A Contribution to Active Infrared Laser Spectroscopy for Remote Substance Detection

In this work we present a stand-off, long wave infrared (LWIR) spectroscopy system for remote detection of hazardous substances. The principle is based upon wavelength selective illumination using External Cavity Quantum Cascade Lasers, that are tunable in the LWIR wavelength range from 7.5 - 10 µm, in which most chemical substances exhibit a highly characteristic absorption behaviour

Variations in Primary Teachers’ Responses and Development during Three Major Science In- Service Programmes

This paper reports on how different types of teachers responded to in-service aimed at developing investigative-based science education (IBSE) in primary schools, and the extent to which they applied their new skills in the classroom. Common items from evaluation questionnaires allowed data to be combined from three major in-service programmes. Using complete data sets from 120 teachers, cluster analysis enabled three teacher types to be identified: a small group of ‘science unsures’, with low attitude scores and little confidence, who showed no response to the innovation; ‘holistic improvers’, who showed the largest improvement in science teaching confidence; and ‘high level, positive progressives’, who were very positive to science teaching throughout and showed gains in confidence in teaching physics and chemistry, as well as in demonstrating the relevance of science to their pupils. Taking account of these teacher types alongside interviews and observations, nine developmental stages in how teachers apply their new expertise in the classroom and the whole school are suggested. Major factorsinfluencing application in the classroom are the teachers’ initial science knowledge and pedagogical expertise, and motivating feedback to teachers when pupils responded positively to the innovation. Assessing teachers’ initial level of subject knowledge and science pedagogical expertise to inform the approach and amount of in-service provision is important. Subsequent mentoring as well as support from the school principal when teachers first try IBSE with pupils promotes successful implementation in the classroom

BERA-TACTYC Early Childhood Research Review 2003-2017

BERA/TACTYC Review of Early Childhood Education and Care in the UK, 2003-2017 has involved a wide range of early childhood specialists, both in the early consultation stages, and in writing the five main sections of the Review. Teams of authors and their reference groups came together from TACTYC – the Association for Professional Development in Early Years, and the BERA Early Childhood Education and Care SIG. Using specific questions to interrogate the literature, each team worked on one of five main themes: Professionalism; Parenting and Family; Play and Pedagogy; Learning, Development and Curriculum, and Assessment and School Readiness. These themes are contextualised within broad policy issues in the UK. The Introduction shows the working methods for the Review, and the Conclusion brings together key messages and suggestions for future research. We hope that the Review will prove useful to a range of early childhood specialists, including students, researchers, practitioners, policy makers and teachers in further and higher education. We intend to create a User Review that will be aimed at practitioners and to engage other stakeholders in current trends and debates. The Review is being launched at a time of change and uncertainty within early childhood education and care, and we hope that the Review will provide a focal point for discussions about future directions in the four UK policy frameworks, the importance of research, and how we use research evidence to inform provision and practice

Effects of carbon dioxide on the searching behaviour of the root-feeding clover weevil <i>Sitona lepidus</i> (Coleoptera: Curculionidae)

The respiratory emission of CO2 from roots is frequently proposed as an attractant that allows soil-dwelling insects to locate host plant roots, but this role has recently become less certain. CO2 is emitted from many sources other than roots, so does not necessarily indicate the presence of host plants, and because of the high density of roots in the upper soil layers, spatial gradients may not always be perceptible by soil-dwelling insects. The role of CO2 in host location was investigated using the clover root weevil Sitona lepidus Gyllenhall and its host plant white clover (Trifolium repens L.) as a model system. Rhizochamber experiments showed that CO2 concentrations were approximately 1000 ppm around the roots of white clover, but significantly decreased with increasing distance from roots. In behavioural experiments, no evidence was found for any attraction by S. lepidus larvae to point emissions of CO2, regardless of emission rates. Fewer than 15% of larvae were attracted to point emissions of CO2, compared with a control response of 17%. However, fractal analysis of movement paths in constant CO2 concentrations demonstrated that searching by S. lepidus larvae significantly intensified when they experienced CO2 concentrations similar to those found around the roots of white clover (i.e. 1000 ppm). It is suggested that respiratory emissions of CO2 may act as a ‘search trigger’ for S. lepidus, whereby it induces larvae to search a smaller area more intensively, in order to detect location cues that are more specific to their host plant.<br/

Development of a method to determine the penetration velocity of a powder actuated fastener

The purpose of this work was to design a system for measuring the velocity of a powder actuated fastener or drivepin during penetration. This system would provide a tool for further investigation into drivepin penetration characteristics. The main characteristic of interest is the instantaneous acceleration from which the forces on the drivepin can be determined. This acceleration was determined by designing a transducer whose output is drivepin position versus time and calculating the instantaneous velocity and acceleration, graphically and numerically, from these data. A powder actuated drivepin is a special nail-like pin which is driven into hard materials by the force of a charge of gunpowder. The powder actuated tool is similar to a pistol except the projectile is the drivepin and the charge is in a separate brass jacket. The penetration velocity previously referred to is the velocity spectrum during the total time the drivepin is in motion. Some of the transducers that were considered are listed with comments which affected their evaluation. Among these transducers, the linear resistance potentiometer was selected for this measuring system. It has the following characteristics: a. Simplicity b. High frequency response c. Good linearity d. Marginal mechanical strength e. Low, but sufficient output With this potentiometric transducer, an oscilloscope and camera were added to provide a time base and a permanent record. The test results or data are recorded as photographs of the oscilloscope trace. Various techniques for differentiating these data are discussed. These techniques include graphical, approximating polynomials by the method of finite differences, and best fitting curve by the method of least squares. Additional mathematical presentations are included to show the measuring system's linearity and frequency response and the equations of motion of the powder actuated tool and piston. The final configuration of the measuring system is a battery energized slide wire mounted inside a barrel and a collector mounted opposite the slide wire. The head of the drivepin contacts the slide wire during penetration and transfers this voltage to the collector. The collector voltage is fed into an oscilloscope for display as a function of time. The external trigger signal for starting the display is obtained from the first motion of drivepin as it passes through a metal foil on the surface of the material to be penetrated. This potentiometric measuring system was found to be adequate for the purpose intended. However, some mechanical modifications are recommended

Measuring the reactivity of a silicon-terminated probe

It is generally accepted that the exposed surfaces of silicon crystals are highly reactive due to the dangling bonds which protrude into the vacuum. However, surface reconstruction can not only modify the reactivity of bulk silicon crystals, but plays a key role in determining the properties of silicon nanocrystals. In this study we probe the reactivity of silicon clusters at the end of a scanning probe tip by examining their interaction with closed shell fullerene molecules. Counter to intuitive expectations, many silicon clusters do not react strongly with the fullerene cage, and we find that only specific highly oriented clusters have sufficient reactivity to break open the existing carbon-carbon bonds

Nurturing Change: Processes and outcomes of workshops using collage and gesture to foster aesthetic qualities and capabilities for distributed leadership

© 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License CC BY (http://creativecommons.org/licenses/by/4.0/)This article reports findings from a study using arts-based and embodied (ABE) approaches to enhancing capacity for distributed leadership and explores the professional learning which took place as a result. The data reported in the article are from the UK research which formed part of the ENABLES (European Arts-Based Development of Distributed Leadership and Innovation in Schools) project led by the University of Hertfordshire, UK, co-funded by an Erasmus+ grant over a two-year period between 2019 and 2021. The article indicates why we see the professional learning as transformative and proposes a concept of aesthetic grounding to express the nature of change arising from the ABE approaches used. Aesthetic grounding has a generative and organic quality that introduces new elements and potential into participants’ future reflexive deliberations concerning their professional practice. Through enrihment of aesthetic grounding, there is potential for, but not certainty of, transformation of practice.Peer reviewe

Measuring the mechanical properties of molecular conformers

Scanning probe-actuated single molecule manipulation has proven to be an exceptionally powerful tool for the systematic atomic-scale interrogation of molecular adsorbates. To date, however, the extent to which molecular conformation affects the force required to push or pull a single molecule has not been explored. Here we probe the mechanochemical response of two tetra(4-bromophenyl)porphyrin conformers using non-contact atomic force microscopy where we find a large difference between the lateral forces required for manipulation. Remarkably, despite sharing very similar adsorption characteristics, variations in the potential energy surface are capable of prohibiting probe-induced positioning of one conformer, while simultaneously permitting manipulation of the alternative conformational form. Our results are interpreted in the context of dispersion-corrected density functional theory calculations which reveal significant differences in the diffusion barriers for each conformer. These results demonstrate that conformational variation significantly modifies the mechanical response of even simple porpyhrins, potentially affecting many other flexible molecules

Simulated structure and imaging of NTCDI on Si(1 1 1)-7 × 7 : a combined STM, NC-AFM and DFT study

The adsorption of naphthalene tetracarboxylic diimide (NTCDI) on Si(1 1 1)-7 × 7 is investigated through a combination of scanning tunnelling microscopy (STM), noncontact atomic force microscopy (NC-AFM) and density functional theory (DFT) calculations. We show that NTCDI adopts multiple planar adsorption geometries on the Si(1 1 1)-7 × 7 surface which can be imaged with intramolecular bond resolution using NC-AFM. DFT calculations reveal adsorption is dominated by covalent bond formation between the molecular oxygen atoms and the surface silicon adatoms. The chemisorption of the molecule is found to induce subtle distortions to the molecular structure, which are observed in NC-AFM images

Drivers of vegetation change in grasslands of the Sheffield region, northern England, between 1965 and 2012/13

Questions: How has vegetation species diversity and species composition changed between 1965 and 2012/13 in acidic and calcareous grasslands? What has driven this change in vegetation? Location: A 2400-km2 area around Sheffield, northern England. Methods: In 1965 a survey was conducted to describe grassland vegetation of the Sheffield region. We repeated this survey in 2012/13, revisiting acidic and calcareous grassland sites (455 quadrats). Climate, N and sulphur deposition, cattle and sheep stocking rates, soil pH, altitude, aspect and slope were considered to be potential drivers of variation in vegetation. We analysed temporal changes in vegetation and examined relationships with spatial and temporal variation in driver variables. Results: Both acidic and calcareous grasslands showed clear changes in species composition between the two time periods. In acidic grasslands there was no significant change in richness but there were declines in diversity. There were significant increases in Ellenberg N. Nitrogen deposition and grazing were identified as potential drivers of spatial and temporal patterns but it was not possible to discriminate the respective impacts of potential drivers. In calcareous grasslands there were declines in species richness, diversity and appropriate diversity indices. Climate and soil pH were identified as potential drivers of spatial and temporal patterns. Conclusions: Despite only small site losses compared to other surveys in the UK, especially within the national park, both calcareous and acidic grasslands showed very clear changes in species composition. In acidic grasslands, high abundance of Pteridium aquilinum was a particular problem and had increased considerably between the two survey periods. Atmospheric N deposition and grazing were identified as drivers of species diversity. A number of calcareous grasslands showed signs of reduced management intensity leading to scrub invasion