33 research outputs found
Wavelength dependences of the optical/UV and X-ray luminosity correlations of quasars
The interband correlations between optical/ultraviolet (UV) and X-ray luminosities of active galactic nuclei (AGNs) are importantfor understanding the disc–coronal connection, as well as using AGN as standard candles for cosmology. It is conventional tomeasure the X-ray luminosity at rest-frame 2 keV and compare to the UV luminosity at the rest-frame 2500 Å, but the wavelengthdependence was never well explored. In this work, we adopt a well-defined sample of 1169 unobscured quasars in the redshiftrange 0.13–4.51, and apply the direct-correlation method to explore how the correlation with the 2 keV luminosity changes atdifferent optical/UV wavelengths, from 1280 to 5550 Å where the spectral quality is high. We find that the luminosity at all UVcontinuum wavelengths correlates with the X-ray luminosity similarly to that at 2500 Å, and that these correlations are betterthan at the optical wavelengths. Strong self-correlation is also found in the broad-band optical/UV continuum, supporting thescenario that it is dominated by the disc emission. Correlations of various emission lines are also investigated (e.g. C IV, C III],Mg II, Hβ, and [O III]λλ4959/5007), including the Baldwin effect and correlations involving linewidths. We find the forms ofthese line correlations are different, and they are also different from their underlying continua, suggesting various complexities inthe line-generation process. We discuss these results in the disc-wind scenario. Our study confirms that the rest-frame 2500 Å is agood wavelength to represent the optical/UV continual properties of quasars, and shows the advantages of the direct-correlationmethod
A multi-wavelength view of distinct accretion regimes in the pulsating ultraluminous X-ray source NGC 1313 X-2
NGC 1313 X-2 is one of the few known pulsating ultraluminous X-ray sources (PULXs), and so is thought to contain a neutron star that accretes at highly super-Eddington rates. However, the physics of this accretion remains to be determined. Here, we report the results of two simultaneous XMM-Newton and HST observations of this PULX taken to observe two distinct X-ray behaviours as defined from its Swift light curve. We find that the X-ray spectrum of the PULX is best described by the hard ultraluminous regime during the observation taken in the lower flux, lower variability amplitude behaviour; its spectrum changes to a broadened disc during the higher flux, higher variability amplitude epoch. However, we see no accompanying changes in the optical/UV fluxes, with the only difference being a reduction in flux in the near-infrared (NIR) as the X-ray flux increased. We attempt to fit irradiation models to explain the UV/optical/IR fluxes but they fail to provide meaningful constraints. Instead, a physical model for the system leads us to conclude that the optical light is dominated by a companion O/B star, albeit with an IR excess that may be indicative of a jet. We discuss how these results may be consistent with the precession of the inner regions of the accretion disc leading to changes in the observed X-ray properties, but not the optical, and whether we should expect to observe reprocessed emission from ULXs
Accretion in Stellar-Mass Black Holes at High X-ray Spectral Resolution
Accretion disks around stellar-mass black holes are optimal regimes in which to make observational tests of seminal theory that applies across the mass scale. High X-ray spectral resolution will enable the most incisive tests. This white paper briefly reviews the key ideas and examines three case studies
Heterogeneity of circulating tumour cell-associated genomic gains in breast cancer and its association with the host immune response.
Tumor cells that preferentially enter circulation include the precursors of metastatic cancer. Previously, we characterized circulating tumor cells (CTC) from patients with breast cancer and identified a signature of genomic regions with recurrent copy-number gains. Through FISH, we now show that these CTC-associated regions are detected within the matched untreated primary tumors of these patients (21% to 69%, median 55.5%, n = 19). Furthermore, they are more prevalent in the metastases of patients who died from breast cancer after multiple rounds of treatment (70% to 100%, median 93%, samples n = 41). Diversity indices revealed that higher spatial heterogeneity for these regions within primary tumors is associated with increased dissemination and metastasis. An identified subclone with multiple regions gained (MRG clone) was enriched in a posttreatment primary breast carcinoma as well as multiple metastatic tumors and local breast recurrences obtained at autopsy, indicative of a distinct early subclone with the capability to resist multiple lines of treatment and eventually cause death. In addition, multiplex immunofluorescence revealed that tumor heterogeneity is significantly associated with the degree of infiltration of B lymphocytes in triple-negative breast cancer, a subtype with a large immune component. Collectively, these data reveal the functional potential of genetic subclones that comprise heterogeneous primary breast carcinomas and are selected for in CTCs and posttreatment breast cancer metastases. In addition, they uncover a relationship between tumor heterogeneity and host immune response in the tumor microenvironment. SIGNIFICANCE: As breast cancers progress, they become more heterogeneous for multiple regions amplified in circulating tumor cells, and intratumoral spatial heterogeneity is associated with the immune landscape
Avoiding Coral Reef Functional Collapse Requires Local and Global Action
oral reefs face multiple anthropogenic threats, from pollution and overfishing to the dual effects of greenhouse gas emissions: rising sea temperature and ocean acidification [1]. While the abundance of coral has declined in recent decades [2, 3], the implications for humanity are difficult to quantify because they depend on ecosystem function rather than the corals themselves. Most reef functions and ecosystem services are founded on the ability of reefs to maintain their three-dimensional structure through net carbonate accumulation [4]. Coral growth only constitutes part of a reef's carbonate budget; bioerosion processes are influential in determining the balance between net structural growth and disintegration [5, 6]. Here, we combine ecological models with carbonate budgets and drive the dynamics of Caribbean reefs with the latest generation of climate models. Budget reconstructions using documented ecological perturbations drive shallow (6-10 m) Caribbean forereefs toward an increasingly fragile carbonate balance. We then projected carbonate budgets toward 2080 and contrasted the benefits of local conservation and global action on climate change. Local management of fisheries (specifically, no-take marine reserves) and the watershed can delay reef loss by at least a decade under "business-as-usual" rises in greenhouse gas emissions. However, local action must be combined with a low-carbon economy to prevent degradation of reef structures and associated ecosystem services
Muscle Logic: New Knowledge Resource for Anatomy Enables Comprehensive Searches of the Literature on the Feeding Muscles of Mammals
Background: In recent years large bibliographic databases have made much of the published literature of biology available for searches. However, the capabilities of the search engines integrated into these databases for text-based bibliographic searches are limited. To enable searches that deliver the results expected by comparative anatomists, an underlying logical structure known as an ontology is required. Development and Testing of the Ontology Here we present the Mammalian Feeding Muscle Ontology (MFMO), a multi-species ontology focused on anatomical structures that participate in feeding and other oral/pharyngeal behaviors. A unique feature of the MFMO is that a simple, computable, definition of each muscle, which includes its attachments and innervation, is true across mammals. This construction mirrors the logical foundation of comparative anatomy and permits searches using language familiar to biologists. Further, it provides a template for muscles that will be useful in extending any anatomy ontology. The MFMO is developed to support the Feeding Experiments End-User Database Project (FEED, https://feedexp.org/), a publicly-available, online repository for physiological data collected from in vivo studies of feeding (e.g., mastication, biting, swallowing) in mammals. Currently the MFMO is integrated into FEED and also into two literature-specific implementations of Textpresso, a text-mining system that facilitates powerful searches of a corpus of scientific publications. We evaluate the MFMO by asking questions that test the ability of the ontology to return appropriate answers (competency questions). We compare the results of queries of the MFMO to results from similar searches in PubMed and Google Scholar. Results and Significance Our tests demonstrate that the MFMO is competent to answer queries formed in the common language of comparative anatomy, but PubMed and Google Scholar are not. Overall, our results show that by incorporating anatomical ontologies into searches, an expanded and anatomically comprehensive set of results can be obtained. The broader scientific and publishing communities should consider taking up the challenge of semantically enabled search capabilities
Sexual dysfunction during treatment with serotonergic and noradrenergic antidepressants: Clinical description and the role of the 5-HTTLPR
Objectives. Sexual dysfunction (SD) is a frequently reported side-effect of antidepressant treatment, particularly of selective serotonin reuptake inhibitors (SSRIs). In the multicentre clinical and pharmacogenetic GENDEP study (Genome-based Therapeutic Drugs for Depression), the effect of the serotonin transporter gene promoter polymorphism 5-HTTLPR on sexual function was investigated during treatment with escitalopram (SSRI) and nortriptyline (tricyclic antidepressant). Methods. A total of 494 subjects with an episode of DSM-IV major depression were randomly assigned to treatment with escitalopram or nortriptyline. Over 12 weeks, depressive symptoms and SD were measured weekly with the Montgomery-Asberg Depression Rating Scale, the Antidepressant Side-Effect Checklist, the UKU Side Effect Rating Scale, and the Sexual Functioning Questionnaire. Results. The incidence of reported SD after 12 weeks of treatment was relatively low, and did not differ significantly between antidepressants (14.9% escitalopram, 19.7% nortriptyline). There was no significant interaction between the 5-HTTLPR and antidepressant on SD. Improvement in depressive symptoms and younger age were both associated with lower SD. The effect of age on SD may have been moderated by the 5-HTTLPR. Conclusions. In GENDEP, rates of reported SD during treatment were lower than those described in previous reports. There was no apparent effect of the 5-HTTLPR on the observed decline in SD. © 2011 Informa Healthcare.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Kinematics of the Broad Emission Line Region in NGC 5548
We derive both total flux and velocity-resolved response functions for the
CIV 1549 emission line from the data obtained in the 1993 NGC 5548 monitoring
campaign. These response functions imply: 1.) the emission region stretches
from inside 1 lt-d to outside 10 lt-d, and is probably better described as
round than flat; 2.) the velocity field is dominated by a red/blue symmetric
component (e.g. 2--d or 3--d random motions, or rotation in a disk) but there
is also {\it significant} radial infall. Quantitative modelling indicates that
the random speeds are typically a few times as large as the radial speed.
However, no simple model gives a completely acceptable fit to the data. These
inferences rule out numerous simple and otherwise plausible models for broad
line region dynamics, including outflowing winds, radial free-fall, rotation in
a disk, or collisionless orbital motion.Comment: AASLaTeX file + uuencoded file containing figure