907 research outputs found
3GPP QoS Model for Networks Using 3GPP QoS Classes
This draft describes an NSIS QoS Model (QOSM) based on 3GPP QoS classes and bearer service attributes. Specifically, this draftdescribes additional optional parameters for QSPEC which carries 3GPP QOSM specific information and how the QSPEC information should be processed in QNEs.\u
Chromatic transit light curves of disintegrating rocky planets
Context. Kepler observations have revealed a class of short period
exoplanets, of which Kepler-1520 b is the prototype, which have comet-like dust
tails thought to be the result of small, rocky planets losing mass. The shape
and chromaticity of the transits constrain the properties of the dust particles
originating from the planet's surface, offering a unique opportunity to probe
the composition and geophysics of rocky exoplanets.
Aims. We aim to approximate the average Kepler long-cadence light curve of
Kepler-1520 b and investigate how the optical thickness and transit
cross-section of a general dust tail can affect the observed wavelength
dependence and depth of transit light curves.
Methods. We developed a new 3D model that ejects sublimating particles from
the planet surface to build up a dust tail, assuming it to be optically thin,
and used 3D radiative transfer computations that fully treat scattering using
the distribution of hollow spheres (DHS) method, to generate transit light
curves between 0.45 and 2.5 m.
Results. We show that the transit depth is wavelength independent for
optically thick tails, potentially explaining why only some observations
indicate a wavelength dependence. From the 3D nature of our simulated tails, we
show that their transit cross-sections are related to the component of particle
ejection velocity perpendicular to the planet's orbital plane and use this to
derive a minimum ejection velocity of 1.2 kms. To fit the average
transit depth of Kepler-1520 b of 0.87%, we require a high dust mas-loss rate
of 7 80 M Gyr which implies planet lifetimes that may be
inconsistent with the observed sample. Therefore, these mass-loss rates should
be considered to be upper limits.Comment: 22 pages, 22 figures, accepted for publication in A&
Circulating antigen tests and urine reagent strips for diagnosis of active schistosomiasis in endemic areas
Background:
Point-of-care (POC) tests for diagnosing schistosomiasis include tests based on circulating antigen detection and urine reagent strip tests. If they had sufficient diagnostic accuracy they could replace conventional microscopy as they provide a quicker answer and are easier to use.
Objectives:
To summarise the diagnostic accuracy of: a) urine reagent strip tests in detecting activeSchistosoma haematobium infection, with microscopy as the reference standard; and b) circulating antigen tests for detecting active Schistosoma infection in geographical regions endemic for Schistosoma mansoni or S. haematobium or both, with microscopy as the reference standard.
Search methods:
We searched the electronic databases MEDLINE, EMBASE, BIOSIS, MEDION, and Health Technology Assessment (HTA) without language restriction up to 30 June 2014.
Selection criteria
We included studies that used microscopy as the reference standard: for S. haematobium, microscopy of urine prepared by filtration, centrifugation, or sedimentation methods; and for S. mansoni, microscopy of stool by Kato-Katz thick smear. We included studies on participants residing in endemic areas only.
Data collection and analysis:
Two review authors independently extracted data, assessed quality of the data using QUADAS-2, and performed meta-analysis where appropriate. Using the variability of test thresholds, we used the hierarchical summary receiver operating characteristic (HSROC) model for all eligible tests (except the circulating cathodic antigen (CCA) POC for S. mansoni, where the bivariate random-effects model was more appropriate). We investigated heterogeneity, and carried out indirect comparisons where data were sufficient. Results for sensitivity and specificity are presented as percentages with 95% confidence intervals (CI).
Main results;
We included 90 studies; 88 from field settings in Africa. The median S. haematobiuminfection prevalence was 41% (range 1% to 89%) and 36% for S. mansoni (range 8% to 95%). Study design and conduct were poorly reported against current standards.
Tests for S. haematobium
Urine reagent test strips versus microscopy
Compared to microscopy, the detection of microhaematuria on test strips had the highest sensitivity and specificity (sensitivity 75%, 95% CI 71% to 79%; specificity 87%, 95% CI 84% to 90%; 74 studies, 102,447 participants). For proteinuria, sensitivity was 61% and specificity was 82% (82,113 participants); and for leukocyturia, sensitivity was 58% and specificity 61% (1532 participants). However, the difference in overall test accuracy between the urine reagent strips for microhaematuria and proteinuria was not found to be different when we compared separate populations (P = 0.25), or when direct comparisons within the same individuals were performed (paired studies; P = 0.21).
When tests were evaluated against the higher quality reference standard (when multiple samples were analysed), sensitivity was marginally lower for microhaematuria (71% vs 75%) and for proteinuria (49% vs 61%). The specificity of these tests was comparable.
Antigen assay
Compared to microscopy, the CCA test showed considerable heterogeneity; meta-analytic sensitivity estimate was 39%, 95% CI 6% to 73%; specificity 78%, 95% CI 55% to 100% (four studies, 901 participants).
Tests for S. mansoni
Compared to microscopy, the CCA test meta-analytic estimates for detecting S. mansoni at a single threshold of trace positive were: sensitivity 89% (95% CI 86% to 92%); and specificity 55% (95% CI 46% to 65%; 15 studies, 6091 participants) Against a higher quality reference standard, the sensitivity results were comparable (89% vs 88%) but specificity was higher (66% vs 55%). For the CAA test, sensitivity ranged from 47% to 94%, and specificity from 8% to 100% (four studies, 1583 participants).
Authors' conclusions:
Among the evaluated tests for S. haematobium infection, microhaematuria correctly detected the largest proportions of infections and non-infections identified by microscopy.
The CCA POC test for S. mansoni detects a very large proportion of infections identified by microscopy, but it misclassifies a large proportion of microscopy negatives as positives in endemic areas with a moderate to high prevalence of infection, possibly because the test is potentially more sensitive than microscopy
An Inner Gaseous Disk around the Herbig Be Star MWC 147
We present high-spectral-resolution, optical spectra of the Herbig Be star
MWC 147, in which we spectrally resolve several emission lines, including the
[O I] lines at 6300 and 6363\deg. Their highly symmetric, double-peaked line
profiles indicate that the emission originates in a rotating circumstellar
disk. We deconvolve the Doppler-broadened [O I] emission lines to obtain a
measure of emission as a function of distance from the central star. The
resulting radial surface brightness profiles are in agreement with a disk
structure consisting of a flat, inner, gaseous disk and a flared, outer, dust
disk. The transition between these components at 2 to 3 AU corresponds to the
estimated dust sublimation radius. The width of the double-peaked Mg II line at
4481\deg suggests that the inner disk extends to at least 0.10 AU, close to the
corotation radius.Comment: accepted for ApJ Letters (Oct. 2010
Luminosity- and morphology-dependent clustering of galaxies
How does the clustering of galaxies depend on their inner properties like
morphological type and luminosity? We address this question in the mathematical
framework of marked point processes and clarify the notion of luminosity and
morphological segregation. A number of test quantities such as conditional
mark-weighted two-point correlation functions are introduced. These descriptors
allow for a scale-dependent analysis of luminosity and morphology segregation.
Moreover, they break the degeneracy between an inhomogeneous fractal point set
and actual present luminosity segregation. Using the Southern Sky Redshift
Survey~2 (da Costa et al. 1998, SSRS2) we find both luminosity and
morphological segregation at a high level of significance, confirming claims by
previous works using these data (Benoist et al. 1996, Willmer et al. 1998).
Specifically, the average luminosity and the fluctuations in the luminosity of
pairs of galaxies are enhanced out to separations of 15Mpc/h. On scales smaller
than 3Mpc/h the luminosities on galaxy pairs show a tight correlation. A
comparison with the random-field model indicates that galaxy luminosities
depend on the spatial distribution and galaxy-galaxy interactions. Early-type
galaxies are also more strongly correlated, indicating morphological
segregation. The galaxies in the PSCz catalog (Saunders et al. 2000) do not
show significant luminosity segregation. This again illustrates that mainly
early-type galaxies contribute to luminosity segregation. However, based on
several independent investigations we show that the observed luminosity
segregation can not be explained by the morphology-density relation alone.Comment: aastex, emulateapj5, 20 pages, 13 figures, several clarifying
comments added, ApJ accepte
Infrared Variability of Two Dusty White Dwarfs
The most heavily polluted white dwarfs often show excess infrared radiation
from circumstellar dust disks, which are modeled as a result of tidal
disruption of extrasolar minor planets. Interaction of dust, gas, and
disintegrating objects can all contribute to the dynamical evolution of these
dust disks. Here, we report on two infrared variable dusty white dwarfs, SDSS
J1228+1040 and G29-38. For SDSS J1228+1040, compared to the first measurements
in 2007, the IRAC [3.6] and [4.5] fluxes decreased by 20% by 2014 to a level
also seen in the recent 2018 observations. For G29-38, the infrared flux of the
10 m silicate emission feature became 10% stronger between 2004 and 2007,
We explore several scenarios that could account for these changes, including
tidal disruption events, perturbation from a companion, and runaway accretion.
No satisfactory causes are found for the flux drop in SDSS J1228+1040 due to
the limited time coverage. Continuous tidal disruption of small planetesimals
could increase the mass of small grains and concurrently change the strength of
the 10 m feature of G29-38. Dust disks around white dwarfs are actively
evolving and we speculate that there could be different mechanisms responsible
for the temporal changes of these disks.Comment: ApJ, in pres
3D-printed patient specific instruments for corrective osteotomies of the lower extremity
3D-printing has become a promising adjunct in orthopedic surgery over the past years. A significant drop in costs and increased availability of the required hardware and software needed for using the technique, have resulted in a relatively fast adaptation of 3D-printing techniques for various indications. In this review, the role of 3D-printing for deformity corrections of the lower extremity is described.</p
Economische effecten Schiphol:Over indirecte effecten en de gevolgen van capaciteitsschaarste
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