3,562 research outputs found
A molecular line scan in the Hubble Deep Field North
We present a molecular line scan in the Hubble Deep Field North (HDF-N) that covers the entire 3mm window (79-115 GHz) using the IRAM Plateau de Bure Interferometer. Our CO redshift coverage spans z2. We reach a CO detection limit that is deep enough to detect essentially all z>1 CO lines reported in the literature so far. We have developed and applied different line searching algorithms, resulting in the discovery of 17 line candidates. We estimate that the rate of false positive line detections is ~2/17. We identify optical/NIR counterparts from the deep ancillary database of the HDF-N for seven of these candidates and investigate their available SEDs. Two secure CO detections in our scan are identified with star-forming galaxies at z=1.784 and at z=2.047. These galaxies have colors consistent with the `BzK' color selection and they show relatively bright CO emission compared with galaxies of similar dust continuum luminosity. We also detect two spectral lines in the submillimeter galaxy HDF850.1 at z=5.183. We consider an additional 9 line candidates as high quality. Our observations also provide a deep 3mm continuum map (1-sigma noise level = 8.6 ÎŒJy/beam). Via a stacking approach, we find that optical/MIR bright galaxies contribute only to <50% of the SFR density at 1<z<3, unless high dust temperatures are invoked. The present study represents a first, fundamental step towards an unbiased census of molecular gas in `normal' galaxies at high-z, a crucial goal of extragalactic astronomy in the ALMA era
Characterization of the three Arabidopsis thaliana RAD21 cohesins reveals differential responses to ionizing radiation
The RAD21/REC8 gene family has been implicated in sister chromatid cohesion and DNA repair in several organisms. Unlike most eukaryotes, Arabidopsis thaliana has three RAD21 gene homologues, and their cloning and characterization are reported here. All three genes, AtRAD21.1, AtRAD21.2, and AtRAD21.3, are expressed in tissues rich in cells undergoing cell division, and AtRAD21.3 shows the highest relative level of expression. An increase in steady-state levels of AtRAD21.1 transcript was also observed, specifically after the induction of DNA damage. Phenotypic analysis of the atrad21.1 and atrad21.3 mutants revealed that neither of the single mutants was lethal, probably due to the redundancy in function of the AtRAD21 genes. However, AtRAD21.1 plays a critical role in recovery from DNA damage during seed imbibition, prior to germination, as atrad21.1 mutant seeds are hypersensitive to radiation damag
THE EVOLVING INTERSTELLAR MEDIUM OF STAR-FORMING GALAXIES SINCE z=2 AS PROBED BY THEIR INFRARED SPECTRAL ENERGY DISTRIBUTIONS
Using data from the mid-infrared to millimeter wavelengths for individual galaxies and for stacked ensembles at 0.5 1012 L â). For galaxies within the MS, we show that the variations of specific star formation rates (sSFRs = SFR/M *) are driven by varying gas fractions. For relatively massive galaxies like those in our samples, we show that the hardness of the radiation field, langUrang, which is proportional to the dust-mass-weighted luminosity (L IR/M dust) and the primary parameter defining the shape of the IR spectral energy distribution (SED), is equivalent to SFE/Z. For MS galaxies with stellar mass log (M */M â) â„ 9.7 we measure this quantity, langUrang, showing that it does not depend significantly on either the stellar mass or the sSFR. This is explained as a simple consequence of the existing correlations between SFR-M *, M *-Z, and M gas-SFR. Instead, we show that langUrang (or equally L IR/M dust) does evolve, with MS galaxies having harder radiation fields and thus warmer temperatures as redshift increases from z = 0 to 2, a trend that can also be understood based on the redshift evolution of the M *-Z and SFR-M * relations. These results motivate the construction of a universal set of SED templates for MS galaxies that are independent of their sSFR or M * but vary as a function of redshift with only one parameter, langUrang
Deep U band and R imaging of GOODS-South: Observations,data reduction and first results
We present deep imaging in the {\em U} band covering an area of 630
arcmin centered on the southern field of the Great Observatories Origins
Deep Survey (GOODS). The data were obtained with the VIMOS instrument at the
ESO Very Large Telescope. The final images reach a magnitude limit (AB, 1, in a 1\arcsec radius aperture), and have good
image quality, with full width at half maximum \approx 0.8\arcsec. They are
significantly deeper than previous U--band images available for the GOODS
fields, and better match the sensitivity of other multi--wavelength GOODS
photometry. The deeper U--band data yield significantly improved photometric
redshifts, especially in key redshift ranges such as , and deeper
color--selected galaxy samples, e.g., Lyman--break galaxies at . We
also present the coaddition of archival ESO VIMOS R band data, with (AB, 1, 1\arcsec radius aperture), and image quality
\approx 0.75 \arcsec. We discuss the strategies for the observations and data
reduction, and present the first results from the analysis of the coadded
images.Comment: Accepted for publication ApJS, 54 pages, 27 figures. Released data
and full-quality paper version available at
http://archive.eso.org/cms/eso-data/data-packages/goods-vimos-imaging-data-release-version-1.
COLDz: Karl G. Jansky Very Large Array discovery of a gas-rich galaxy in COSMOS
The broad spectral bandwidth at mm and cm-wavelengths provided by the recent upgrades to the Karl G. Jansky Very Large Array (VLA) has made it possible to conduct unbiased searches for molecular CO line emission at redshifts, z > 1.31. We present the discovery of a gas-rich, star-forming galaxy at z = 2.48, through the detection of CO(1-0) line emission in the COLDz survey, through a sensitive, Ka-band (31 to 39 GHz) VLA survey of a 6.5 square arcminute region of the COSMOS field. We argue that the broad line (FWHM ~570 +/- 80 km/s) is most likely to be CO(1-0) at z=2.48, as the integrated emission is spatially coincident with an infrared-detected galaxy with a photometric redshift estimate of z = 3.2 +/- 0.4. The CO(1-0) line luminosity is L'_CO = (2.2 +/- 0.3) x 10^{10} K km/s pc^2, suggesting a cold molecular gas mass of M_gas ~ (2 - 8)x10^{10}M_solar depending on the assumed value of the molecular gas mass to CO luminosity ratio alpha_CO. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is L_IR = 2.5x10^{12} L_solar and the star-formation rate is ~250 M_solar/yr, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is ~114+/-19 L_solar/(K km/s pc^2), similar to galaxies with similar SFRs selected at UV/optical to radio wavelengths. This discovery confirms the potential for molecular emission line surveys as a route to study populations of gas-rich galaxies in the future
Serial counts of Mycobacterium tuberculosis in sputum as surrogate markers of the sterilising activity of rifampicin and pyrazinamide in treating pulmonary tuberculosis
BACKGROUND: Since the sterilising activity of new antituberculosis drugs is difficult to assess by conventional phase III studies, surrogate methods related to eventual relapse rates are required. METHODS: A suitable method is suggested by a retrospective analysis of viable counts of Mycobacterium tuberculosis in 12-hr sputum collections from 122 newly diagnosed patients with pulmonary tuberculosis in Nairobi, done pretreatment and at 2, 7, 14 and 28 days. Treatment was with isoniazid and streptomycin, supplemented with either thiacetazone (SHT) or rifampicin + pyrazinamide (SHRZ). RESULTS: During days 0â2, a large kill due to isoniazid occurred, unrelated to treatment or HIV status; thereafter it decreased exponentially. SHRZ appeared to have greater sterilising activity than SHT during days 2â7 (p = 0.044), due to rifampicin, and during days 14â28, probably due mainly to pyrazinamide. The greatest discrimination between SHRZ and SHT treatments was found between regression estimates of kill over days 2â28 (p = 0.0005) in patients who remained positive up to 28 days with homogeneous kill rates. No associations were found between regression estimates and the age, sex, and extent of disease or cavitation. An increased kill in HIV seropositive patients, unrelated to the treatment effect, was evident during days 2â28 (p = 0.007), mainly during days 2â7. CONCLUSIONS: Surrogate marker studies should either be in small groups treated with monotherapy during days 2 to about 7 or as add-ons or replacements in isoniazid-containing standard regimens from days 2 to 28 in large groups
Using technology to deliver cancer follow-up : a systematic review
Peer reviewedPublisher PD
Site Evaluation and RFI spectrum measurements in Portugal at the frequency range 0.408-10 GHz for a GEM polarized galactic radio emission experiment
We probed for Radio Frequency Interference (RFI) for the three potential
Galactic Emission Mapping Experiment (GEM) sites at Portugal using custom made
omnidirectional disconic antennas. For the installation of a 10-meter dish
dedicated to the mapping of Polarized Galactic Emission foreground planned for
2005-2007 in the 5-10 GHz band, the three sites chosen as suitable to host the
antenna were surveyed for local radio pollution in the frequency range
[0.01-10] GHz. Tests were done to look for radio broadcasting and mobile phone
emission lines in the radio spectrum. The results show one of the sites to be
almost entirely RFI clean and showing good conditions to host the experiment.Comment: 9 pages, 6 figures, submitted to New Astronom
The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths
We present the Planck Sky Model (PSM), a parametric model for the generation
of all-sky, few arcminute resolution maps of sky emission at submillimetre to
centimetre wavelengths, in both intensity and polarisation. Several options are
implemented to model the cosmic microwave background, Galactic diffuse emission
(synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H-II
regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic
Sunyaev-Zeldovich signals from clusters of galaxies. Each component is
simulated by means of educated interpolations/extrapolations of data sets
available at the time of the launch of the Planck mission, complemented by
state-of-the-art models of the emission. Distinctive features of the
simulations are: spatially varying spectral properties of synchrotron and dust;
different spectral parameters for each point source; modeling of the clustering
properties of extragalactic sources and of the power spectrum of fluctuations
in the cosmic infrared background. The PSM enables the production of random
realizations of the sky emission, constrained to match observational data
within their uncertainties, and is implemented in a software package that is
regularly updated with incoming information from observations. The model is
expected to serve as a useful tool for optimizing planned microwave and
sub-millimetre surveys and to test data processing and analysis pipelines. It
is, in particular, used for the development and validation of data analysis
pipelines within the planck collaboration. A version of the software that can
be used for simulating the observations for a variety of experiments is made
available on a dedicated website.Comment: 35 pages, 31 figure
How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?
Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3â
mâ
sâ1) and three terrain conditions at each speed: (i) level, (ii) repeated 5â
cm low-contrast obstacles (90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies
- âŠ