45 research outputs found
Simulation of dimensionality effects in thermal transport
The discovery of nanostructures and the development of growth and fabrication
techniques of one- and two-dimensional materials provide the possibility to
probe experimentally heat transport in low-dimensional systems. Nevertheless
measuring the thermal conductivity of these systems is extremely challenging
and subject to large uncertainties, thus hindering the chance for a direct
comparison between experiments and statistical physics models. Atomistic
simulations of realistic nanostructures provide the ideal bridge between
abstract models and experiments. After briefly introducing the state of the art
of heat transport measurement in nanostructures, and numerical techniques to
simulate realistic systems at atomistic level, we review the contribution of
lattice dynamics and molecular dynamics simulation to understanding nanoscale
thermal transport in systems with reduced dimensionality. We focus on the
effect of dimensionality in determining the phononic properties of carbon and
semiconducting nanostructures, specifically considering the cases of carbon
nanotubes, graphene and of silicon nanowires and ultra-thin membranes,
underlying analogies and differences with abstract lattice models.Comment: 30 pages, 21 figures. Review paper, to appear in the Springer Lecture
Notes in Physics volume "Thermal transport in low dimensions: from
statistical physics to nanoscale heat transfer" (S. Lepri ed.
Feasibility of an incentive scheme to promote active travel to school: a pilot cluster randomised trial
Abstract Background In Great Britain, 19% of trips to primary school within 1 mile, and 62% within 1â2 miles, are by car. Active travel to school (ATS) offers a potential source of moderate-to-vigorous physical activity (MVPA). This study tested the feasibility of an intervention to promote ATS in 9â10 year olds and associated trial procedures. Methods A parallel cluster randomised pilot trial was conducted over 9 weeks in two schools from a low-income area in northeast England. Measures included daily parental ATS reports (optionally by SMS) and child ATS reports, as well as accelerometry (ActiGraph GT3X+). At baseline, all children were asked to wear the accelerometer for the same week; in the post-randomisation phase, small subsamples were monitored each week. In the 2 weeks when a child wore the accelerometer, parents also reported the start and finish times of the journey to school. The intervention consisted of a lottery-based incentive scheme; every ATS day reported by the parent, whether by paper or SMS, corresponded to one ticket entered into a weekly ÂŁ5 voucher draw. Before each draw session, the researcher prepared the tickets and placed them into an opaque bag, from which one was randomly picked by the teacher at the draw session. Results Four schools replied positively (3.3%, N = 123) and 29 participants were recruited in the two schools selected (33.0%, N = 88). Participant retention was 93.1%. Most materials were returned on time: accelerometers (81.9%), parental reports (82.1%) and child reports (97.9%). Draw sessions lasted on average 15.9 min (IQR 10â20) and overall session attendance was 94.5%. Parent-child report agreement regarding ATS was moderate (k = 0.53, CI 95% 0.45; 0.60). Differences in minutes of accelerometer-assessed MVPA between parent-reported ATS and non-ATS trips were assessed during two timeframes: during the journey to school based on the times reported by the parent (U = 390.5, p < 0.05, 2.46 (n = 99) vs 0.76 (n = 13)) and in the hour before classes (U = 665.5, p < 0.05, 4.99 (n = 104) vs 2.55 (n = 19)). Differences in MVPA minutes between child-reported ATS and non-ATS trips were also significant for each of the timeframes considered (U = 596.5, p < 0.05, 2.40 (n = 128) vs 0.81 (n = 15) and U = 955.0, p < 0.05, 4.99 (n = 146) vs 2.59 (n = 20), respectively). Conclusions Data suggest the feasibility of an ATS incentive scheme and of most trial procedures. School recruitment stood out as requiring further piloting. Trial registration ClinicalTrials.gov: NCT02282631 . Registered 5th September 2014
Active children through incentive vouchers â evaluation (ACTIVE): a mixed-method feasibility study
BackgroundAdolescents face many barriers to physical activity, demonstrated by the decline in physical activity levels in teenage populations. This study aimed to assess the feasibility of overcoming such barriers via the implementation of an activity-promoting voucher scheme to teenagers in deprived areas.MethodsAll Year 9 pupils (nâ=â115; 13.3â±â0.48 years; 51 % boys) from one secondary school in Wales (UK) participated. Participants received ÂŁ25 of activity vouchers every month for six months for physical activity or sporting equipment. Focus groups (nâ=â7), with 43 pupils, and qualitative interviews with teachers (nâ=â2) were conducted to assess feasibility, in addition to a process evaluation utilising the RE-AIM framework. Quantitative outcomes at baseline, five months (during intervention) and twelve months (follow-up) included: physical activity (accelerometer), aerobic fitness (12 min Cooper run) and self-reported activity (PAQ-A). Motivation to exercise (BREQ-2) was measured three months post-baseline and at follow-up.ResultsQualitative findings showed that vouchers encouraged friends to socialise through activity, provided opportunities to access local activities that pupils normally could not afford, and engaged both those interested and disinterested in physical education. Improvements in weekend moderate-to-vigorous physical activity and reductions in sedentary behaviour were observed in both sexes. Boysâ fitness significantly improved during the voucher scheme. âNon-activeâ pupils (those not meeting recommended guidelines of 60 minsâdayâ1) and those with higher motivation to exercise had higher voucher use.ConclusionsAdolescents, teachers and activity providers supported the voucher scheme and felt the vouchers enabled deprived adolescents to access more physical activity opportunities. Voucher usage was associated with improved attitudes to physical activity, increased socialisation with friends and improved fitness and physical activity; presenting interesting avenues for further exploration in a larger intervention trial
80P XRCC6BP1: A key DNA repair gene in platinum-resistant NSCLC
Background In the absence of specific treatable mutations, platinum-based doublet chemotherapy remains the gold standard treatment for NSCLC patients. However, its clinical efficacy is hindered in many patients due to both intrinsic and acquired resistance to these agents, in particular, cisplatin. Alterations in the DNA repair capacity of damaged cells is now recognised as an important factor in mediating this phenomenon. Methods DNA Repair Pathway RT2 Profiler Arrays were used to elucidate key DNA repair genes in H460 cisplatin resistant (CisR) and corresponding parental (PT) NSCLC cell lines previously generated in our laboratory. DNA repair genes significantly altered in CisR cells were validated using RT-PCR and western blot analysis, respectively. Loss of function studies were carried out using siRNA technology. The effect of gene knockdown on apoptosis was assessed by Annexin V/propidium iodide (PI) staining using the CytellÂź Imaging System. DNA damage and repair in response to cisplatin following gene knockdown was investigated using the ÎłH2AX foci formation assay. The translational relevance of these genes was examined in a cohort of chemo-naĂŻve matched normal and tumour lung tissues (n = 20). Results We identified a number of important DNA repair genes differentially regulated between H460 PT and CisR NSCLC cells. These included XRCC6BP1, TOP3A, XPA, PMS1 and hSSB1. XRCC6BP1 mRNA was significantly increased (19.4-fold) in H460 CisR cells relative to their PT counterparts. Gene silencing of XRCC6BP1 re-sensitized CisR lung cancer cells to the pro-apoptotic effects of cisplatin and significantly reduced the DNA repair capacity of these cells. Relative to matched normal lung tissues, XRCC6BP1 mRNA was significantly increased in adenocarcinoma tissues (AD), while hSSB1 mRNA was significantly increased in both AD and squamous cell carcinoma (SCC) tissues. Conclusions We have identified XRCC6BP1, in addition to hSSB1, as key DNA repair genes implicated in cisplatin resistant NSCLC. Our data highlights the potential of targeting XRCC6BP1, at least in part, in re-sensitizing chemoresistant lung cancer cells to the cytotoxic effects of cisplatin chemotherapy
2: XRCC6BP1: A key player in cisplatin resistance and lung cancer stem cells
Alterations in the DNA repair capacity of damaged cells is now recognised as an important factor in mediating resistance to chemotherapeutic agents