Continuity tester screens out faulty socket connections

A device, used before and after assembly, tests the continuity of an electrical circuit through each pin and socket of multiple connector sockets. Electrically insulated except at the contact area, a test probe is dimensioned to make contact only in properly formed sockets

Factors affecting penicillium roquefortii (penicillium glaucum) in internally mould ripened cheeses: implications for pre-packed blue cheeses

The amount and vivid colour of blue veins of internally mould ripened cheeses are desirable quality characteristics. It is therefore important that there is a sufficient amount of veining and that it maintains its blue appearance to be appealing to consumers therefore leading to maximised sales potential and profit for the manufacturing company. Optimum in vitro growth mimicking the conditions typically found in prepacked blue cheeses, and using lactose as the sole carbon source, was facilitated by a gas mixture of 5% oxygen ⁄0% carbon dioxide ⁄ balance nitrogen). The work undertaken in this study determined that the factors for optimum in vitro growth of Penicillium roquefortii (strain PRB6) were: a temperature of 20 ± 1 �C, pH of 6.0 ± 0.1, and a relative humidity of 70 ± 0.1%. Further in vitro studies have also shown that the increasing ‘in-pack’ carbon dioxide concentration not only depresses the growth of P. roquefortii but also affects immature conidiospore pigmentation (no effect has been seen on mature conidiospore pigmentation). The implications of this study suggest that the majority of pre-packed internally mould ripened blue cheeses on sale in supermarkets are packaged in inappropriate materials. For some cheeses (e.g. the Roquefort-type cheeses) this is not an issue since these are packed in a much more mature state and some loss of veining colour is not appreciably noticeable

A pandemic summer: Impact on teaching and learning for mastery in Power Maths primary schools

We report on findings from a 2019-2021 study of use and impact of Power Maths, a ‘mastery’-oriented primary (R-year 6) resource. The study follows 40 classes of 2019-20 Power Maths-using year 1, 3 and 5 children and their teachers over two years, exploring teacher/pupil use and impact on learning. We report initial high-level findings. Summer 2020 study data serendipitously enabled us to understand aspects of teachers’ work over the pandemic period. Teachers reported particular challenges in addressing new areas requiring conceptual development, and inability to effectively develop children’s mathematical language or reasoning, or to monitor deep progress in mathematics learning. However, some children’s learning benefited from small group in-school provision, and others’ from more contextualised and less time-constrained ‘home schooling’. Tentatively, children returning to school often showed initially slow, but accelerating, recovery from confidence and learning loss

Continuous and discrete models of cooperation in complex bacterial colonies

We study the effect of discreteness on various models for patterning in bacterial colonies. In a bacterial colony with branching pattern, there are discrete entities - bacteria - which are only two orders of magnitude smaller than the elements of the macroscopic pattern. We present two types of models. The first is the Communicating Walkers model, a hybrid model composed of both continuous fields and discrete entities - walkers, which are coarse-graining of the bacteria. Models of the second type are systems of reaction diffusion equations, where the branching of the pattern is due to non-constant diffusion coefficient of the bacterial field. The diffusion coefficient represents the effect of self-generated lubrication fluid on the bacterial movement. We implement the discreteness of the biological system by introducing a cutoff in the growth term at low bacterial densities. We demonstrate that the cutoff does not improve the models in any way. Its only effect is to decrease the effective surface tension of the front, making it more sensitive to anisotropy. We compare the models by introducing food chemotaxis and repulsive chemotactic signaling into the models. We find that the growth dynamics of the Communication Walkers model and the growth dynamics of the Non-Linear diffusion model are affected in the same manner. From such similarities and from the insensitivity of the Communication Walkers model to implicit anisotropy we conclude that the increased discreteness, introduced be the coarse-graining of the walkers, is small enough to be neglected.Comment: 16 pages, 10 figures in 13 gif files, to be published in proceeding of CMDS

Assessment to support the development of problem-solving goals in mathematics curricula 5-16

Current mathematics education policy perspectives in England, as well as in many other developed nations, privilege problem solving as a key 21st century skill (e.g. DfE, 2014; Kaur, 2014). Importantly, there is among the mathematics, mathematics education and end-user communities widespread embrace of problem solving as a centrally valued mathematical activity (e.g. ACME, 2011). However, English teachers and assessors often have limited experience of teaching for/assessing genuine problem solving, and performance in mathematics in England is high-stakes (Ofsted, 2012). Problem solving is therefore unlikely to be widely developed in classrooms unless summatively assessed at key points including GCSE, the standard English external assessment at age 16. A coherent curriculum system (Schmidt and Prawat, 2006) whereby intended curriculum, assessments, resources and teacher development are aligned and consistent, is key to supporting principled enactment (Golding, 2017). We report on a set of longitudinal efficacy studies which, among other intentions, evaluate the impact on teachers and students of a leading curriculum and assessment provider’s support for, and assessment of, problem solving for the 2014 Mathematics National Curriculum for 5-16 year olds (DfE, 2014). These are highly influential in England because they are widely adopted: the provider’s GCSE assessments at 16, for example, accounted for about two-thirds of all cohort entries in 2017. Key theoretical constructs used are those of performativity (Ball, 1994) and curriculum coherence (Schmidt and Prawat, 2006). Teacher interviews (n=452), student focus groups (n=172), classroom observations (n=101) and student survey responses (n~3300) over two early years of curriculum enactment show teachers and students perceive the approaches adopted in related curriculum materials and in the first set of provider GCSE examination papers not only employ highly valid assessment of, and approaches to, mathematical problem solving, but support that with provision of free surround materials specifically designed to build up students' ability to demonstrate related skills in summative timed assessments. However, we also evidence early and emerging constraints on both assessment and classroom enactment of problem solving in the curriculum: teacher skills and knowledge for related teaching across the range of students, teacher time and opportunity to harness the (additional or included) professional development opportunities provided with the resources, perceptions of superficial interpretations of ‘problem solving’ in national assessments at age 11, and pressures on schools and GCSE assessors to adopt enactments of ‘problem solving’ that are of limited validity, or for a subset of students only. Teachers attribute this to a) the challenges associated with defining an agreed meaning for mathematical problem solving and b) perceived in-school tensions between validly enacting that and meeting high-stakes performance measures. We discuss some implications

Uncovering rate variation of lateral gene transfer during bacterial genome evolution

<p>Abstract</p> <p>Background</p> <p>Large scale genome arrangement, such as whole gene insertion/deletion, plays an important role in bacterial genome evolution. Various methods have been employed to study the dynamic process of gene insertions and deletions, such as parsimony methods and maximum likelihood methods. Previous maximum likelihood studies have assumed that the rate of gene insertions/deletions is constant over different genes. This assumption is unrealistic. For instance, it has been shown that informational genes are less likely to be laterally transferred than non-informational genes. However, how much of the variation in gene transfer rates is due to the difference between informational genes and non-informational genes is unclear. In this study, a Γ-distribution was incorporated in the likelihood estimation by considering rate variation for gene insertions/deletions between genes. This makes it possible to address whether a difference between informational genes and non-informational genes is the main contributor to rate variation of lateral gene transfers.</p> <p>Results</p> <p>The results show that models incorporating rate variation fit the data better than do constant rate models in many phylogenetic groups. Even though informational genes are less likely to be laterally transferred than non-informational genes, the degree of rate variation for insertions/deletions did not change dramatically and remained high even when informational genes were excluded from the study. This suggests that the variation in rate of insertions/deletions is not due mainly to the simple difference between informational genes and non-informational genes. Among genes that are not classified as informational and among the informational genes themselves, there are still large differences in the rates that these genes are inserted and deleted.</p> <p>Conclusion</p> <p>While the difference in informational gene rates contributes to rate variation, it is only a small fraction of the variation present; instead, a substantial amount of rate variation for insertions/deletions remains among both informational genes and among non-informational genes.</p

‘Hard to focus, difficult to learn’: Covid19 Impacts on teaching, learning and progression for A Levels in Mathematics

We explore year 13 (age 17-18) student accounts of how Covid19 has impacted their learning for pre-university mathematics qualifications in England. Findings derive from the final year of a four-year study (2017/18 to 2020/21) exploring enactment and impact of reformed mathematics ‘A Levels’, and efficacy of associated Pearson resources and assessments. Research tools were adapted to focus on impacts of Covid19. In this cohort’s first year of A level (2019/20), teaching and learning was severely disrupted. Teachers anticipated significant, wide-ranging learning gaps as students progressed to year 13. Using data from Autumn 2020 and Spring 2021 we analyse student accounts of how continued disruptions to teaching and learning have impacted them. Variable access to teachers, barriers to collaborative work, and challenges of remote or reduced contact working have resulted in reduced depth and breadth of learning. Additionally, many students reported negative impacts on mathematical confidence and wider mental health