2,278 research outputs found

    MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. IV. The Parent Luminosity Function of Radio-Loud Blazars

    Get PDF
    (Abridged) We use a complete sample of active galactic nuclei (AGN) selected on the basis of relativistically beamed 15 GHz radio flux density to derive the parent radio luminosity function (RLF) of bright radio-selected blazar cores. We use a maximum likelihood method to fit a beamed RLF to the observed data and thereby recover the parameters of the intrinsic (unbeamed) RLF. We analyze two subsamples of the MOJAVE sample: the first contains only objects of known FR II class, with a total of 103 sources, and the second subsample adds 24 objects of uncertain FR class for a total of 127 sources. Both subsamples exclude four known FR I radio galaxies and two gigahertz-peaked spectrum sources. We obtain good fits to both subsamples using a single power law intrinsic RLF with pure density evolution function. We find that a previously reported break in the observed MOJAVE RLF actually arises from using incomplete bins (because of the luminosity cutoff) across a steep and strongly evolving RLF, and does not reflect a break in the intrinsic RLF. The derived space density of the parent population of the FR II sources from the MOJAVE sample (with L>1.3e25 W/Hz) is approximately 1600/Gpc^3.Comment: 31 pages, 7 figures and 2 tables. Accepted for publication in ApJ. Changes: classification of sources based on radio morphology instead of optical classes; added the parameters of the RLF of the FR II sources; added more explanations; added a table listing the sample sources; added 2 extra figures related to the observed break in the RLF; updated reference

    Patient-Reported Outcomes Measurement Information System physical function correlates with Toronto Extremity Salvage Score in an orthopaedic oncology population

    Get PDF
    Background: The National Institute of Health\u27s Patient-Reported Outcomes Measurement Information System (PROMIS) uses computerised-adaptive testing to reduce survey burden and improve sensitivity. PROMIS is being used across medical and surgical disciplines but has not been studied in orthopaedic oncology. Questions/purposes: The aim of the study was to compare PROMIS measures with upper extremity (UE) and lower extremity (LE) Toronto Extremity Salvage Score (TESS) by assessing the following: (1) responder burden, (2) correlation between scores and (3) floor/ceiling effects. Patients and methods: This cross-sectional trial analysed all 97 adult patients treated surgically for a bone or soft tissue tumour at a tertiary institution between November 2015 and March 2016. TESS (UE or LE) and PROMIS (Physical Function, Pain Interference and Depression) surveys were administered preoperatively. Pearson correlations between each PROMIS domain and TESS were calculated, as were floor/ceiling effects of each outcome measure. Results: (1) Completion of three PROMIS questionnaires required a mean total of 16.8 (+/- 5.8 standard deviation) questions, compared with 31 and 32 questions for the LE and UE TESS questionnaires, respectively. (2) The PROMIS Physical Function scores demonstrated a strong positive correlation with the LE TESS (r = 0.84; 95% confidence interval [CI], 0.72-0.91; p \u3c 0.001) and moderate positive correlation with the UE TESS (r = 0.64; 95% CI, 0.34-0.83; p = 0.055). The PROMIS Depression scores demonstrated a weak negative correlation with both the LE TESS (r = -0.38; 95% CI, -0.61 to -0.10; p = 0.010) and with UE TESS (r = -0.38; 95% CI, -0.67 to -0.01; p = 0.055). The PROMIS Pain Interference scores demonstrated a strong negative correlation with the LE TESS (r = -0.71; 95% CI, -0.83 to -0.52; p \u3c 0.001) and a moderate negative correlation with the UE TESS (r = -0.62; 95% CI, -0.81 to -0.30; p = 0.001). (3) The UE TESS had a range of scores from 16 to 100 with a 27% ceiling effect and no floor effect, and the LE TESS had a range from 10 to 98 with no floor or ceiling effect. There was no floor or ceiling effect for any PROMIS measures. Conclusions: In an orthopaedic oncology population, the PROMIS Physical Function and Pain Interference scores correlate with the TESS and have the benefit of reduced survey burden and ceiling effect. The PROMIS Depression scores may provide additional information regarding patient outcomes not captured by the TESS. Level of Evidence: Level III. The translational potential of this article: Patient reported outcome measures asses patients\u27 symptoms, function and health-related quality of life and are designed to capture more clinical information than can be gathered by objective medial testing alone. As reimbursements and the understanding of patient outcomes are becoming tied to performance on PROMIS measures, it is an important step to establish how PROMIS measures correlate and compare to traditional legacy measures

    Global well-posedness for a Smoluchowski equation coupled with Navier-Stokes equations in 2D

    Full text link
    We prove global existence for a nonlinear Smoluchowski equation (a nonlinear Fokker-Planck equation) coupled with Navier-Stokes equations in two dimensions. The proof uses a deteriorating regularity estimate and the tensorial structure of the main nonlinear terms

    An experimental testbed for NEAT to demonstrate micro-pixel accuracy

    Full text link
    NEAT is an astrometric mission proposed to ESA with the objectives of detecting Earth-like exoplanets in the habitable zone of nearby solar-type stars. In NEAT, one fundamental aspect is the capability to measure stellar centroids at the precision of 5e-6 pixel. Current state-of-the-art methods for centroid estimation have reached a precision of about 4e-5 pixel at Nyquist sampling. Simulations showed that a precision of 2 micro-pixels can be reached, if intra and inter pixel quantum efficiency variations are calibrated and corrected for by a metrology system. The European part of the NEAT consortium is designing and building a testbed in vacuum in order to achieve 5e-6 pixel precision for the centroid estimation. The goal is to provide a proof of concept for the precision requirement of the NEAT spacecraft. In this paper we give the basic relations and trade-offs that come into play for the design of a centroid testbed and its metrology system. We detail the different conditions necessary to reach the targeted precision, present the characteristics of our current design and describe the present status of the demonstration.Comment: SPIE proceeding

    Seismic response and wavefield characterization using a very dense 2D seismic array on an active landslide (Cavola, Italy)

    Get PDF
    A dense 2D array (95 broad-band stations) was installed in a grid-like configuration over a 130x56 m area on the active landslide of Cavola in northern Apennines. Outcropping rocks consist of Monte Piano (fractured flysch and clayey melanges) and Ranzano (muddy and sandstone turbidite) formations of Eocene-Oligocene age. These units are covered by a 4-km long landslide with maximum thickness more than 60 m. In historical times there are three instances of activity triggered by meteorological events, in 1938, 1940, and 1960. The latter event was the most damaging, involving an area of 1.3 km2 and partial destruction of the Cavola village. Recent SAR interferometric analyses coupled to inclinometer data for the supposedly dormant period 1995-2001 show movements between 10-15 mm/yr affecting mainly areas close to the landslide side-scarps and to a new industrial district with active sliding surface at a depth of 10-15 m. The landslide structure beneath the array was reconstructed by means of active and passive seismic surveys, in-situ velocity measurements and geoelectrical tomography obtaining clay thickness ranging from 0 to 45 m and with average shear-velocity of 350 m/s. The inferred model is used for numerical 2D simulation of earthquake ground motion for different incidence angle and type of waves. The data from 11 of more than 100 local earthquakes recorded at the array have been used for the comparison with model results. The long data records (3 months of continuous recording) allow investigation of properties of ambient noise in terms of temporal stability and wavefield composition. We find that local industrial sources affect the H/V spectral ratios and their interpretation in terms of resonant frequencies. Analysis of noise polarization is also performed, revealing different patterns depending on the nature of the noise source

    Seismic response of L’Aquila (Central Appennines, Italy) from 2D numerical simulation

    Get PDF
    Experimental and modeling approaches fulfill complementary needs in the assessment of the seismic soil response. Here we present some results from 2D simulation performed for the L’Aquila basin (Central Appennines, Italy). The city of L’Aquila on April 6th, 2009 at 01:32 UTC was struck by a magnitude Mw=6.3 earthquake localized about 2 kilometers west of the city centre at hypocentral depth 9 km. The city of L’Aquila suffered wide spread destructive damage in its historical centre where housing is mainly 2 to 3 storey medieval masonry. Several reinforced concrete buildings built in the late 70s collapsed in the south-west section of the city and also monumental, historical churches were severely damaged. Because of its location, the ground motion recorded in the city is strongly influenced by the source rupture mechanism, nonetheless, local amplification are expected to have influenced the ground shacking. L’Aquila is indeed built over a Quaternary terraced alluvial-lacustrine basin with a rather complex lithology as well as surface topography. The 2D seismic modeling of L’Aquila terrace was already performed by several authors along transversally oriented (NE-SW) geological sections. In this study we present some new results obtained by the use of longitudinal cross sections (NW-SE) in order to better understand the role of lateral geological heterogeneities as derived by recent geological and geophysical data. The simulations have been performed using the impedance-operator-based numerical code. The models of L’Aquila terrace are based on geological and geophysical investigations performed in the framework of the micro-zoning activities of the city following the disastrous April 6th 2009 Mw=6.3 earthquake and in subsequent studies. The depth to the bedrock of the basin is constrained by gravimetric and deep borehole data with an estimated maximum depth of about 300 m. The basin is filled by silt and silty-clay of lacustrine origin topped by a breccia layer (BrA) of gravitational-fluvial origin. BrA does not extend continuously over the terrace and in particular in the southern area of the city it is locally replaced by silt and silty-clay of lacustrine origin with lens of BrA and gravel with silt. Locally, on the top of the terrace lens of less competent red silt were found by the recent deep borehole surveys performed in the micro-zoning activities. We have further constrained our 2D models using the resonance frequencies from noise and earthquake spectral ratios for selected sites. The wave velocities have been inferred by MASW and cross-hole analyses. We have compared the spectral ratios obtained from SH, P-SV and Rayleigh incident waves field in the range 0 -90 to the observed spectral ratios computed using the earthquake aftershocks recorded by the micro-zoning portable network. The modeling results are able to match the resonance frequency obtained by seismological data and to verify the role of the reversal in the velocity-depth profile and the lateral continuity of the top fast layer (BrA)
    • …
    corecore