Using neural networks to estimate redshift distributions. An application to CFHTLenS

We present a novel way of using neural networks (NN) to estimate the redshift distribution of a galaxy sample. We are able to obtain a probability density function (PDF) for each galaxy using a classification neural network. The method is applied to 58714 galaxies in CFHTLenS that have spectroscopic redshifts from DEEP2, VVDS and VIPERS. Using this data we show that the stacked PDF's give an excellent representation of the true $N(z)$ using information from 5, 4 or 3 photometric bands. We show that the fractional error due to using N(z_(phot)) instead of N(z_(truth)) is <=1 on the lensing power spectrum P_(kappa) in several tomographic bins. Further we investigate how well this method performs when few training samples are available and show that in this regime the neural network slightly overestimates the N(z) at high z. Finally the case where the training sample is not representative of the full data set is investigated. An IPython notebook accompanying this paper is made available here: https://bitbucket.org/christopher_bonnett/nn_noteboo

Environmental education and the issue of nature

Much official environmental education policy in the UK and elsewhere makes scant reference to nature as such, and the issue of our underlying attitude towards it is rarely addressed. For the most part such policy is preoccupied with the issue of meeting ‘sustainably’ what are taken to be present and future human needs. This paper considers a range of issues posed by this anthropocentric approach and will explore the view that environmental education -- indeed any education -- worthy of the name needs to bring a range of searching questions concerning nature to the attention of learners, and to encourage them to develop their own on-going responses to them. It is argued that our present environmental predicament not only provides an exciting opportunity to re-focus education on the issue of our relationship to nature, but positively requires the exploration of this issue for its long term resolution. Extensive implications for the curriculum and the culture of the school are raised

Boundary layer integral matrix procedure: Verification of models

The three turbulent models currently available in the JANNAF version of the Aerotherm Boundary Layer Integral Matrix Procedure (BLIMP-J) code were studied. The BLIMP-J program is the standard prediction method for boundary layer effects in liquid rocket engine thrust chambers. Experimental data from flow fields with large edge-to-wall temperature ratios are compared to the predictions of the three turbulence models contained in BLIMP-J. In addition, test conditions necessary to generate additional data on a flat plate or in a nozzle are given. It is concluded that the Cebeci-Smith turbulence model be the recommended model for the prediction of boundary layer effects in liquid rocket engines. In addition, the effects of homogeneous chemical reaction kinetics were examined for a hydrogen/oxygen system. Results show that for most flows, kinetics are probably only significant for stoichiometric mixture ratios

NASA-Ames three-dimensional potential flow analysis system (POTFAN) equation solver code (SOLN) version 1

A computer program known as SOLN was developed as an independent segment of the NASA-Ames three-dimensional potential flow analysis systems of linear algebraic equations. Methods used include: LU decomposition, Householder's method, a partitioning scheme, and a block successive relaxation method. Due to the independent modular nature of the program, it may be used by itself and not necessarily in conjunction with other segments of the POTFAN system

Around the table: Are multiple-touch surfaces better than single-touch for children's collaborative interactions?

This paper presents a classroom study that investigated the potential of using touch tabletop technology to support children's collaborative learning interactions. Children aged 7-10 worked in groups of three on a collaborative planning task in which they designed a seating plan for their classroom. In the single-touch condition, the tabletop surface allowed only one child to interact with the digital content at a time. In the multiple-touch condition, the children could interact with the digital content simultaneously. Results showed that touch condition did not affect the frequency or equity of interactions, but did influence the nature of children's discussion. In the multiple-touch condition, children talked more about the task; in the single-touch condition, they talked more about turn taking. We also report age and gender differences

Anomaly detection for machine learning redshifts applied to SDSS galaxies

We present an analysis of anomaly detection for machine learning redshift estimation. Anomaly detection allows the removal of poor training examples, which can adversely influence redshift estimates. Anomalous training examples may be photometric galaxies with incorrect spectroscopic redshifts, or galaxies with one or more poorly measured photometric quantity. We select 2.5 million 'clean' SDSS DR12 galaxies with reliable spectroscopic redshifts, and 6730 'anomalous' galaxies with spectroscopic redshift measurements which are flagged as unreliable. We contaminate the clean base galaxy sample with galaxies with unreliable redshifts and attempt to recover the contaminating galaxies using the Elliptical Envelope technique. We then train four machine learning architectures for redshift analysis on both the contaminated sample and on the preprocessed 'anomaly-removed' sample and measure redshift statistics on a clean validation sample generated without any preprocessing. We find an improvement on all measured statistics of up to 80% when training on the anomaly removed sample as compared with training on the contaminated sample for each of the machine learning routines explored. We further describe a method to estimate the contamination fraction of a base data sample.Comment: 13 pages, 8 figures, 1 table, minor text updates to macth MNRAS accepted versio

Systemic wisdom, the 'selving' of nature, and knowledge transformation: education for the 'greater whole'

Considerations arising in the context of burgeoning concerns about the environment can provoke an exploration of issues that have significance both for environmental education in particular and education more generally. Notions of the ‘greater whole’ and ‘systemic wisdom’ that feature in some strands of environmental discourse are a case in point. It is argued that interpretations of these notions arising in currently influential scientific and systems thinking understandings of nature that attempt to overcome a corrosive separation of humankind and nature through a dilution or dismissal of the distinction between the human and non-human, self and other, require critical evaluation if they are not to bring their own dangers. Merleau-Pontian understandings of object constitution in a subjectively informed life-world and ideas of the ‘selving’ of natural things are drawn upon in developing a non-discursively grounded interpretation of systemic wisdom. The latter is taken to raise questions that have considerable transformative potential for conventional views of knowledge and its curriculum organisation

Calculation of three-dimensional compressible laminar and turbulent boundary flows. Three-dimensional compressible boundary layers of reacting gases over realistic configurations

A three-dimensional boundary-layer code was developed for particular application to realistic hypersonic aircraft. It is very general and can be applied to a wide variety of boundary-layer flows. Laminar, transitional, and fully turbulent flows of compressible, reacting gases are efficiently calculated by use of the code. A body-oriented orthogonal coordinate system is used for the calculation and the user has complete freedom in specifying the coordinate system within the restrictions that one coordinate must be normal to the surface and the three coordinates must be mutually orthogonal

Quality of outcome reporting in phase II studies in pulmonary tuberculosis

Tuberculosis (TB) remains a major killer amongst the infectious diseases. Current treatment involves a four-drug regimen for at least 6 months. New drugs and regimens are required to shorten treatment duration, reduce toxicity and combat drug resistance, but the optimal methodology to define the critical path for novel regimens is not well defined. We undertook a systematic review to summarise outcomes reported in Phase II trials of patients with newly diagnosed pulmonary TB to assess the need for a core outcome set. A systematic search of databases (PubMed, MEDLINE, EMBASE and LILACs) was conducted on 1 May 2015 to retrieve relevant peer-reviewed articles. Reference lists of included studies were also searched. This systematic review considered all reported outcomes. Risk of bias was considered via sequence generation, allocation concealment, blinding, reasons for exclusions, and selective reporting. Of 55 included studies, 20 were Phase IIB studies based on culture conversion, 32 were Phase IIA studies based on quantitative bacteriology, and three considered alternative outcomes. Large variation in reported outcomes and trial characteristics was observed across the included studies. Bacteriological results were as often expressed in terms of positivity as negativity, with varying definitions of culture conversion. Variation in reporting was particularly marked for Phase IIA studies, where multiple time intervals were typically selected for analysis and sometimes resulted in differing interpretations of the efficacy of drugs or regimens. Within both Phase IIA and IIB studies, there was variation in the time points at which the study participants were sampled, as well as in the bacteriological media and methods used. For successful future meta-analysis of early-phase studies, the findings of this review suggest that development of a core outcome set would be desirable. This would enable trial results to be more easily compared and combined, potentially leading to more effective development of new treatment strategies for patients with TB. Pending development of, and agreement on, such a core outcome set, we suggest some interim recommendations for reporting of future phase II studies of pulmonary tuberculosis

An exploration of young people’s narratives of hope following experience of psychosis

Aims: To expand understandings of how young people with psychosis experience hope. This included to which factors young people attributed changes in their hopefulness and the role played by professionals and others with lived experience. Method: Ten young people recovering from an experience of psychosis were interviewed using narrative methodology. Results: The experience of hope as an overarching strand throughout the narratives had three common elements: sense of belonging, which included social inclusion, the importance of information and the significance of planning and occupation. Professionals played an important role in facilitating small steps forwards. Conclusions: The findings suggest the importance to young people of a sense of belonging and achieving small goals to facilitate hopeful thinking and, for clinicians, the value of supporting new peer relationships and meaningful occupation