582 research outputs found
A population of luminous accreting black holes with hidden mergers
Major galaxy mergers are thought to play an important part in fuelling the
growth of supermassive black holes. However, observational support for this
hypothesis is mixed, with some studies showing a correlation between merging
galaxies and luminous quasars and others showing no such association. Recent
observations have shown that a black hole is likely to become heavily obscured
behind merger-driven gas and dust, even in the early stages of the merger, when
the galaxies are well separated (5 to 40 kiloparsecs). Merger simulations
further suggest that such obscuration and black-hole accretion peaks in the
final merger stage, when the two galactic nuclei are closely separated (less
than 3 kiloparsecs). Resolving this final stage requires a combination of
high-spatial-resolution infrared imaging and high-sensitivity hard-X-ray
observations to detect highly obscured sources. However, large numbers of
obscured luminous accreting supermassive black holes have been recently
detected nearby (distances below 250 megaparsecs) in X-ray observations. Here
we report high-resolution infrared observations of hard-X-ray-selected black
holes and the discovery of obscured nuclear mergers, the parent populations of
supermassive-black-hole mergers. We find that obscured luminous black holes
(bolometric luminosity higher than 2x10^44 ergs per second) show a significant
(P<0.001) excess of late-stage nuclear mergers (17.6 per cent) compared to a
sample of inactive galaxies with matching stellar masses and star formation
rates (1.1 per cent), in agreement with theoretical predictions. Using
hydrodynamic simulations, we confirm that the excess of nuclear mergers is
indeed strongest for gas-rich major-merger hosts of obscured luminous black
holes in this final stage.Comment: To appear in the 8 November 2018 issue of Nature. This is the
authors' version of the wor
Targeted Disruption of the Low-Affinity Leukemia Inhibitory Factor-Receptor Gene Causes Placental, Skeletal, Neural and Metabolic Defects and Results in Perinatal Death
The low-affinity receptor for leukemia inhibitory factor (LIFR)* interacts with gp130 to induce an intracellular signal cascade, The LIFR-gp130 heterodimer is implicated in the function of diverse systems, Normal placentation is disrupted in LIFR mutant animals, which leads to poor intrauterine nutrition but allows fetuses to continue to term. Fetal bone volume is reduced greater than three-fold and the number of osteoclasts is increased six-fold, resulting in severe osteopenia of perinatal bone. Astrocyte numbers are reduced in the spinal cord and brain stem. Late gestation fetal livers contain relatively high stores of glycogen, indicating a metabolic disorder. Hematologic and primordial germ cell compartments appear normal. Pleiotropic defects in the mutant animals preclude survival beyond the day of birth
Virtual reality, ultrasound-guided liver biopsy simulator: Development and performance discrimination
Objectives: The aim of this article was to identify and prospectively investigate simulated ultrasound-guided targeted liver biopsy performance metrics as differentiators between levels of expertise in interventional radiology.Methods: Task analysis produced detailed procedural step documentation allowing identification of critical procedure steps and performance metrics for use in a virtual reality ultrasound-guided targeted liver biopsy procedure. Consultant (n=14; male=11, female=3) and trainee (n=26; male=19, female=7) scores on the performance metricswere compared. Ethical approval was granted by the Liverpool Research Ethics Committee (UK). Independent t-tests and analysis of variance (ANOVA) investigated differences between groups.Results: Independent t-tests revealed significant differences between trainees and consultants on three performance metrics: targeting, p=0.018, t=22.487 (22.040 to20.207); probe usage time, p=0.040, t=2.132 (11.064 to 427.983); mean needle length in beam, p=0.029, t=22.272 (20.028 to 20.002). ANOVA reported significant differences across years of experience (0–1, 1–2, 3+ years) on seven performance metrics: no-go area touched, p=0.012; targeting, p=0.025; length of session, p=0.024; probe usage time, p=0.025; total needle distance moved, p=0.038; number of skin contacts, p<0.001; total time in no-go area, p=0.008. More experienced participants consistently received better performance scores on all 19 performance metrics.Conclusion: It is possible to measure and monitor performance using simulation, with performance metrics providing feedback on skill level and differentiating levels of expertise. However, a transfer of training study is required
Efficacy and Safety of Technosphere Inhaled Insulin Compared With Technosphere Powder Placebo in Insulin-Naive Type 2 Diabetes Suboptimally Controlled With Oral Agents
OBJECTIVE—This double-blind, placebo-controlled, randomized, multicenter, parallel-group study compared the efficacy, safety, and tolerability of Technosphere insulin with Technosphere powder as placebo in insulin-naive type 2 diabetic patients whose diabetes was suboptimally controlled with oral antidiabetic agents
Sexual Display and Mate Choice in an Energetically Costly Environment
Sexual displays and mate choice often take place under the same set of environmental conditions and, as a consequence, may be exposed to the same set of environmental constraints. Surprisingly, however, very few studies consider the effects of environmental costs on sexual displays and mate choice simultaneously. We conducted an experiment, manipulating water flow in large flume tanks, to examine how an energetically costly environment might affect the sexual display and mate choice behavior of male and female guppies, Poecilia reticulata. We found that male guppies performed fewer sexual displays and became less choosy, with respect to female size, in the presence of a water current compared to those tested in still water. In contrast to males, female responsive to male displays did not differ between the water current treatments and females exhibited no mate preferences with respect to male size or coloration in either treatment. The results of our study underscore the importance of considering the simultaneous effects of environmental costs on the sexual behaviors of both sexes
Perspective from a Younger Generation -- The Astro-Spectroscopy of Gisbert Winnewisser
Gisbert Winnewisser's astronomical career was practically coextensive with
the whole development of molecular radio astronomy. Here I would like to pick
out a few of his many contributions, which I, personally, find particularly
interesting and put them in the context of newer results.Comment: 14 pages. (Co)authored by members of the MPIfR (Sub)millimeter
Astronomy Group. To appear in the Proceedings of the 4th
Cologne-Bonn-Zermatt-Symposium "The Dense Interstellar Medium in Galaxies"
eds. S. Pfalzner, C. Kramer, C. Straubmeier, & A. Heithausen (Springer:
Berlin
English language proficiency and the accommodations for language non-concordance amongst patients utilizing chiropractic college teaching clinics
Background: The number of households in the United States that are not proficient in the English language is growing and presenting a challenge to the health care system. Over nineteen percent of the US population speak a language other than English in the home. This increase in language discordance generates a greater need to find and implement accommodations in the clinical setting to insure accurate and efficient diagnosis and treatment as well as provide for patient safety. Aim: The purpose of this study is to determine the percentage of patients accessing the chiropractic college teaching clinics who are not proficient in the English language and to what extent the colleges provide accommodations for that language disparity. Methods: The clinic directors and deans of the Association of Chiropractic Colleges were surveyed via an on-line survey engine. The survey queried the percentage of the patient population that is not English language proficient, the accommodations the college currently has in place, if the college has a language specific consent to treat document and if the college has a written policy concerning patients without English proficiency. Results: Fifty percent of the contacted chiropractic colleges responded to the survey. In the respondent college clinics 16.5% of the patient population is not proficient in English, with over 75% speaking Spanish. All but one of the respondents provide some level of accommodation for the language non-concordance. Forty five percent of the responding colleges employ a language specific consent to treat form. The implementation of accommodations and the use of a language specific consent to treat form is more prevalent at colleges with a higher percentage of non-English speaking patients. Conclusions: The percentage of patients with limited English proficiency accessing services at the teaching clinics of the chiropractic colleges mirrors the numbers in the general population. There is a wide disparity in the accommodations that the individual colleges make to address this language discordance. There is a need to further develop accurate and meaningful accommodations to address language disparity in the chiropractic teaching clinics.https://doi.org/10.1186/2045-709X-21-
A Multi-Proxy Reconstruction of Environmental Change in the Vicinity of the North Bay Outlet of Pro-Glacial Lake Algonquin
We present a multi-proxy study of environmental conditions during and after the recessional phases of pro-glacial Lake Algonquin in the vicinity of the North Bay outlet, Great Lakes Basin. Data presented comes from a new sedimentary profile obtained from the Balsam Creek kettle lake c. 34 km north-east of the city of North Bay. This site lies close to the north-east margin of the maximum extent of the post-Algonquin lake sequence, which drained through the Ottawa-Mattawa valley system. Our data are presented against a Bayesian age-depth model, supporting and extending regional understanding of vegetation succession in this part of north-east Ontario. The core profile provides a minimum age for the formation of the glacial outwash delta in which the kettle is set, as well as tentative timing for the Payette (post-Algonquin) lake phase. We highlight two discrete intervals during the Early Holocene, with modelled mean ages of: 8475–8040 cal. BP (332–316 cm) and 7645 cal. BP (286 cm), when climatic aridity affected the growth of vegetation within the kettle vicinity. Association with volcanic activity is posited. Cryptotephra dating to 7660–7430 cal. BP (mean age: 7580 cal. BP) is chronologically and geochemically assigned to the Mazama climactic eruption, while an earlier ash accumulation 8710–7865 cal. BP is tentatively sourced to an unknown eruption also in the Cascades region of Oregon. Outside of these periods, the Balsam Creek sequence shows considerable habitat stability and a character akin to that seen at more southerly latitudes. On this evidence we propose that access to reliable resources within kettle features could have aided the initial colonisation of northern Ontario’s environmentally dynamic early post-glacial landscape
A prospective study of serum insulin-like growth factor-I (IGF-I), IGF-II, IGF-binding protein-3 and breast cancer risk.
The associations between serum concentrations of insulin-like growth factor-I (IGF-I), IGF-II and IGF-binding proteins (IGFBP)-3 and risk of breast cancer were investigated in a nested case-control study involving 117 cases (70 premenopausal and 47 postmenopausal at blood collection) and 350 matched controls within a cohort of women from the island of Guernsey, UK. Women using exogenous hormones at the time of blood collection were excluded. Premenopausal women in the top vs bottom third of serum IGF-I concentration had a nonsignificantly increased risk for breast cancer after adjustment for IGFBP-3 (odds ratio (OR) 1.71; 95% confidence interval (CI): 0.74-3.95; test for linear trend, P=0.21). Serum IGFBP-3 was associated with a reduction in risk in premenopausal women after adjustment for IGF-I (top third vs the bottom third: OR 0.49; 95% CI: 0.21-1.12, P for trend=0.07). Neither IGF-I nor IGFBP-3 was associated with risk in postmenopausal women and serum IGF-II concentration was not associated with risk in pre- or postmenopausal women. These data are compatible with the hypothesis that premenopausal women with a relatively high circulating concentration of IGF-I and low IGFBP-3 are at an increased risk of developing breast cancer
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