Small carbon chains in circumstellar envelopes

Observations were made for a number of carbon-rich circumstellar envelopes using the Phoenix spectrograph on the Gemini South telescope to determine the abundance of small carbon chain molecules. Vibration-rotation lines of the $\nu_{3}$ antisymmetric stretch of C$_{3}$ near 2040 cm$^{-1}$ (4.902 $\mu$m) have been used to determine the column density for four carbon-rich circumstellar envelopes: CRL 865, CRL 1922, CRL 2023 and IRC +10216. We additionally calculate the column density of C$_{5}$ for IRC +10216, and provide an upper limit for 5 more objects. An upper limit estimate for the C$_{7}$ column density is also provided for IRC+10216. A comparison of these column densities suggest a revision to current circumstellar chemical models may be needed

Surface diffusion coefficients for room acoustics : free-field measures

A surface diffusion coefficient is needed in room acoustics to enable the quality of diffusing surfaces to be evaluated. It may also facilitate more accurate geometric room acoustic models. This paper concentrates on diffusion coefficients derived from free-field polar responses. An extensive set of two- and three-dimensional measurements and predictions was used to test the worth of different diffusion coefficient definitions. The merits and problems associated with these types of coefficients are discussed, and past parameters reviewed. Two new coefficients are described. The new measure based on the autocorrelation function is forwarded as the best free-field coefficient. The strengths and weaknesses of the coefficient are defined. © 2000 Acoustical Society of America

Group Communication Patterns for High Performance Computing in Scala

We developed a Functional object-oriented Parallel framework (FooPar) for high-level high-performance computing in Scala. Central to this framework are Distributed Memory Parallel Data structures (DPDs), i.e., collections of data distributed in a shared nothing system together with parallel operations on these data. In this paper, we first present FooPar's architecture and the idea of DPDs and group communications. Then, we show how DPDs can be implemented elegantly and efficiently in Scala based on the Traversable/Builder pattern, unifying Functional and Object-Oriented Programming. We prove the correctness and safety of one communication algorithm and show how specification testing (via ScalaCheck) can be used to bridge the gap between proof and implementation. Furthermore, we show that the group communication operations of FooPar outperform those of the MPJ Express open source MPI-bindings for Java, both asymptotically and empirically. FooPar has already been shown to be capable of achieving close-to-optimal performance for dense matrix-matrix multiplication via JNI. In this article, we present results on a parallel implementation of the Floyd-Warshall algorithm in FooPar, achieving more than 94 % efficiency compared to the serial version on a cluster using 100 cores for matrices of dimension 38000 x 38000

Clustering and Micro-immiscibility in Alcohol-Water Mixtures: Evidence from Molecular Dynamics Simulations

We have investigated the hydrogen-bonded structures in liquid methanol and a 7:3 mole fraction aqueous solution using classical Molecular Dynamics simulations at 298K and ambient pressure. We find that, in contrast to recent predictions from X-ray emission studies, the hydrogen-bonded structure in liquid methanol is dominated by chain and small ring structures. In the methanol-rich solution, we find evidence of micro-immiscibility, supporting recent conclusions derived from neutron diffraction data.Comment: 5 pages, 4 figure

Learning as participation in early clinical experience: its meaning for student physiotherapists

This research explores the meaning of learning as a process of social participation in clinical practice. The study focused on six first‐year student physiotherapists during a period of early clinical experience on a work integrated learning programme. The programme was unique at the time of the study in that it placed students in clinical settings from the first week of their undergraduate experience. The research applied a case study design and qualitative data were gathered from each student via on‐line learning journals, reflection lines and pre/post experience interviews. Data were analysed, between and within cases, to develop a sense of progressive narrative through the experiences made significant by each participant over the course of the clinical experience. An abductive logic was applied to develop a more theoretical explanation of learning as participation in clinical practice for each participant. The study concludes that these individuals adopted an agentic approach and recognised the benefit to their learning of proactively seeking opportunities to get involved in practice. Interaction with a range of co‐participants was valued, for a variety of reasons. Students were more willing to discuss their own deficits and ask questions of junior clinicians. Interactions with senior clinicians were more likely to challenge and extend the students’ practice. Interactions with non‐physiotherapy colleagues in the multidisciplinary team were valued for the different perspectives they offered. Students valued participation in situations where they could assume greater responsibility, as long as their efforts were recognised by the clinical educator. Participants did not always see value in “routine” practice where there was little opportunity to be involved in decision making or discussion, describing their involvement as being “an extra pair of hands”. Participants described their performance of secondary Discourses of practice in the construction of their respective identities, which I describe as productive worker, trustworthy student, engaged student and junior professional. These Discourses supported participants’ bids for recognition and progressive involvement in communities of clinical practice. However, where the participant identity was associated too strongly with a particular Discourse the educator could restrict access to learning opportunities. Participants dis‐identified themselves from Discourses that conflicted with individual habitus and conveyed lack of care or unethical behaviour. Where power relations challenged the possibility of overt rejection, participants were strategic and excluded these Discourses from their future, rather than current repertoires. At the start of their early clinical experience, participants expressed a desire to “learn by doing” and “learn on the job”. These cases demonstrate that even at an early stage of experience, participants were contributing to the productivity of the workplace and they felt valued when their contributions were recognised. These cases demonstrate that mutual relations support participation but require ongoing negotiation. Considering mutuality as a mechanism for participation in early clinical experience can support analysis of the ways in which social relations support both learning and work objectives. Mutuality as a mechanism for participation requires the learner and educator to recognise these dual objectives. Changing conditions of practice can threaten mutuality. Where a threat occurs, it is countered by adaptive practices that continue to support mutuality in terms of engagement, repertoire and enterprise with the community of clinical practice

Hot methane line lists for exoplanet and brown dwarf atmospheres

We present comprehensive experimental line lists of methane (CH4) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300 - 1400 degC at twelve 100 degC intervals spanning the 960 - 5000 cm-1 (2.0 - 10.4 microns) region of the infrared. This range encompasses the dyad, pentad and octad regions, i.e., all fundamental vibrational modes along with a number of combination, overtone and hot bands. Using our CH4 spectra, we have estimated empirical lower state energies (Elow in cm-1) and our values have been incorporated into the line lists along with line positions (cm-1) and calibrated line intensities (S' in cm molecule-1). We expect our hot CH4 line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.Comment: Supplementary material is provided via the Astrophysical Journal referenc

Teachers' classroom feedback: still trying to get it right

This article examines feedback traditionally given by teachers in schools. Such feedback tends to focus on children's acquisition and retrieval of externally prescribed knowledge which is then assessed against mandated tests. It suggests that, from a sociocultural learning perspective, feedback directed towards such objectives may limit children's social development. In this article, I draw on observation and interview data gathered from a group of 27 9- to 10-year olds in a UK primary school. These data illustrate the children's perceived need to conform to, rather than negotiate, the teacher's feedback comments. They highlight the children's sense that the teacher's feedback relates to school learning but not to their own interests. The article also includes alternative examples of feedback which draw on children's own inquiries and which relate to the social contexts within which, and for whom, they act. It concludes by suggesting that instead of looking for the right answer to the question of what makes teachers' feedback effective in our current classrooms, a more productive question might be how a negotiation can be opened up among teachers and learners themselves, about how teachers' feedback could support children's learning most appropriately

Comparison of three fluorosis indices in a Namibian community with twice optimum fluoride in the drinking water

KIMIn Otjiwarongo, a town in Namibia with twice the optimum fluoride in the drinking water (1.56 ppm) the Dean (Dean, Arnold and Elvove, 1942), Thylstrup and Fejerskov (Thylstrup and Fejerskov, 1978) and TSIF (Horowitz et al, 1984) indices of fluorosis were compared in permanent teeth of the children aged 11 y living in the region. Fluorosis severety was skewed in all instances to lower scores within each index. With the Thylstrup and Fejerskov and TSIF indices it was possible to compare fluorosis by individual teeth; the former was significantly more sensitive in diagnosis (56 per cent vs 50 per cent prevalence). It is recommended that the aims of a fluorosis investigation be carefully detailed before selecting the fluorosis index to be used. If detailed information on individual teeth related to fluoride ingestion is needed the Thylstrup and Fejerskov index is recommended, especially in areas with raised fluoride intakes where it is anticipated that the fluorosis levels will be mainly in the low levels of severit

Dental caries of 11 to 12 year-old South African children and WHO guidelines for the year 2000

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The measurement of household socio-economic position in tuberculosis prevalence surveys: a sensitivity analysis.

OBJECTIVE: To assess the robustness of socio-economic inequalities in tuberculosis (TB) prevalence surveys. DESIGN: Data were drawn from the TB prevalence survey conducted in Lusaka Province, Zambia, in 2005-2006. We compared TB socio-economic inequalities measured through an asset-based index (Index 0) using principal component analysis (PCA) with those observed using three alternative indices: Index 1 and Index 2 accounted respectively for the biases resulting from the inclusion of urban assets and food-related variables in Index 0. Index 3 was built using regression-based analysis instead of PCA to account for the effect of using a different assets weighting strategy. RESULTS: Household socio-economic position (SEP) was significantly associated with prevalent TB, regardless of the index used; however, the magnitude of inequalities did vary across indices. A strong association was found for Index 2, suggesting that the exclusion of food-related variables did not reduce the extent of association between SEP and prevalent TB. The weakest association was found for Index 1, indicating that the exclusion of urban assets did not lead to higher extent of TB inequalities. CONCLUSION: TB socio-economic inequalities seem to be robust to the choice of SEP indicator. The epidemiological meaning of the different extent of TB inequalities is unclear. Further studies are needed to confirm our conclusions