2,849 research outputs found
Large grains in the disk of CQ Tau
No full textWe present 7 mm observations of the dusty disk surrounding the 10 Myr old 1.5 Msun pre-main-sequence star CQ Tauri obtained at the Very Large Array with 0.8 arcsec resolution and 0.1 mJy rms sensitivity. These observations resolve the 7 mm emission in approximately the north-south direction, confirming previous results obtained with lower resolution. We use a two-layer flared disk model to interpret the observed fluxes from 7 mm to 1.3 mm together with the resolved 7 mm structure. We find that the disk radius is constrained to the range 100 to 300 AU, depending on the steepness of the disk surface density distribution. The power law index of the dust opacity coefficient, beta , is constrained to be 0.5 to 0.7. Since the models indicate that the disk is optically thin at millimeter wavelengths for radii greater than 8 AU, the contribution of an optically thick region to the emission is less than 10%. This implies that high optical depth or complex disk geometry cannot be the cause of the observed shallow millimeter spectral index. Instead, the new analysis supports the earlier suggestion that dust particles in the disk have grown to sizes as large as a few centimeters. The dust in the CQ Tauri system appears to be evolved much like that in the TW Hydra system, a well-studied pre-main-sequence star of similar age and lower mass. The survival of gas-rich disks with incomplete grain evolution at such old ages deserves further investigations
Constraints on Properties of the Protoplanetary Disks around UX Orionis and CQ Tauri
No full textWe present Very Large Array observations of the intermediate-mass pre-main-sequence stars UX Ori and CQ Tau at 7 mm, 3.6 cm, and 6 cm. These stars are members of the UX Ori variability class, where the origin of optical variability is thought to derive from inhomogeneities in circumstellar disks. Both stars are detected at 7 mm but not at longer wavelengths, which confirms that the millimeter emission is dominated by dust. The UX Ori system exhibits a remarkably flat spectral index in the millimeter range, with αmm~2 (Fν~ναmm). Two different disk models can reproduce this property: (1) a physically small disk with optically thick emission, truncated at a radius of about 30 AU, or (2) a massive (~0.3-1 Msolar) disk mainly composed of dust particles grown to radii of 10 cm (``pebbles''). The observations do not spatially resolve the 7 mm emission. We discuss implications of these two models and suggest observational tests that will discriminate between them. The CQ Tau system exhibits a spectral index in the millimeter range of αmm~2.6, consistent with values commonly found for disks around pre-main-sequence stars. The observations marginally resolve the 7 mm emission as an elongated structure with full width at half-maximum of 2.4"×1.1" (240×110 AU at 100 pc distance). The size and inclination of ~63° (implied by circular symmetry) are consistent with flared disk models that have previously been suggested to explain the optical colors and polarization properties
Resolving the molecular environment of super star clusters in Henize 2-10
No full textContext: The rate of star formation both in the Galaxy and in external galaxies should be related to the physical properties of the molecular clouds from which stars form. This is expected for the starbursts found both in irregular galaxies and in some mergers. The dwarf galaxy Henize 2-10 is particularly interesting in this context as it shows a number of newly formed super star clusters (SSCs) associated with a very rich molecular environment. Aims: We present a high angular resolution study of the molecular gas associated with the SSCs with the aim of deriving the physical properties of the parent molecular clouds. The final goal is to test the expectation that the formation of SSCs requires exceptionally dense and massive clouds. Methods: We have used the Submillimeter Array with an angular resolution of 1.9 arcsec × 1.3 arcsec to map the J = 2-1 transition of CO in Henize 2-10. Supplementary measurements of HCN(J = 1-0), 13CO(J = 2-1) and millimeter continuum were obtained with the APEX, IRAM 30 m and SEST single dish telescopes. Results: Our single dish observations confirm the association of the newly formed SSCs in Henize 2-10 with dense molecular gas. Our interferometric observations resolve the CO(2-1) emission in several giant molecular clouds. Overall the molecular gas accounts for approximately half of the mass in the central regions of Henize 2-10. Although we find indications that the molecular clouds associated with the formation of SSCs in Henize 2-10 are massive and dense, the tracer we used (CO) and the linear resolution of our observations (60 × 80 pc) are still not adequate to test the expectation that exceptionally dense and massive cores are required for SSCs formation
Rapporteur’s report – innovative geotechnologies for energy transition
No full textThe 9th Society for Underwater Technology (SUT) International Conference on Offshore Site Investigation and Geotechnics (OSIG) closed with a Rapporteur’s report given by the author. This paper provides a record of that report, transcribed from a video recording. The presentation slides are shown as Figures.</p
DEFRApH - Sample collection and handling procedures
No full textAll chemical and biogeochemical process in the sea are affected by the acidity of the water. Acidity is therefore fundamental property of seawater. The growing concern that the acidity of the oceans might be increasing has revealed weaknesses in our knowledge of this fundamental property and its variation in space and time. In 2008 the DEFRApH project (DEFRA contract ME4133) was initiated to provide this missing information in UK related waters. It required sampling for and analysis of the total inorganic carbon and total alkalinity content of samples. This reports documents the procedures sued for sampling. A companion document Hartman Dumousseaud and Roberts (NOC Internal Document No. 01) describes in detail the analytical procedures used and the calculation of the results
Author Correction:Prefrontal cortical ChAT-VIP interneurons provide local excitation by cholinergic synaptic transmission and control attention (Nature Communications, (2019), 10, 1, (5280), 10.1038/s41467-019-13244-9)
No full textThe original version of this Article contained an error in the spelling of the author Wilma D.J. van de Berg, which was incorrectly given as Wilma D.J. van den Berg. This has now been corrected in both the PDF and HTML versions of the Article.</p
Sunitinib treatment exacerbates intratumoral heterogeneity in metastatic renal cancer
No full textThis work was supported by the Chief Scientist Office, Scotland (ETM37; to G.D. Stewart, A.C.P. Riddick, M. Aitchison, and D.J. Harrison), Cancer Research UK (Experimental Cancer Medicine Centre; to T. Powles, London and D.J. Harrison, Edinburgh), Medical Research Council (to A. Laird and D.J. Harrison), Royal College of Surgeons of Edinburgh (to A. Laird), Melville Trust (to A. Laird), Medical Research Council (MC_UU_12018/25; to I.M. Overton), Royal Society of Edinburgh Scottish Government Fellowship cofunded by Marie Curie Actions (to I.M. Overton), Renal Cancer Research Fund (to G.D. Stewart), Kidney Cancer Scotland (to G.D. Stewart) and an educational grant from Pfizer (to T. Powles).Purpose: The aim of this study was to investigate the effect of VEGF targeted therapy (sunitinib) on molecular intratumoral heterogeneity (ITH) in metastatic clear cell renal cancer (mccRCC). Experimental design: Multiple tumor samples (n=187 samples) were taken from the primary renal tumors of mccRCC patients who were sunitinib treated (n=23, SuMR clinical trial) or untreated (n=23, SCOTRRCC study). ITH of pathological grade, DNA (aCGH), mRNA (Illumina Beadarray) and candidate proteins (reverse phase protein array) were evaluated using unsupervised and supervised analyses (driver mutations, hypoxia and stromal related genes). ITH was analysed using intratumoral protein variance distributions and distribution of individual patient aCGH and gene expression clustering. Results: Tumor grade heterogeneity was greater in treated compared to untreated tumors (P=0.002). In unsupervised analysis, sunitinib therapy was not associated with increased ITH in DNA or mRNA. However, there was an increase in ITH for the driver mutation gene signature (DNA and mRNA) as well as increasing variability of protein expression with treatment (p<0.05). Despite this variability, significant chromosomal and transcript changes to key targets of sunitinib, such as VHL, PBRM1 and CAIX, occurred in the treated samples. Conclusions: These findings suggest that sunitinib treatment has significant effects on the expression and ITH of key tumor and treatment specific genes/proteins in mccRCC. The results, based on primary tumor analysis, do not support the hypothesis that resistant clones are selected and predominate following targeted therapy.Peer reviewe
A circumbinary protoplanetary disk in a polar configuration
No full textNearly all young stars are initially surrounded by ‘protoplanetary’ disks of gas and dust, and in the case of single stars at least 30% of these disks go on to form planets1. The process of protoplanetary disk formation can result in initial misalignments, where the disk orbital plane is different from the stellar equator in single-star systems, or different from the binary orbital plane in systems with two stars2. A quirk of the dynamics means that initially misaligned ‘circumbinary’ disks—those that surround two stars—are predicted to evolve to one of two possible stable configurations: one where the disk and binary orbital planes are coplanar and one where they are perpendicular (a ‘polar’ configuration)3–5. Previous work has found coplanar circumbinary disks6, but no polar examples were known until now. Here, we report the first discovery of a protoplanetary circumbinary disk in the polar configuration, supporting the predictions that such disks should exist. The disk shows some characteristics that are similar to disks around single stars, and that are attributed to dust growth. Thus, the first stages of planet formation appear able to proceed in polar circumbinary disks
All-optical regeneration of phase-encoded signals
No full textIn this Chapter we review the need, general principles and approaches used to regenerate phase encoded signals of differing levels of coding complexity. We will describe the key underpinning technology and present the current state-of-the-art, incorporating an appropriate historic perspective throughout. The chapter finishes with a discussion of emerging research trends and broader future perspectives
Reply to the discussion by McCarron on “Modelling spatial variability in as-laid embedment for high pressure and high temperature (HPHT) pipeline design”
No full textN/AThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
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