Robust Machine Learning Applied to Astronomical Datasets I: Star-Galaxy Classification of the SDSS DR3 Using Decision Trees

We provide classifications for all 143 million non-repeat photometric objects in the Third Data Release of the Sloan Digital Sky Survey (SDSS) using decision trees trained on 477,068 objects with SDSS spectroscopic data. We demonstrate that these star/galaxy classifications are expected to be reliable for approximately 22 million objects with r < ~20. The general machine learning environment Data-to-Knowledge and supercomputing resources enabled extensive investigation of the decision tree parameter space. This work presents the first public release of objects classified in this way for an entire SDSS data release. The objects are classified as either galaxy, star or nsng (neither star nor galaxy), with an associated probability for each class. To demonstrate how to effectively make use of these classifications, we perform several important tests. First, we detail selection criteria within the probability space defined by the three classes to extract samples of stars and galaxies to a given completeness and efficiency. Second, we investigate the efficacy of the classifications and the effect of extrapolating from the spectroscopic regime by performing blind tests on objects in the SDSS, 2dF Galaxy Redshift and 2dF QSO Redshift (2QZ) surveys. Given the photometric limits of our spectroscopic training data, we effectively begin to extrapolate past our star-galaxy training set at r ~ 18. By comparing the number counts of our training sample with the classified sources, however, we find that our efficiencies appear to remain robust to r ~ 20. As a result, we expect our classifications to be accurate for 900,000 galaxies and 6.7 million stars, and remain robust via extrapolation for a total of 8.0 million galaxies and 13.9 million stars. [Abridged]Comment: 27 pages, 12 figures, to be published in ApJ, uses emulateapj.cl

Data Mining and Machine Learning in Astronomy

We review the current state of data mining and machine learning in astronomy. 'Data Mining' can have a somewhat mixed connotation from the point of view of a researcher in this field. If used correctly, it can be a powerful approach, holding the potential to fully exploit the exponentially increasing amount of available data, promising great scientific advance. However, if misused, it can be little more than the black-box application of complex computing algorithms that may give little physical insight, and provide questionable results. Here, we give an overview of the entire data mining process, from data collection through to the interpretation of results. We cover common machine learning algorithms, such as artificial neural networks and support vector machines, applications from a broad range of astronomy, emphasizing those where data mining techniques directly resulted in improved science, and important current and future directions, including probability density functions, parallel algorithms, petascale computing, and the time domain. We conclude that, so long as one carefully selects an appropriate algorithm, and is guided by the astronomical problem at hand, data mining can be very much the powerful tool, and not the questionable black box.Comment: Published in IJMPD. 61 pages, uses ws-ijmpd.cls. Several extra figures, some minor additions to the tex

Utility of a next generation framework for assessment of genomic damage: A case study using the industrial chemical benzene

We recently published a next generation framework for assessing the risk of genomic damage via exposure to chemical substances. The framework entails a systematic approach with the aim to quantify risk levels for substances that induce genomic damage contributing to human adverse health outcomes. Here, we evaluated the utility of the framework for assessing the risk for industrial chemicals, using the case of benzene. Benzene is a well‐studied substance that is generally considered a genotoxic carcinogen and is known to cause leukemia. The case study limits its focus on occupational and general population health as it relates to benzene exposure. Using the framework as guidance, available data on benzene considered relevant for assessment of genetic damage were collected. Based on these data, we were able to conduct quantitative analyses for relevant data sets to estimate acceptable exposure levels and to characterize the risk of genetic damage. Key observations include the need for robust exposure assessments, the importance of information on toxicokinetic properties, and the benefits of cheminformatics. The framework points to the need for further improvement on understanding of the mechanism(s) of action involved, which would also provide support for the use of targeted tests rather than a prescribed set of assays. Overall, this case study demonstrates the utility of the next generation framework to quantitatively model human risk on the basis of genetic damage, thereby enabling a new, innovative risk assessment concept. Environ. Mol. Mutagen. 61:94–113, 2020. © 2019 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.JRC.F.3-Chemicals Safety and Alternative Method

Families’ perceptions of and experiences related to a pediatric weight management program.

Objective: To examine parents' and children's perceptions of and experiences related to a Parents as Agents of Change (PAC) intervention for managing pediatric obesity. Methods: Ten families were recruited from a PAC intervention. Participants were interviewed before (10 adults and 9 children), during (9 adults and 8 children), and after (8 adults) the intervention. Results: Before the intervention, families reported goals to increase physical activity, plan and eat healthier meals, reduce screen time, and lose weight. During the intervention, families described different approaches to making behavior changes depending on who assumed responsibility (parent, child, or shared responsibility). After the intervention, group setting, goal setting, and portion size activities were viewed positively. Suggestions for improvement included engaging children and reducing intervention length. Conclusions and Implications: Practitioners delivering PAC interventions should discuss families' goals and concerns, and who is responsible for making lifestyle changes. Practical activities are valuable. The length of interventions and engagement of children should be considere

Stellar Cruise Control: Weakened Magnetic Braking Leads to Sustained Rapid Rotation of Old Stars

Despite a growing sample of precisely measured stellar rotation periods and ages, the strength of magnetic braking and the degree of departure from standard (Skumanich-like) spindown have remained persistent questions, particularly for stars more evolved than the Sun. Rotation periods can be measured for stars older than the Sun by leveraging asteroseismology, enabling models to be tested against a larger sample of old field stars. Because asteroseismic measurements of rotation do not depend on starspot modulation, they avoid potential biases introduced by the need for a stellar dynamo to drive starspot production. Using a neural network trained on a grid of stellar evolution models and a hierarchical model-fitting approach, we constrain the onset of weakened magnetic braking. We find that a sample of stars with asteroseismically-measured rotation periods and ages is consistent with models that depart from standard spindown prior to reaching the evolutionary stage of the Sun. We test our approach using neural networks trained on model grids produced by separate stellar evolution codes with differing physical assumptions and find that the choices of grid physics can influence the inferred properties of the braking law. We identify the normalized critical Rossby number ${\rm Ro}_{\rm crit}/{\rm Ro}_\odot = 0.91\pm0.03$ as the threshold for the departure from standard rotational evolution. This suggests that weakened magnetic braking poses challenges to gyrochronology for roughly half of the main sequence lifetime of sun-like stars.Comment: 26 pages, 10 figure

Interventions to improve continence for children and young people with neurodisability: a national survey of practitioner and family perspectives and experiences.

Objective Describe families’ experiences of interventions to improve continence in children and young people with neurodisability, and health professionals’ and school and social care staff’s perspectives regarding factors affecting intervention use. Design Four online surveys were developed and advertised to parent carers, young people with neurodisability, health professionals and school and social care staff, via societies, charities, professional contacts, schools, local authorities, and national parent carer and family forums, who shared invitations with their networks. Survey questions explored: difficulties helping children and young people use interventions; acceptability of interventions and waiting times; ease of use and availability of interventions, and facilitators and barriers to improving continence. Results 1028 parent carers, 26 young people, 352 health professionals and 202 school and social care staff registered to participate. Completed surveys were received from 579 (56.3%) parent carers, 20 (77%) young people, 193 (54.8%) health professionals, and 119 (58.9%) school and social care staff. Common parent carer-reported difficulties in using interventions to help their children and young people to learn to use the toilet included their child’s lack of understanding about what was required (reported by 337 of 556 (60.6%) parent carers who completed question) and their child’s lack of willingness (343 of 556, 61.7%). Almost all (142 of 156, 91%) health professionals reported lack of funding and resources as barriers to provision of continence services. Many young people (14 of 19, 74%) were unhappy using toilet facilities while out and about. Conclusions Perceptions that children lack understanding and willingness, and inadequate facilities impact the implementation of toileting interventions for children and young people with neurodisability. Greater understanding is needed for children to learn developmentally appropriate toileting skills. Further research is recommended around availability and acceptability of interventions to ensure quality of life is unaffected

Violent and victimized bodies: sexual violence policy in England and Wales

This paper uses the notion of the body to frame an archaeology of sexual violence policy in England and Wales, applying and developing Pillow’s ideas. It argues that the dominant construction is of sexual violence as an individualized crime, with the solution being for a survivor to report, and with support often instrumentalized in relation to criminal justice objectives. However, criminal justice proceedings can intensify or create further trauma for sexual violence survivors. Furthermore, in addition to criminalizing the violent body and supporting the victimized one, there is a need for policy to produce alternative types of bodies through preventative interventions. Much sexual violence is situated within (hetero) sexual dynamics constructing a masculine aggressor and a feminine body which eventually yields. Prevention must therefore focus on developing embodied boundaries, and narratives at the margins of policy could underpin such efforts

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

Beams of atoms and molecules are stalwart tools for spectroscopy and studies of collisional processes. The supersonic expansion technique can create cold beams of many species of atoms and molecules. However, the resulting beam is typically moving at a speed of 300-600 m/s in the lab frame, and for a large class of species has insufficient flux (i.e. brightness) for important applications. In contrast, buffer gas beams can be a superior method in many cases, producing cold and relatively slow molecules in the lab frame with high brightness and great versatility. There are basic differences between supersonic and buffer gas cooled beams regarding particular technological advantages and constraints. At present, it is clear that not all of the possible variations on the buffer gas method have been studied. In this review, we will present a survey of the current state of the art in buffer gas beams, and explore some of the possible future directions that these new methods might take