Astronomy Department
University of California, Berkeley
University of California

J. Berian James Brahe Fellow

Astronomy Department
B-20 Hearst Field Annex
Berkeley, CA 94720-3411

Tel: +1 (510) 642-5275
Fax: +1 (510) 642-3411
The author's email address

I am a cosmologist. Presently, I hold the Sophie and Tycho Brahe Fellowship in Astrophysics jointly between the University of California at Berkeley and the Dark Cosmology Centre at the University of Copenhagen.

My research is in the fields of observational and theoretical cosmology; particularly, statistics of large-scale structure, galaxy formation and evolution, type Ia supernovae and the foundations of relativistic cosmology. My curriculum vitae is available online and upon request in digital hard-copy.

News & Recent Publications

30 May Scrimgeour et al. (2012), MNRAS, in press
Work led by Morag Scrimgeour for the WiggleZ collaboration on the homogeneity scale of structure in the Universe as traced by the galaxy distribution has been acceepted for publication. I was delighted to help with the framing of these results as a probabilistic statement about the scale of homogeneity. Congratulations to Morag, Tam, Chris and the WiggleZ team for such rigorous coverage of a far-reaching (no pun intended; your mileage may vary) topic!
29 May Congratulations are in order for Kristoffer Stensbo-Smidt, who successfully defended his Masters thesis, titled Ranking and decomposing the Universe: investigating the non-linear regime of structure formation. Kristoffer defended some very original and impressive conclusions with characteristic flair, and handled tough and exacting questions from the examiners.
26 May - 2 June I am in Copenhagen this week, working at the Dark Cosmology Centre. The proximate cause of this visit is the thesis examination of Kristoffer Stensbo-Smidt, for which Fergus Simpson has kindly agreed to act as external examiner ('censor' in the Danish, though I have instructed him that only very mild censorship will be allowed).
7 - 11 May Our machine-learning workshop 'From Data to Knowledge' is kicking off today! I am chairing the morning session on 'Time-series clustering and classification'. You can follow the progress of the meeting on Twitter with the #berkeleystreaming hashtag.
4 May J. B. James (2012), ApJ 751 40
My paper 'Physics of non-Gaussian fields and the cosmological genus statistic' has been published in ApJ and I have posted the journal version to the arxiv. I'm very grateful to the referee, who provided a very thorough and very helpful set of suggestions. Many thanks also to Chris Blake and Alan Heavens for their close reading of the text.
16 Apr I am lecturing today's AY250 graduate course at Berkeley, on Bayesian Inference for Python. A recording of the slides and audio is available online (see Lecture 11).
7 - 8 Mar I am helping out with the iPython tutorial at PyCon—the iPython notebook is a huge advance for scientific development; everyone should use it. I am also catching up on the latest developments in pandas and in High Performance Python.
14 Feb This term, we are running the AY250 graduate course on Python Computing for Science. Webcasts of the lectures are available here. This week, Stefan van der Walt, Joey Richards and I are teaching scikits.image, scikit-learn and scikits.statsmodels—all very important packages!
13 Jan - 9 Feb Chris Blake (Swinburne) is visiting to collaborate on analysis of the WiggleZ galaxy redshift survey. We are inventing new methods to correct statistics drawn from large galaxy data sets for noise and incompletely understood selection effects! Chris is delivering a seminar about WiggleZ in the UC Berkeley Astronomy Department on 24 January.
13 - 22 Jan Fergus Simpson (Edinburgh) is visiting us at UC Berkeley and LBL to work on projects extedning our recent PRL paper on 'clipping the cosmos'. Fergus is talking about our work in the Physics Department at UCB on Jan 17.
13 - 15 Jan I am lecturing at the Python Bootcamp that we are running at UC Berkeley. This will be a fantastic, intense, deep introduction to working with Python for science. I am lecturing on SciPy and Scientific Programming in Python generally: my lecture slides and iPython notebooks for this course can be found here.
4 - 6 Jan I am attending a BOSS collaboration meeting at NYU.
19 Dec I am working at the Dark Cosmology Centre in Copenhagen from the 19th to the 23rd of December.
1 -3 Dec We are hosting David Marsh in the UC Berkeley Astronomy Department, and at LBL. Doddy works on some great topics in theoretical cosmology and has done some really interesting work extending transfer function formalism to axions.
8 Nov J. B. James (2011), ApJ, submitted
I have submitted my paper 'Physics of non-Gaussian fields and the cosmological genus statistic' to the Astrophysical Journal and placed it on the arXiv. This paper develops a method to pick apart all the different sources of non-gaussianity that can appear in genus measurements from galaxy redshift surveys. Naturally, comments are very welcome at this point!
8 Oct We are attending the Workshop on Statistical Methods for Astronomy and Astrophysics at UC Davis. (This was a great meeting for interaction between the astronomy and statistical communities, so a big thanks to the organisers, Paul Baines and Ethan Anderes.)
7 Oct Richards et al. (2011), ApJ, in press
Joey Richards tells me that our paper on active learning for lightcurve classification has been accepted for publication in the Astrophysical Journal.
19 Sep A. Bodaghee, J. Tomsick, J. Rodriguez & J.B. James (2011), ApJ, in press
Arash Bodaghee has posted to the arΧiv our paper on the clustering between high-mass X-ray binaries and OB associations in the Milky Way, which has now been accepted for publication in the Astrophysical Journal.
14 - 16 Sep I am attending the BigBOSS collaboration meeting in Tucson, AZ this week.
1 SepI have moved to the Astronomy Department at UC Berkeley as a postdoctoral researcher.
8 - 12 Aug We are hosting the 2011 DARK summer workshop, 'DEUS: Current and future challenges of the Dark and Early Universes'. Update: This workshop was a huge success—thanks to all the participants for their lively contributions.
2 - 4 AugBrahe astroinformatics workshop: This week at DARK we are hosting a number of talks on time-domain science, in association with our visitors from Berkeley. Further details are available here.
1 - 21 Aug Dovi Poznanski, Adam Miller and Dan Perley, of the Astronomy Department at UC Berkeley, are visiting DARK for several weeks during the summer, as part of the Brahe programme exchange between DARK and Berkeley.
26 JulF. Simpson, J.B. James, A.F. Heavens & C. Heymans (2011), submitted to PRL
Fergus Simpson has submitted our paper on 'Clipping the Cosmos', a technique to extend bispectrum estimation across scales well inside the non-linear regime.
18 - 22 JulI am working at UC Berkeley and LBNL this week.
11 - 15 JulThis week I am attending a WiggleZ cosmology team workshop, to discuss progress is publication of the WiggleZ cosmology papers.
4 - 8 JulI am working with Geraint Lewis and the Gravitational Astrophysics group at the University of Sydney.
27 Jun - 1 JulI am working at the Centre for Astrophysics and Supercomputing Swinburne University in Melbourne, Australia, with Chris Blake, Greg Poole and the WiggleZ team, on large-scale structure analysis of WiggleZ survey data.
17 JuneCongratulations to Morten Holm Christensen, who received the highest grade for his Bachelor project disseration on 'The Metric Equivalence Problem in General Relativity'. Well done Morten, and thanks to Alan Heavens for acting as the external examiner of this work.
13 - 17 JuneI am at the Statistical Challenges in Modern Astrophysics meeting at the Pennsylvania State University.
7 - 9 JuneThe Niels Bohr Institute is hosting a three-day workshop on cosmology and astro-particle physics from the LHC and Planck.
23 - 24 MayThe Dark Cosmology Centre and Space Science Centre are hosting a Euclid start-up meeting to discuss Scandinavian involvement in this important future mission! Further information is available here.
3 MayAllevato et al. (2011), ApJ, in press
Viola Allevato has published our work on clusters and AGN in the COSMOS field. These results extend measurement of the redshift evolution of AGN bias up to redshift 2. Congratulations to Viola & Alexis!
10 Apr Morten Holm Christensen has started his Bachelorprojekt at DARK, on the topic of metric equivalence of spacetimes. Welcome Morten!
11 Feb Kristoffer Stensbo-Smidt has joined DARK as a Masters student. He will be working on the evolution of large-scale structure in non-Gaussian cosmologies. Welcome Kristoffer!
5 Feb - 9 Apr Henrik Brink and I are working with Josh Bloom in the Astronomy Department at UC Berkeley and at Lawrence Berkeley National Lab.
4 Feb Christopher Heje Grønbech, Edin Ikanovic and Joachim Mortensen have passed their Bachelorprojeckt examination, based on the dissertation 'Ranking the Universe'. Congratulations!
17 - 26 Jan I am based in School of Physics at the University of Sydney, working with Geraint Lewis and the Gravitational Astrophysics group.
10 - 15 Jan I am working with Chris Blake at the Centre for Astrophysics and Supercomputing in Swinburne, Australia on the cosmological analysis of the WiggleZ galaxy redshift survey.