The Molecular Gas Distribution and Schmidt Law in M33

The relationship between the star formation rate and surface density of neutral gas within the disk of M33 is examined with new imaging observations of CO J=1-0 emission gathered with the FCRAO 14m telescope and IRAS HiRes images of the 60 micron and 100 micron emission. The Schmidt law, Sigma_SFR ~ Sigma_gas^n, is constructed using radial profiles of the HI 21cm, CO, and far infrared emission. A strong correlation is identified between the star formation rate and molecular gas surface density. This suggests that the condensation of giant molecular clouds is the limiting step to star formation within the M33 disk. The corresponding molecular Schmidt index, n_{mol}, is 1.36 +/- 0.08. The star formation rate has a steep dependence on total mass gas surface density, (Sigma_{HI}+Sigma_{H_2}), owing to the shallow radial profile of the atomic gas which dominates the total gas surface density for most radii. The disk pressure of the gas is shown to play a prominent role in regulating the molecular gas fraction in M33.Comment: 19 pages + 5 figures. Accepted for publication in Ap

Bibliography of the frogs of the Leptodactylus clade - Adenomera, Hydrolaetare, Leptodactylus, Lithodytes (Ampbibia, Anura, Leptodactylidae). Volume 1. References

In the funded proposal to NSF, RdS and WRH included a project to create an electronic database for all publications containing mention of species names for Adenomera, Leptodactylus, and Vanzolinius (Vanzolinius has since been synonymized with Leptodactylus). At the beginning of the project, there were about 2,000 references on 3x5 cards. Miriam H. Heyer (MHH) was contracted to create the EndNote® file. MHH entered all citations into EndNote® and examined the literature citations in those publications to determine whether any of them contained information on the genera of interest. WRH anticipated that the intensive bibliography would yield a total of 3,000 references for the genera involved. That estimate was too modest – at the end of the NSF funding for the project, 31 May 2008, we had located more than 5,000 citations. The EndNote® file of 31 May 2008 is the basis for this bibliography. About halfway through the project, the Frost et al. publication (2006) appeared. We made two decisions based on this significant work: 1) We included citations for the genera Hydrolaetare and Lithodytes. The evidence provided by Frost et al. 2006 is compelling that Adenomera, Hydrolaetare, Leptodactylus, and Lithodytes form a robust clade. 2) The relationships of Lithodytes and Adenomera as sister taxa and both genera being the sister clade to Leptodactylus has been confirmed in other primarily molecular studies. The relationships involved thus appear to be robust. We differ philosophically, not on the basis of data, with the conclusion of Frost et al. 2006 to combine Adenomera, Leptodactylus, and Lithodytes into a single genus, Leptodactylus and recognize the subgenus Lithodytes for the clade Adenomera + Lithodytes. This topic will be pursued in a future publication involving RdS, WRH, and others

BIBLIOGRAPHY OF THE FROGS OF THE LEPTODACTYLUS CLADE – ADENOMERA, HYDROLAETARE, LEPTODACTYLUS, LITHODYTES (AMPHIBIA, ANURA, LEPTODACTYLIDAE) VOLUME 2. INDICES

The bibliography (Volume 1) is organized alphabetically by last name of the first author. The Species Index, Keyword Index, and Geographic Index are organized by the unique number that EndNote® assigns to each record. To find a reference from the three indices, one must utilize the References by EndNote® Number, listed in numerical order. There is sufficient information associated with the EndNote® numerical order entry to find the specific reference involved in Volume 1 – References. Complete authors names are used in the EndNote® Number index for the EndNote® records that contain such information. Note that there are some “missing” record numbers – these represent duplicate records, one of which was deleted from the EndNote® file. Currently recognized species in the Species Index are indicated by bold font. Other species names are synonyms or nomina nuda. The Keyword Index lists terms from the Keyword section of each citation in Volume I. The Geographic Index lists countries and/or geographic regions that are taken from the Keyword sections in Volume I

CO Abundance Variations in the Orion Molecular Cloud

Infrared stellar photometry from 2MASS and spectral line imaging observations of 12CO and 13CO J = 1-0 line emission from the FCRAO 14m telescope are analysed to assess the variation of the CO abundance with physical conditions throughout the Orion A and Orion B molecular clouds. Three distinct Av regimes are identified in which the ratio between the 13CO column density and visual extinction changes corresponding to the photon dominated envelope, the strongly self-shielded interior, and the cold, dense volumes of the clouds. Within the strongly self-shielded interior of the Orion A cloud, the 13CO abundance varies by 100% with a peak value located near regions of enhanced star formation activity. The effect of CO depletion onto the ice mantles of dust grains is limited to regions with AV > 10 mag and gas temperatures less than 20 K as predicted by chemical models that consider thermal-evaporation to desorb molecules from grain surfaces. Values of the molecular mass of each cloud are independently derived from the distributions of Av and 13CO column densities with a constant 13CO-to-H2 abundance over various extinction ranges. Within the strongly self-shielded interior of the cloud (Av > 3 mag), 13CO provides a reliable tracer of H2 mass with the exception of the cold, dense volumes where depletion is important. However, owing to its reduced abundance, 13CO does not trace the H2 mass that resides in the extended cloud envelope, which comprises 40-50% of the molecular mass of each cloud. The implied CO luminosity to mass ratios, M/L_{CO}, are 3.2 and 2.9 for Orion A and Orion B respectively, which are comparable to the value (2.9), derived from gamma-ray observations of the Orion region. Our results emphasize the need to consider local conditions when applying CO observations to derive H2 column densities.Comment: Accepted for publication in MNRAS. 21 pages, 14 figure

Tpr1, a Schizosaccharomyces pombe protein involved in potassium transport

AbstractThe Schizosaccharomyces pombe Tpr1 was isolated as suppressor of the Saccharomyces cerevisiae Δ trk1,2 potassium uptake deficient phenotype. Tpr1, for tetratrico peptide repeat, encodes a 1039 amino acid residues protein with several reiterated TPR units displaying significant homology to p150TSP, a recently identified phosphoprotein of mouse, to S. cerevisiae CTR9 and to related sequences of human, Caenorhabditis elegans, Methanoccocus jannaschii and Arabidopsis thaliana. Expression of Tpr1 restored growth on 0.2 mM K+ media, induced K+ transport with a KT of 4.6 mM and resumed inward currents of −90 pÅ at −250 mV (pH 7.2) conducting K+ and other alkali-metal ions. The tetratrico peptide repeat is a degenerate motif of 34 amino acids that is repeated several times within TPR-containing proteins and has been suggested to mediate protein-protein interactions. The sequence and putative binding properties of Tpr1 suggest the protein unlikely as transporter but involved in the enhancement of K+ uptake via conventional carriers

Turbulent Driving Scales in Molecular Clouds

Supersonic turbulence in molecular clouds is a dominant agent that strongly affects the clouds' evolution and star formation activity. Turbulence may be initiated and maintained by a number of processes, acting at a wide range of physical scales. By examining the dynamical state of molecular clouds, it is possible to assess the primary candidates for how the turbulent energy is injected. The aim of this paper is to constrain the scales at which turbulence is driven in the molecular interstellar medium, by comparing simulated molecular spectral line observations of numerical magnetohydrodynamic (MHD) models and molecular spectral line observations of real molecular clouds. We use principal component analysis, applied to both models and observational data, to extract a quantitative measure of the driving scale of turbulence. We find that only models driven at large scales (comparable to, or exceeding, the size of the cloud) are consistent with observations. This result applies also to clouds with little or no internal star formation activity. Astrophysical processes acting on large scales, including supernova-driven turbulence, magnetorotational instability, or spiral shock forcing, are viable candidates for the generation and maintenance of molecular cloud turbulence. Small scale driving by sources internal to molecular clouds, such as outflows, can be important on small scales, but cannot replicate the observed large-scale velocity fluctuations in the molecular interstellar medium.Comment: 8 pages, 7 figures, accepted for publication in A&