The EXPLORE Project I: A Deep Search for Transiting Extrasolar Planets

(Abridged) We discuss the design considerations of the EXPLORE (EXtra-solar PLanet Occultation REsearch) project, a series of transiting planet searches using 4-m-class telescopes to continuously monitor a single field of stars in the Galactic Plane in each ~2 week observing campaign. We discuss the general factors which determine the efficiency and the number of planets found by a transit search, including time sampling strategy and field selection. The primary goal is to select the most promising planet candidates for radial velocity follow-up observations. We show that with very high photometric precision light curves that have frequent time sampling and at least two detected transits, it is possible to uniquely solve for the main parameters of the eclipsing system (including planet radius) based on several important assumptions about the central star. Together with a measured spectral type for the star, this unique solution for orbital parameters provides a powerful method for ruling out most contaminants to transiting planet candidates. For the EXPLORE project, radial velocity follow-up observations for companion mass determination of the best candidates are done on 8-m-class telescopes within two or three months of the photometric campaigns. This same-season follow-up is made possible by the use of efficient pipelines to produce high quality light curves within weeks of the observations. We conclude by presenting early results from our first search, EXPLORE I, in which we reached <1% rms photometric precision (measured over a full night) on ~37,000 stars to I <= 18.2.Comment: accepted by ApJ. Main points unchanged but more thorough discussion of some issues. 36 pages, including 14 figure

A circumnuclear disk of atomic hydrogen in Centaurus A

We present new observations, performed with the Australia Telescope Compact Array, of the HI absorption in the central regions of Centaurus A. For the first time, absorption is detected against the radio core at velocities blueshifted with respect to the systemic velocity. Moreover, the data show that the nuclear redshifted absorption component is broader than reported before. With these new results, the kinematics of the HI in the inner regions of Cen A appears very similar to that observed in emission for the molecular circumnuclear disk. This suggests that the central HI absorption is not, as was previously claimed, evidence of gas infall into the AGN, but instead is due to a cold, circumnuclear disk.Comment: Accepted for publication in A&A Letter, 4 pages, 2 figure

Ornamental plants, 1985: a summary of research

Field transplant survival of Amelanchier liners produced by tissue culture / Daniel K. Struve and R. Daniel Lineberger -- An evaluation of strawdust - an alternative growing media / Elton M. Smith and Sharon A. Treaster -- Growth of container grown nursery stock produced in composted municipal sludge amended media / Elton M. Smith and Sharon A. Treaster -- Soil temperature effects on root regeneration of scarlet oak seedlings / Daniel K. Struve arid Bruno C. Moser -- Lighting Viburnum opulus 'Nanum' cuttings to increase winter survival / Elton M. Smith and Sharon A. Treaster -- Treatments of etiolated dormant rose shoots / Elton M. Smith and Sharon A. Treaster -- Evaluation of flowering crabapple susceptibility to apple scab in Ohio – 1984 / Elton M. Smith and Sharon A. Treaster -- Tolerance of azalea, cotoneaster, and euonymus to Devrinol, Goal, and Goal Combinations / Elton M. Smith and Sharon A. Treaster -- Micropropagation of chimeral african violets / R. Daniel Lineberger and Mark Druckenbrod -- capital requirements of overwintering structures for nurseries in Ohio - 1984 / Reed D. Taylor, Daryl T. Gillette, and Elton M. Smith -- annual fixed costs of overwintering plants in nurseries differentiated by type of structure for Ohio - 1984 / Daryl T. Gillette, Reed D. Taylor, and Elton M. Smith -- Comparative costs of overwintering plants in nurseries differentiated by system for Ohio - 1984 / Reed D. Taylor, Daryl T. Gillette, and Elton M. Smit

New Observations and Analysis of the Bright Semi-Detached Eclipsing Binary mu1 Sco

Using new and published photometric observations of mu1 Sco (HR 6247), spanning 70 years, a period of 1.4462700(5) days was determined. It was found that the epoch of primary minimum suggested by Shobbrook at HJD 2449534.178 requires an adjustment to HJD 2449534.17700(9) to align all the available photometric datasets. Using the resulting combined-data light-curve, radial velocities derived from IUE data and the modelling software PHOEBE, a new system solution for this binary was obtained. It appears that the secondary is close to, or just filling, its Roche-lobe.Comment: 4 figures, 6 tables, 9 pages, uses mn2e.sty, to be published in MNRA

The neodymium isotope fingerprint of Adélie coast bottom water

Adélie Land Bottom Water (ALBW), a variety of Antarctic Bottom Water formed off the Adélie Land coast of East Antarctica, ventilates the abyssal layers of the Australian sector of the Southern Ocean as well as the eastern Indian and Pacific Oceans. We present the first dissolved neodymium (Nd) isotope and concentration measurements for ALBW. The summertime signature of ALBW is characterized by εNd = −8.9, distinct from Ross Sea Bottom Water, and similar to Weddell Sea Bottom Water. Adélie Land Shelf Water, the precursor water mass for wintertime ALBW, features the least radiogenic Nd fingerprint observed around Antarctica to date (εNd = −9.9). Local geology around Antarctica is important in setting the chemical signature of individual varieties of Antarctic Bottom Water, evident from the shelf water signature, which should be considered in the absence of direct wintertime observations

Radiosensitization of HNSCC cells by EGFR inhibition depends on the induction of cell cycle arrests

The increase in cellular radiosensitivity by EGF receptor (EGFR) inhibition has been shown to be attributable to the induction of a G1-arrest in p53-proficient cells. Because EGFR targeting in combination with radiotherapy is used to treat head and neck squamous cell carcinomas (HNSCC) which are predominantly p53 mutated, we tested the effects of EGFR targeting on cellular radiosensitivity, proliferation, apoptosis, DNA repair and cell cycle control using a large panel of HNSCC cell lines. In these experiments EGFR targeting inhibited signal transduction, blocked proliferation and induced radiosensitization but only in some cell lines and only under normal (pre-plating) conditions. This sensitization was not associated with impaired DNA repair (53BP1 foci) or induction of apoptosis. However, it was associated with the induction of a lasting G2-arrest. Both, the radiosensitization and the G2-arrest were abrogated if the cells were re-stimulated (delayed plating) with actually no radiosensitization being detectable in any of the 14 tested cell lines. Therefore we conclude that EGFR targeting can induce a reversible G2 arrest in p53 deficient HNSCC cells, which does not consequently result in a robust cellular radiosensitization. Together with recent animal and clinical studies our data indicate that EGFR inhibition is no effective strategy to increase the radiosensitivity of HNSCC cells.</p

Cold gas in massive early-type galaxies: The case of NGC 1167

We present a study of the morphology and kinematics of the neutral hydrogen in the gas-rich (M_HI=1.5x10^{10}Msun), massive early-type galaxy NGC 1167, which was observed with the Westerbork Synthesis Radio Telescope (WSRT). The HI is located in a 160kpc disk (~3xD_25) and has low surface density (<2Msun pc^{-2}). The disk shows regular rotation for r<65kpc but several signs of recent and ongoing interaction and merging with fairly massive companions are observed. No population of cold gas clouds is observed - in contrast to what is found in some spiral galaxies. This suggests that currently the main mechanism bringing in cold gas to the disk is the accretion of fairly massive satellite galaxies, rather than the accretion of a large number of small gas clumps. NGC 1167 is located in a (gas-) rich environment: we detect eight companions with a total HI mass of ~6x10^9Msun within a projected distance of 350kpc. Deep optical images show a disrupted satellite at the northern edge of the HI disk. The observed rotation curve shows a prominent bump of about 50km/s (in the plane of the disk) at r=1.3xR_25. This feature in the rotation curve occurs at the radius where the HI surface density drops significantly and may be due to large-scale streaming motions in the disk. We suspect that both the streaming motions and the HI density distribution are the result of the interaction/accretion with the disrupted satellite. Like in other galaxies with wiggles and bumps in the rotation curve, HI scaling describes the observed rotation curve best. We suggest that interactions create streaming motions and features in the HI density distribution and that this is the reason for the success of HI scaling in fitting such rotation curves.Comment: 17 pages, 11 figures; A&A in pres

Recurrent radio emission and gas supply: the case of the radio galaxy B2 0258+35

Outlined is the discovery of a very faint, diffuse, low surface-brightness (0.5 \mJybeam, 1.4 \mJyarcminsq on average) structure around the radio source B2 0258+35 hosted by an HI-rich early-type galaxy (NGC 1167). Since B2 0258+35 is a young Compact Steep Spectrum (CSS) source, the newly discovered structure could represent a remnant from an earlier stage of AGN activity. We go on by explaining in detail all the possibilities for triggering the radio activity in B2 0258+35 regarding gas accretion in a recurrent AGN activity framework. NGC 1167 hosts a very regular, extended and massive \HI\ disc that has been studied in great detail. Previous studies of the \HI\ closer to the core seem to go against the assumption of a circum-nuclear disc of \HI\ as the source of the accreting gas. We consider the cooling of gas from the hot, X-ray halo as a possible alternative option for the fueling of the AGN, as suggested in the case of other sources of similar radio power as B2 0258+35. Estimates are given for the age of the faint diffuse emission as well as for the current accretion rate, which are in good agreement with literature values. If our assumptions about the accretion mechanism are correct, similar large-scale, relic-like structures should be more commonly found around early-type galaxies and this will be hopefully confirmed by the next generation of sensitive, low-frequency radio surveys.Comment: 3 figures, accepted for publication in Astronomy and Astrophysics (17.07.2012

Heat Resistance Mediated by a New Plasmid Encoded Clp ATPase, ClpK, as a Possible Novel Mechanism for Nosocomial Persistence of Klebsiella pneumoniae

Klebsiella pneumoniae is an important opportunistic pathogen and a frequent cause of nosocomial infections. We have characterized a K. pneumoniae strain responsible for a series of critical infections in an intensive care unit over a two-year period. The strain was found to be remarkably thermotolerant providing a conceivable explanation of its persistence in the hospital environment. This marked phenotype is mediated by a novel type of Clp ATPase, designated ClpK. The clpK gene is encoded by a conjugative plasmid and we find that the clpK gene alone renders an otherwise sensitive E. coli strain resistant to lethal heat shock. Furthermore, one third of a collection of nosocomial K. pneumoniae isolates carry clpK and exhibit a heat resistant phenotype. The discovery of ClpK as a plasmid encoded factor and its profound impact on thermal stress survival sheds new light on the biological relevance of Clp ATPases in acquired environmental fitness and highlights the challenges of mobile genetic elements in fighting nosocomial infections