355 research outputs found
An experimental investigation of the hypergolic ignition of some polymeric fuels with oxygen
Hypergolic ignition of polymeric fuels with oxyge
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Supporting practitioner-led inquiry into classroom dialogue with a research-informed professional learning resource: A design-based approach
Funder: Economic and Social Research Council; Id: http://dx.doi.org/10.13039/501100000269Research indicating the educational value of classroom dialogue, in which participants engage critically and constructively with other perspectives, is long established but classroom practice evolves slowly. Outcomes of practitioner professional development in this area are inconsistent and often dependent on costly, external input. Our study aimed to understand whether and how practitionerâled inquiry may offer an alternative, sustainable and scalable way of developing dialogic practices, characterising effective organisational models. The Teacher Scheme for Educational Dialogue Analysis (TâSEDA) resource pack was designed to support iterative cycles of practitioner inquiry based on systematic analysis of classroom dialogue and reflecting critically with peers, using customisable coding tools and templates. This open resource embeds research findings about dialogue forms that are productive for student learning. We report our designâbased research comprising nested inquiry cycles involving 74 practitioners from early years to tertiary levels. Data were derived from surveys, inquiry reports and interviews. Participants successfully used and adapted the resources for their own goals, needs and diverse contexts across seven countries. The largely autonomous process was typically supported by local facilitators working with groups of practitioners; data analysis focused on illuminating models of institutional organisation of inquiry, uses of TâSEDA resources, participant perceptions and factors underlying (dis)engagement. The findings offer insights into knowledge mobilisation and educational change processes. They yield design principles for scalability and sustainability based on a nonâprescriptive model of local ownership and facilitation of selfâdirected practitioner inquiry and purposeâdriven adaptation in complex educational circumstances
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Developing a coding scheme for analysing classroom dialogue across d educational contexts.
The research reported sought to develop a framework for systematically analysing classroom dialogue for application across a range of educational settings. The paper outlines the development and refinement of a coding scheme that attempts to represent and operationalise commonalities amongst some key theorists in the field concerning productive forms of educational dialogue. The team has tested it using video recordings from classroom settings in the UK and Mexico, across age phases, subject areas, and different interactional contexts including whole class, group and paired work. Our Scheme for Educational Dialogue Analysis (SEDA) is situated within a sociocultural paradigm, and draws on Hymes' Ethnography of Communication to highlight the importance of context. We examined how such a tool could be used in practice. We found that concentrating on the âcommunicative actâ to explore dialogue between participants was an appropriate level of granularity, while clustering the 33 resulting codes according to function of the acts helped to highlight dialogic sequences within lessons. We report on the application of the scheme in two different learning contexts and reflect on its fitness for purpose, including perceived limitations. Development of specialised sub-schemes and a version for teachers is underway.This collaborative work was carried out for a project entitled âA Tool for Analysing Dialogic Interactions in Classroomsâ (http://tinyurl.com/BAdialogue) funded through the British Academy International Partnership and Mobility Scheme (ref. RG66509), between January 2013 - December 2015. We are most grateful to colleagues on the project teams who made significant contributions and helpful input during development and testing of the scheme and preparation of the manuscript, including Farah Ahmed, Riikka Hofmann, Christine Howe, Ruth Kershner, Fiona Jackson, Karen Littleton, Neil Mercer, Paul Warwick (UK team); Mariana AlarcĂłn, Nube Estrada, Erika Gil, Kissy GuzmĂĄn, Flora HernĂĄndez, JosĂ© HernĂĄndez, HaydeĂ© Pedraza, Ana Luisa Rubio, Brenda Itzel SĂĄnchez, Ana Laura Trigo, Maricela Velez (Mexico team). We also thank all of the teachers (especially Lloyd and Tania) and students who participated in our previous research from which examples were taken. We appreciate the support of the Economic and Social Research Council, sponsor of most of the UK teamâs work in this area over the years
Translation and manipulation of silicon nanomembranes using holographic optical tweezers
We demonstrate the use of holographic optical tweezers for trapping and manipulating silicon nanomembranes. These macroscopic free-standing sheets of single-crystalline silicon are attractive for use in next-generation flexible electronics. We achieve three-dimensional control by attaching a functionalized silica bead to the silicon surface, enabling non-contact trapping and manipulation of planar structures with high aspect ratios (high lateral size to thickness). Using as few as one trap and trapping powers as low as several hundred milliwatts, silicon nanomembranes can be rotated and translated in a solution over large distances
Generalized Interpolation Material Point Approach to High Melting Explosive with Cavities Under Shock
Criterion for contacting is critically important for the Generalized
Interpolation Material Point(GIMP) method. We present an improved criterion by
adding a switching function. With the method dynamical response of high melting
explosive(HMX) with cavities under shock is investigated. The physical model
used in the present work is an elastic-to-plastic and thermal-dynamical model
with Mie-Gr\"uneissen equation of state. We mainly concern the influence of
various parameters, including the impacting velocity , cavity size , etc,
to the dynamical and thermodynamical behaviors of the material. For the
colliding of two bodies with a cavity in each, a secondary impacting is
observed. Correspondingly, the separation distance of the two bodies has a
maximum value in between the initial and second impacts. When the
initial impacting velocity is not large enough, the cavity collapses in a
nearly symmetric fashion, the maximum separation distance increases
with . When the initial shock wave is strong enough to collapse the cavity
asymmetrically along the shock direction, the variation of with
does not show monotonic behavior. Our numerical results show clear indication
that the existence of cavities in explosive helps the creation of ``hot
spots''.Comment: Figs.2,4,7,11 in JPG format; Accepted for publication in J. Phys. D:
Applied Physic
Horticultural Availability and Homeowner Preferences Drive Plant Diversity and Composition in Urban Yards
Understanding the factors that influence biodiversity in urban areas is important for informing management efforts aimed at enhancing the ecosystem services in urban settings and curbing the spread of invasive introduced species. We determined the ecological and socioeconomic factors that influence patterns of plant richness, phylogenetic diversity, and composition in 133 private household yards in the MinneapolisâSaint Paul Metropolitan area, Minnesota, USA. We compared the composition of spontaneously occurring plant species and those planted by homeowners with composition in natural areas (at the Cedar Creek Ecosystem Science Reserve) and in the horticulture pool of species available from commercial growers. Yard area and fertilizer frequency influenced species richness of the spontaneous species but expressed homeowner values did not. In contrast, the criteria that homeowners articulated as important in their management decisions, including aesthetics, wildlife, neatness and food provision, significantly predicted cultivated species richness. Strikingly, the composition of plant species that people cultivated in their yards resembled the taxonomic and phylogenetic composition of species available commercially. In contrast, the taxonomic and phylogenetic composition of spontaneous species showed high similarity to natural areas. The large fraction of introduced species that homeowners planted was a likely consequence of what was available for them to purchase. The study links the composition and diversity of yard flora to their natural and anthropogenic sources and sheds light on the human factors and values that influence the plant diversity in residential areas of a major urban system. Enhanced understanding of the influences of the sources of plants, both native and introduced, that enter urban systems and the human factors and values that influence their diversity is critical to identifying the levers to manage urban biodiversity and ecosystem services
Three serendipitous pathways in E. coli can bypass a block in pyridoxal-5âČ-phosphate synthesis
Overexpression of seven different genes restores growth of a ÎpdxB strain of E. coli, which cannot make pyridoxal phosphate (PLP), on M9/glucose.None of the enzymes encoded by these genes has a promiscuous 4-phosphoerythronate dehydrogenase activity that can replace the activity of PdxB.Overexpression of these genes restores PLP synthesis by three different serendipitous pathways that feed into the normal PLP synthesis pathway downstream of the blocked step.Reactions in one of these pathways are catalyzed by low-level activities of enzymes of unknown function and a promiscuous activity of an enzyme that normally has a role in another pathway; one reaction appears to be non-enzymatic
The Non-Uniform Distribution of Galaxies from Data of the SDSS DR7 Survey
We have analyzed the spatial distribution of galaxies from the release of the
Sloan Digital Sky Survey of galactic redshifts (SDSS DR7), applying the
complete correlation function (conditional density), two-point conditional
density (cylinder), and radial density methods. Our analysis demonstrates that
the conditional density has a power-law form for scales lengths 0.5-30 Mpc/h,
with the power-law corresponding to the fractal dimension D = 2.2+-0.2; for
scale lengths in excess of 30 Mpc/h, it enters an essentially flat regime, as
is expected for a uniform distribution of galaxies. However, in the analysis
applying the cylinder method, the power-law character with D = 2.0+-0.3
persists to scale lengths of 70 Mpc/h. The radial density method reveals
inhomogeneities in the spatial distribution of galaxies on scales of 200 Mpc/h
with a density contrast of two, confirming that translation invariance is
violated in the distribution of galaxies to 300 Mpc/h, with the sampling depth
of the SDSS galaxies being 600 Mpc/h.Comment: 22 page
Cross-site comparison of ribosomal depletion kits for Illumina RNAseq library construction
Background
Ribosomal RNA (rRNA) comprises at least 90% of total RNA extracted from mammalian tissue or cell line samples. Informative transcriptional profiling using massively parallel sequencing technologies requires either enrichment of mature poly-adenylated transcripts or targeted depletion of the rRNA fraction. The latter method is of particular interest because it is compatible with degraded samples such as those extracted from FFPE and also captures transcripts that are not poly-adenylated such as some non-coding RNAs. Here we provide a cross-site study that evaluates the performance of ribosomal RNA removal kits from Illumina, Takara/Clontech, Kapa Biosystems, Lexogen, New England Biolabs and Qiagen on intact and degraded RNA samples.
Results
We find that all of the kits are capable of performing significant ribosomal depletion, though there are differences in their ease of use. All kits were able to remove ribosomal RNA to below 20% with intact RNA and identify ~â14,000 protein coding genes from the Universal Human Reference RNA sample at >1FPKM. Analysis of differentially detected genes between kits suggests that transcript length may be a key factor in library production efficiency.
Conclusions
These results provide a roadmap for labs on the strengths of each of these methods and how best to utilize them. Keywords: RNAseqr; RNA depletion; Illumina; NGS; ABRF; TranscriptomicsNational Cancer Institute (U.S.) (Grant P30-CA14051)National Institute of Environmental Health Sciences (Grant P30-ES002109
The distribution of pond snail communities across a landscape: separating out the influence of spatial position from local habitat quality for ponds in south-east Northumberland, UK
Ponds support a rich biodiversity because the heterogeneity of individual ponds creates, at the landscape scale, a diversity of habitats for wildlife. The distribution of pond animals and plants will be influenced by both the local conditions within a pond and the spatial distribution of ponds across the landscape. Separating out the local from the spatial is difficult because the two are often linked. Pond snails are likely to be affected by both local conditions, e.g. water hardness, and spatial patterns, e.g. distance between ponds, but studies of snail communities struggle distinguishing between the two. In this study, communities of snails were recorded from 52 ponds in a biogeographically coherent landscape in north-east England. The distribution of snail communities was compared to local environments characterised by the macrophyte communities within each pond and to the spatial pattern of ponds throughout the landscape. Mantel tests were used to partial out the local versus the landscape respective influences. Snail communities became more similar in ponds that were closer together and in ponds with similar macrophyte communities as both the local and the landscape scale were important for this group of animals. Data were collected from several types of ponds, including those created on nature reserves specifically for wildlife, old field ponds (at least 150 years old) primarily created for watering livestock and subsidence ponds outside protected areas or amongst coastal dunes. No one pond type supported all the species. Larger, deeper ponds on nature reserves had the highest numbers of species within individual ponds but shallow, temporary sites on farm land supported a distinct temporary water fauna. The conservation of pond snails in this region requires a diversity of pond types rather than one idealised type and ponds scattered throughout the area at a variety of sites, not just concentrated on nature reserves
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