Can Self-Organizing Maps accurately predict photometric redshifts?

We present an unsupervised machine learning approach that can be employed for estimating photometric redshifts. The proposed method is based on a vector quantization approach called Self--Organizing Mapping (SOM). A variety of photometrically derived input values were utilized from the Sloan Digital Sky Survey's Main Galaxy Sample, Luminous Red Galaxy, and Quasar samples along with the PHAT0 data set from the PHoto-z Accuracy Testing project. Regression results obtained with this new approach were evaluated in terms of root mean square error (RMSE) to estimate the accuracy of the photometric redshift estimates. The results demonstrate competitive RMSE and outlier percentages when compared with several other popular approaches such as Artificial Neural Networks and Gaussian Process Regression. SOM RMSE--results (using $\Delta$z=z$_{phot}$--z$_{spec}$) for the Main Galaxy Sample are 0.023, for the Luminous Red Galaxy sample 0.027, Quasars are 0.418, and PHAT0 synthetic data are 0.022. The results demonstrate that there are non--unique solutions for estimating SOM RMSEs. Further research is needed in order to find more robust estimation techniques using SOMs, but the results herein are a positive indication of their capabilities when compared with other well-known methods.Comment: 5 pages, 3 figures, submitted to PAS

A Systematic Analysis of Supernova Light in Gamma-Ray Burst Afterglows

We systematically reanalyzed all Gamma-Ray Burst (GRB) afterglow data published through the end of 2002, in an attempt to detect the predicted supernova light component and to gain statistical insight on its phenomenological properties. We fit the observed photometric light curves as the sum of an afterglow, an underlying host galaxy, and a supernova component. The latter is modeled using published multi-color light curves of SN 1998bw as a template. The total sample of afterglows with established redshifts contains 21 bursts (GRB 970228 - GRB 021211). For nine of these GRBs a weak supernova excess (scaled to SN 1998bw) was found, what makes this to one of the first samples of high-z core collapse supernovae. Among this sample are all bursts with redshifts less than ~0.7. These results strongly support the notion that in fact all afterglows of long-duration GRBs contain light from an associated supernova. A statistics of the physical parameters of these GRB-supernovae shows that SN 1998bw was at the bright end of its class, while it was not special with respect to its light curve shape. Finally, we have searched for a potential correlation of the supernova luminosities with the properties of the corresponding bursts and optical afterglows, but we have not found such a relation.Comment: 25 pages, 7 figures, accepted by ApJ; revised, shortened and updated compared to version 1; Title slightly changed; all figures showing individual afterglow light curves removed, as advised by the referee; conclusions unchange

JCMmode: An Adaptive Finite Element Solver for the Computation of Leaky Modes

We present our simulation tool JCMmode for calculating propagating modes of an optical waveguide. As ansatz functions we use higher order, vectorial elements (Nedelec elements, edge elements). Further we construct transparent boundary conditions to deal with leaky modes even for problems with inhomogeneous exterior domains as for integrated hollow core Arrow waveguides. We have implemented an error estimator which steers the adaptive mesh refinement. This allows the precise computation of singularities near the metal's corner of a Plasmon-Polariton waveguide even for irregular shaped metal films on a standard personal computer.Comment: 11 page

The flying fox manual: A new handbook for wildlife carers in Australia

This long-awaited first edition of the ‘flying fox manual’ would certainly have, had it appeared any earlier, created turmoil and debate among both wildlife carers and ecologists in Australia and beyond. Beliefs, myths and own recipes passed on from carer generation to carer generation still dominate flying fox care throughout the continent, where thousands of animals are taken into temporary or permanent care every year. This includes all age classes from orphaned young over injured adults to animals for experimental studies. Through a combination of scientific insight and practical experience, however, the author convincingly takes a long overdue stand against outdated methods and convincingly argues for a release-oriented, wildlife-focussed approach in flying fox care. Extensive research, cooperation with many contributors from all fields of natural sciences and careful review of all aspects of Megachiroptera in care has led to a volume which is capable of finally filling a wide-open gap in available literature, meeting a pressing need amongst volunteer as well as professional carers for accurate and up-to-date information

Evaluating behavioral intention to increase classroom Geotechnology usage following geoinquiry implementation

As educational practices include foundational and cutting-edge preparation, the value of problem-based instruction employing industry-standard technologies increases. Geospatial technologies (GST), are a group of professional technologies, including GIS (Geographic Information Systems), used by industries to make informed decisions with spatial data. This study investigated educator behavioral intention to use GIS/GST in classroom practice, and the moderating effect, if any, of the GeoInquiry, a curricular resource. The UTAUT framework was employed to evaluate and quantify the factors impacting behavioral intention (performance expectancy, effort expectancy, social influence, and facilitating conditions). These data were examined to identify moderation by GeoInquiry usage. One hundred and two surveys were completed by educators in 27 states. The survey results indicate a moderate statistically significant relationship between each of the factors and behavioral intention. An increase in any factor will increase behavioral intention. The mean response increased for the group that used GeoInquiries in classroom instruction, indicating correlation between each factor and GeoInquiry usage. Statistically significant differences related to using GeoInquiries in classroom instruction were identified for effort expectancy, facilitating conditions, and behavioral intention. Similar results related to the degree of GeoInquiry usage were not found. Implications include professional development for both educators and administrators, the continued development of curricular resources, and an alignment of both professional development and curricular resources to high yield instructional strategies, standards, and student engagement. Recommendations for future research include expanding the number of survey respondents, modifying items, conducting structured interviews, social network analysis, and developing curricular resources, which could impact student learning with digital mapping technology

The prompt optical/near-infrared flare of GRB 050904: the most luminous transient ever detected

With a redshift of z=6.295, GRB 050904 is the most distant gamma-ray burst ever discovered. It was an energetic event at all wavelengths and the afterglow was observed in detail in the near-infrared bands. We gathered all available optical and NIR afterglow photometry of this GRB to construct a composite NIR light curve spanning several decades in time and flux density. Transforming the NIR light curve into the optical, we find that the afterglow of GRB 050904 was more luminous at early times than any other GRB afterglow in the pre-\emph{Swift} era, making it at these wavelengths the most luminous transient ever detected. Given the intrinsic properties of GRB 050904 and its afterglow, we discuss if this burst is markedly different from other GRBs at lower redshifts.Comment: The Astronomical Journal, in press; revised version, including the comments of the referee (one figure added, text restructured, all conclusions unchanged), 7 pages, 3 figure