Monday, February 22, 2010

SciAm asks "Does the U.S. Produce Too Many Scientists?"

Does the U.S. Produce Too Many Scientists?

American science education lags behind that of many other nations, right? So why does it produce so many talented young researchers who cannot find a job in their chosen field of study?

Headline of a lengthy online article at Scientific American.

I've reproduced my comment (slightly edited to fix some minor grammatical errors) below:
A poor title for the article. A better one would be "Are there enough scientific careers for scientists in the US?"

Within astrophysics there certainly is a massive demographic imbalance between the number of talented and committed PhD students continuing in academia as postdocs and soft-money researchers, and the number of tenured and tenure-equivalent jobs. Everyone knows this, at least when they're doing the PhD. They just make the mistake of thinking that if they're talented and love research that they'll get the job they're qualified for.

The problem is not that there is a career pyramid with significant losses of personal at each level compared to the old days of a few postdoc positions that fed directly into a similar number of tenured positions.

The problems are that (a) progression or success is more lottery than meritocracy (for a number of annoying reasons, but shear numbers of job candidates is one), and (b) there is no real career track for those who aren't lucky enough to land a classic tenure-track job.

University administrations and tenured faculty have little inclination to change this: the postdocs do much of the research, and are expendable as they're easily replaceable (by similarly talented and eager applicants). Soft money scientists bring in large amounts of overhead to the Universities, and even if many leave when their patience or grants run out their ranks are always easily filled by former postdocs desperate to carry on doing what they love.
And that "dskan" commenter - what alternate Universe did they come from?

Friday, February 19, 2010

Interesting Astrophysics: Feb 01 to Feb 19, 2010

I have no time to provide commentary, so without further interruption here are the papers and preprints that I consider interesting that have appeared over the period Feb 01-19, 2010.

Galaxies and Starbursts

The AGN properties of the starburst galaxy NGC 7582
T.V. Ricci, J.E. Steiner, R.B. Menezes, A. Garcia-Rissmann, R. Cid Fernandes, arXiv:1001.5269 [ps, pdf, other]
Comments: 1 page, 2 figures, to be published in the Proceedings of the IAU Symposium no. 267

The stellar populations of the AGN/Starburst galaxy NGC7582
T.V. Ricci, J.E. Steiner, R.B. Menezes, A. Garcia-Rissmann, R. Cid Fernandes, arXiv:1001.5271 [ps, pdf, other]
Comments: 2 pages, 2 figures, to be published in the Proceedings of the IAU Symposium no. 262

Their abstract: "NGC 7582 is defined as a Starburst/AGN galaxy, since its optical and X-Ray spectra reveal both characteristics. In this work, we show the results of a stellar population modeling in a datacube taken with the Gemini South telescope. We found that $\sim$ 90% of the light in the field of view is emitted by stars that are less than 1 billion years old. A strong burst occurred about $\sim$ 6 million years ago and has nearly solar metallicity. We also found a Wolf-Rayet cluster."

Star Formation in the Outer Filaments of NGC 1275
R.E.A. Canning, A.C. Fabian, R.M. Johnstone, J.S. Sanders, C.J. Conselice, C.S. Crawford, J.S. Gallagher III, E. Zweibel, arXiv:1002.1056 [pdf, ps, other]
Comments: Accepted for publication in MNRAS, 14 pages, 14 figures, 3 tables

A panoramic view of the Milky Way analogue NGC 891
M. Mouhcine, R. Ibata, M. Rejkuba, arXiv:1002.0461 [pdf, ps, other]
Comments: 2 figures, Apj Letter, in press

A panoramic view of M81: New stellar systems in the debris field
M. Mouhcine, R. Ibata, arXiv:1002.0456 [pdf, ps, other]
Comments: 8 pages, MNRAS

Evidence of Early Enrichment of the Galactic Disk by Large-Scale Winds
T. Tsujimoto, J. Bland-Hawthorn, K.C. Freeman, arXiv:1002.3181 [pdf, ps, other]
Comments: 9 pages including 5 figures, accepted for publication in PASJ

Starburst evolution: free-free absorption in the radio spectra of luminous IRAS galaxies
M. S. Clemens, A. Scaife, O. Vega, A. Bressan, arXiv:1002.3334 [pdf, ps, other]
Comments: 13 pages, 5 figures, accepted by MNRAS

Metal-line emission from the warm-hot intergalactic medium: II. Ultraviolet
Serena Bertone, Joop Schaye, C.M. Booth, Claudio Dalla Vecchia, Tom Theuns, Robert P.C. Wiersma, arXiv:1002.3393 [pdf, ps, other]
Comments: 21 pages, 22 figures. Submitted to MNRAS

Their abstract: "Approximately half the baryons in the local Universe are thought to reside in the warm-hot intergalactic medium (WHIM). Emission lines from metals in the UV band are excellent tracers of the cooler fraction of this gas. We present predictions for the surface brightness of a sample of UV lines that could potentially be observed by the next generation of UV telescopes at z<1. We use a subset of simulations from the OWLS project to create emission maps and to investigate the effect of varying the physical prescriptions for star formation, supernova and AGN feedback, chemodynamics and radiative cooling. Most models produce results in agreement within a factor of a few, indicating that the predictions are robust. Of the lines we consider, C III is the strongest line, but it typically traces gas colder than 10^5 K. The same is true for Si IV. The second strongest line, C IV, traces circum-galactic gas with T~10^5 K. O VI and Ne VIII probe the warmer (T~10^5.5 K and T~10^6 K, respectively) and more diffuse gas that may be a better tracer of the large scale structure. N V emission is intermediate between C IV and O VI. The intensity of all emission lines increases strongly with gas density and metallicity, and for the bright emission it is tightly correlated with the temperature for which the line emissivity is highest. In particular, the C III, C IV, Si IV and O VI emission that is sufficiently bright to be potentially detectable in the near future (>10^3 photon/s/cm^2/sr), comes from relatively dense (rho>10^2 rho_mean) and metal rich (Z>0.1 Z_sun) gas. As such, emission lines are highly biased tracers of the missing baryons and are not an optimal tool to close the baryon budget. However, they do provide a powerful means to detect the gas cooling onto or flowing out of galaxies and groups. (Abridged)"

Black Holes and AGN

Timing the starburst-AGN connection
Vivienne Wild, Timothy Heckman, Stephane Charlot, arXiv:1002.3156 [pdf, ps, other]
Comments: 16 pages, 12 figures, accepted for publication in MNRAS

Interstellar Medium

Metal-Ion Absorption in Conductively Evaporating Clouds
Orly Gnat, Amiel Sternberg, Christopher F. McKee, arXiv:1002.1309 [pdf, ps, other]
Comments: Submitted to ApJ

ITERA: IDL Tool for Emission-line Ratio Analysis
Brent Groves, Mark Allen, arXiv:1002.3372 [pdf, ps, other]
Comments: Accepted for New Astronomy, 3 figures. ITERA tool available to download from this http URL

Stars, Supernove and Planets

The Birth Environment of the Solar System
Fred C. Adams, arXiv:1001.5444 [ps, pdf, other]
Comments: 58 pages including 7 figures, to appear in Annual Reviews of Astronomy and Astrophysics (2010, Vol. 48)

Absract in full: "This paper reviews our current understanding of the possible birth environments of our Solar System. Since most stars form within groups and clusters, the question becomes one of determining the nature of the birth aggregate of the Sun. This discussion starts by reviewing Solar System properties that provide constraints on our environmental history. We then outline the range of star-forming environments that are available in the Galaxy, and discuss how they affect star and planet formation. The nature of the solar birth cluster is constrained by many physical considerations, including radiation fields provided by the background environment, dynamical scattering interactions, and by the necessity of producing the short-lived radioactive nuclear species inferred from meteoritic measurements. Working scenarios for the solar birth aggregate can be constructed, as discussed herein, although significant uncertainties remain."

A scenario of planet erosion by coronal radiation
J. Sanz-Forcada, I. Ribas, G. Micela, A. M. T. Pollock, D. Garcia-Alvarez, E. Solano, C. Eiroa, arXiv:1002.1875 [pdf, ps, other]
Comments: Accepted by A&A Letters (8 Feb. 2010). 4 pages, 3 figures, 1 online table (included)

On the Disruption of Star Clusters in a Hierarchical Interstellar Medium
Bruce G. Elmegreen, Deidre A. Hunter, arXiv:1002.2823 [pdf, ps, other]
Comments: ApJ vol. 712, March 20, 2010, 33 pages 15 figures

Do Wolf-Rayet stars have similar locations in hosts as type Ib/c supernovae and long gamma-ray bursts?
G. Leloudas, J. Sollerman, A. J. Levan, J. P. U. Fynbo, D. Malesani, J. R. Maund, arXiv:1002.3164 [pdf, ps, other]
Comments: Under review in A&amp;A. The present version includes suggestions from the referee

Wednesday, February 17, 2010

Monday, February 01, 2010

You can't trust grades, and can't trust letters of recommendation, so what can you trust?

There is an hidden disadvantage for students here. A-B-C-D-F grades have become nearly useless as entry gauges for many professions (the article emphasizes nursing and education). That means that employers have to lean more and more on other indicators. Letters of recommendation are more inflated than grades, so they don't help. That brings us to tangible things like internships, standardized test scores, and interviews.

Oh and intangibles. Like nepotism.

From John Hawk's paleoanthropology weblog, discussing grade inflation.

Personally this paragraph hits home for two reasons:
  1. Having both written and read Astronomy job-related letters of recommendation I certainly think there is a huge variance in their accuracy and honesty, yet they seem to be given greater weight than objective publication records and citation counts. Possibly a majority are semi-accurate, but there is a sizable minority that are hyped out of all resemblance to reality (some I have read you might are laughable or must be jokes, except the joke is on the rest of us when those candidates get the nice jobs). The sad fact of the matter is that given that the number of higher level astro jobs available is always smaller than the number of qualified applicants such inflated letters of recommendation do often appear to work... at least in the cases where I have read seemingly hyped letters of recommendation for a candidate, and later investigate their papers and follow their career progression.
  2. Having just had to look into what my high school grades were for the first time in almost twenty years I was very annoyed to also find that GCSE's and A-levels (this was the UK) have suffered monotonic grade inflation for approximately the last 30 years. What were pretty damn good grades for the time now seem average. And its not just that schools are better at teaching to slowly varying exams (or that students are smarter - hah!)... they're now giving out C grades in GCSE science if get only 18% of the questions right and A* grades if you get 51%.
[GPA grade inflation graph from Harold Marcuse (UC Santa Barbara)]