Three-dimensional extinction mapping using Gaussian random fields

We present a scheme for using stellar catalogues to map the three-dimensional distributions of extinction and dust within our Galaxy. Extinction is modelled as a Gaussian random field, whose covariance function is set by a simple physical model of the ISM that assumes a Kolmogorov-like power spectrum of turbulent fluctuations. As extinction is modelled as a random field, the spatial resolution of the resulting maps is set naturally by the data available; there is no need to impose any spatial binning. We verify the validity of our scheme by testing it on simulated extinction fields and show that its precision is significantly improved over previous dust-mapping efforts. The approach we describe here can make use of any photometric, spectroscopic or astrometric data; it is not limited to any particular survey. Consequently, it can be applied to a wide range of data from both existing and future surveys.Comment: 16 pages, 12 figures. Submitted for publication in MNRAS. Text revise

Flagellar Radial Spoke Protein 2 Is a Calmodulin Binding Protein Required for Motility in \u3cem\u3eChlamydomonas reinhardtii\u3c/em\u3e

Genetic and morphological studies have revealed that the radial spokes regulate ciliary and flagellar bending. Functional and biochemical analysis and the discovery of calmodulin in the radial spokes suggest that the regulatory mechanism involves control of axonemal protein phosphorylation and calcium binding to spoke proteins. To identify potential regulatory proteins in the radial spoke, in-gel kinase assays were performed on isolated axonemes and radial spoke fractions. The results indicated that radial spoke protein 2 (RSP2) can bind ATP and transfer phosphate in vitro. RSP2 was cloned and mapped to the PF24 locus, a gene required for motility. Sequencing revealed that pf24 contains a point mutation converting the first ATG to ATA, resulting in only trace amounts of RSP2 and confirming the RSP2 mapping. Surprisingly, the sequence does not include signature domains for conventional kinases, indicating that RSP2 may not perform as a protein kinase in vivo. However, the predicted RSP2 protein sequence contains Ca2+-dependent calmodulin binding motifs and a GAF domain, a domain found in diverse signaling proteins for binding small ligands including cyclic nucleotides. As predicted from the sequence, recombinant RSP2 binds calmodulin in a calcium-dependent manner. We postulate that RSP2 is a regulatory subunit of the radial spoke involved in localization of calmodulin for control of motility

Personality characteristics related to volunteering, pseudovolunteering and non-volunteering for different kinds of psychological experiments

Volunteer subjects are utilized in a large portion of experiments concerned with human behavior. Yet the use of volunteers is a form of systematic sampling bias which may well distort research findings. This study was undertaken to explore some of the factors related to volunteering for psychological experiments at Richmond College in the hope of providing future researchers with insight into reasons why the use of volunteer subjects may bias their research results and of stimulating them to use more representative, albeit less convenient sampling procedures

On the Word ντηρδες in Thucydides VII. 36, 2

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Marginal likelihoods of distances and extinctions to stars: computation and compact representation

We present a method for obtaining the likelihood function of distance and extinction to a star given its photometry. The other properties of the star (its mass, age, metallicity and so on) are marginalised assuming a simple Galaxy model. We demonstrate that the resulting marginalised likelihood function can be described faithfully and compactly using a Gaussian mixture model. For dust mapping applications we strongly advocate using monochromatic over bandpass extinctions, and provide tables for converting from the former to the latter for different stellar types.Comment: 14 pages, 12 figures. Accepted for publication in MNRAS. Source code is available at https://github.com/stuartsal