a dynamic transition in electroconvection

This is a study of the global fluctuations in power dissipation and light transmission through a liquid crystal just above the onset of electroconvection. The source of the fluctuations is found to be the creation and annihilation of defects. They are spatially uncorrelated and yet temporally correlated. The temporal correlation is seen to persist for extremely long times. There seems to be an especially close relation between defect creation/annihilat ion in electroconvection and thermal plumes in Rayleigh-B\'enard convection

Effects of acute fatigue on the volitional and magnetically-evoked electromechanical delay of the knee flexors in males and females

Neuromuscular performance capabilities, including those measured by evoked responses, may be adversely affected by fatigue; however, the capability of the neuromuscular system to initiate muscle force rapidly under these circumstances is yet to be established. Sex-differences in the acute responses of neuromuscular performance to exercise stress may be linked to evidence that females are much more vulnerable to ACL injury than males. Optimal functioning of the knee flexors is paramount to the dynamic stabilisation of the knee joint, therefore the aim of this investigation was to examine the effects of acute maximal intensity fatiguing exercise on the voluntary and magnetically-evoked electromechanical delay in the knee flexors of males and females. Knee flexor volitional and magnetically-evoked neuromuscular performance was assessed in seven male and nine females prior to and immediately after: (i) an intervention condition comprising a fatigue trial of 30-seconds maximal static exercise of the knee flexors, (ii) a control condition consisting of no exercise. The results showed that the fatigue intervention was associated with a substantive reduction in volitional peak force (PFV) that was greater in males compared to females (15.0%, 10.2%, respectively, p < 0.01) and impairment to volitional electromechanical delay (EMDV) in females exclusively (19.3%, p < 0.05). Similar improvements in magnetically-evoked electromechanical delay in males and females following fatigue (21%, p < 0.001), however, may suggest a vital facilitatory mechanism to overcome the effects of impaired voluntary capabilities, and a faster neuromuscular response that can be deployed during critical times to protect the joint system

Optical Non-Contact Railway Track Measurement with Static Terrestrial Laser Scanning to Better than 1.5mm RMS

The railway industry requires track to be monitored for a variety of reasons, particularly when any type of physical works take place within the vicinity of the asset (e.g. demolition, construction and redevelopment works). Terrestrial laser scanning (TLS) has considerable potential as a survey method for rail measurement due to its non-contact nature and independence from physical targeting at track level. The consensus from recently published work using static terrestrial laser scanning is that rail measurements to the order of 3mm RMS are routinely possible. Such measures are appropriate for extracting the gauge, cant and twist parameters required by the rail industry, however engineering specifications designed to ensure safe and comfortable running of the trains ideally require measurements of better quality. This paper utilises standard design rail profiles from the UK industry to optimise the way in which TLS point cloud data are fitted to the rail geometry. The work is based on the use of off the shelf phase-based TLS systems each capable of delivering single point measurements of the order of 5mm to cooperative surfaces. The paper describes a workflow which focuses the fitting process onto discrete planar rail elements derived from the design rail geometry. The planar fitting process is improved through understanding how data from these scanners respond to rail surfaces. Of particular importance is the removal of noisy data from the shiny running surfaces. Results from a sequence of multi-station TLS surveys of the same set of double tracks taken from platform level highlight the capability to obtain fits to the rail model of better than 1.5mm RMS. Whilst fitting can be carried out on a single side of a rail, the paper highlights the challenge of obtaining an accurate TLS registration necessary to extract both sides of each rail to the same level of accuracy. This configuration is proven over inter-TLS instrument separations of the order of 30m and demonstrates the TLS network coverage necessary to achieve such results even in the presence of an occluding electric third rail

Governing the governors : a case study of college governance in English further education

This paper addresses the nature of governors in the governance of further education colleges in an English context (1). It explores the complex relationship between governors (people/agency), government (policy/structure) and governance (practice), in a college environment. While recent research has focused on the governance of schooling and higher education there has been little attention paid to the role of governors in the lifelong learning sector. The objective of the paper is to contribute to the debate about the purpose of college governance at a time when the Learning and Skills Council (LSC) commissioning era ends, and new government bodies responsible for further education and training, including local authorities, arrive. The paper analyses the nature of FE governance through the perspectives and experiences of governors, as colleges respond to calls from government for greater improvement and accountability in the sector (LSIS, 2009a). What constitutes creative governance is complex and controversial in the wider framework of regulation and public policy reform (Stoker, 1997; Seddon, 2008). As with other tricky concepts such as leadership, professionalism and learning, college governance is best defined in the contexts, cultures and situations in which it is located. College governance does not operate in a vacuum. It involves governors, chairs, principals, professionals, senior managers, clerks, community, business and wider agencies, including external audit and inspection regimes. Governance also acts as a prism through which national education and training reforms are mediated, at local level. While governing bodies are traditionally associated with the business of FE - steering, setting the tone and style, dealing with finance, funding, audit and procedural matters – they are increasingly being challenged to be more creative and responsive to the wider society. Drawing on a recent case study of six colleges, involving governors and key policy stakeholders, this paper explores FE governance in a fast changing policy environment

Influence of CMV/EBV Serostatus on Respiratory Infection Incidence During 4 Months of Winter Training in a Student Cohort of Endurance Athletes

The purpose of this study was to examine the influence of previous infection with cytomegalovirus (CMV) or Epstein Barr virus (EBV) on the incidence, severity and duration of upper respiratory tract illness (URTI) episodes in endurance athletes during a 4-month winter training period. Blood samples were obtained from 236 healthy subjects (186 males, 70 females) who were engaged in regular sports training (predominantly endurance-based activities such as running, cycling, swimming, triathlon, team games and racquet sports) at the start of the study period for CMV and EBV serostatus analysis. Their baseline characteristics were (mean ± SD) age: 21 ± 2 years, body mass: 73.5 ± 11.2 kg, height: 176.5 ± 9.3 cm, body mass index 23.6 ± 2.2 kg/m2. Weekly training and daily illness logs were kept. Self-reported weekly training duration averaged 9.6 ± 5.2 h/week and 4.0 ± 1.6% of the cohort experienced a URTI episode each week. Twenty-five percent of the subject cohort were CMV positive with a similar proportion in males (24%) and females (26%) whereas 84% of the subject cohort were EBV positive with a similar proportion in males (84%) and females (83%). In addition, 21% of the subject cohort were both CMV and EBV positive (CMV+EBV+) whereas 13% of the subject cohort had no prior CMV or EBV infection (CMV-EBV-). With regard to CMV/EBV serostatus, the results indicated that there was no difference in the proportion of subjects who presented with symptoms of infection between CMV/EBV positive and negative groups. Athletes with previous CMV infection had fewer URTI symptom days during the study period than those with no previous infection [mean and interquartile range (IQR), positives 2 (0-7) days, negatives 4 (1-9) days, P = 0.033] and EBV serostatus had no influence on URTI episode incidence, severity or duration. Moreover, we found that athletes with prior infection of both CMV and EBV had fewer URTI episodes and symptom days than athletes who were seronegative for both CMV and EBV [mean (IQR), URTI episodes: positives 0 (0-1), negatives 1 (0-2), P = 0.04; symptom days: positives 2 (0-7), negatives 8 (2-12), P = 0.01]. The reasons for this are still unclear but could be related to the previously reported elevated T cytotoxic cell response to exercise in individuals with positive CMV serostatus. Previous coinfection with CMV and EBV might promote protective immune surveillance to lower the risk of URTI

Influence of Prolonged Exercise and Hydration Status on Antigen-Stimulated Cytokine Production by Whole Blood Culture

Prolonged, strenuous exercise has been associated with a temporal depression of host defence, increasing susceptibility to upper respiratory tract illness (URTI). An elevated anti-inflammatory cytokine response to antigen challenge at rest has been reported as a risk factor for URTI. Chronic, strenuous exercise training appears to augment this anti-inflammatory response, with IL-10 release predicting URTI susceptibility in athletes. The purpose of this study was to determine the acute effects of a bout of prolonged exercise and hydration status on antigen-stimulated cytokine production. Twelve healthy males cycled for 120 minutes at 60% of maximal oxygen uptake on two occasions, once in a euhydrated state and once moderately hypohydrated. For the euhydrated trial, participants drank ad libitum during the 24 hours prior to the trial, and were provided with 250 mL water every 30 minutes during exercise. For the hypohydrated trial, fluid intake was restricted to 500 mL water during the 24 hours leading up to the trial, and no fluid was ingested during exercise. Blood samples were collected immediately before and after exercise, and following 2 hours of passive recovery. A full blood count was obtained, and plasma analysed for cortisol. In vitro antigen-stimulated cytokine production was determined from whole blood culture, using a multi-antigen vaccine as stimulant. Fluid restriction resulted in body mass loss of 1.3 ± 0.7 % and 3.9 ± 1.0 % before and after exercise, respectively. Exercise elicited a significant leukocytosis and elevated plasma cortisol, with no differences between trials. Post-exercise IL-10 production following stimulation was significantly higher than pre-exercise (p\u3c0.01). Both IL-4 (p\u3c0.05) and IL-10 (p\u3c0.01) release per lymphocyte were significantly increased 2 hours post-exercise compared with pre-exercise. Antigen-stimulated IL-6 production was significantly reduced 2 hours post-exercise (p\u3c0.05), an effect that remained significant when expressed per monocyte (p\u3c0.01). Although not quite reaching statistical significance, antigen-stimulated IFN-γ and IL-8 release tended to decrease following exercise, as did monocyte production of TNF-α. IL-1β and IL-2 production were not significantly altered by exercise. No significant effect of hydration status was observed for any of the measured variables. Prolonged exercise appears to result in augmented anti-inflammatory cytokine release in response to antigen challenge, possibly coupled with an acute suppression of pro-inflammatory cytokine production. These findings correspond with previous studies using mitogen or endotoxin as stimulant. Neither cytokine production nor plasma cortisol was affected by moderate hypohydration induced by fluid restriction for 24 hours prior to and during exercise