Centrifuge modelling of building response to tunnel excavation

Understanding the building response to tunnelling-induced settlements is an important aspect of urban tunnelling in soft ground. Previous centrifuge modelling research demonstrated significant potential to study this tunnel–soil–structure interaction problem. However, these recent studies were limited by simplified building models, which might result in uncertainties when interpreting the building performance to tunnelling subsidence. This paper presents an experimental modelling procedure and the results of a series of centrifuge tests, involving relatively complex surface structures subjected to tunnelling in sand. Powder-based three-dimensional (3D) printing was adopted to fabricate building models with realistic layouts, facade openings and foundations. The 3D printed material had a Young's modulus and a brittle response similar to historic masonry. Modelling effects and boundary conditions are quantified. The good agreement between the experimentally obtained results and previous research demonstrates that the soil–structure interaction during tunnel excavation is well replicated. The experimental procedure provides a framework to quantify how building features affect the response of buildings to tunnelling subsidence.The authors are grateful to EPSRC grant EP/K018221/1 and Crossrail for the financial support

Stepped wedge cluster randomized controlled trial designs: a review of reporting quality and design features

Background The stepped wedge (SW) cluster randomized controlled trial (CRCT) design is being used with increasing frequency. However, there is limited published research on the quality of reporting of SW-CRCTs. We address this issue by conducting a literature review. Methods Medline, Ovid, Web of Knowledge, the Cochrane Library, PsycINFO, the ISRCTN registry, and ClinicalTrials.gov were searched to identify investigations employing the SW-CRCT design up to February 2015. For each included completed study, information was extracted on a selection of criteria, based on the CONSORT extension to CRCTs, to assess the quality of reporting. Results A total of 123 studies were included in our review, of which 39 were completed trial reports. The standard of reporting of SW-CRCTs varied in quality. The percentage of trials reporting each criterion varied to as low as 15.4%, with a median of 66.7%. Conclusions There is much room for improvement in the quality of reporting of SW-CRCTs. This is consistent with recent findings for CRCTs. A CONSORT extension for SW-CRCTs is warranted to standardize the reporting of SW-CRCTs.This work was supported by the Wellcome Trust (grant number 099770/Z/12/Z to MJG); the Medical Research Council (grant number MC_UP_1302/2 to APM) and the National Institute for Health Research Cambridge Biomedical Research Centre (MC_UP_1302/4 to JMSW)

Who will follow the leader? Managers' perceptions of management development activities: an international comparison: SKOPE Research Paper No. 51, Autumn 2004

This article contributes to the on-going debate surrounding management education and development through an examination of the development experiences of managers studying for an MBA by distance learning at Warwick Business School. It analyses the extent to which management development opportunities, both formal and informal, are seen to support managers in their day-to-day roles and deliver those skills necessary for the future. The research also provides the opportunity to compare responses from UK managers with those from managers in other countries. The survey evidence shows that in some respects the experience of UK and Overseas respondents are quite similar; they both receive large amounts of training and development from their employers and show a preference for more ‘non-formal’ routes of learning. In other ways their experiences are quite different: UK managers take up their first full-time job and their first managerial appointment earlier than the overseas respondents and overseas respondents placed much more emphasis on networking and learning from outside their own organisations than did UK managers. The research also suggests that integrating management development activities with other human resource policies and practices, such as performance evaluation and reward remains problematic and that there is a strong perception amongst managers both in the UK and overseas that their organisations do not view management development in a strategic way. When looking at future development needs respondents from both the UK and overseas highlighted the need for leadership skills as a priority for themselves but focused on more general management and operational skills as the main priority for their colleagues. One possible explanation for this is that the respondents were only to well aware of the fact that that leaders need followers. This is, however, a view at which is at odds with current policy arguments in the UK where leadership skills are seen to be necessary for all managers

Large-Scale Evaluation of Maize Germplasm for Low-Phosphorus Tolerance

<div><p>Low-phosphorus (LP) stress is a global problem for maize production and has been exacerbated by breeding activities that have reduced the genetic diversity of maize. Although LP tolerance in maize has been previously evaluated, the evaluations were generally performed with only a small number of accessions or with samples collected from a limited area. In this research, 826 maize accessions (including 580 tropical/subtropical accessions and 246 temperate accessions) were evaluated for LP tolerance under field conditions in 2011 and 2012. Plant height (PH) and leaf number were measured at three growth stages. The normalized difference vegetation index (NDVI) and fresh ear weight (FEW) were also measured. Genetic correlation analysis revealed that FEW and NDVI were strongly correlated with PH, especially at later stages. LP-tolerant and -sensitive accessions were selected based on the relative trait values of all traits using principal component analysis, and all the 14 traits of the tolerant maize accessions showed less reduction than the sensitive accessions under LP conditions. LP tolerance was strongly correlated with agronomic performance under LP stress conditions, and both criteria could be used for genetic analysis and breeding of LP tolerance. Temperate accessions showed slightly better LP tolerance than tropical/subtropical ones, although more tolerant accessions were identified from tropical/subtropical accessions, which could be contributed by their larger sample size. This large-scale evaluation provides useful information, LP-tolerant germplasm resources and evaluation protocol for genetic analysis and developing maize varieties for LP tolerance.</p></div

Responses of LP tolerant and susceptible accessions to LP stress.

<p>Photos were taken at 57 DAP in 2012.</p

Basic chemical characteristics of the soil (0 to 20 cm depth) used to evaluate 826 maize accessions in Guangzhou, China.

<p>Basic chemical characteristics of the soil (0 to 20 cm depth) used to evaluate 826 maize accessions in Guangzhou, China.</p

Classification of 826 maize accessions for their responses to LP stress based on LPTI and LPPI.

<p>LPPI: LP performance index; LPTI: LP tolerance index; TG: tolerant and good-performance group; SG: sensitive and good-performance group; TP: tolerant and poor-performance group; SP: sensitive and poor-performance group. The number in the bracketsis the number of maize accessions in each group.</p

Distribution of all traits measured for 826 maize accessions.

<p>PH: plant height; LN: leaf number; NDVI: normalized difference vegetation index; FEW: fresh ear weight; DAP: days after planting; LP: low-P; NP: normal-P; Percentage: the number of accessions in each interval divided by the total number of accessions.</p