Probing The Dust-To-Gas Ratio of z > 0 Galaxies Through Gravitational Lenses

We report the detection of differential gas column densities in three gravitational lenses, MG0414+0534, HE1104-1805, and PKS1830-211. Combined with the previous differential column density measurements in B1600+434 and Q2237+0305 and the differential extinction measurements of these lenses, we probe the dust-to-gas ratio of a small sample of cosmologically distant normal galaxies. We obtain an average dust-to-gas ratio of E(B-V)/NH =(1.4\pm0.5) e-22 mag cm^2/atoms with an estimated intrinsic dispersion in the ratio of ~40%. This average dust-to-gas ratio is consistent with the average Galactic value of 1.7e-22 mag cm^2/atoms and the estimated intrinsic dispersion is also consistent with the 30% observed in the Galaxy.Comment: 14 pages, 4 figures, Accepted by Ap

Mass and dust in the disk of a spiral lens galaxy

Gravitational lensing is a potentially important probe of spiral galaxy structure, but only a few cases of lensing by spiral galaxies are known. We present Hubble Space Telescope and Magellan observations of the two-image quasar PMN J2004-1349, revealing that the lens galaxy is a spiral galaxy. One of the quasar images passes through a spiral arm of the galaxy and suffers 3 magnitudes of V-band extinction. Using simple lens models, we show that the mass quadrupole is well-aligned with the observed galaxy disk. A more detailed model with components representing the bulge and disk gives a bulge-to-disk mass ratio of 0.16 +/- 0.05. The addition of a spherical dark halo, tailored to produce an overall flat rotation curve, does not change this conclusion.Comment: ApJ, in press [9pp, 7 figs

PKS 1830-211: A Face-On Spiral Galaxy Lens

We present new Hubble Space Telescope images of the gravitational lens PKS 1830-211, which allow us to characterize the lens galaxy and update the determination of the Hubble constant from this system. The I-band image shows that the lens galaxy is a face-on spiral galaxy with clearly delineated spiral arms. The southwestern image of the background quasar passes through one of the spiral arms, explaining the previous detections of large quantities of molecular gas and dust in front of this image. The lens galaxy photometry is consistent with the Tully-Fisher relation, suggesting the lens galaxy is a typical spiral galaxy for its redshift. The lens galaxy position, which was the main source of uncertainty in previous attempts to determine H_0, is now known precisely. Given the current time delay measurement and assuming the lens galaxy has an isothermal mass distribution, we compute H_0 = 44 +/- 9 km/s/Mpc for an Omega_m = 0.3 flat cosmological model. We describe some possible systematic errors and how to reduce them. We also discuss the possibility raised by Courbin et al. (2002), that what we have identified as a single lens galaxy is actually a foreground star and two separate galaxies.Comment: 21 pp., 4 figs., accepted by ApJ, section added to discuss related work by Courbin et al. (astro-ph/0202026

Optical and Radio observations of the bright GRB010222 afterglow: evidence for rapid synchrotron cooling?

We report photometric observations of the optical afterglow of GRB010222 in V,R and I passbands carried out at UPSO, Naini Tal between 22-27 Feb 2001. We determine CCD Johnson BV and Cousins RI photometric magnitudes for 31 stars in the field of GRB010222 and use them to calibrate our measurements as well as other published BVRI photometric magnitudes of GRB010222 afterglow. We construct the light curve in V,R,I passbands and from a broken power-law fit determine the decay indices of 0.74+/-0.05 and 1.35+/-0.04 before and after the break at 0.7 days. Using reported X-ray flux measurements at 0.35 and 9.13 days after the burst we determine X-ray to opt/IR spectral index of 0.61+/-0.02 and 0.75+/-0.02 on these two days. We also report upper limits to the radio flux obtained from the RATAN-600 telescope and the GMRT, and millimeter-wave upper limits obtained from the Plateau de Bure Millimeter interferometer. We argue that the synchrotron cooling frequency is below the optical band for most of the observing period. We also estimate an initial jet opening angle of about 2.0n^(1/8) degrees, where n is the number density of the ambient medium.Comment: 16 pages, 4 postscript figures, minor revisions according to referee's comments, millimeter upper limit added, accepted for publication in Bulletin of the Astronomical Society of Indi

On the origin of the various types of radio emission in GRS 1915+105

We investigate the association between the radio ``plateau'' states and the large superluminal flares in GRS 1915+105 and propose a qualitative scenario to explain this association. We identify several candidate superluminal flare events from available monitoring data on this source and analyze the contemporaneous RXTE pointed observations. We detect a strong correlation between the average X-ray flux during the ``plateau'' state and the total energy emitted in radio during the subsequent radio flare. We find that the sequence of events is similar for all large radio flares with a fast rise and exponential decay morphology. Based on these results, we propose a qualitative scenario in which the separating ejecta during the superluminal flares are observed due to the interaction of the matter blob ejected during the X-ray soft dips, with the steady jet already established during the ``plateau'' state. This picture can explain all types of radio emission observed from this source in terms of its X-ray emission characteristics.Comment: Corrected typo in the author names, contents unchanged, accepted in Ap

PEComa of the lung

Perivascular epithelioid cell tumor (PEComa), also called clear cell \u2032sugar\u2032 tumor of the lung, is a rare benign tumor arising from perivascular epithelioid cells (PECs). We report a case of a 15-year-old boy who presented with right lower lobe lesion which turned out to be a clear cell tumor of the lung. An [18F]-fluoro-2-deoxy-D-glucose (FDG) - positron emission tomography (PET) scan revealed mild FDG uptake in the lung lesion (SUV< 1) with no active uptake elsewhere in the body. We discuss the clinical, radiologic and immunohistochemical features of clear cell \u2032sugar\u2032 tumor of lung and compare them with published literature

Quality indicators in surgical oncology: systematic review of measures used to compare quality across hospitals

Background: Measurement and reporting of quality indicators at the hospital level has been shown to improve outcomes and support patient choice. Although there are many studies validating individual quality indicators, there has been no systematic approach to understanding what quality indicators exist for surgical oncology and no standardization for their use. The aim of this study was to review quality indicators used to assess variation in quality in surgical oncology care across hospitals or regions. It also sought to describe the aims of these studies and what, if any, feedback was offered to the analysed groups. Methods: A literature search was performed to identify studies published between 1 January 2000 and 23 October 2023 that applied surgical quality indicators to detect variation in cancer care at the hospital or regional level. Results: A total of 89 studies assessed 91 unique quality indicators that fell into the following Donabedian domains: process indicators (58; 64%); outcome indicators (26; 29%); structure indicators (6; 7%); and structure and outcome indicators (1; 1%). Purposes of evaluating variation included: identifying outliers (43; 48%); comparing centres with a benchmark (14; 16%); and supplying evidence of practice variation (29; 33%). Only 23 studies (26%) reported providing the results of their analyses back to those supplying data. Conclusion: Comparisons of quality in surgical oncology within and among hospitals and regions have been undertaken in high-income countries. Quality indicators tended to be process measures and reporting focused on identifying outlying hospitals. Few studies offered feedback to data suppliers

Evidence for Synchrotron Bubbles from GRS 1915+105

We present GMRT observations of the Galactic microquasar GRS 1915+105 at 1.28 GHz for 8 days from 2001 June 18 to July 1. We have seen several isolated radio flares of varying magnitudes (20 - 50 mJy) and durations (6 - 35 min) and we model them as due to adiabatically expanding synchrotron emitting clouds (synchrotron bubbles) ejected from the accretion disk. By applying this model, we provide a new method to estimate the electron power-law index p, hence the spectral index, from single frequency radio observations. This method does not require correction for the optical depth time delay effects which may be important in the case of optically thick radio emission. Using our estimated value of p and simultaneous multiwavelength data from literature, we have calculated the time of ejection of the synchrotron plasma and the time delays at different observed frequencies. Our estimates are in good agreement with the observed time delays.Comment: Accepted for publication in A&A Letter

The International Collaboration for Research methods Development in Oncology (CReDO) workshops: shaping the future of global oncology research

Low-income and middle-income countries (LMICs) have a disproportionately high burden of cancer and cancer mortality. The unique barriers to optimum cancer care in these regions necessitate context-specific research. The conduct of research in LMICs has several challenges, not least of which is a paucity of formal training in research methods. Building capacity by training early career researchers is essential to improve research output and cancer outcomes in LMICs. The International Collaboration for Research methods Development in Oncology (CReDO) workshop is an initiative by the Tata Memorial Centre and the National Cancer Grid of India to address gaps in research training and increase capacity in oncology research. Since 2015, there have been five CReDO workshops, which have trained more than 250 oncologists from India and other countries in clinical research methods and protocol development. Participants from all oncology and allied fields were represented at these workshops. Protocols developed included clinical trials, comparative effectiveness studies, health services research, and observational studies, and many of these protocols were particularly relevant to cancer management in LMICs. A follow-up of these participants in 2020 elicited an 88% response rate and showed that 42% of participants had made progress with their CReDO protocols, and 73% had initiated other research protocols and published papers. In this Policy Review, we describe the challenges to research in LMICs, as well as the evolution, structure, and impact of CReDO and other similar workshops on global oncology research