Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds. III. X-ray emission from wind-embedded shocks

NASA Astrophysics Data System (ADS)

Carneiro, L. P.; Puls, J.; Sundqvist, J. O.; Hoffmann, T. L.

2016-05-01

Context. Extreme ultraviolet (EUV) and X-ray radiation emitted from wind-embedded shocks in hot, massive stars can affect the ionization balance in their outer atmospheres and can be the mechanism responsible for producing highly ionized atomic species detected in stellar wind UV spectra. Aims: To allow for these processes in the context of spectral analysis, we have implemented the emission from wind-embedded shocks and related physics into our unified, NLTE model atmosphere/spectrum synthesis code FASTWIND. Methods: The shock structure and corresponding emission is calculated as a function of user-supplied parameters (volume filling factor, radial stratification of shock strength, and radial onset of emission). We account for a temperature and density stratification inside the postshock cooling zones, calculated for radiative and adiabatic cooling in the inner and outer wind, respectively. The high-energy absorption of the cool wind is considered by adding important K-shell opacities, and corresponding Auger ionization rates have been included in the NLTE network. To test our implementation and to check the resulting effects, we calculated a comprehensive model grid with a variety of X-ray emission parameters. Results: We tested and verified our implementation carefully against corresponding results from various alternative model atmosphere codes, and studied the effects from shock emission for important ions from He, C, N, O, Si, and P. Surprisingly, dielectronic recombination turned out to play an essential role for the ionization balance of O iv/O v (particularly in dwarfs with Teff~ 45 000 K). Finally, we investigated the frequency dependence and radial behavior of the mass absorption coefficient, κν(r), which is important in the context of X-ray line formation in massive star winds. Conclusions: In almost all of the cases considered, direct ionization is of major influence because of the enhanced EUV radiation field, and Auger ionization only affects N vi and O vi significantly. The approximation of a radially constant κν is justified for r ≳ 1.2 R∗ and λ ≲ 18 Å and also for many models at longer wavelengths. To estimate the actual value of this quantity, however, the He II opacities need to be calculated from detailed NLTE modeling, at least for wavelengths longer than 18 to 20 Å, and information on the individual CNO abundances has to be present.

Stellar laboratories. VII. New Kr iv - vii oscillator strengths and an improved spectral analysis of the hot, hydrogen-deficient DO-type white dwarf RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Quinet, P.; Hoyer, D.; Werner, K.; Richter, P.; Kruk, J. W.; Demleitner, M.

2016-05-01

Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: New Kr iv-vii oscillator strengths for a large number of lines enable us to construct more detailed model atoms for our NLTE model-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. Methods: We calculated Kr iv-vii oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines that are exhibited in high-resolution and high S/N ultraviolet (UV) observations of the hot white dwarf RE 0503-289. Results: We reanalyzed the effective temperature and surface gravity and determined Teff = 70000 ± 2000 K and log (g/ cm s-2) = 7.5 ± 0.1. We newly identified ten Kr v lines and one Kr vi line in the spectrum of RE 0503-289. We measured a Kr abundance of -3.3 ± 0.3 (logarithmic mass fraction). We discovered that the interstellar absorption toward RE 0503-289 has a multi-velocity structure within a radial-velocity interval of -40 km s-1

The solution of radiative transfer problems in molecular bands without the LTE assumption by accelerated lambda iteration methods

NASA Technical Reports Server (NTRS)

Kutepov, A. A.; Kunze, D.; Hummer, D. G.; Rybicki, G. B.

1991-01-01

An iterative method based on the use of approximate transfer operators, which was designed initially to solve multilevel NLTE line formation problems in stellar atmospheres, is adapted and applied to the solution of the NLTE molecular band radiative transfer in planetary atmospheres. The matrices to be constructed and inverted are much smaller than those used in the traditional Curtis matrix technique, which makes possible the treatment of more realistic problems using relatively small computers. This technique converges much more rapidly than straightforward iteration between the transfer equation and the equations of statistical equilibrium. A test application of this new technique to the solution of NLTE radiative transfer problems for optically thick and thin bands (the 4.3 micron CO2 band in the Venusian atmosphere and the 4.7 and 2.3 micron CO bands in the earth's atmosphere) is described.

Panchromatic Calibration of Astronomical Observations with State-of-the-Art White Dwarf Model Atmospheres

NASA Astrophysics Data System (ADS)

Rauch, T.

2016-05-01

Theoretical spectral energy distributions (SEDs) of white dwarfs provide a powerful tool for cross-calibration and sensitivity control of instruments from the far infrared to the X-ray energy range. Such SEDs can be calculated from fully metal-line blanketed NLTE model-atmospheres that are e.g. computed by the Tübingen NLTE Model-Atmosphere Package (TMAP) that has arrived at a high level of sophistication. TMAP was successfully employed for the reliable spectral analysis of many hot, compact post-AGB stars. High-quality stellar spectra obtained over a wide energy range establish a data base with a large number of spectral lines of many successive ions of different species. Their analysis allows to determine effective temperatures, surface gravities, and element abundances of individual (pre-)white dwarfs with very small error ranges. We present applications of TMAP SEDs for spectral analyses of hot, compact stars in the parameter range from (pre-) white dwarfs to neutron stars and demonstrate the improvement of flux calibration using white-dwarf SEDs that are e.g. available via registered services in the Virtual Observatory.

NLTE4 Plasma Population Kinetics Database

National Institute of Standards and Technology Data Gateway

SRD 159 NLTE4 Plasma Population Kinetics Database (Web database for purchase)   This database contains benchmark results for simulation of plasma population kinetics and emission spectra. The data were contributed by the participants of the 4th Non-LTE Code Comparison Workshop who have unrestricted access to the database. The only limitation for other users is in hidden labeling of the output results. Guest users can proceed to the database entry page without entering userid and password.

Signatures of Hot Molecular Hydrogen Absorption from Protoplanetary Disks. I. Non-thermal Populations

NASA Astrophysics Data System (ADS)

Hoadley, Keri; France, Kevin; Arulanantham, Nicole; Loyd, R. O. Parke; Kruczek, Nicholas

2017-09-01

The environment around protoplanetary disks (PPDs) regulates processes that drive the chemical and structural evolution of circumstellar material. We perform a detailed empirical survey of warm molecular hydrogen (H2) absorption observed against H I-Lyα (Lyα: λ1215.67) emission profiles for 22 PPDs, using archival Hubble Space Telescope ultraviolet (UV) spectra to identify H2 absorption signatures and quantify the column densities of H2 ground states in each sightline. We compare thermal equilibrium models of H2 to the observed H2 rovibrational level distributions. We find that, for the majority of targets, there is a clear deviation in high-energy states (T exc ≳ 20,000 K) away from thermal equilibrium populations (T(H2) ≳ 3500 K). We create a metric to estimate the total column density of non-thermal H2 (N(H2)nLTE) and find that the total column densities of thermal (N(H2)) and N(H2)nLTE correlate for transition disks and targets with detectable C IV-pumped H2 fluorescence. We compare N(H2) and N(H2)nLTE to circumstellar observables and find that N(H2)nLTE correlates with X-ray and far-UV luminosities, but no correlations are observed with the luminosities of discrete emission features (e.g., Lyα, C IV). Additionally, N(H2) and N(H2)nLTE are too low to account for the H2 fluorescence observed in PPDs, so we speculate that this H2 may instead be associated with a diffuse, hot, atomic halo surrounding the planet-forming disk. We create a simple photon-pumping model for each target to test this hypothesis and find that Lyα efficiently pumps H2 levels with T exc ≥ 10,000 K out of thermal equilibrium.

NLTE Line Blanketed Model Atmospheres for Hot, Metal-rich White Dwarfs

NASA Astrophysics Data System (ADS)

Hubeny, I.; Lanz, T.

1993-05-01

Recent observations of some hot DA white dwarfs (Feige 24, G191 B2B - Sion et al. 1992, Ap.J. 391, L29; Vennes et al. 1992, Ap.J. 392, L27) and subsequent analyses have demonstrated that their atmospheres are contaminated with heavy metal species with appreciable abundances. So far, modeling was mostly limited to calculating synthetic spectra (usually in LTE), based on previously calculated model atmospheres that were constructed assuming a simplified chemical composition. However, in reality the metal lines may also significantly influence the temperature structure, and consequently the ionization balance of some important species. Since the effective temperature is rather high (55000 to 60000 K), the NLTE effects may be important despite the high gravity. Therefore, in order to settle the question on metal abundances of hot DA white dwarfs, we need to calculate NLTE fully line blanketed model atmospheres. Using our previously developed hybrid complete linearization/accelerated lambda iteration method, we have calculated a set of NLTE models including H, He, C, N, O, and Fe, with some 13000 lines of Fe IV, Fe V and Fe VI taken into account explicitly in model construction. The NLTE departure coefficients for all levels of Fe IV, Fe V, and Fe VI are then employed in the spectrum synthesis program SYNSPEC. In the first part of this study, we present a theoretical comparison between models computed with adding more and more opacity sources, and show how the temperature structure and synthetic spectra develop. We also discuss possible errors arising from using an inconsistent spectrum synthesis (the metals considered only in the spectrum synthesis, not in the model construction). In the second part, we compare the computed UV spectra with with available observations of Feige 24 and G191 B2B, and deduce limits for the iron abundance of these stars.

TMAP: Tübingen NLTE Model-Atmosphere Package

NASA Astrophysics Data System (ADS)

Werner, Klaus; Dreizler, Stefan; Rauch, Thomas

2012-12-01

The Tübingen NLTE Model-Atmosphere Package (TMAP) is a tool to calculate stellar atmospheres in spherical or plane-parallel geometry in hydrostatic and radiative equilibrium allowing departures from local thermodynamic equilibrium (LTE) for the population of atomic levels. It is based on the Accelerated Lambda Iteration (ALI) method and is able to account for line blanketing by metals. All elements from hydrogen to nickel may be included in the calculation with model atoms which are tailored for the aims of the user.

RED SUPERGIANTS AS COSMIC ABUNDANCE PROBES: THE SCULPTOR GALAXY NGC 300

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gazak, J. Zachary; Kudritzki, Rolf; Bresolin, Fabio

2015-06-01

We present a quantitative spectroscopic study of 27 red supergiants (RSGs) in the Sculptor Galaxy NGC 300. J-band spectra were obtained using KMOS on the Very Large Telescope and studied with state of the art synthetic spectra including NLTE corrections for the strongest diagnostic lines. We report a central metallicity of [Z] = −0.03 ± 0.05 with a gradient of −0.083 ± 0.014 [dex/kpc], in agreement with previous studies of blue supergiants and H ii-region auroral line measurements. This result marks the first application of the J-band spectroscopic method to a population of individual RSG stars beyond the Local Groupmore » of galaxies and reveals the great potential of this technique.« less

Galactic evolution of copper in the light of NLTE computations

NASA Astrophysics Data System (ADS)

Andrievsky, S.; Bonifacio, P.; Caffau, E.; Korotin, S.; Spite, M.; Spite, F.; Sbordone, L.; Zhukova, A. V.

2018-01-01

We have developed a model atom for Cu with which we perform statistical equilibrium computations that allow us to compute the line formation of Cu I lines in stellar atmospheres without assuming local thermodynamic equilibrium (LTE). We validate this model atom by reproducing the observed line profiles of the Sun, Procyon and 11 metal-poor stars. Our sample of stars includes both dwarfs and giants. Over a wide range of stellar parameters, we obtain excellent agreement among different Cu I lines. The 11 metal-poor stars have iron abundances in the range - 4.2 ≤ [Fe/H] ≤ -1.4, the weighted mean of the [Cu/Fe] ratios is -0.22 dex, with a scatter of -0.15 dex. This is very different from the results from LTE analysis (the difference between NLTE and LTE abundances reaches 1 dex) and in spite of the small size of our sample, it prompts for a revision of the Galactic evolution of Cu.

UV spectroscopy including ISM line absorption: of the exciting star of Abell 35

NASA Astrophysics Data System (ADS)

Ziegler, M.; Rauch, T.; Werner, K.; Kruk, J. W.

Reliable spectral analysis that is based on high-resolution UV observations requires an adequate, simultaneous modeling of the interstellar line absorption and reddening. In the case of the central star of the planetary nebula Abell 35, BD-22 3467, we demonstrate our current standard spectral-analysis method that is based on the Tübingen NLTE Model-Atmosphere Package (TMAP). We present an on- going spectral analysis of FUSE and HST/STIS observations of BD-22 3467.

OXYGEN ABUNDANCES IN CEPHEIDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luck, R. E.; Andrievsky, S. M.; Korotin, S. N.

2013-07-01

Oxygen abundances in later-type stars, and intermediate-mass stars in particular, are usually determined from the [O I] line at 630.0 nm, and to a lesser extent, from the O I triplet at 615.7 nm. The near-IR triplets at 777.4 nm and 844.6 nm are strong in these stars and generally do not suffer from severe blending with other species. However, these latter two triplets suffer from strong non-local thermodynamic equilibrium (NLTE) effects and thus see limited use in abundance analyses. In this paper, we derive oxygen abundances in a large sample of Cepheids using the near-IR triplets from an NLTEmore » analysis, and compare those abundances to values derived from a local thermodynamic equilibrium (LTE) analysis of the [O I] 630.0 nm line and the O I 615.7 nm triplet as well as LTE abundances for the 777.4 nm triplet. All of these lines suffer from line strength problems making them sensitive to either measurement complications (weak lines) or to line saturation difficulties (strong lines). Upon this realization, the LTE results for the [O I] lines and the O I 615.7 nm triplet are in adequate agreement with the abundance from the NLTE analysis of the near-IR triplets.« less

Cretin Memory Flow on Sierra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langer, S. H.; Scott, H. A.

2016-08-05

The Cretin iCOE project has a goal of enabling the efficient generation of Non-LTE opacities for use in radiation-hydrodynamic simulation codes using the Nvidia boards on LLNL’s upcoming Sierra system. Achieving the desired level of accuracy for some simulations require the use of a vary large number of atomic configurations (a configuration includes the atomic level for all electrons and how they are coupled together). The NLTE rate matrix needs to be solved separately in each zone. Calculating NLTE opacities can consume more time than all other physics packages used in a simulation.

Signatures of Hot Molecular Hydrogen Absorption from Protoplanetary Disks. I. Non-thermal Populations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoadley, Keri; France, Kevin; Arulanantham, Nicole

2017-09-01

The environment around protoplanetary disks (PPDs) regulates processes that drive the chemical and structural evolution of circumstellar material. We perform a detailed empirical survey of warm molecular hydrogen (H{sub 2}) absorption observed against H i-Ly α (Ly α : λ 1215.67) emission profiles for 22 PPDs, using archival Hubble Space Telescope ultraviolet (UV) spectra to identify H{sub 2} absorption signatures and quantify the column densities of H{sub 2} ground states in each sightline. We compare thermal equilibrium models of H{sub 2} to the observed H{sub 2} rovibrational level distributions. We find that, for the majority of targets, there is amore » clear deviation in high-energy states ( T {sub exc} ≳ 20,000 K) away from thermal equilibrium populations ( T (H{sub 2}) ≳ 3500 K). We create a metric to estimate the total column density of non-thermal H{sub 2} ( N (H{sub 2}){sub nLTE}) and find that the total column densities of thermal ( N (H{sub 2})) and N (H{sub 2}){sub nLTE} correlate for transition disks and targets with detectable C iv-pumped H{sub 2} fluorescence. We compare N (H{sub 2}) and N (H{sub 2}){sub nLTE} to circumstellar observables and find that N (H{sub 2}){sub nLTE} correlates with X-ray and far-UV luminosities, but no correlations are observed with the luminosities of discrete emission features (e.g., Ly α , C iv). Additionally, N (H{sub 2}) and N (H{sub 2}){sub nLTE} are too low to account for the H{sub 2} fluorescence observed in PPDs, so we speculate that this H{sub 2} may instead be associated with a diffuse, hot, atomic halo surrounding the planet-forming disk. We create a simple photon-pumping model for each target to test this hypothesis and find that Ly α efficiently pumps H{sub 2} levels with T {sub exc} ≥ 10,000 K out of thermal equilibrium.« less

Collisional-radiative modeling of tungsten at temperatures of 1200–2400 eV

DOE PAGES

Colgan, James; Fontes, Christopher; Zhang, Honglin; ...

2015-04-30

We discuss new collisional-radiative modeling calculations of tungsten at moderate temperatures of 1200 to 2400 eV. Such plasma conditions are relevant to ongoing experimental work at ASDEX Upgrade and are expected to be relevant for ITER. Our calculations are made using the Los Alamos National Laboratory (LANL) collisional-radiative modeling ATOMIC code. These calculations formed part of a submission to the recent NLTE-8 workshop that was held in November 2013. This series of workshops provides a forum for detailed comparison of plasma and spectral quantities from NLTE collisional-radiative modeling codes. We focus on the LANL ATOMIC calculations for tungsten that weremore » submitted to the NLTE-8 workshop and discuss different models that were constructed to predict the tungsten emission. In particular, we discuss comparisons between semi-relativistic configuration-average and fully relativistic configuration-average calculations. As a result, we also present semi-relativistic calculations that include fine-structure detail, and discuss the difficult problem of ensuring completeness with respect to the number of configurations included in a CR calculation.« less

Oxygen-Sodium Anticorrelation in Field RR Lyr-Type Stars

NASA Astrophysics Data System (ADS)

Andrievsky, S.; Korotin, S.; Lyashko, D.; Tsymbal, V.

2017-06-01

We have performed analysis of a large amount of the fields RR Lyr type stars spectra with the aim to derive NLTE oxygen and sodium abundances in our program stars. Fundamental parameters (Teff, log g, Vt) and metallicity were found using the method of the fitting between synthetic and observed spectra using the SME program which was developed by N. Piskunov and J. A. Valenti. As a result of this analysis anticorrelation between oxygen (O/H) and sodium (Na/H) abundances was found.

Spectral Analysis within the Virtual Observatory: The GAVO Service TheoSSA

NASA Astrophysics Data System (ADS)

Ringat, E.

2012-03-01

In the last decade, numerous Virtual Observatory organizations were established. One of these is the German Astrophysical Virtual Observatory (GAVO) that e.g. provides access to spectral energy distributions via the service TheoSSA. In a pilot phase, these are based on the Tübingen NLTE Model-Atmosphere Package (TMAP) and suitable for hot, compact stars. We demonstrate the power of TheoSSA in an application to the sdOB primary of AA Doradus by comparison with a “classical” spectral analysis.

NLTE steady-state response matrix method.

NASA Astrophysics Data System (ADS)

Faussurier, G.; More, R. M.

2000-05-01

A connection between atomic kinetics and non-equilibrium thermodynamics has been recently established by using a collisional-radiative model modified to include line absorption. The calculated net emission can be expressed as a non-local thermodynamic equilibrium (NLTE) symmetric response matrix. In the paper, this connection is extended to both cases of the average-atom model and the Busquet's model (RAdiative-Dependent IOnization Model, RADIOM). The main properties of the response matrix still remain valid. The RADIOM source function found in the literature leads to a diagonal response matrix, stressing the absence of any frequency redistribution among the frequency groups at this order of calculation.

Molecular description of steady supersonic free jets

NASA Astrophysics Data System (ADS)

Montero, S.

2017-09-01

A detailed analysis of the non-local thermal equilibrium (n-LTE) problem in the paraxial zone of silence of supersonic free jets is reported. The study is based on a hybrid approach that combines Navier-Stokes equations with a kinetic equation derived from the generalized Boltzmann (Waldmann-Snider) equation. The resulting system is solved for those flow quantities not easily amenable to experimental measure (translational temperature, flow velocity, and entropy) in terms of the quantities that can be measured accurately (distance, number density, population of rotational states, and their gradients). The reported solutions are essentially exact and are formulated in terms of macroscopic quantities, as well as in terms of elementary collision processes. Emphasis is made on the influence of dissipative effects onto the flow (viscous and diabatic) and of the breakdown of thermal equilibrium onto the evolution of entropy and translational temperature. The influence of inelastic collisions onto these effects is analysed in depth. The reported equations are aimed at optimizing the experimental knowledge of the n-LTE problem and its quantitative interpretation in terms of state-to-state rates for inelastic collisions.

Modeling the near-ultraviolet band of GK stars. III. Dependence on abundance pattern

DOE Office of Scientific and Technical Information (OSTI.GOV)

Short, C. Ian; Campbell, Eamonn A., E-mail: ishort@ap.smu.ca

2013-06-01

We extend the grid of non-LTE (NLTE) models presented in Paper II to explore variations in abundance pattern in two ways: (1) the adoption of the Asplund et al. (GASS10) abundances, (2) for stars of metallicity, [M/H], of –0.5, the adoption of a non-solar enhancement of α-elements by +0.3 dex. Moreover, our grid of synthetic spectral energy distributions (SEDs) is interpolated to a finer numerical resolution in both T {sub eff} (ΔT {sub eff} = 25 K) and log g (Δlog g = 0.25). We compare the values of T {sub eff} and log g inferred from fitting LTE andmore » NLTE SEDs to observed SEDs throughout the entire visible band, and in an ad hoc 'blue' band. We compare our spectrophotometrically derived T {sub eff} values to a variety of T {sub eff} calibrations, including more empirical ones, drawn from the literature. For stars of solar metallicity, we find that the adoption of the GASS10 abundances lowers the inferred T {sub eff} value by 25-50 K for late-type giants, and NLTE models computed with the GASS10 abundances give T {sub eff} results that are marginally in better agreement with other T {sub eff} calibrations. For stars of [M/H] = –0.5 there is marginal evidence that adoption of α-enhancement further lowers the derived T {sub eff} value by 50 K. Stellar parameters inferred from fitting NLTE models to SEDs are more dependent than LTE models on the wavelength region being fitted, and we find that the effect depends on how heavily line blanketed the fitting region is, whether the fitting region is to the blue of the Wien peak of the star's SED, or both.« less

A New Stellar Atmosphere Grid and Comparisons with HST /STIS CALSPEC Flux Distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bohlin, Ralph C.; Fleming, Scott W.; Gordon, Karl D.

The Space Telescope Imaging Spectrograph has measured the spectral energy distributions for several stars of types O, B, A, F, and G. These absolute fluxes from the CALSPEC database are fit with a new spectral grid computed from the ATLAS-APOGEE ATLAS9 model atmosphere database using a chi-square minimization technique in four parameters. The quality of the fits are compared for complete LTE grids by Castelli and Kurucz (CK04) and our new comprehensive LTE grid (BOSZ). For the cooler stars, the fits with the MARCS LTE grid are also evaluated, while the hottest stars are also fit with the NLTE Lanzmore » and Hubeny OB star grids. Unfortunately, these NLTE models do not transition smoothly in the infrared to agree with our new BOSZ LTE grid at the NLTE lower limit of T {sub eff} = 15,000 K. The new BOSZ grid is available via the Space Telescope Institute MAST archive and has a much finer sampled IR wavelength scale than CK04, which will facilitate the modeling of stars observed by the James Webb Space Telescope . Our result for the angular diameter of Sirius agrees with the ground-based interferometric value.« less

A New Stellar Atmosphere Grid and Comparisons with HST/STIS CALSPEC Flux Distributions

NASA Astrophysics Data System (ADS)

Bohlin, Ralph C.; Mészáros, Szabolcs; Fleming, Scott W.; Gordon, Karl D.; Koekemoer, Anton M.; Kovács, József

2017-05-01

The Space Telescope Imaging Spectrograph has measured the spectral energy distributions for several stars of types O, B, A, F, and G. These absolute fluxes from the CALSPEC database are fit with a new spectral grid computed from the ATLAS-APOGEE ATLAS9 model atmosphere database using a chi-square minimization technique in four parameters. The quality of the fits are compared for complete LTE grids by Castelli & Kurucz (CK04) and our new comprehensive LTE grid (BOSZ). For the cooler stars, the fits with the MARCS LTE grid are also evaluated, while the hottest stars are also fit with the NLTE Lanz & Hubeny OB star grids. Unfortunately, these NLTE models do not transition smoothly in the infrared to agree with our new BOSZ LTE grid at the NLTE lower limit of T eff = 15,000 K. The new BOSZ grid is available via the Space Telescope Institute MAST archive and has a much finer sampled IR wavelength scale than CK04, which will facilitate the modeling of stars observed by the James Webb Space Telescope. Our result for the angular diameter of Sirius agrees with the ground-based interferometric value.

Non-LTE aluminium abundances in late-type stars

NASA Astrophysics Data System (ADS)

Nordlander, T.; Lind, K.

2017-11-01

Aims: Aluminium plays a key role in studies of the chemical enrichment of the Galaxy and of globular clusters. However, strong deviations from LTE (non-LTE) are known to significantly affect the inferred abundances in giant and metal-poor stars. Methods: We present non-local thermodynamic equilibrium (NLTE) modeling of aluminium using recent and accurate atomic data, in particular utilizing new transition rates for collisions with hydrogen atoms, without the need for any astrophysically calibrated parameters. For the first time, we perform 3D NLTE modeling of aluminium lines in the solar spectrum. We also compute and make available extensive grids of abundance corrections for lines in the optical and near-infrared using one-dimensional model atmospheres, and apply grids of precomputed departure coefficients to direct line synthesis for a set of benchmark stars with accurately known stellar parameters. Results: Our 3D NLTE modeling of the solar spectrum reproduces observed center-to-limb variations in the solar spectrum of the 7835 Å line as well as the mid-infrared photospheric emission line at 12.33 μm. We infer a 3D NLTE solar photospheric abundance of A(Al) = 6.43 ± 0.03, in exact agreement with the meteoritic abundance. We find that abundance corrections vary rapidly with stellar parameters; for the 3961 Å resonance line, corrections are positive and may be as large as +1 dex, while corrections for subordinate lines generally have positive sign for warm stars but negative for cool stars. Our modeling reproduces the observed line profiles of benchmark K-giants, and we find abundance corrections as large as -0.3 dex for Arcturus. Our analyses of four metal-poor benchmark stars yield consistent abundances between the 3961 Å resonance line and lines in the UV, optical and near-infrared regions. Finally, we discuss implications for the galactic chemical evolution of aluminium.

Stellar atmosphere modeling of extremely hot, compact stars

NASA Astrophysics Data System (ADS)

Rauch, Thomas; Ringat, Ellen; Werner, Klaus

Present X-ray missions like Chandra and XMM-Newton provide excellent spectra of extremely hot white dwarfs, e.g. burst spectra of novae. Their analysis requires adequate NLTE model atmospheres. The Tuebingen Non-LTE Model-Atmosphere Package (TMAP) can calculate such model at-mospheres and spectral energy distributions at a high level of sophistication. We present a new grid of models that is calculated in the parameter range of novae and supersoft X-ray sources and show examples of their application.

NLTE modeling of a small active region filament observed with the VTT

NASA Astrophysics Data System (ADS)

Schwartz, P.; Balthasar, H.; Kuckein, C.; Koza, J.; Gömöry, P.; Rybák, J.; Heinzel, P.; Kučera, A.

2016-11-01

An active region mini-discretionary-filament was observed with the Vacuum Tower Telescope (VTT) in Tenerife simultaneously in the He I infrared triplet using the Tenerife Infrared Polarimeter 1 (TIP 1), in Hα with the TESOS Fabry-Pérot interferometer, and in Ca II 8542 Å with the VTT spectrograph. The spectropolarimetric data were inverted using the HAZEL code and Hα profiles were modelled by solving a NLTE radiative transfer in a simple isobaric and isothermal 2D slab irradiated both from its bottom and sides from the solar surface. It was found that the mini-discretionary-filament is composed of horizontal fluxtubes, along which the cool plasma of T˜10 000 K can flow with very large, even supersonic, velocities.

Accelerating NLTE radiative transfer by means of the Forth-and-Back Implicit Lambda Iteration: A two-level atom line formation in 2D Cartesian coordinates

NASA Astrophysics Data System (ADS)

Milić, Ivan; Atanacković, Olga

2014-10-01

State-of-the-art methods in multidimensional NLTE radiative transfer are based on the use of local approximate lambda operator within either Jacobi or Gauss-Seidel iterative schemes. Here we propose another approach to the solution of 2D NLTE RT problems, Forth-and-Back Implicit Lambda Iteration (FBILI), developed earlier for 1D geometry. In order to present the method and examine its convergence properties we use the well-known instance of the two-level atom line formation with complete frequency redistribution. In the formal solution of the RT equation we employ short characteristics with two-point algorithm. Using an implicit representation of the source function in the computation of the specific intensities, we compute and store the coefficients of the linear relations J=a+bS between the mean intensity J and the corresponding source function S. The use of iteration factors in the ‘local’ coefficients of these implicit relations in two ‘inward’ sweeps of 2D grid, along with the update of the source function in other two ‘outward’ sweeps leads to four times faster solution than the Jacobi’s one. Moreover, the update made in all four consecutive sweeps of the grid leads to an acceleration by a factor of 6-7 compared to the Jacobi iterative scheme.

Observing the metal-poor solar neighbourhood: a comparison of galactic chemical evolution predictions*†

NASA Astrophysics Data System (ADS)

Mishenina, T.; Pignatari, M.; Côté, B.; Thielemann, F.-K.; Soubiran, C.; Basak, N.; Gorbaneva, T.; Korotin, S. A.; Kovtyukh, V. V.; Wehmeyer, B.; Bisterzo, S.; Travaglio, C.; Gibson, B. K.; Jordan, C.; Paul, A.; Ritter, C.; Herwig, F.; NuGrid Collaboration

2017-08-01

Atmospheric parameters and chemical compositions for 10 stars with metallicities in the region of -2.2 < [Fe/H] < -0.6 were precisely determined using high-resolution, high signal-to-noise, spectra. For each star, the abundances, for 14-27 elements, were derived using both local thermodynamic equilibrium (LTE) and non-LTE (NLTE) approaches. In particular, differences by assuming LTE or NLTE are about 0.10 dex; depending on [Fe/H], Teff, gravity and element lines used in the analysis. We find that the O abundance has the largest error, ranging from 0.10 and 0.2 dex. The best measured elements are Cr, Fe, and Mn; with errors between 0.03 and 0.11 dex. The stars in our sample were included in previous different observational work. We provide a consistent data analysis. The data dispersion introduced in the literature by different techniques and assumptions used by the different authors is within the observational errors, excepting for HD103095. We compare these results with stellar observations from different data sets and a number of theoretical galactic chemical evolution (GCE) simulations. We find a large scatter in the GCE results, used to study the origin of the elements. Within this scatter as found in previous GCE simulations, we cannot reproduce the evolution of the elemental ratios [Sc/Fe], [Ti/Fe], and [V/Fe] at different metallicities. The stellar yields from core-collapse supernovae are likely primarily responsible for this discrepancy. Possible solutions and open problems are discussed.

A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munafò, A., E-mail: munafo@illinois.edu; Alfuhaid, S. A., E-mail: alfuhai2@illinois.edu; Panesi, M., E-mail: mpanesi@illinois.edu

2015-10-07

The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled systemmore » of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.« less

NON-LOCAL THERMODYNAMICAL EQUILIBRIUM EFFECTS ON THE IRON ABUNDANCE OF ASYMPTOTIC GIANT BRANCH STARS IN 47 TUCANAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lapenna, E.; Mucciarelli, A.; Lanzoni, B.

2014-12-20

We present the iron abundance of 24 asymptotic giant branch (AGB) stars, members of the globular cluster 47 Tucanae, obtained with high-resolution spectra collected with the FEROS spectrograph at the MPG/ESO 2.2 m Telescope. We find that the iron abundances derived from neutral lines (with a mean value [Fe I/H] =–0.94 ± 0.01, σ = 0.08 dex) are systematically lower than those derived from single ionized lines ([Fe II/H] =–0.83 ± 0.01, σ = 0.05 dex). Only the latter are in agreement with those obtained for a sample of red giant branch (RGB) cluster stars, for which the Fe I andmore » Fe II lines provide the same iron abundance. This finding suggests that non-local thermodynamical equilibrium (NLTE) effects driven by overionization mechanisms are present in the atmosphere of AGB stars and significantly affect the Fe I lines while leaving Fe II features unaltered. On the other hand, the very good ionization equilibrium found for RGB stars indicates that these NLTE effects may depend on the evolutionary stage. We discuss the impact of this finding on both the chemical analysis of AGB stars and on the search for evolved blue stragglers.« less

Program Package for the Analysis of High Resolution High Signal-To-Noise Stellar Spectra

NASA Astrophysics Data System (ADS)

Piskunov, N.; Ryabchikova, T.; Pakhomov, Yu.; Sitnova, T.; Alekseeva, S.; Mashonkina, L.; Nordlander, T.

2017-06-01

The program package SME (Spectroscopy Made Easy), designed to perform an analysis of stellar spectra using spectral fitting techniques, was updated due to adding new functions (isotopic and hyperfine splittins) in VALD and including grids of NLTE calculations for energy levels of few chemical elements. SME allows to derive automatically stellar atmospheric parameters: effective temperature, surface gravity, chemical abundances, radial and rotational velocities, turbulent velocities, taking into account all the effects defining spectral line formation. SME package uses the best grids of stellar atmospheres that allows us to perform spectral analysis with the similar accuracy in wide range of stellar parameters and metallicities - from dwarfs to giants of BAFGK spectral classes.

VizieR Online Data Catalog: NLTE spectral analysis of white dwarf G191-B2B (Rauch+, 2013)

NASA Astrophysics Data System (ADS)

Rauch, T.; Werner, K.; Bohlin, R.; Kruk, J. W.

2013-08-01

In the framework of the Virtual Observatory, the German Astrophysical Virtual Observatory developed the registered service TheoSSA. It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code. In case of the DA white dwarf G191-B2B, we demonstrate that the model reproduces not only its overall continuum shape but also the numerous metal lines exhibited in its ultraviolet spectrum. (3 data files).

Analysis of the Non-LTE Lithium Abundance for a Large Sample of F-, G-, and K-Giants and Supergiants

NASA Astrophysics Data System (ADS)

Lyubimkov, L. S.; Petrov, D. V.

2017-09-01

A five-dimensional interpolation method and corresponding computer program are developed for using published calculations to determine the non-LTE correction ΔNLTE to the lithium abundance logɛ(Li) derived from the Li I 6707.8 Å line. The ΔNLTE value is determined from the following five parameters: the effective temperature Teff, the acceleration of gravity logg, the metallicity index [Fe/H], the microturbulent velocity Vt, and the LTE Li abundance logɛ(Li) . The program is used to calculate values of ΔNLTE and the non-LTE Li abundance for 91 single bright giants from the list of Lebre, et al. By combining these results with data for 55 stars from the previous paper, we obtain the non-LTE values of logɛ(Li) for 146 FGK-giants and supergiants. We confirm that, because of the absence of the Li line in the spectra of most of these stars, it is only possible to estimate for them an upper bound for the Li abundance. A large spread is confirmed in logɛ(Li) for stars with masses M ≤ 6M ⦿ . A comparison of these results with model calculations of stars confirms the unique sensitivity of the lithium abundance to the initial rotation velocity V0. We discuss the giants and supergiants with lithium abundances logɛ(Li) = 1.4 ± 0.3 , which could have a rotational velocity V0=0 km/s and have already undergone deep convective mixing. Li-rich giants with lithium abundances logɛ(Li) ≥ 2 and nearly up to the initial value of logɛ(Li) = 3.2 ± 0.1 are examined. It is shown that the fraction of Li-rich giants with V0 ≈ 0 - 50 km/s is consistent with current evolutionary models. The other stars of this type, as well as all of the "super Li-rich" giants, for which the standard theory is untenable, can be explained by invoking the hypothesis of recent lithium synthesis in the star or an alternative hypothesis according to which a giant planet is engulfed by the star.

A Grid of NLTE Line-blanketed Model Atmospheres of Early B-Type Stars

NASA Astrophysics Data System (ADS)

Lanz, Thierry; Hubeny, Ivan

2007-03-01

We have constructed a comprehensive grid of 1540 metal line-blanketed, NLTE, plane-parallel, hydrostatic model atmospheres for the basic parameters appropriate to early B-type stars. The BSTAR2006 grid considers 16 values of effective temperatures, 15,000 K<=Teff<=30,000 K with 1000 K steps, 13 surface gravities, 1.75<=logg<=4.75 with 0.25 dex steps, six chemical compositions, and a microturbulent velocity of 2 km s-1. The lower limit of logg for a given effective temperature is set by an approximate location of the Eddington limit. The selected chemical compositions range from twice to one-tenth of the solar metallicity and metal-free. Additional model atmospheres for B supergiants (logg<=3.0) have been calculated with a higher microturbulent velocity (10 km s-1) and a surface composition that is enriched in helium and nitrogen and depleted in carbon. This new grid complements our earlier OSTAR2002 grid of O-type stars (our Paper I). The paper contains a description of the BSTAR2006 grid and some illustrative examples and comparisons. NLTE ionization fractions, bolometric corrections, radiative accelerations, and effective gravities are obtained over the parameter range covered by the grid. By extrapolating radiative accelerations, we have determined an improved estimate of the Eddington limit in absence of rotation between 55,000 and 15,000 K. The complete BSTAR2006 grid is available at the TLUSTY Web site.

CHEMICAL ANALYSIS OF ASYMPTOTIC GIANT BRANCH STARS IN M62

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lapenna, E.; Mucciarelli, A.; Ferraro, F. R.

2015-11-10

We have collected UVES-FLAMES high-resolution spectra for a sample of 6 asymptotic giant branch (AGB) and 13 red giant branch (RGB) stars in the Galactic globular cluster (GC) M62 (NGC 6266). Here we present the detailed abundance analysis of iron, titanium, and light elements (O, Na, Mg, and Al). For the majority (five out of six) of the AGB targets, we find that the abundances of both iron and titanium determined from neutral lines are significantly underestimated with respect to those obtained from ionized features, the latter being, instead, in agreement with those measured for the RGB targets. This ismore » similar to recent findings in other clusters and may suggest the presence of nonlocal thermodynamic equilibrium (NLTE) effects. In the O–Na, Al–Mg, and Na–Al planes, the RGB stars show the typical correlations observed for GC stars. Instead, all the AGB targets are clumped in the regions where first-generation stars are expected to lie, similar to what was recently found for the AGB population of NGC 6752. While the sodium and aluminum abundances could be underestimated as a consequence of the NLTE bias affecting iron and titanium, the oxygen line used does not suffer from the same effects, and the lack of O-poor AGB stars therefore is a solid result. We can thus conclude that none of the investigated AGB stars belongs to the second stellar generation of M62. We also find an RGB star with extremely high sodium abundance ([Na/Fe] = +1.08 dex)« less

Lithium abundance and 6Li/7Li ratio in the active giant HD 123351. I. A comparative analysis of 3D and 1D NLTE line-profile fits

NASA Astrophysics Data System (ADS)

Mott, A.; Steffen, M.; Caffau, E.; Spada, F.; Strassmeier, K. G.

2017-08-01

Context. Current three-dimensional (3D) hydrodynamical model atmospheres together with detailed spectrum synthesis, accounting for departures from local thermodynamic equilibrium (LTE), permit to derive reliable atomic and isotopic chemical abundances from high-resolution stellar spectra. Not much is known about the presence of the fragile 6Li isotope in evolved solar-metallicity red giant branch (RGB) stars, not to mention its production in magnetically active targets like HD 123351. Aims: A detailed spectroscopic investigation of the lithium resonance doublet in HD 123351 in terms of both abundance and isotopic ratio is presented. From fits of the observed spectrum, taken at the Canada-France-Hawaii telescope, with synthetic line profiles based on 1D and 3D model atmospheres, we seek to estimate the abundance of the 6Li isotope and to place constraints on its origin. Methods: We derive the lithium abundance A(Li) and the 6Li/7Li isotopic ratio by fitting different synthetic spectra to the Li-line region of a high-resolution CFHT spectrum (R = 120 000, S/N = 400). The synthetic spectra are computed with four different line lists, using in parallel 3D hydrodynamical CO5BOLD and 1D LHD model atmospheres and treating the line formation of the lithium components in non-LTE (NLTE). The fitting procedure is repeated with different assumptions and wavelength ranges to obtain a reasonable estimate of the involved uncertainties. Results: We find A(Li) = 1.69 ± 0.11 dex and 6Li/7Li = 8.0 ± 4.4% in 3D-NLTE, using the line list of Meléndez et al. (2012, A&A, 543, A29), updated with new atomic data for V I, which results in the best fit of the lithium line profile of HD 123351. Two other line lists lead to similar results but with inferior fit qualities. Conclusions: Our 2σ detection of the 6Li isotope is the result of a careful statistical analysis and the visual inspection of each achieved fit. Since the presence of a significant amount of 6Li in the atmosphere of a cool evolved star is not expected in the framework of standard stellar evolution theory, non-standard, external lithium production mechanisms, possibly related to stellar activity or a recent accretion of rocky material, need to be invoked to explain the detection of 6Li in HD 123351.

FUSE Observations of Galactic and LMC Novae in Outburst

NASA Technical Reports Server (NTRS)

Huschildt, P. H.

2001-01-01

This document is a collection of five abstracts from papers written on the 'FUSE Observations of Galactic and LMC Novae in Outburst'. The titles are the following: (1) Analyzing FUSE Observations of Galactic and LMC Novae; (2) Detailed NLTE Model Atmospheres for Novae during Outburst: Modeling Optical and Ultraviolet Observations for Nova LMC 1988; (3) Numerical Solution of the Expanding Stellar Atmosphere Problem; (4) A Non-LTE Line-Blanketed Expanding Atmosphere Model for A-supergiant Alpha Cygni; and (5) Non-LTE Model Atmosphere Analysis of the Early Ultraviolet Spectra of Nova Andromedae 1986. A list of journal publications is also included.

Non-LTE effects in Al I lines

NASA Astrophysics Data System (ADS)

Menzhevitski, V. S.; Shimansky, V. V.; Shimanskaya, N. N.

2012-07-01

We present the theoretical analysis of the Al I line formation in the spectra of late-type stars ignoring the assumption of local thermodynamic equilibrium (LTE). The calculations were based on the 39-level aluminum atom model for one-dimensional hydrostatic stellar atmosphere models with the parameters: T eff from 4000 to 9000 K, log g = 0.0-4.5, and metallicity [ A] = 0.0;-1.0;-2.0;-3.0;-4.0. The aluminum atom model and the method of calculations were tested by the study of line profiles in the solar spectrum. We refined the oscillator strengths and Van-der-Vaals broadening constants C 6 of the investigated transitions. We conclude that the Al I atom is in the overionization state: the 3 p level is underpopulated in the line formation region. This leads to the line weakening, as compared with the LTE results. The overionization effect becomes more pronounced with increasing temperature and decreasing metallicity. We show that the use of various atomic data (ionization cross-sections) for the low levels of Al I does not change the behavior of non-LTE deviations, whereas the value of these deviations varies essentially. For nine selected Al I lines we calculated the grids of theoretical non-LTE corrections (Δ X NLTE = log ɛ NLTE - log ɛ LTE) to the Al abundances determinedwith the LTE assumption. The non-LTE corrections are positive and significant for the stars with temperatures T eff > 6000 K. These corrections weakly depend on log g, and increase with declining stellar metallicity.

NESSY: NLTE spectral synthesis code for solar and stellar atmospheres

NASA Astrophysics Data System (ADS)

Tagirov, R. V.; Shapiro, A. I.; Schmutz, W.

2017-07-01

Context. Physics-based models of solar and stellar magnetically-driven variability are based on the calculation of synthetic spectra for various surface magnetic features as well as quiet regions, which are a function of their position on the solar or stellar disc. Such calculations are performed with radiative transfer codes tailored for modeling broad spectral intervals. Aims: We aim to present the NLTE Spectral SYnthesis code (NESSY), which can be used for modeling of the entire (UV-visible-IR and radio) spectra of solar and stellar magnetic features and quiet regions. Methods: NESSY is a further development of the COde for Solar Irradiance (COSI), in which we have implemented an accelerated Λ-iteration (ALI) scheme for co-moving frame (CMF) line radiation transfer based on a new estimate of the local approximate Λ-operator. Results: We show that the new version of the code performs substantially faster than the previous one and yields a reliable calculation of the entire solar spectrum. This calculation is in a good agreement with the available observations.

Radiative Transfer in Stellar Atmospheres

NASA Astrophysics Data System (ADS)

Rutten, Robert J.

2003-05-01

The main topic treated in these graduate course notes is the classical theory of radiative transfer for explaining stellar spectra. It needs relatively much attention to be mastered. Radiative transfer in gaseous media that are neither optically thin nor fully opaque and scatter to boot is a key part of astrophysics but not a transparent subject. These course notes represent a middle road between Mihalas' "Stellar Atmospheres" (graduate level and up) and the books by Novotny and Boehm-Vitense (undergraduate level). They are at about the level of Gray's "The observation and analysis of stellar photospheres" but emphasize NLTE radiative transfer rather than observational techniques and data interpretation.

Theoretical White Dwarf Spectra on Demand: TheoSSA

NASA Astrophysics Data System (ADS)

Ringat, E.; Rauch, T.

2010-11-01

In the last decades, a lot of progress was made in spectral analysis. The quality (e.g. resolution, S/N ratio) of observed spectra has improved much and several model-atmosphere codes were developed. One of these is the ``Tübingen NLTE Model-Atmosphere Package'' (TMAP), that is a highly developed program for the calculation of model atmospheres of hot, compact objects. In the framework of the German Astrophysical Virtual Observatory (GAVO), theoretical spectral energy distributions (SEDs) can be downloaded via TheoSSA. In a pilot phase, TheoSSA is based on TMAP model atmospheres. We present the current state of this VO service.

How to Model Super-Soft X-ray Sources?

NASA Astrophysics Data System (ADS)

Rauch, Thomas

2012-07-01

During outbursts, the surface temperatures of white dwarfs in cataclysmic variables exceed by far half a million Kelvin. In this phase, they may become the brightest super-soft sources (SSS) in the sky. Time-series of high-resolution, high S/N X-ray spectra taken during rise, maximum, and decline of their X-ray luminosity provide insights into the processes following such outbursts as well as in the surface composition of the white dwarf. Their analysis requires adequate NLTE model atmospheres. The Tuebingen Non-LTE Model-Atmosphere Package (TMAP) is a powerful tool for their calculation. We present the application of TMAP models to SSS spectra and discuss their validity.

VizieR Online Data Catalog: Formation of MW halo and its dwarf satellites (Mashonkina+, 2017)

NASA Astrophysics Data System (ADS)

Mashonkina, L.; Jablonka, P.; Pakhomov, Yu; Sitnova, T.; North, P.

2017-04-01

Tables A.1 and A.2 from the article are presented. The first table contains atomic parameters of FeI/II and TiI/II lines. The second atmospheric parameters and FeI/II, TiI/II nLTE abundances. (2 data files).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Latour, M.; Fontaine, G.; Brassard, P.

As part of a multifaceted effort to better exploit the asteroseismological potential of the pulsating sdB star Feige 48, we present an improved spectroscopic analysis of that star based on new grids of NLTE, fully line-blanketed model atmospheres. To that end, we gathered four high signal-to-noise ratio time-averaged optical spectra of varying spectral resolutions from 1.0 Å to 8.7 Å, and we made use of the results of four independent studies to fix the abundances of the most important metals in the atmosphere of Feige 48. The mean atmospheric parameters we obtained from our four spectra of Feige 48 are:more » T {sub eff} = 29,850 ± 60 K, log g = 5.46 ± 0.01, and log N(He)/N(H) = –2.88 ± 0.02. We also modeled, for the first time, the He II line at 1640 Å from the STIS archive spectrum of the star, and with this line we found an effective temperature and a surface gravity that match well with the values obtained with the optical data. With some fine tuning of the abundances of the metals visible in the optical domain, we were able to achieve a very good agreement between our best available spectrum and our best-fitting synthetic one. Our derived atmospheric parameters for Feige 48 are in rather good agreement with previous estimates based on less sophisticated models. This underlines the relatively small effects of the NLTE approach combined with line blanketing in the atmosphere of this particular star, implying that the current estimates of the atmospheric parameters of Feige 48 are reliable and secure.« less

Absolute Spectrophotometric Calibration to 1% from the FUV through the near-IR

NASA Astrophysics Data System (ADS)

Finley, David

2005-07-01

We propose a significant improvement to the existing HST calibration. The current calibration is based on three primary DA white dwarf standards, GD 71, GD 153, and G 191-B2B. The standard fluxes are calculated using NLTE models, with effective temperatures and gravities that were derived from Balmer line fits using LTE models. We propose to improve the accuracy and internal consistency of the calibration by deriving corrected effective temperatures and gravities based on fitting the observed line profiles with updated NLTE models, and including the fit results from multiple STIS spectra, rather than the {usually} 1 or 2 ground-based spectra used previously. We will also determine the fluxes for 5 new, fainter primary or secondary standards, extending the standard V magnitude lower limit from 13.4 to 16.5, and extending the wavelength coverage from 0.1 to 2.5 micron. The goal is to achieve an overall flux accuracy of 1%, which will be needed, for example, for the upcoming supernova survey missions to measure the equation of state of the dark energy that is accelerating the expansion of the universe.

Uncertainties in (E)UV model atmosphere fluxes

NASA Astrophysics Data System (ADS)

Rauch, T.

2008-04-01

Context: During the comparison of synthetic spectra calculated with two NLTE model atmosphere codes, namely TMAP and TLUSTY, we encounter systematic differences in the EUV fluxes due to the treatment of level dissolution by pressure ionization. Aims: In the case of Sirius B, we demonstrate an uncertainty in modeling the EUV flux reliably in order to challenge theoreticians to improve the theory of level dissolution. Methods: We calculated synthetic spectra for hot, compact stars using state-of-the-art NLTE model-atmosphere techniques. Results: Systematic differences may occur due to a code-specific cutoff frequency of the H I Lyman bound-free opacity. This is the case for TMAP and TLUSTY. Both codes predict the same flux level at wavelengths lower than about 1500 Å for stars with effective temperatures (T_eff) below about 30 000 K only, if the same cutoff frequency is chosen. Conclusions: The theory of level dissolution in high-density plasmas, which is available for hydrogen only should be generalized to all species. Especially, the cutoff frequencies for the bound-free opacities should be defined in order to make predictions of UV fluxes more reliable.

Non-LTE Line-Blanketed Model Atmospheres of B-type Stars

NASA Astrophysics Data System (ADS)

Lanz, T.; Hubeny, I.

2005-12-01

We present an extension of our OSTAR2002 grid of NLTE model atmospheres to B-type stars. We have calculated over 1,300 metal line-blanketed, NLTE, plane-parallel, hydrostatic model atmospheres for the basic parameters appropriate to B stars. The grid covers 16 effective temperatures from 15,000 to 30,000 K, with 1000 K steps, 13 surface gravities, log g≤ 4.75 down to the Eddington limit, and 5 compositions (2, 1, 0.5, 0.2, and 0.1 times solar). We have adopted a microturbulent velocity of 2 km/s for all models. In the lower surface gravity range (log g≤ 3.0), we supplemented the main grid with additional model atmospheres accounting for higher microtutbulent velocity (10 km/s) and for alterated surface composition (He and N-rich, C-deficient), as observed in B supergiants. The models incorporate basically all known atomic levels of 46 ions of H, He, C, N, O, Ne, Mg, Al, Si, S, and Fe, which are grouped into 1127 superlevels. Models and spectra will be available at our Web site, http://nova.astro.umd.edu.

The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis. II. Early chemical enrichment

NASA Astrophysics Data System (ADS)

Mashonkina, L.; Jablonka, P.; Sitnova, T.; Pakhomov, Yu.; North, P.

2017-12-01

We present the non-local thermodynamic equilibrium (NLTE) abundances of up to 10 chemical species in a sample of 59 very metal-poor (VMP, -4 ≤ [Fe/H] ≾-2) stars in seven dwarf spheroidal galaxies (dSphs) and in the Milky Way (MW) halo. Our results are based on high-resolution spectroscopic datasets and homogeneous and accurate atmospheric parameters determined in Paper I. We show that once the NLTE effects are properly taken into account, all massive galaxies in our sample, that is, the MW halo and the classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax, reveal a similar plateau at [α/Fe] ≃ 0.3 for each of the α-process elements: Mg, Ca, and Ti. We put on a firm ground the evidence for a decline in α/Fe with increasing metallicity in the Boötes I ultra-faint dwarf galaxy (UFD), that is most probably due to the ejecta of type Ia supernovae. For Na/Fe, Na/Mg, and Al/Mg, the MW halo and all dSphs reveal indistinguishable trends with metallicity, suggesting that the processes of Na and Al synthesis are identical in all systems, independent of their mass. The dichotomy in the [Sr/Ba] versus [Ba/H] diagram is observed in the classical dSphs, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr. We show that Sr in the massive galaxies is well correlated with Mg suggesting a strong link to massive stars and that its origin is essentially independent of Ba, for most of the [Ba/H] range. Our three UFDs, that is Boötes I, UMa II, and Leo IV, are depleted in Sr and Ba relative to Fe and Mg, with very similar ratios of [Sr/Mg] ≃-1.3 and [Ba/Mg] ≃-1 on the entire range of their Mg abundances. The subsolar Sr/Ba ratios of Boötes I and UMa II indicate a common r-process origin of their neutron-capture elements. Sculptor remains the classical dSph, in which the evidence for inhomogeneous mixing in the early evolution stage, at [Fe/H] <-2, is the strongest. Full Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A89

Stellar laboratories . VIII. New Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths and the Al, Zr, and Xe abundances in the hot white dwarfs G191-B2B and RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Gamrath, S.; Quinet, P.; Löbling, L.; Hoyer, D.; Werner, K.; Kruk, J. W.; Demleitner, M.

2017-03-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To search for zirconium and xenon lines in the ultraviolet (UV) spectra of G191-B2B and RE 0503-289, new Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths were calculated. This allows, for the first time, determination of the Zr abundance in white dwarf (WD) stars and improvement of the Xe abundance determinations. Methods: We calculated Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths to consider radiative and collisional bound-bound transitions of Zr and Xe in our NLTE stellar-atmosphere models for the analysis of their lines exhibited in UV observations of the hot WDs G191-B2B and RE 0503-289. Results: We identified one new Zr iv, 14 new Zr v, and ten new Zr vi lines in the spectrum of RE 0503-289. Zr was detected for the first time in a WD. We measured a Zr abundance of -3.5 ± 0.2 (logarithmic mass fraction, approx. 11 500 times solar). We identified five new Xe vi lines and determined a Xe abundance of -3.9 ± 0.2 (approx. 7500 times solar). We determined a preliminary photospheric Al abundance of -4.3 ± 0.2 (solar) in RE 0503-289. In the spectra of G191-B2B, no Zr line was identified. The strongest Zr iv line (1598.948 Å) in our model gave an upper limit of -5.6 ± 0.3 (approx. 100 times solar). No Xe line was identified in the UV spectrum of G191-B2B and we confirmed the previously determined upper limit of -6.8 ± 0.3 (ten times solar). Conclusions: Precise measurements and calculations of atomic data are a prerequisite for advanced NLTE stellar-atmosphere modeling. Observed Zr iv-vi and Xe vi-vii line profiles in the UV spectrum of RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. Tables A.9-A.12 and B.5-B.7 are only available via the German Astrophysical Virtual Observatory (GAVO) service TOSS (http://dc.g-vo.org/TOSS).

(F)UV Spectroscopy of K648: Abundance Determination of Trace Elements

NASA Astrophysics Data System (ADS)

Mohamad-Yob, S. J.; Ziegler, M.; Rauch, T.; Werner, K.

2010-11-01

We present preliminary results of an ongoing spectral analysis of K 648, the central star of the planetary nebula Ps 1, based on high resolution FUV spectra. K 648, in M 15 is one of only four known PNe in globular clusters. The formation of this post-AGB object in a globular cluster is still unclear. Our aim is to determine Teff, log g, and the abundances of trace elements, in order to improve our understanding of post-AGB evolution of extremely metal-poor stars, especially PN formation in globular clusters. We analyzed FUSE, HST/STIS, and HST/FOS observations. A grid of stellar model atmospheres was calculated using the Tübingen NLTE Model Atmosphere Package (TMAP).

VizieR Online Data Catalog: Very metal poor stars in MW halo (Mashonkina+, 2017)

NASA Astrophysics Data System (ADS)

Mashonkina, L.; Jablonka, P.; Sitnova, T.; Pakhomov, Yu; North, P.

2017-10-01

Tables 3 and 4 from the article are presented. They include the LTE and NLTE abundances from individual lines and average abundances of the investigated stars in the dSphs Sculptor (Scl), Ursa Minor (UMi), Fornax (Fnx), Sextans (Sex), Bootes I (Boo), UMa II, and Leo IV and the Milky Way (MW) halo. (3 data files).

New RADIOM algorithm using inverse EOS

NASA Astrophysics Data System (ADS)

Busquet, Michel; Sokolov, Igor; Klapisch, Marcel

2012-10-01

The RADIOM model, [1-2], allows one to implement non-LTE atomic physics with a very low extra CPU cost. Although originally heuristic, RADIOM has been physically justified [3] and some accounting for auto-ionization has been included [2]. RADIOM defines an ionization temperature Tz derived from electronic density and actual electronic temperature Te. LTE databases are then queried for properties at Tz and NLTE values are derived from them. Some hydro-codes (like FAST at NRL, Ramis' MULTI, or the CRASH code at U.Mich) use inverse EOS starting from the total internal energy Etot and returning the temperature. In the NLTE case, inverse EOS requires to solve implicit relations between Te, Tz, and Etot. We shall describe these relations and an efficient solver successively implemented in some of our codes. [4pt] [1] M. Busquet, Radiation dependent ionization model for laser-created plasmas, Ph. Fluids B 5, 4191 (1993).[0pt] [2] M. Busquet, D. Colombant, M. Klapisch, D. Fyfe, J. Gardner. Improvements to the RADIOM non-LTE model, HEDP 5, 270 (2009).[0pt] [3] M.Busquet, Onset of pseudo-thermal equilibrium within configurations and super-configurations, JQSRT 99, 131 (2006)

Non-LTE line formation of Fe in late-type stars - IV. Modelling of the solar centre-to-limb variation in 3D

NASA Astrophysics Data System (ADS)

Lind, K.; Amarsi, A. M.; Asplund, M.; Barklem, P. S.; Bautista, M.; Bergemann, M.; Collet, R.; Kiselman, D.; Leenaarts, J.; Pereira, T. M. D.

2017-07-01

Our ability to model the shapes and strengths of iron lines in the solar spectrum is a critical test of the accuracy of the solar iron abundance, which sets the absolute zero-point of all stellar metallicities. We use an extensive 463-level Fe atom with new photoionization cross-sections for Fe I and quantum mechanical calculations of collisional excitation and charge transfer with neutral hydrogen; the latter effectively remove a free parameter that has hampered all previous line formation studies of Fe in non-local thermodynamic equilibrium (NLTE). For the first time, we use realistic 3D NLTE calculations of Fe for a quantitative comparison to solar observations. We confront our theoretical line profiles with observations taken at different viewing angles across the solar disc with the Swedish 1-m Solar Telescope. We find that 3D modelling well reproduces the observed centre-to-limb behaviour of spectral lines overall, but highlight aspects that may require further work, especially cross-sections for inelastic collisions with electrons. Our inferred solar iron abundance is log (ɛFe) = 7.48 ± 0.04 dex.

Height formation of bright points observed by IRIS in Mg II line wings during flux emergence

NASA Astrophysics Data System (ADS)

Grubecka, M.; Schmieder, B.; Berlicki, A.; Heinzel, P.; Dalmasse, K.; Mein, P.

2016-09-01

Context. A flux emergence in the active region AR 111850 was observed on September 24, 2013 with the Interface Region Imaging Spectrograph (IRIS). Many bright points are associated with the new emerging flux and show enhancement brightening in the UV spectra. Aims: The aim of this work is to compute the altitude formation of the compact bright points (CBs) observed in Mg II lines in the context of searching Ellerman bombs (EBs). Methods: IRIS provided two large dense rasters of spectra in Mg II h and k lines, Mg II triplet, C II and Si IV lines covering all the active region and slit jaws in the two bandpasses (1400 Å and 2796 Å) starting at 11:44 UT and 15:39 UT, and lasting 20 min each. Synthetic profiles of Mg II and Hα lines are computed with non-local thermodynamic equlibrium (NLTE) radiative transfer treatment in 1D solar atmosphere model including a hotspot region defined by three parameters: temperature, altitude, and width. Results: Within the two IRIS rasters, 74 CBs are detected in the far wings of the Mg II lines (at +/-1 Å and 3.5 Å). Around 10% of CBs have a signature in Si IV and CII. NLTE models with a hotspot located in the low atmosphere were found to fit a sample of Mg II profiles in CBs. The Hα profiles computed with these Mg II CB models are consistent with typical EB profiles observed from ground based telescopes e.g. THEMIS. A 2D NLTE modelling of fibrils (canopy) demonstrates that the Mg II line centres can be significantly affected but not the peaks and the wings of Mg II lines. Conclusions: We conclude that the bright points observed in Mg II lines can be formed in an extended domain of altitudes in the photosphere and/or the chromosphere (400 to 750 km). Our results are consistent with the theory of heating by Joule dissipation in the atmosphere produced by magnetic field reconnection during flux emergence.

Stellar Laboratories . [VI. New Mo IV - VII Oscillator Strengths and the Molybdenum Abundance in the Hot White Dwarfs G191-B2B and RE 0503-289

NASA Technical Reports Server (NTRS)

Rauch, T.; Quinet, T.; Hoyer, D.; Werner, K.; Demleitner, M.; Kruk, J. W.

2016-01-01

For the spectral analysis of high-resolution and high signal-to-noise (SN) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To identify molybdenum lines in the ultraviolet (UV) spectra of the DA-type white dwarf G191B2B and the DO-type white dwarf RE 0503289 and, to determine their photospheric Mo abundances, reliable Mo iv-vii oscillator strengths are used. Methods: We newly calculated Mo iv-vii oscillator strengths to consider their radiative and collisional bound-bound transitions indetail in our NLTE stellar-atmosphere models for the analysis of Mo lines exhibited in high-resolution and high SN UV observations of RE 0503289.Results. We identified 12 Mo v and nine Mo vi lines in the UV spectrum of RE 0503289 and measured a photospheric Mo abundance of 1.2 3.0 104(mass fraction, 22 500 56 400 times the solar abundance). In addition, from the As v and Sn iv resonance lines,we measured mass fractions of arsenic (0.51.3 105, about 300 1200 times solar) and tin (1.33.2 104, about 14 300 35 200 times solar). For G191B2B, upper limits were determined for the abundances of Mo (5.3 107, 100 times solar) and, in addition, for Kr (1.1106, 10 times solar) and Xe (1.7107, 10 times solar). The arsenic abundance was determined (2.35.9 107, about 21 53 times solar). A new, registered German Astrophysical Virtual Observatory (GAVO) service, TOSS, has been constructed to provide weighted oscillator strengths and transition probabilities.Conclusions. Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. Observed Mo v-vi line profiles in the UV spectrum of the white dwarf RE 0503289 were well reproduced with our newly calculated oscillator strengths. For the first time, this allowed the photospheric Mo abundance in a white dwarf to be determined.

Stellar Laboratories: 3. New Ba 5, Ba 6, and Ba 7 Oscillator Strengths and the Barium Abundance in the Hot White Dwarfs G191-B2B and RE 0503-289

NASA Technical Reports Server (NTRS)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, Jeffrey Walter

2014-01-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. Reliable Ba 5-7 oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods. We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results. For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g=7.5. The Ba abundance is 3.5 +/- 0.5 × 10(exp-4) (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 +/- 0.5 × 10(exp-6) (about 265 times solar). Conclusions. Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely.

BD-22deg3467, a DAO-type Star Exciting the Nebula Abell 35

NASA Technical Reports Server (NTRS)

Ziegler, M.; Rauch, T.; Werner, K.; Koppen, J.; Kruk, J. W.

2013-01-01

Spectral analyses of hot, compact stars with non-local thermodynamical equilibrium (NLTE) model-atmosphere techniques allow the precise determination of photospheric parameters such as the effective temperature (T(sub eff)), the surface gravity (log g), and the chemical composition. The derived photospheric metal abundances are crucial constraints for stellar evolutionary theory. Aims. Previous spectral analyses of the exciting star of the nebula A35, BD-22deg3467, were based on He+C+N+O+Si+Fe models only. For our analysis, we use state-of-the-art fully metal-line blanketed NLTE model atmospheres that consider opacities of 23 elements from hydrogen to nickel. We aim to identify all observed lines in the ultraviolet (UV) spectrum of BD-22deg3467 and to determine the abundances of the respective species precisely. Methods. For the analysis of high-resolution and high signal-to-noise ratio (S/N) far-ultraviolet (FUSE) and UV (HST/STIS) observations, we combined stellar-atmosphere models and interstellar line-absorption models to fully reproduce the entire observed UV spectrum. Results. The best agreement with the UV observation of BD-22deg3467 is achieved at T(sub eff) = 80 +/- 10 kK and log g = 7.2 +/- 0.3. While T(sub eff) of previous analyses is verified, log g is significantly lower. We re-analyzed lines of silicon and iron (1/100 and about solar abundances, respectively) and for the first time in this star identified argon, chromium, manganese, cobalt, and nickel and determined abundances of 12, 70, 35, 150, and 5 times solar, respectively. Our results partially agree with predictions of diffusion models for DA-type white dwarfs. A combination of photospheric and interstellar line-absorption models reproduces more than 90% of the observed absorption features. The stellar mass is M approx. 0.48 Solar Mass. Conclusions. BD.22.3467 may not have been massive enough to ascend the asymptotic giant branch and may have evolved directly from the extended horizontal branch to the white dwarf state. This would explain why it is not surrounded by a planetary nebula. However, the star, ionizes the ambient interstellar matter, mimicking a planetary nebula.

The Virtual Observatory Service TheoSSA: Establishing a Database of Synthetic Stellar Flux Standards I. NLTE Spectral Analysis of the DA-Type White Dwarf G191-B2B *,**,***,****

NASA Technical Reports Server (NTRS)

Rauch, T.; Werner, K.; Bohlin, R.; Kruk, J. W.

2013-01-01

Hydrogen-rich, DA-type white dwarfs are particularly suited as primary standard stars for flux calibration. State-of-the-art NLTE models consider opacities of species up to trans-iron elements and provide reliable synthetic stellar-atmosphere spectra to compare with observations. Aims. We will establish a database of theoretical spectra of stellar flux standards that are easily accessible via a web interface. Methods. In the framework of the Virtual Observatory, the German Astrophysical Virtual Observatory developed the registered service TheoSSA. It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code. In case of the DA white dwarf G191-B2B, we demonstrate that the model reproduces not only its overall continuum shape but also the numerous metal lines exhibited in its ultraviolet spectrum. Results. TheoSSA is in operation and contains presently a variety of SEDs for DA-type white dwarfs. It will be extended in the near future and can host SEDs of all primary and secondary flux standards. The spectral analysis of G191-B2B has shown that our hydrostatic models reproduce the observations best at Teff =60 000 +/- 2000K and log g=7.60 +/- 0.05.We newly identified Fe vi, Ni vi, and Zn iv lines. For the first time, we determined the photospheric zinc abundance with a logarithmic mass fraction of -4.89 (7.5 × solar). The abundances of He (upper limit), C, N, O, Al, Si, O, P, S, Fe, Ni, Ge, and Sn were precisely determined. Upper abundance limits of about 10% solar were derived for Ti, Cr, Mn, and Co. Conclusions. The TheoSSA database of theoretical SEDs of stellar flux standards guarantees that the flux calibration of all astronomical data and cross-calibration between different instruments can be based on the same models and SEDs calculated with different model-atmosphere codes and are easy to compare.

Stellar Laboratories II. New Zn Iv and Zn v Oscillator Strengths and Their Validation in the Hot White Dwarfs G191-B2B and RE0503-289

NASA Technical Reports Server (NTRS)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

2014-01-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise (SN) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. In a recent analysis of the ultraviolet (UV) spectrum of the DA-type white dwarf G191B2B,21 Zn iv lines were newly identified. Because of the lack of Zn iv data, transition probabilities of the isoelectronic Ge vi were adapted for a first, coarse determination of the photospheric Zn abundance.Aims. Reliable Zn iv and Zn v oscillator strengths are used to improve the Zn abundance determination and to identify more Zn lines in the spectra of G191B2B and the DO-type white dwarf RE 0503289. Methods. We performed new calculations of Zn iv and Zn v oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of the Zn iv v spectrum exhibited in high-resolution and high-SN UV observations of G191B2B and RE 0503289. Results. In the UV spectrum of G191B2B, we identify 31 Zn iv and 16 Zn v lines. Most of these are identified for the first time in any star. We can reproduce well almost all of them at log Zn 5.52 0.2 (mass fraction, about 1.7 times solar). In particular, the Zn iv Zn v ionization equilibrium, which is a very sensitive Teff indicator, is well reproduced with the previously determined Teff 60 000 2000 K and log g 7.60 0.05. In the spectrum of RE 0503289, we identified 128 Zn v lines for the first time and determined log Zn 3.57 0.2 (155 times solar). Conclusions. Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Zn iv and Zn v line profiles in two white dwarf (G191B2B and RE 0503289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed us to determine the photospheric Zn abundance of these two stars precisely.

(F)UV Spectral Analysis of Hot, Hydrogen-Rich Central Stars of Planetary Nebulae

NASA Astrophysics Data System (ADS)

Ziegler, M.; Rauch, T.; Werner, K.; Kruk, J. W.

2010-11-01

Metal abundances of CSPNe are not well known although they provide important constraints on AGB nucleosynthesis. We aim to determine metal abundances of two hot, hydrogen-rich CSPNe (namely of A35 and NGC3587, the latter also known as M97 or the Owl Nebula) and to derive Teff and log g precisely from high-resolution, high-S/N (far-) ultraviolet observations obtained with FUSE and HST/STIS. For this purpose, we utilize NLTE model atmospheres calculated with TMAP, the Tübingen Model Atmosphere Package. Due to strong line absorption of the ISM, simultaneous modeling of interstellar features has become a standard tool in our analyses. We present preliminary results, demonstrating the importance of combining stellar and interstellar models, in order to clearly identify and measure the strengths of strategic photospheric lines.

Kinetic and radiation-hydrodynamic modeling of x-ray heating in laboratory photoionized plasmas

NASA Astrophysics Data System (ADS)

Mancini, Roberto

2017-06-01

In experiments performed at the Z facility of Sandia National Laboratories a cm-scale cell filled with neon gas was driven by the burst of broadband x-rays emitted at the collapse of a wire-array z-pinch turning the gas into a photoionized plasma. Transmission spectroscopy of a narrowband portion of the x-ray flux was used to diagnose the plasma. The data show a highly-ionized neon plasma with a rich line absorption spectrum that permits the extraction of the ionization distribution among Be-, Li-, He- and H-like ions. Analysis of the spectra produced atomic ground and low excited state areal densities in these ions, and from the ratio of first-excited to ground state populations in Li-like neon a temperature of 19±4eV was extracted to characterize the x-ray heating of the plasma. To interpret this observation, we have performed data-constrained view-factor calculations of the spectral distribution of the x-ray drive, self-consistent modeling of electron and atomic kinetics, and radiation-hydrodynamic simulations. For the conditions of the experiment, the electron distribution thermalizes quickly, has a negligible high-energy tail, and is very well approximated by a single Maxwellian distribution. Radiation-hydrodynamic simulations with either LTE or NLTE (i.e. non-equilibrium) atomic physics provide a more complete modeling of the experiment. We found that in order to compute electron temperatures consistent with observation inline non-equilibrium collisional-radiative neon atomic kinetics needs to be taken into account. We discuss the details of LTE and NLTE simulations, and the impact of atomic physics on the radiation heating and cooling rates that determine the plasma temperature. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451, and the Z Facility Fundamental Science Program of SNL.

White Dwarf Model Atmospheres: Synthetic Spectra for Supersoft Sources

NASA Astrophysics Data System (ADS)

Rauch, Thomas

2013-01-01

The Tübingen NLTE Model-Atmosphere Package (TMAP) calculates fully metal-line blanketed white dwarf model atmospheres and spectral energy distributions (SEDs) at a high level of sophistication. Such SEDs are easily accessible via the German Astrophysical Virtual Observatory (GAVO) service TheoSSA. We discuss applications of TMAP models to (pre) white dwarfs during the hottest stages of their stellar evolution, e.g. in the parameter range of novae and supersoft sources.

Modeling the Atmosphere of Solar and Other Stars: Radiative Transfer with PHOENIX/3D

NASA Astrophysics Data System (ADS)

Baron, Edward

The chemical composition of stars is an important ingredient in our understanding of the formation, structure, and evolution of both the Galaxy and the Solar System. The composition of the sun itself is an essential reference standard against which the elemental contents of other astronomical objects are compared. Recently, redetermination of the elemental abundances using three-dimensional, time-dependent hydrodynamical models of the solar atmosphere has led to a reduction in the inferred metal abundances, particularly C, N, O, and Ne. However, this reduction in metals reduces the opacity such that models of the Sun no longer agree with the observed results obtained using helioseismology. Three dimensional (3-D) radiative transfer is an important problem in physics, astrophysics, and meteorology. Radiative transfer is extremely computationally complex and it is a natural problem that requires computation on the exascale. We intend to calculate the detailed compositional structure of the Sun and other stars at high resolution with full NLTE, treating the turbulent velocity flows in full detail in order to compare results from hydrodynamics and helioseismology, and understand the nature of the discrepancies found between the two approaches. We propose to perform 3-D high-resolution radiative transfer calculations with the PHOENIX/3D suite of solar and other stars using 3-D hydrodynamic models from different groups. While NLTE radiative transfer has been treated by the groups doing hydrodynamics, they are necessarily limited in their resolution to the consideration of only a few (4-20) frequency bins, whereas we can calculate full NLTE including thousands of wavelength points, resolving the line profiles, and solving the scattering problem with extremely high angular resolution. The code has been used for the analysis of supernova spectra, stellar and planetary spectra, and for time-dependent modeling of transient objects. PHOENIX/3D runs and scales very well on Cray XC-30 and XC-40 machines (tested up to 100,800 CPU cores) and should scale up to several million cores for large simulations. Non-local problems, particularly radiation hydrodynamics problems, are at the forefront of computational astrophysics and we will share our work with the community. Our research program brings a unified modeling strategy to the results of several disparate groups and thus will provide a unifying framework with which to assess the metal abundance of the stars and the chemical evolution of the galaxy. We will bring together 3-D hydrodynamical models, detailed radiative transfer, and astronomical abundance studies. We will also provide results of interest to the atomic physics and plasma physics communities. Our work will use data from NASA telescopes including the Hubble Space Telescope and the James Webb Space telescope. The ability to work with data from the UV to the far IR is crucial from validating our results. Our work will also extend the exascale computational capabilities, which is a national goal.

Modelling of the 10-micrometer natural laser emission from the mesospheres of Mars and Venus

NASA Technical Reports Server (NTRS)

Deming, D.; Mumma, M. J.

1983-01-01

The NLTE radiative transfer problem is solved to obtain the 00 deg 1 vibrational state population. This model successfully reproduces the existing center-to-limb observations, although higher spatial resolution observations are needed for a definitive test. The model also predicts total fluxes which are close to the observed values. The strength of the emission is predicted to be closely related to the instantaneous near-IR solar heating rate.

Modeling of the 10-micron natural laser emission from the mesospheres of Mars and Venus

NASA Technical Reports Server (NTRS)

Deming, D.; Mumma, M. J.

1983-01-01

The NLTE radiative transfer problem is solved to obtain the 00 deg 1 vibrational state population. This model successfully reproduces the existing center-to-limb observations, although higher spatial resolution observations are needed for a definitive test. The model also predicts total fluxes which are close to the observed values. The strength of the emission is predicted to be closely related to the instantaneous near-IR solar heating rate.

Nitrogen excess in slowly-rotating β Cephei stars: deep mixing or diffusion?

NASA Astrophysics Data System (ADS)

Morel, T.; Butler, K.; Aerts, C.; Neiner, C.; Briquet, M.

2007-06-01

We present the results of an NLTE abundance study of a small sample of β Cephei stars, which point to the existence of a population of slowly-rotating B-type pulsators exhibiting a significant amount of nitrogen-enriched material at their surface. Although the origin of this nitrogen excess remains unclear, an overabundance preferentially occurring in stars with a detected magnetic field seems to emerge at this stage. Full details can be found in Morel et al. (2006).

Radiative transfer in molecular lines

NASA Astrophysics Data System (ADS)

Asensio Ramos, A.; Trujillo Bueno, J.; Cernicharo, J.

2001-07-01

The highly convergent iterative methods developed by Trujillo Bueno and Fabiani Bendicho (1995) for radiative transfer (RT) applications are generalized to spherical symmetry with velocity fields. These RT methods are based on Jacobi, Gauss-Seidel (GS), and SOR iteration and they form the basis of a new NLTE multilevel transfer code for atomic and molecular lines. The benchmark tests carried out so far are presented and discussed. The main aim is to develop a number of powerful RT tools for the theoretical interpretation of molecular spectra.

Model-Atmosphere Spectra of Central Stars of Planetary Nebulae - Access via the Virtual Observatory Service TheoSSA

NASA Astrophysics Data System (ADS)

Rauch, T.; Reindl, N.

2014-04-01

In the framework of the Virtual Observatory (VO), the German Astrophysical Virtual Observatory GAVO project provides easy access to theoretical spectral energy distributions (SEDs) within the registered GAVO service TheoSSA (http://dc.g-vo.org/theossa). TheoSSA is based on the well established Tübingen NLTE Model-Atmosphere Package (TMAP) for hot, compact stars. This includes central stars of planetary nebulae. We show examples of TheoSSA in operation.

Quantitative Studies of the Optical and UV Spectra of Galactic Early B Supergiants

NASA Technical Reports Server (NTRS)

Searle, S. C.; Prinja, R. K.; Massa, D.; Ryans, R.

2008-01-01

We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0-B5 supergiants of luminosity classes Ia, Ib, Iab, and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical comparison of the model predictions to observed UV spectral features is made. Methods. Fundamental parameters (e.g., T(sub eff), log L(sub *), mass-loss rates and CNO abundances) are derived for individual stars using CMFGEN, a nLTE, line-blanketed model atmosphere code. The impact of these newly derived parameters on the Galactic B supergiant Ten scale, mass discrepancy, and wind-momentum luminosity relation is examined. Results. The B supergiant temperature scale derived here shows a reduction of about 1000-3000 K compared to previous results using unblanketed codes. Mass-loss rate estimates are in good agreement with predicted theoretical values, and all of the 20 BO-B5 supergiants analysed show evidence of CNO processing. A mass discrepancy still exists between spectroscopic and evolutionary masses, with the largest discrepancy occuring at log (L/(solar)L approx. 5.4. The observed WLR values calculated for B0-B0.7 supergiants are higher than predicted values, whereas the reverse is true for B1-B5 supergiants. This means that the discrepancy between observed and theoretical values cannot be resolved by adopting clumped (i.e., lower) mass-loss rates as for O stars. The most surprising result is that, although CMFGEN succeeds in reproducing the optical stellar spectrum accurately, it fails to precisely reproduce key UV diagnostics, such as the N v and C IV P Cygni profiles. This problem arises because the models are not ionised enough and fail to reproduce the full extent of the observed absorption trough of the P Cygni profiles. Conclusions. Newly-derived fundamental parameters for early B supergiants are in good agreement with similar work in the field. The most significant discovery, however, is the failure of CMFGEN to predict the correct ionisation fraction for some ions. Such findings add further support to revising the current standard model of massive star winds, as our understanding of these winds is incomplete without a precise knowledge of the ionisation structure and distribution of clumping in the wind. Key words. techniques: spectroscopic - stars: mass-loss - stars: supergiants - stars: abundances - stars: atmospheres - stars: fundamental parameters

The D/H Ratio in Interstellar Gas towards G191-B2B from STIS Echelle Observations

NASA Astrophysics Data System (ADS)

Sahu, M. S.; Landsman, W. B.; Bruhweiler, F. C.; Gull, T. R.; Bowers, C. A.; Lindler, D.; Feggans, K.; Barstow, M. A.; Hubeny, I.; Holberg, J. B.

1999-05-01

We present STIS echelle observations of interstellar D i and H i Lyα and N i (1199.5, 1200.2 and 1200.7 Angstroms), C ii 1334.5 Angstroms, C(*) ii 1335.7 Angstroms, O i 1302 Angstroms, Si ii (1190, 1193, 1260, 1304 and 1526 Angstroms), Si iii 1206.5 Angstroms, Al ii 1670.8 Angstroms, S ii 1259.5 Angstroms and Fe ii 1608.5 Angstroms in the line of sight to the nearby (69 pc) hot, white dwarf (WD) G191-B2B. Compared to the GHRS study of G191-B2B by Vidal-Madjar et al. 1998 (VM98), the STIS E140H spectra have a higher velocity resolution (3 km s(-1) ), better S/N (between 20 to 50) and broader wavelength coverage (1150 to 1700 Angstroms). We use the Barstow & Hubeny stratified non-LTE model atmosphere calculations which include the effects of line-blanketing from more than 9x10(6) atomic transitions (mainly Ni and Fe), both to determine the NLTE shape of the stellar Lyalpha profile and to estimate the contamination of the interstellar lines by WD photospheric lines. The interstellar N i 1200.7 Angstroms, Si ii 1193 & 1304 Angstroms and Fe ii lines show no contamination by WD photospheric lines and are given more weight in our analysis. VM98 reported three components while we detect only two velocity components in all the interstellar species observed: one at ~ 8.5 km s(-1) and one at ~ 19.3 km s(-1) which we identify as the LIC component. Using the NLTE stellar Lyα profile and a total column density of N(H i) ~ 2 x 10(18) cm(-2) for both components (consistent with EUVE observations), we derive confidence contours. We find the D/H ratio with 2sigma confidence limits to lie within 1.77+/-0.2x10(-5) . This value is consistent with the value of (D/H)LIC = 1.6+/-0.1x10(-5) determined towards Capella (Linsky et al. 1995). The STIS data provide no evidence for local or cloud-to-cloud variation in the D/H ratio as suggested by VM98. Re-analysis of the GHRS data and comparison to the STIS data is in progress.

Stellar parameters for the central star of the planetary nebula PRTM 1 using the German Astrophysical Virtual Observatory service TheoSSA

NASA Astrophysics Data System (ADS)

Rauch, T.; Demleitner, M.; Hoyer, D.; Werner, K.

2018-04-01

The German Astrophysical Virtual Observatory (GAVO) developed the registered service TheoSSA (theoretical stellar spectra access) and the supporting registered VO tool TMAW (Tübingen Model-Atmosphere WWW interface). These allow individual spectral analyses of hot, compact stars with state-of-the-art non-local thermodynamical equilibrium (NLTE) stellar-atmosphere models that presently consider opacities of the elements H, He, C, N, O, Ne, Na, and Mg, without requiring detailed knowledge about the involved background codes and procedures. Presently, TheoSSA provides easy access to about 150 000 pre-calculated stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code. In the case of the exciting star of PN PRTM 1, we demonstrate the easy way to calculate individual NLTE stellar model-atmospheres to reproduce an observed optical spectrum. We measured T_eff = 98 000± 5 000 K, log (g / cm/s^2) = 5.0^{+0.3}_{-0.2}, and photospheric mass fractions of H =7.5 × 10-1 (1.02 times solar), He =2.4 × 10-1 (0.96), C =2.0 × 10-3 (0.84), N =3.2 × 10-4 (0.46), and O =8.5 × 10-3 (1.48) with uncertainties of ±0.2 dex. We determined the stellar mass and luminosity of 0.73^{+0.16}_{-0.15} M_{⊙} and log (L/L⊙) = 4.2 ± 0.4, respectively.

VizieR Online Data Catalog: BVIc light curves of SZ Cam (Tamajo+, 2012)

NASA Astrophysics Data System (ADS)

Tamajo, E.; Munari, U.; Siviero, A.; Tomasella, L.; Dallaporta, S.

2012-01-01

We present a spectroscopic and photometric analysis of the multiple system and early-type eclipsing binary SZ Cam (O9 IV + B0.5 V), which consists of an eclipsing SB2 pair of orbital period P=2.7-days in a long orbit (~55yrs) around a non-eclipsing SB1 pair of orbital period P=2.8-days. We have reconstructed the spectra of the individual components of SZ Cam from the observed composite spectra using the technique of spectral disentangling. We used them together with extensive and accurate BV IC CCD photometry to obtain an orbital solution. Our photometry revealed the presence of a beta Cep variable in the SZ Cam hierarchical system, probably located within the non-eclipsing SB1 pair. The pulsation period is 0.33265+/-0.00005-days and the observed total amplitude in the B band is 0.0105+/-0.0005mag. NLTE analysis of the disentangled spectra provided atmospheric parameters for all three components, consistent with those derived from orbital solution. (1 data file).

LITHIUM IN THE UPPER CENTAURUS LUPUS AND LOWER CENTAURUS CRUX SUBGROUPS OF SCORPIUS-CENTAURUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bubar, Eric J.; Schaeuble, Marc; King, Jeremy R.

2011-12-15

We utilize spectroscopically derived model atmosphere parameters and the Li I {lambda}6104 subordinate line and the {lambda}6708 doublet to derive lithium abundances for 12 members of the Upper Centaurus Lupus and Lower Centaurus Crux subgroups of the Scorpius-Centaurus OB Association. The results indicate any intrinsic Li scatter in our 0.9-1.4 M{sub Sun} stars is limited to {approx}0.15 dex, consistent with the lack of dispersion in {>=}1.0 M{sub Sun} stars in the 100 Myr Pleiades and 30-50 Myr IC 2391 and 2602 clusters. Both ab initio uncertainty estimates and the derived abundances themselves indicate that the {lambda}6104 line yields abundances withmore » equivalent or less scatter than is found from the {lambda}6708 doublet as a result of lower uncertainties for the subordinate feature, a result of low sensitivity to broadening in the subordinate feature. Because non-local thermodynamic equilibrium (NLTE) corrections are less susceptible to changes in surface gravity and/or metallicity for the 6104 A line, the subordinate Li feature is preferred for deriving lithium abundances in young Li-rich stellar association stars with T{sub eff} {>=} 5200 K. At these temperatures, we find no difference between the Li abundances derived from the two Li I lines. For cooler stars, having temperatures at which main-sequence dwarfs show abundance patterns indicating overexcitation and overionization, the {lambda}6104-based Li abundances are {approx}0.4 dex lower than those derived from the {lambda}6708 doublet. The trends of the abundances from each feature with T{sub eff} suggest that this difference is due to (near)UV photoionization, which in NLTE preferentially ionizes Li atoms in the subordinate 2p state relative to the 2s resonance line state due to opacity effects. Consequently, this overionization of Li in the 2p state, apparently not adequately accounted for in NLTE corrections, weakens the {lambda}6104 feature in cooler stars. Accordingly, the {lambda}6708-based abundances may give more reliable estimates of the mean Li abundance in cool young stars. Our mean Li abundance, log N(Li) =3.50 {+-} 0.07 is {approx}0.2 dex larger than the meteoritic value. While stellar models suggest that Li depletion of at least 0.4 dex, and possibly much larger, should have occurred in our lowest mass star(s), our Li abundances show no decline with decreasing mass indicative of such depletion.« less

Early chemical enrichment of the Galactic dwarf satellites from a homogeneous and NLTE abundance analysis

NASA Astrophysics Data System (ADS)

Mashonkina, Lyudmila; Jablonka, Pascale; Sitnova, Tatyana; Pakhomov, Yuri; North, Pierre

2018-06-01

We review recent abundance results for very metal-poor (VMP, -4 ≤ [Fe/H] ≤ -2) stars in seven dwarf spheroidal galaxies (dSphs) and in the Milky Way (MW) halo comparison sample that were obtained based on high-resolution spectroscopic datasets, homogeneous and accurate atmospheric parameters, and the non-local thermodynamic equilibrium (NLTE) line formation for 10 chemical species. A remarkable gain of using such an approach is the reduction, compared to a simple compilation of the literature data, of the spread in abundance ratios at given metallicity within each galaxy and from one to the other. We show that all massive galaxies in our sample, that is, the MW halo and the classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax, reveal a similar plateau at [α/Fe] \\simeq 0.3 for each of the α-process elements: Mg, Ca, and Ti. We put on a firm ground the evidence for a decline in α/Fe with increasing metallicity in the Boötes I ultra-faint dwarf galaxy (UFD), that is most probably due to the ejecta of type Ia supernovae. In our classical dSphs, we observe the dichotomy in the [Sr/Ba] versus [Ba/H] diagram, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr at the earliest evolution stages of these galaxies. Our three UFDs, that is Boötes I, UMa II, and Leo IV, are depleted in Sr and Ba relative to Fe and Mg, with very similar ratios of [Sr/Mg] ≈ -1.3 and [Ba/Mg] ≈ -1 on the entire range of their Mg abundances. The subsolar Sr/Ba ratios of Boötes I and UMa II indicate a common r-process origin of their neutron-capture elements. For Na/Fe, Na/Mg, and Al/Mg, the MW halo and all dSphs reveal indistinguishable trends with metallicity, suggesting that the processes of Na and Al synthesis are identical in all systems, independent of their mass. Sculptor remains the classical dSph, in which the evidence for inhomogeneous mixing in the early evolution stage, at [Fe/H] < -2, is the strongest.

A Massively Parallel Code for Polarization Calculations

NASA Astrophysics Data System (ADS)

Akiyama, Shizuka; Höflich, Peter

2001-03-01

We present an implementation of our Monte-Carlo radiation transport method for rapidly expanding, NLTE atmospheres for massively parallel computers which utilizes both the distributed and shared memory models. This allows us to take full advantage of the fast communication and low latency inherent to nodes with multiple CPUs, and to stretch the limits of scalability with the number of nodes compared to a version which is based on the shared memory model. Test calculations on a local 20-node Beowulf cluster with dual CPUs showed an improved scalability by about 40%.

Problems in abundance determination from UV spectra of hot supergiants

NASA Astrophysics Data System (ADS)

Deković, M. Sarta; Kotnik-Karuza, D.; Jurkić, T.; Dominis Prester, D.

2010-03-01

We present measurements of equivalent widths of the UV, presumably photospheric lines: C III 1247 Å, N III 1748 Å, N III 1752 Å, N IV 1718 Å and He II 1640 Å in high-resolution IUE spectra of 24 galactic OB supergiants. Equivalent widths measured from the observed spectra have been compared with their counterparts in the Tlusty NLTE synthetic spectra. We discuss possibilities of static plan-parallel model to reproduce observed UV spectra of hot massive stars and possible reasons why observations differ from the model so much.

Computing NLTE Opacities -- Node Level Parallel Calculation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holladay, Daniel

Presentation. The goal: to produce a robust library capable of computing reasonably accurate opacities inline with the assumption of LTE relaxed (non-LTE). Near term: demonstrate acceleration of non-LTE opacity computation. Far term (if funded): connect to application codes with in-line capability and compute opacities. Study science problems. Use efficient algorithms that expose many levels of parallelism and utilize good memory access patterns for use on advanced architectures. Portability to multiple types of hardware including multicore processors, manycore processors such as KNL, GPUs, etc. Easily coupled to radiation hydrodynamics and thermal radiative transfer codes.

The Relationship of Sodium and Oxygen in Galactic Field RR Lyrae Stars

NASA Astrophysics Data System (ADS)

Andrievsky, S.; Wallerstein, G.; Korotin, S.; Lyashko, D.; Kovtyukh, V.; Tsymbal, V.; Davis, C. E.; Gomez, T.; Huang, W.; Farrell, E. M.

2018-02-01

We analyzed 62 high-resolution spectra of 30 Galactic Field RR Lyrae-type stars with the aim of deriving their atmospheric parameters (T eff , {log}g, V t ), metallicity ([Fe/H]), radial velocities, and NLTE abundances of oxygen and sodium. We found that there is no clear anti-correlation between [O/Fe] and [Na/Fe] as is seen in globular clusters. On this basis, we conclude that the majority of field RR Lyrae-type stars should hardly be considered to be remnants of the dissolution of globular clusters.

Handling of Atomic Data

NASA Astrophysics Data System (ADS)

Rauch, T.; Deetjen, J. L.

2003-01-01

State-of-the-art NLTE model atmosphere codes have arrived at a high level of ``numerical'' sophistication and are an adequate tool to analyze the available high-quality spectra from the infrared to the X-ray wavelength range. The computational capacities allow the calculation which include all elements from hydrogen up to the iron group and the lack of reliable atomic data has become a crucial problem for further progress. We summarize briefly the available sources of atomic data and how these are implemented in the Tübingen Model Atmosphere Package (TMAP).

Hot stars in young massive clusters: Mapping the current Galactic metallicity

NASA Astrophysics Data System (ADS)

de la Fuente, Diego; Najarro, Francisco; Davies, Ben; Trombley, Christine; Figer, Donald F.; Herrero, Artemio

2013-06-01

Young Massive Clusters (YMCs) with ages < 6 Myr are ideal tools for mapping the current chemical abundances in the Galactic disk for several reasons. First of all, the locations of these clusters can be known through spectrophotometric distances. Secondly, their young ages guarantee that these objects present the same chemical composition than the surrounding environment where they are recently born. Finally, the YMCs host very massive stars whose extreme luminosities allow to accomplish detailed spectroscopic analyses even in the most distant regions of the Milky Way. Our group has carried out ISAAC/VLT spectroscopic observations of hot massive stars belonging to several YMCs in different locations around the Galactic disk. As a result, high signal-to-noise, near-infrared spectra of dozens of blue massive stars (including many OB supergiants, Wolf-Rayet stars and a B hypergiant) have been obtained. These data are fully reduced, and NLTE spherical atmosphere modeling is in process. Several line diagnostics will be combined in order to calculate metal abundances accurately for each cluster. The diverse locations of the clusters will allow us to draw a two-dimensional chemical map of the Galactic disk for the first time. The study of the radial and azimuthal variations of elemental abundances will be crucial for understanding the chemical evolution of the Milky Way. Particularly, the ratio between Fe-peak and alpha elements will constitute a powerful tool to investigate the past stellar populations that originated the current Galactic chemistry.

The fast non-LTE code DEDALE

NASA Astrophysics Data System (ADS)

Gilleron, Franck; Piron, Robin

2015-12-01

We present Dédale, a fast code implementing a simplified non-local-thermodynamic-equilibrium (NLTE) plasma model. In this approach, the stationary collisional-radiative rates equations are solved for a set of well-chosen Layzer complexes in order to determine the ion state populations. The electronic structure is approximated using the screened hydrogenic model (SHM) of More with relativistic corrections. The radiative and collisional cross-sections are based on Kramers and Van Regemorter formula, respectively, which are extrapolated to derive analytical expressions for all the rates. The latter are improved thereafter using Gaunt factors or more accurate tabulated data. Special care is taken for dielectronic rates which are compared and rescaled with quantum calculations from the Averroès code. The emissivity and opacity spectra are calculated under the same assumptions as for the radiative rates, either in a detailed manner by summing the transitions between each pair of complexes, or in a coarser statistical way by summing the one-electron transitions averaged over the complexes. Optionally, nℓ-splitting can be accounted for using a WKB approach in an approximate potential reconstructed analytically from the screened charges. It is also possible to improve the spectra by replacing some transition arrays with more accurate data tabulated using the SCO-RCG or FAC codes. This latter option is particularly useful for K-shell emission spectroscopy. The Dédale code was used to submit neon and tungsten cases in the last NLTE-8 workshop (Santa Fe, November 4-8, 2013). Some of these results are presented, as well as comparisons with Averroès calculations.

Progress towards a more predictive model for hohlraum radiation drive and symmetry

NASA Astrophysics Data System (ADS)

Jones, O. S.; Suter, L. J.; Scott, H. A.; Barrios, M. A.; Farmer, W. A.; Hansen, S. B.; Liedahl, D. A.; Mauche, C. W.; Moore, A. S.; Rosen, M. D.; Salmonson, J. D.; Strozzi, D. J.; Thomas, C. A.; Turnbull, D. P.

2017-05-01

For several years, we have been calculating the radiation drive in laser-heated gold hohlraums using flux-limited heat transport with a limiter of 0.15, tabulated values of local thermodynamic equilibrium gold opacity, and an approximate model for not in a local thermodynamic equilibrium (NLTE) gold emissivity (DCA_2010). This model has been successful in predicting the radiation drive in vacuum hohlraums, but for gas-filled hohlraums used to drive capsule implosions, the model consistently predicts too much drive and capsule bang times earlier than measured. In this work, we introduce a new model that brings the calculated bang time into better agreement with the measured bang time. The new model employs (1) a numerical grid that is fully converged in space, energy, and time, (2) a modified approximate NLTE model that includes more physics and is in better agreement with more detailed offline emissivity models, and (3) a reduced flux limiter value of 0.03. We applied this model to gas-filled hohlraum experiments using high density carbon and plastic ablator capsules that had hohlraum He fill gas densities ranging from 0.06 to 1.6 mg/cc and hohlraum diameters of 5.75 or 6.72 mm. The new model predicts bang times to within ±100 ps for most experiments with low to intermediate fill densities (up to 0.85 mg/cc). This model predicts higher temperatures in the plasma than the old model and also predicts that at higher gas fill densities, a significant amount of inner beam laser energy escapes the hohlraum through the opposite laser entrance hole.

A Reduced-order NLTE Kinetic Model for Radiating Plasmas of Outer Envelopes of Stellar Atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munafò, Alessandro; Mansour, Nagi N.; Panesi, Marco, E-mail: munafo@illinois.edu, E-mail: nagi.n.mansour@nasa.gov, E-mail: m.panesi@illinois.edu

The present work proposes a self-consistent reduced-order NLTE kinetic model for radiating plasmas found in the outer layers of stellar atmospheres. A detailed collisional-radiative kinetic mechanism is constructed by leveraging the most up-to-date set of ab initio and experimental data available in the literature. This constitutes the starting point for the derivation of a reduced-order model, obtained by lumping the bound energy states into groups. In order to determine the needed thermo-physical group properties, uniform and Maxwell–Boltzmann energy distributions are used to reconstruct the energy population of each group. Finally, the reduced set of governing equations for the material gasmore » and the radiation field is obtained based on the moment method. Applications consider the steady flow across a shock wave in partially ionized hydrogen. The results clearly demonstrate that adopting a Maxwell–Boltzmann grouping allows, on the one hand, for a substantial reduction of the number of unknowns and, on the other, to maintain accuracy for both gas and radiation quantities. Also, it is observed that, when neglecting line radiation, the use of two groups already leads to a very accurate resolution of the photo-ionization precursor, internal relaxation, and radiative cooling regions. The inclusion of line radiation requires adopting just one additional group to account for optically thin losses in the α , β , and γ lines of the Balmer and Paschen series. This trend has been observed for a wide range of shock wave velocities.« less

HUBBLE SPACE TELESCOPE FAR ULTRAVIOLET SPECTROSCOPY OF THE RECURRENT NOVA T PYXIDIS

PubMed Central

Godon, Patrick; Sion, Edward M.; Starrfield, Sumner; Livio, Mario; Williams, Robert E.; Woodward, Charles E.; Kuin, Paul; Page, Kim L.

2018-01-01

With six recorded nova outbursts, the prototypical recurrent nova T Pyxidis (T Pyx) is the ideal cataclysmic variable system to assess the net change of the white dwarf mass within a nova cycle. Recent estimates of the mass ejected in the 2011 outburst ranged from a few ~10−5 M⊙ to 3.3 × 10−4 M⊙, and assuming a mass accretion rate of 10−8−10−7 M⊙ yr−1 for 44 yr, it has been concluded that the white dwarf in T Pyx is actually losing mass. Using NLTE disk modeling spectra to fit our recently obtained Hubble Space Telescope COS and STIS spectra, we find a mass accretion rate of up to two orders of magnitude larger than previously estimated. Our larger mass accretion rate is due mainly to the newly derived distance of T Pyx (4.8 kpc, larger than the previous 3.5 kpc estimate), our derived reddening of E(B − V) = 0.35 (based on combined IUE and GALEX spectra), and NLTE disk modeling (compared to blackbody and raw flux estimates in earlier works). We find that for most values of the reddening (0.25 ≤ E(B−V) ≤ 0.50) and white dwarf mass (0.70 M⊙ ≤ Mwd ≤ 1.35 M⊙) the accreted mass is larger than the ejected mass. Only for a low reddening (~0.25 and smaller) combined with a large white dwarf mass (0.9 M⊙ and larger) is the ejected mass larger than the accreted one. However, the best results are obtained for a larger value of reddening. PMID:29430290

HUBBLE SPACE TELESCOPE FAR ULTRAVIOLET SPECTROSCOPY OF THE RECURRENT NOVA T PYXIDIS.

PubMed

Godon, Patrick; Sion, Edward M; Starrfield, Sumner; Livio, Mario; Williams, Robert E; Woodward, Charles E; Kuin, Paul; Page, Kim L

2014-04-01

With six recorded nova outbursts, the prototypical recurrent nova T Pyxidis (T Pyx) is the ideal cataclysmic variable system to assess the net change of the white dwarf mass within a nova cycle. Recent estimates of the mass ejected in the 2011 outburst ranged from a few ~10 -5 M ⊙ to 3.3 × 10 -4 M ⊙ , and assuming a mass accretion rate of 10 -8 -10 -7 M ⊙ yr -1 for 44 yr, it has been concluded that the white dwarf in T Pyx is actually losing mass. Using NLTE disk modeling spectra to fit our recently obtained Hubble Space Telescope COS and STIS spectra, we find a mass accretion rate of up to two orders of magnitude larger than previously estimated. Our larger mass accretion rate is due mainly to the newly derived distance of T Pyx (4.8 kpc, larger than the previous 3.5 kpc estimate), our derived reddening of E ( B - V ) = 0.35 (based on combined IUE and GALEX spectra), and NLTE disk modeling (compared to blackbody and raw flux estimates in earlier works). We find that for most values of the reddening (0.25 ≤ E ( B - V ) ≤ 0.50) and white dwarf mass (0.70 M ⊙ ≤ M wd ≤ 1.35 M ⊙ ) the accreted mass is larger than the ejected mass. Only for a low reddening (~0.25 and smaller) combined with a large white dwarf mass (0.9 M ⊙ and larger) is the ejected mass larger than the accreted one. However, the best results are obtained for a larger value of reddening.

Global hot-star wind models for stars from Magellanic Clouds

NASA Astrophysics Data System (ADS)

Krtička, J.; Kubát, J.

2018-04-01

We provide mass-loss rate predictions for O stars from Large and Small Magellanic Clouds. We calculate global (unified, hydrodynamic) model atmospheres of main sequence, giant, and supergiant stars for chemical composition corresponding to Magellanic Clouds. The models solve radiative transfer equation in comoving frame, kinetic equilibrium equations (also known as NLTE equations), and hydrodynamical equations from (quasi-)hydrostatic atmosphere to expanding stellar wind. The models allow us to predict wind density, velocity, and temperature (consequently also the terminal wind velocity and the mass-loss rate) just from basic global stellar parameters. As a result of their lower metallicity, the line radiative driving is weaker leading to lower wind mass-loss rates with respect to the Galactic stars. We provide a formula that fits the mass-loss rate predicted by our models as a function of stellar luminosity and metallicity. On average, the mass-loss rate scales with metallicity as Ṁ Z0.59. The predicted mass-loss rates are lower than mass-loss rates derived from Hα diagnostics and can be reconciled with observational results assuming clumping factor Cc = 9. On the other hand, the predicted mass-loss rates either agree or are slightly higher than the mass-loss rates derived from ultraviolet wind line profiles. The calculated P V ionization fractions also agree with values derived from observations for LMC stars with Teff ≤ 40 000 K. Taken together, our theoretical predictions provide reasonable models with consistent mass-loss rate determination, which can be used for quantitative study of stars from Magellanic Clouds.

Mesospheric dynamics and chemistry from SME data

NASA Technical Reports Server (NTRS)

Strobel, Darrell F.

1987-01-01

A fast Curtis matrix calculation of cooling rates due to the 15 micron band of CO2 is modified to parameterize the detailed calculations by Dickinson (1984) of infrared cooling by CO2 in the mesosphere and lower thermosphere. The calculations included separate NLTE treatment of the different 15 micron bands likely to be important for cooling. The goal was to compress the detailed properties of the different bands into a modified Curtis matrix, which represents one composite band with appropriate averaged radiative properties to allow for a simple and quick calculation of cooling rates given a temperature profile. Vertical constituent transport in the mesosphere was also studied.

Asiago eclipsing binaries program IV. SZ Camelopardalis, a β Cephei pulsator in a quadruple, eclipsing system

NASA Astrophysics Data System (ADS)

Tamajo, E.; Munari, U.; Siviero, A.; Tomasella, L.; Dallaporta, S.

2012-03-01

We present a spectroscopic and photometric analysis of the multiple system and early-type eclipsing binary SZ Cam (O9 IV + B0.5 V), which consists of an eclipsing SB2 pair of orbital period P = 2.7 days in a long orbit (~55 yrs) around a non-eclipsing SB1 pair of orbital period P = 2.8 days. We have reconstructed the spectra of the individual components of SZ Cam from the observed composite spectra using the technique of spectral disentangling. We used them together with extensive and accurate BVIC CCD photometry to obtain an orbital solution. Our photometry revealed the presence of a β Cep variable in the SZ Cam hierarchical system, probably located within the non-eclipsing SB1 pair. The pulsation period is (0.33265 ± 0.00005) days and the observed total amplitude in the B band is (0.0105 ± 0.0005) mag. NLTE analysis of the disentangled spectra provided atmospheric parameters for all three components, consistent with those derived from orbital solution. Full Table 3 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A139

Stellar laboratories. II. New Zn iv and Zn v oscillator strengths and their validation in the hot white dwarfs G191-B2B and RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

2014-04-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. In a recent analysis of the ultraviolet (UV) spectrum of the DA-type white dwarf G191-B2B, 21 Zn iv lines were newly identified. Because of the lack of Zn iv data, transition probabilities of the isoelectronic Ge vi were adapted for a first, coarse determination of the photospheric Zn abundance. Aims: Reliable Zn iv and Zn v oscillator strengths are used to improve the Zn abundance determination and to identify more Zn lines in the spectra of G191-B2B and the DO-type white dwarf RE 0503-289. Methods: We performed new calculations of Zn iv and Zn v oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of the Zn iv - v spectrum exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: In the UV spectrum of G191-B2B, we identify 31 Zn iv and 16 Zn v lines. Most of these are identified for the first time in any star. We can reproduce well almost all of them at log Zn = -5.52 ± 0.2 (mass fraction, about 1.7 times solar). In particular, the Zn iv / Zn v ionization equilibrium, which is a very sensitive Teff indicator, is well reproduced with the previously determined and log g = 7.60 ± 0.05. In the spectrum of RE 0503-289, we identified 128 Zn v lines for the first time and determined log Zn = -3.57 ± 0.2 (155 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Zn iv and Zn v line profiles in two white dwarf (G191-B2B and RE 0503-289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed us to determine the photospheric Zn abundance of these two stars precisely. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Tables 1 and 2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/564/A41

Stellar laboratories. VI. New Mo iv-vii oscillator strengths and the molybdenum abundance in the hot white dwarfs G191-B2B and RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Quinet, P.; Hoyer, D.; Werner, K.; Demleitner, M.; Kruk, J. W.

2016-03-01

Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To identify molybdenum lines in the ultraviolet (UV) spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and, to determine their photospheric Mo abundances, reliable Mo iv-vii oscillator strengths are used. Methods: We newly calculated Mo iv-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Mo lines exhibited in high-resolution and high S/N UV observations of RE 0503-289. Results: We identified 12 Mo v and 9 Mo vi lines in the UV spectrum of RE 0503-289 and measured a photospheric Mo abundance of 1.2-3.0 × 10-4 (mass fraction, 22 500-56 400 times the solar abundance). In addition, from the As v and Sn iv resonance lines, we measured mass fractions of arsenic (0.5-1.3 × 10-5, about 300-1200 times solar) and tin (1.3-3.2 × 10-4, about 14 300-35 200 times solar). For G191-B2B, upper limits were determined for the abundances of Mo (5.3 × 10-7, 100 times solar) and, in addition, for Kr (1.1 × 10-6, 10 times solar) and Xe (1.7 × 10-7, 10 times solar). The arsenic abundance was determined (2.3-5.9 × 10-7, about 21-53 times solar). A new, registered German Astrophysical Virtual Observatory (GAVO) service, TOSS, has been constructed to provide weighted oscillator strengths and transition probabilities. Conclusions: Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. Observed Mo v-vi line profiles in the UV spectrum of the white dwarf RE 0503-289 were well reproduced with our newly calculated oscillator strengths. For the first time, this allowed the photospheric Mo abundance in a white dwarf to be determined. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Tables A.10-A.13 are only available via the German Astrophysical Virtual Observatory (GAVO) service TOSS (http://dc.g-vo.org/TOSS).

The virtual observatory service TheoSSA: Establishing a database of synthetic stellar flux standards. I. NLTE spectral analysis of the DA-type white dwarf G191-B2B

NASA Astrophysics Data System (ADS)

Rauch, T.; Werner, K.; Bohlin, R.; Kruk, J. W.

2013-12-01

Context. Hydrogen-rich, DA-type white dwarfs are particularly suited as primary standard stars for flux calibration. State-of-the-art NLTE models consider opacities of species up to trans-iron elements and provide reliable synthetic stellar-atmosphere spectra to compare with observations. Aims: We will establish a database of theoretical spectra of stellar flux standards that are easily accessible via a web interface. Methods: In the framework of the Virtual Observatory, the German Astrophysical Virtual Observatory developed the registered service TheoSSA. It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code. In case of the DA white dwarf G191-B2B, we demonstrate that the model reproduces not only its overall continuum shape but also the numerous metal lines exhibited in its ultraviolet spectrum. Results: TheoSSA is in operation and contains presently a variety of SEDs for DA-type white dwarfs. It will be extended in the near future and can host SEDs of all primary and secondary flux standards. The spectral analysis of G191-B2B has shown that our hydrostatic models reproduce the observations best at and log g = 7.60 ± 0.05. We newly identified Fe vi, Ni vi, and Zn iv lines. For the first time, we determined the photospheric zinc abundance with a logarithmic mass fraction of -4.89 (7.5 × solar). The abundances of He (upper limit), C, N, O, Al, Si, O, P, S, Fe, Ni, Ge, and Sn were precisely determined. Upper abundance limits of about 10% solar were derived for Ti, Cr, Mn, and Co. Conclusions: The TheoSSA database of theoretical SEDs of stellar flux standards guarantees that the flux calibration of all astronomical data and cross-calibration between different instruments can be based on the same models and SEDs calculated with different model-atmosphere codes and are easy to compare. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Figures 1, 6, 10-12, 23, A.1, A.2 and Tables 2-4 are available in electronic form at http://www.aanda.orgTable 5 and Figs. A.1 and A.2 (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A106

Stellar laboratories. III. New Ba v, Ba vi, and Ba vii oscillator strengths and the barium abundance in the hot white dwarfs G191-B2B and RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

2014-06-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: Reliable Ba v-vii oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods: We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g = 7.5. The Ba abundance is 3.5 ± 0.5 × 10-4 (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 ± 0.5 × 10-6 (about 265 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Tables 1-3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A10

Observations and NLTE modeling of Ellerman bombs

NASA Astrophysics Data System (ADS)

Berlicki, A.; Heinzel, P.

2014-07-01

Context. Ellerman bombs (EBs) are short-lived, compact, and spatially well localized emission structures that are observed well in the wings of the hydrogen Hα line. EBs are also observed in the chromospheric CaII lines and in UV continua as bright points located within active regions. Hα line profiles of EBs show a deep absorption at the line center and enhanced emission in the line wings with maxima around ±1 Å from the line center. Similar shapes of the line profiles are observed for the CaII IR line at 8542 Å. In CaII H and K lines the emission peaks are much stronger, and EBs emission is also enhanced in the line center. Aims: It is generally accepted that EBs may be considered as compact microflares located in lower solar atmosphere that contribute to the heating of these low-lying regions, close to the temperature minimum of the atmosphere. However, it is still not clear where exactly the emission of EBs is formed in the solar atmosphere. High-resolution spectrophotometric observations of EBs were used for determining of their physical parameters and construction of semi-empirical models. Obtained models allow us to determine the position of EBs in the solar atmosphere, as well as the vertical structure of the activated EB atmosphere Methods: In our analysis we used observations of EBs obtained in the Hα and CaII H lines with the Dutch Open Telescope (DOT). These one-hour long simultaneous sequences obtained with high temporal and spatial resolution were used to determine the line emissions. To analyze them, we used NLTE numerical codes for the construction of grids of 243 semi-empirical models simulating EBs structures. In this way, the observed emission could be compared with the synthetic line spectra calculated for all such models. Results: For a specific model we found reasonable agreement between the observed and theoretical emission and thus we consider such model as a good approximation to EBs atmospheres. This model is characterized by an enhanced temperature in the lower chromosphere and can be considered as a compact structure (hot spot), which is responsible for the emission observed in the wings of chromospheric lines, in particular in the Hα and CaII H lines. Conclusions: For the first time the set of two lines Hα and CaII H was used to construct semi-empirical models of EBs. Our analysis shows that EBs can be described by a "hot spot" model, with the temperature and/or density increase through a few hundred km atmospheric structure. We confirmed that EBs are located close to the temperature minimum or in the lower chromosphere. Two spectral features (lines in our case), observed simultaneously, significantly strengthen the constraints on a realistic model.

"SMART": A Compact and Handy FORTRAN Code for the Physics of Stellar Atmospheres

NASA Astrophysics Data System (ADS)

Sapar, A.; Poolamäe, R.

2003-01-01

A new computer code SMART (Spectra from Model Atmospheres by Radiative Transfer) for computing the stellar spectra, forming in plane-parallel atmospheres, has been compiled by us and A. Aret. To guarantee wide compatibility of the code with shell environment, we chose FORTRAN-77 as programming language and tried to confine ourselves to common part of its numerous versions both in WINDOWS and LINUX. SMART can be used for studies of several processes in stellar atmospheres. The current version of the programme is undergoing rapid changes due to our goal to elaborate a simple, handy and compact code. Instead of linearisation (being a mathematical method of recurrent approximations) we propose to use the physical evolutionary changes or in other words relaxation of quantum state populations rates from LTE to NLTE has been studied using small number of NLTE states. This computational scheme is essentially simpler and more compact than the linearisation. This relaxation scheme enables using instead of the Λ-iteration procedure a physically changing emissivity (or the source function) which incorporates in itself changing Menzel coefficients for NLTE quantum state populations. However, the light scattering on free electrons is in the terms of Feynman graphs a real second-order quantum process and cannot be reduced to consequent processes of absorption and emission as in the case of radiative transfer in spectral lines. With duly chosen input parameters the code SMART enables computing radiative acceleration to the matter of stellar atmosphere in turbulence clumps. This also enables to connect the model atmosphere in more detail with the problem of the stellar wind triggering. Another problem, which has been incorporated into the computer code SMART, is diffusion of chemical elements and their isotopes in the atmospheres of chemically peculiar (CP) stars due to usual radiative acceleration and the essential additional acceleration generated by the light-induced drift. As a special case, using duly chosen pixels on the stellar disk, the spectrum of rotating star can be computed. No instrumental broadening has been incorporated in the code of SMART. To facilitate study of stellar spectra, a GUI (Graphical User Interface) with selection of labels by ions has been compiled to study the spectral lines of different elements and ions in the computed emergent flux. An amazing feature of SMART is that its code is very short: it occupies only 4 two-sided two-column A4 sheets in landscape format. In addition, if well commented, it is quite easily readable and understandable. We have used the tactics of writing the comments on the right-side margin (columns starting from 73). Such short code has been composed widely using the unified input physics (for example the ionisation cross-sections for bound-free transitions and the electron and ion collision rates). As current restriction to the application area of the present version of the SMART is that molecules are since ignored. Thus, it can be used only for luke and hot stellar atmospheres. In the computer code we have tried to avoid bulky often over-optimised methods, primarily meant to spare the time of computations. For instance, we compute the continuous absorption coefficient at every wavelength. Nevertheless, during an hour by the personal computer in our disposal AMD Athlon XP 1700+, 512MB DDRAM) a stellar spectrum with spectral step resolution λ / dλ = 3D100,000 for spectral interval 700 -- 30,000 Å is computed. The model input data and the line data used by us are both the ones computed and compiled by R. Kurucz. In order to follow presence and representability of quantum states and to enumerate them for NLTE studies a C++ code, transforming the needed data to the LATEX version, has been compiled. Thus we have composed a quantum state list for all neutrals and ions in the Kurucz file 'gfhyperall.dat'. The list enables more adequately to compose the concept of super-states, including partly correlating super-states. We are grateful to R. Kurucz for making available by CD-ROMs and Internet his computer codes ATLAS and SYNTHE used by us as a starting point in composing of the new computer code. We are also grateful to Estonian Science Foundation for grant ESF-4701.

How Do Type Ia Supernova Nebular Spectra Depend on Explosion Properties? Insights from Systematic Non-LTE Modeling

NASA Astrophysics Data System (ADS)

Botyánszki, János; Kasen, Daniel

2017-08-01

We present a radiative transfer code to model the nebular phase spectra of supernovae (SNe) in non-LTE (NLTE). We apply it to a systematic study of SNe Ia using parameterized 1D models and show how nebular spectral features depend on key physical parameters, such as the time since explosion, total ejecta mass, kinetic energy, radial density profile, and the masses of 56Ni, intermediate-mass elements, and stable iron-group elements. We also quantify the impact of uncertainties in atomic data inputs. We find the following. (1) The main features of SN Ia nebular spectra are relatively insensitive to most physical parameters. Degeneracy among parameters precludes a unique determination of the ejecta properties from spectral fitting. In particular, features can be equally well fit with generic Chandrasekhar mass ({M}{ch}), sub-{M}{Ch}, and super-{M}{Ch} models. (2) A sizable (≳0.1 {M}⊙ ) central region of stable iron-group elements, often claimed as evidence for {M}{Ch} models, is not essential to fit the optical spectra and may produce an unusual flat-top [Co III] profile. (3) The strength of [S III] emission near 9500 Å can provide a useful diagnostic of explosion nucleosynthesis. (4) Substantial amounts (≳0.1 {M}⊙ ) of unburned C/O mixed throughout the ejecta produce [O III] emission not seen in observations. (5) Shifts in the wavelength of line peaks can arise from line-blending effects. (6) The steepness of the ejecta density profile affects the line shapes, offering a constraint on explosion models. (7) Uncertainties in atomic data limit the ability to infer physical parameters.

No breakdown of the radiatively driven wind theory in low-metallicity environments

NASA Astrophysics Data System (ADS)

Bouret, J.-C.; Lanz, T.; Hillier, D. J.; Martins, F.; Marcolino, W. L. F.; Depagne, E.

2015-05-01

We present a spectroscopic analysis of Hubble Space Telescope/Cosmic Origins Spectrograph observations of three massive stars in the low metallicity dwarf galaxies IC 1613 and WLM. These stars, were previously observed with Very Large Telescope (VLT)/X-shooter by Tramper et al., who claimed that their mass-loss rates are higher than expected from theoretical predictions for the underlying metallicity. A comparison of the far ultraviolet (FUV) spectra with those of stars of similar spectral types/luminosity classes in the Galaxy, and the Magellanic Clouds provides a direct, model-independent check of the mass-loss-metallicity relation. Then, a quantitative spectroscopic analysis is carried out using the non-LTE (NLTE) stellar atmosphere code CMFGEN. We derive the photospheric and wind characteristics, benefiting from a much better sensitivity of the FUV lines to wind properties than Hα. Iron and CNO abundances are measured, providing an independent check of the stellar metallicity. The spectroscopic analysis indicates that Z/Z⊙ = 1/5, similar to a Small Magellanic Cloud-type environment, and higher than usually quoted for IC 1613 and WLM. The mass-loss rates are smaller than the empirical ones by Tramper et al., and those predicted by the widely used theoretical recipe by Vink et al. On the other hand, we show that the empirical, FUV-based, mass-loss rates are in good agreement with those derived from mass fluxes computed by Lucy. We do not concur with Tramper et al. that there is a breakdown in the mass-loss-metallicity relation.

VizieR Online Data Catalog: CoRoT red giants abundances (Morel+, 2014)

NASA Astrophysics Data System (ADS)

Morel, T.; Miglio, A.; Lagarde, N.; Montalban, J.; Rainer, M.; Poretti, E.; Eggenberger, P.; Hekker, S.; Kallinger, T.; Mosser, B.; Valentini, M.; Carrier, F.; Hareter, M.; Mantegazza, L.

2014-02-01

The equivalent widths were measured manually assuming Gaussian profiles or Voigt profiles for the few lines with extended damping wings. Lines with an unsatisfactory fit or significantly affected by telluric features were discarded. Only values eventually retained for the analysis are provided. For the chemical abundances, the usual notation is used: [X/Y]=[log({epsilon}(X))-log({epsilon}(Y))]star - [log({epsilon}(X))-log({epsilon}(Y))]⊙ with log{epsilon}(X)=12+log[N(X)/N(H)] (N is the number density of the species). For lithium, the following notation is used: [Li/H]=log(N(Li))star-log(N(Li))⊙. The adopted solar abundances are taken from Grevesse & Sauval (1998SSRv...85..161G), except for Li for which we adopt our derived values: log({epsilon}(Li))⊙=1.09 and 1.13 in LTE and NLTE, respectively (see text). All the abundances are computed under the assumption of LTE, except Li for which values corrected for departures from LTE using the data of Lind et al. (2009A&A...503..541L) are also provided. All the quoted error bars are 1-sigma uncertainties. (6 data files).

First Detection of Krypton and Xenon in a White Dwarf

NASA Astrophysics Data System (ADS)

Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

2012-07-01

We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 Kr VI- VII and Xe VI- VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 ± 0.5 and log Xe = -4.2 ± 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and that the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell flash or a binary white dwarf merger.

Model Atmospheres for Novae in Outburst: Summary of Research

NASA Technical Reports Server (NTRS)

Hauschildt, Peter H.

1999-01-01

This paper presents a final report and summary of research on Model Atmospheres for Novae in Outburst. Some of the topics include: 1) Detailed NLTE (non-local thermodynamic equilibrium) Model Atmospheres for Novae during Outburst: II. Modeling optical and ultraviolet observations of Nova LMC 1988 #1; 2) A Non-LTE Line-Blanketed Stellar Atmosphere Model of the Early B Giant epsilon CMa; 3) Spectroscopy of Low Metallicity Stellar atmospheres; 4) Infrared Colors at the Stellar/Substellar Boundary; 5) On the abundance of Lithium in T CrB; 6) Numerical Solution of the Expanding Stellar Atmosphere Problem; and 7) The NextGen Model Atmosphere grid for 3000 less than or equal to T (sub eff) less than or equal to 10000K.

An LTE effective temperature scale for red supergiants in the Magellanic clouds

NASA Astrophysics Data System (ADS)

Tabernero, H. M.; Dorda, R.; Negueruela, I.; González-Fernández, C.

2018-05-01

We present a self-consistent study of cool supergiants (CSGs) belonging to the Magellanic clouds. We calculated stellar atmospheric parameters using LTE KURUCZ and MARCS atmospheric models for more than 400 individual targets by fitting a careful selection of weak metallic lines. We explore the existence of a Teff scale and its implications in two different metallicity environments (each Magellanic cloud). Critical and in-depth tests have been performed to assess the reliability of our stellar parameters (i.e. internal error budget, NLTE systematics). In addition, several Monte Carlo tests have been carried out to infer the significance of the Teff scale found. Our findings point towards a unique Teff scale that seems to be independent of the environment.

The Born-again Planetary Nebula A78: An X-Ray Twin of A30

NASA Astrophysics Data System (ADS)

Toalá, J. A.; Guerrero, M. A.; Todt, H.; Hamann, W.-R.; Chu, Y.-H.; Gruendl, R. A.; Schönberner, D.; Oskinova, L. M.; Marquez-Lugo, R. A.; Fang, X.; Ramos-Larios, G.

2015-01-01

We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar wind and a point-like source at the position of the central star (CSPN). We present the spectral analysis of the CSPN, using for the first time an NLTE code for expanding atmospheres that takes line blanketing into account for the UV and optical spectra. The wind abundances are used for the X-ray spectral analysis of the CSPN and the diffuse emission. The X-ray emission from the CSPN in A78 can be modeled by a single C VI emission line, while the X-ray emission from its diffuse component is better described by an optically thin plasma emission model with a temperature of kT = 0.088 keV (T ≈ 1.0 × 106 K). We estimate X-ray luminosities in the 0.2-2.0 keV energy band of L X, CSPN = (1.2 ± 0.3) × 1031 erg s-1 and L X, DIFF = (9.2 ± 2.3) × 1030 erg s-1 for the CSPN and diffuse components, respectively.

The origin and evolution of the odd-Z iron-peak elements Sc, V, Mn, and Co in the Milky Way stellar disk

NASA Astrophysics Data System (ADS)

Battistini, Chiara; Bensby, Thomas

2015-05-01

Context. Elements heavier than Li are produced in the interiors of stars. However, for many elements the exact production sites and the timescales on which they are dispersed into the interstellar medium are unknown. Having a clear picture on the origins of the elements is important for our ability to trace and understand the formation and chemical evolution of the Milky Way and its stellar populations. Aims: The aim of this study is to investigate the origin and evolution of Sc, V, Mn, and Co for a homogeneous and statistically significant sample of stars probing the different populations of the Milky Way, in particular the thin and thick disks. Methods: Using high-resolution spectra obtained with the MIKE, FEROS, SOFIN, FIES, UVES, and HARPS spectrographs, we determine Sc, V, Mn, and Co abundances for a large sample of F and G dwarfs in the solar neighborhood. The method is based on spectral synthesis and using one-dimensional, plane-parallel, local thermodynamic equilibrium (LTE) model stellar atmospheres calculated with the MARCS 2012 code. The non-LTE (NLTE) corrections from the literature were applied to Mn and Co. Results: We find that the abundance trends derived for Sc (594 stars), V (466 stars), and Co (567 stars) are very similar to what has been observed for the α-elements in the thin and thick disks. On the contrary, Mn (569 stars) is generally underabundant relative to the Sun (i.e., [ Mn/Fe ] < 0) for [ Fe/H ] < 0. In addition, for Mn, when NLTE corrections are applied, the trend changes and is almost flat over the entire metallicity range of the stars in our sample (-2 ≲ [ Fe/H ] ≲ + 0.4). The [Sc/Fe]-[Fe/H] abundance trends show a small separation between the thin and thick disks, while for V and Co they completely overlap. For Mn there is a small difference in [Mn/Fe], but only when NLTE corrections are used. Comparisons with Ti as a reference element show flat trends for all the elements except for Mn that show well separated [Mn/Ti]-[Ti/H] trends for the thin and thick disks. Conclusions: The elements Sc and V present trends compatible with production from type II supernovae (SNII) events. In addition, Sc clearly shows a metallicity dependence for [ Fe/H ] < -1. Instead, Mn is produced in SNII events for [ Fe/H ] ≲ -0.4 and then type Ia supernovae start to produce Mn. Finally, Co appears to be produced mainly in SNII with suggestion of enrichment from hypernovae at low metallicities. This paper includes data gathered with the 6.5 m Magellan Telescopes located at the Las Campanas Observatory, Chile; the Nordic Optical Telescope (NOT) on La Palma, Spain; the Very Large Telescope (VLT) at the European Southern Observatory (ESO) on Paranal, Chile (ESO Proposal ID 69.B-0277 and 72.B-0179); the ESO 1.5-m, 2.2-m. and 3.6-m telescopes on La Silla, Chile (ESO Proposal ID 65.L-0019, 67.B-0108, 76.B-0416, 82.B-0610); and data from UVES Paranal Observatory Project (ESO DDT Program ID 266.D-5655).Full versions of Tables 2 and 5 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A9Appendices are available in electronic form at http://www.aanda.org

Galactic evolution of oxygen. OH lines in 3D hydrodynamical model atmospheres

NASA Astrophysics Data System (ADS)

González Hernández, J. I.; Bonifacio, P.; Ludwig, H.-G.; Caffau, E.; Behara, N. T.; Freytag, B.

2010-09-01

Context. Oxygen is the third most common element in the Universe. The measurement of oxygen lines in metal-poor unevolved stars, in particular near-UV OH lines, can provide invaluable information about the properties of the Early Galaxy. Aims: Near-UV OH lines constitute an important tool to derive oxygen abundances in metal-poor dwarf stars. Therefore, it is important to correctly model the line formation of OH lines, especially in metal-poor stars, where 3D hydrodynamical models commonly predict cooler temperatures than plane-parallel hydrostatic models in the upper photosphere. Methods: We have made use of a grid of 52 3D hydrodynamical model atmospheres for dwarf stars computed with the code CO5BOLD, extracted from the more extended CIFIST grid. The 52 models cover the effective temperature range 5000-6500 K, the surface gravity range 3.5-4.5 and the metallicity range -3 < [Fe/H] < 0. Results: We determine 3D-LTE abundance corrections in all 52 3D models for several OH lines and ion{Fe}{i} lines of different excitation potentials. These 3D-LTE corrections are generally negative and reach values of roughly -1 dex (for the OH 3167 with excitation potential of approximately 1 eV) for the higher temperatures and surface gravities. Conclusions: We apply these 3D-LTE corrections to the individual O abundances derived from OH lines of a sample the metal-poor dwarf stars reported in Israelian et al. (1998, ApJ, 507, 805), Israelian et al. (2001, ApJ, 551, 833) and Boesgaard et al. (1999, AJ, 117, 492) by interpolating the stellar parameters of the dwarfs in the grid of 3D-LTE corrections. The new 3D-LTE [O/Fe] ratio still keeps a similar trend as the 1D-LTE, i.e., increasing towards lower [Fe/H] values. We applied 1D-NLTE corrections to 3D ion{Fe}{i} abundances and still see an increasing [O/Fe] ratio towards lower metallicites. However, the Galactic [O/Fe] ratio must be revisited once 3D-NLTE corrections become available for OH and Fe lines for a grid of 3D hydrodynamical model atmospheres.

UV Spectroscopy of face-on accretion disks

NASA Astrophysics Data System (ADS)

Wade, Richard

1996-07-01

We will obtain GHRS spectra at 1 Angstrom resolution of three novalike variables that have low orbital inclinations, BD-7D3007 {= RW Sex}, HD174107 {= V603 Aql}, and MV-LYR. The blending and broadening of absorption lines from the accretion disk will not be as severe in these objects as in more edge-on systems, and we expect to see individual lines or blends that are distinctively characteristic of the varying projected velocities at different temperatures { i.e. radii} in the disk. These aspects of the UV disk spectrum have not previously been used as a tool to study accretion disk physics. Comparison of line strengths with our detailed models will indicate whether it is necessary to consider irradiated or NLTE disks, and test in a new way whether the disks are in steady state. The shapes of lines that would be formed in the inner disk will tell whether the inner disk is actually present, an important check on observational and theoretical suggestions that the inner disk is missing in some cataclysmic variables. The improved understanding and characterization of the photospheric spectrum will aid in the analysis of the wind-formed P Cygni lines that are seen in these objects. We will use grating G140L, covering much of the mid-UV spectrum with S/N up to 200.

First Detection of Krypton and Xenon in a White Dwarf

NASA Technical Reports Server (NTRS)

Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

2012-01-01

We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 KrVI-VII and Xe VI-VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 plus or minus 0.5 and log Xe = -4.2 plus or minus 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the-precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and thaI the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell nash or a binary white dwarf merger.

Microbial Diagnostic Array Workstation (MDAW): a web server for diagnostic array data storage, sharing and analysis

PubMed Central

Scaria, Joy; Sreedharan, Aswathy; Chang, Yung-Fu

2008-01-01

Background Microarrays are becoming a very popular tool for microbial detection and diagnostics. Although these diagnostic arrays are much simpler when compared to the traditional transcriptome arrays, due to the high throughput nature of the arrays, the data analysis requirements still form a bottle neck for the widespread use of these diagnostic arrays. Hence we developed a new online data sharing and analysis environment customised for diagnostic arrays. Methods Microbial Diagnostic Array Workstation (MDAW) is a database driven application designed in MS Access and front end designed in ASP.NET. Conclusion MDAW is a new resource that is customised for the data analysis requirements for microbial diagnostic arrays. PMID:18811969

Microbial Diagnostic Array Workstation (MDAW): a web server for diagnostic array data storage, sharing and analysis.

PubMed

Scaria, Joy; Sreedharan, Aswathy; Chang, Yung-Fu

2008-09-23

Microarrays are becoming a very popular tool for microbial detection and diagnostics. Although these diagnostic arrays are much simpler when compared to the traditional transcriptome arrays, due to the high throughput nature of the arrays, the data analysis requirements still form a bottle neck for the widespread use of these diagnostic arrays. Hence we developed a new online data sharing and analysis environment customised for diagnostic arrays. Microbial Diagnostic Array Workstation (MDAW) is a database driven application designed in MS Access and front end designed in ASP.NET. MDAW is a new resource that is customised for the data analysis requirements for microbial diagnostic arrays.

The CNO Bi-cycle in the Open Cluster NGC 752

NASA Astrophysics Data System (ADS)

Hawkins, Keith; Schuler, S.; King, J.; The, L.

2011-01-01

The CNO bi-cycle is the primary energy source for main sequence stars more massive than the sun. To test our understanding of stellar evolution models using the CNO bi-cycle, we have undertaken light-element (CNO) abundance analysis of three main sequence dwarf stars and three red giant stars in the open cluster NGC 752 utilizing high resolution (R 50,000) spectroscopy from the Keck Observatory. Preliminary results indicate, as expected, there is a depletion of carbon in the giants relative to the dwarfs. Additional analysis is needed to determine if the amount of depletion is in line with model predictions, as seen in the Hyades open cluster. Oxygen abundances are derived from the high-excitation O I triplet, and there is a 0.19 dex offset in the [O/H] abundances between the giants and dwarfs which may be explained by non-local thermodynamic equilibrium (NLTE), although further analysis is needed to verify this. The standard procedure for spectroscopically determining stellar parameters used here allows for a measurement of the cluster metallicity, [Fe/H] = 0.04 ± 0.02. In addition to the Fe abundances we have determined Na, Mg, and Al abundances to determine the status of other nucleosynthesis processes. The Na, Mg and Al abundances of the giants are enhanced relative to the dwarfs, which is consistent with similar findings in giants of other open clusters. Support for K. Hawkins was provided by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program and the Department of Defense ASSURE program through Scientific Program Order No. 13 (AST-0754223) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.

Systematic Review and Meta-Analysis of Studies Evaluating Diagnostic Test Accuracy: A Practical Review for Clinical Researchers-Part II. Statistical Methods of Meta-Analysis

PubMed Central

Lee, Juneyoung; Kim, Kyung Won; Choi, Sang Hyun; Huh, Jimi

2015-01-01

Meta-analysis of diagnostic test accuracy studies differs from the usual meta-analysis of therapeutic/interventional studies in that, it is required to simultaneously analyze a pair of two outcome measures such as sensitivity and specificity, instead of a single outcome. Since sensitivity and specificity are generally inversely correlated and could be affected by a threshold effect, more sophisticated statistical methods are required for the meta-analysis of diagnostic test accuracy. Hierarchical models including the bivariate model and the hierarchical summary receiver operating characteristic model are increasingly being accepted as standard methods for meta-analysis of diagnostic test accuracy studies. We provide a conceptual review of statistical methods currently used and recommended for meta-analysis of diagnostic test accuracy studies. This article could serve as a methodological reference for those who perform systematic review and meta-analysis of diagnostic test accuracy studies. PMID:26576107

On the Iron Abundance Anomaly in K-dwarf and Hyades Stars

NASA Astrophysics Data System (ADS)

Aleo, Patrick D.; Sobotka, Alexander C.; Ramírez, Ivan

2017-09-01

Using standard 1D-LTE model atmosphere analysis, we provide an in-depth investigation of iron abundance as derived from neutral and singly ionization iron lines (Fe I, II) in nearby star clusters. Specifically, we replicate the discrepancy regarding Δ[Fe/H], wherein the difference of Fe II-Fe I increases for stars of the same cluster with decreasing T eff, reaching an astonishing 1.0 dex at T eff ˜ 4000 K. Previous studies have investigated this anomaly in the Pleiades and Hyades clusters with no concrete solution. In this analysis, we probe two samples: 63 wide binary field stars where the primary star is of Sun-like temperatures and the secondary is a K-dwarf, ranging from 4231 K ≤ T eff ≤ 6453 K, and 33 Hyades stars of temperatures 4268 K ≤ T eff ≤ 6072 K. Previous studies have found discrepancies on the order of 1.0 dex. However, we find that these studies have neglected line-blending effects of certain Fe II lines, namely λ = {4508.29 Å, 4993.34 Å, 5197.58 Å, 5325.55 Å, 5425.26 Å, 6456.38 Å}. When these lines are removed from the line-list, we find Δ[Fe/H] decreases to ˜0.6 dex in the field binaries and ˜0.3 dex in the Hyades. The reason for this remaining trend is investigated by probing NLTE effects, as well as age and activity considerations using Ca II H+K emission and Li absorption, but these results appear to be small to negligible.

THE BORN-AGAIN PLANETARY NEBULA A78: AN X-RAY TWIN OF A30

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toalá, J. A.; Guerrero, M. A.; Marquez-Lugo, R. A.

We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar wind and a point-like source at the position of the central star (CSPN). We present the spectral analysis of the CSPN, using for the first time an NLTE code for expanding atmospheres that takes line blanketing into account for the UV and optical spectra. The wind abundances aremore » used for the X-ray spectral analysis of the CSPN and the diffuse emission. The X-ray emission from the CSPN in A78 can be modeled by a single C VI emission line, while the X-ray emission from its diffuse component is better described by an optically thin plasma emission model with a temperature of kT = 0.088 keV (T ≈ 1.0 × 10{sup 6} K). We estimate X-ray luminosities in the 0.2-2.0 keV energy band of L {sub X,} {sub CSPN} = (1.2 ± 0.3) × 10{sup 31} erg s{sup –1} and L {sub X,} {sub DIFF} = (9.2 ± 2.3) × 10{sup 30} erg s{sup –1} for the CSPN and diffuse components, respectively.« less

FUSE Spectroscopy of the Accreting Hot Components in Symbiotic Variables.

PubMed

Sion, Edward M; Godon, Patrick; Mikolajewska, Joanna; Sabra, Bassem; Kolobow, Craig

2017-04-01

We have conducted a spectroscopic analysis of the far ultraviolet archival spectra of four symbiotic variables, EG And, AE Ara, CQ Dra and RW Hya. RW Hya and EG And have never had a recorded outburst while CQ Dra and AE Ara have outburst histories. We analyze these systems while they are in quiescence in order to help reveal the physical properties of their hot components via comparisons of the observations with optically thick accretion disk models and NLTE model white dwarf photospheres. We have extended the wavelength coverage down to the Lyman Limit with FUSE spectra. We find that the hot component in RW Hya is a low mass white dwarf with a surface temperature of 160,000K. We re-examine whether or not the symbiotic system CQ Dra is a triple system with a red giant transferring matter to a hot component made up of a cataclysmic variable in which the white dwarf has a surface temperature as low as ∼20,000K. The very small size of the hot component contributing to the shortest wavelengths of the FUSE spectrum of CQ Dra agrees with an optically thick and geometrically thin (∼4% of the WD surface) hot (∼ 120, 000K) boundary layer. Our analysis of EG And reveals that its hot component is a hot, bare, low mass white dwarf with a surface temperature of 80-95,000K, with a surface gravity log( g ) = 7.5. For AE Ara, we also find that a low gravity (log( g ) ∼ 6) hot ( T ∼ 130, 000K) WD accounts for the hot component.

On the Iron Abundance Anomaly in K-dwarf and Hyades Stars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aleo, Patrick D.; Sobotka, Alexander C.; Ramírez, Ivan

Using standard 1D-LTE model atmosphere analysis, we provide an in-depth investigation of iron abundance as derived from neutral and singly ionization iron lines (Fe i, ii) in nearby star clusters. Specifically, we replicate the discrepancy regarding Δ[Fe/H], wherein the difference of Fe ii–Fe i increases for stars of the same cluster with decreasing T {sub eff}, reaching an astonishing 1.0 dex at T {sub eff} ∼ 4000 K. Previous studies have investigated this anomaly in the Pleiades and Hyades clusters with no concrete solution. In this analysis, we probe two samples: 63 wide binary field stars where the primary starmore » is of Sun-like temperatures and the secondary is a K-dwarf, ranging from 4231 K ≤ T {sub eff} ≤ 6453 K, and 33 Hyades stars of temperatures 4268 K ≤ T {sub eff} ≤ 6072 K. Previous studies have found discrepancies on the order of 1.0 dex. However, we find that these studies have neglected line-blending effects of certain Fe ii lines, namely λ = (4508.29 Å, 4993.34 Å, 5197.58 Å, 5325.55 Å, 5425.26 Å, 6456.38 Å). When these lines are removed from the line-list, we find Δ[Fe/H] decreases to ∼0.6 dex in the field binaries and ∼0.3 dex in the Hyades. The reason for this remaining trend is investigated by probing NLTE effects, as well as age and activity considerations using Ca ii H+K emission and Li absorption, but these results appear to be small to negligible.« less

The helium 10830 A line in early-type stars - An atlas of Fabry-Perot scans

NASA Technical Reports Server (NTRS)

Meisel, D. D.; Frank, Z. A.; Packard, M. L.; Saunders, B. A.

1982-01-01

Representative profiles of He I 10830 A in 65 early-type (O6-A1) stars over a wide range of luminosity are presented. The atlas scans were obtained using the Vaughan Fabry-Perot interferometer on the C. E. K. Mees 0.6 m and KPNO 0.9 m telescopes and usually cover a range of plus or minus 15 A at 1 A resolution with sampling distances between 0.5 A and 2 A depending on the photometer integration time required to reach reasonable Poisson counting statistics. The majority of the scans show very shallow, broad features which do not agree with plane-parallel NLTE model atmosphere calculations of the 10830 line by Auer and Mihalas (1972). Difficulties connected with previous theoretical studies of this line are briefly discussed, and suggestions for possible future modifications to the theory are made.

VizieR Online Data Catalog: Horizontal temperature at Venus upper atmosphere (Peralta+, 2016)

NASA Astrophysics Data System (ADS)

Peralta, J.; Lopez-Valverde, M. A.; Gilli, G.; Piccialli, A.

2015-11-01

The dayside atmospheric temperatures in the UMLT of Venus (displayed in Figure 7A of this article) are listed as a CSV data file. These values consist of averages in bins of 5° in latitude and 0.25-hours in local time from dayside temperatures covering five years of data (from 2006/05/14 to 2011/06/05). These temperatures were inferred from the CO2 NLTE nadir spectra measured by the instrument VIRTIS-H onboard Venus Express (see article for full description of the procedure), and are representative of the atmospheric region between 10-2 to 10-5mb. Along with the temperatures, we also provide the corresponding error and the number of temperatures averaged in each bin. The format of the CSV file reasonably agrees with the expected format of the data files to be provided in the future version of the Venus International Reference Atmosphere (VIRA). (1 data file).

TheoSSA - Model WD Spectra on Demand: The Impact of Ne, Na, Mg, and Iron-group Elements on the Balmer Lines

NASA Astrophysics Data System (ADS)

Reindl, N.; Rauch, T.

2015-06-01

The registered German Astrophysical Virtual Observatory (GAVO) service TheoSSA provides easy access to synthetic stellar spectra. This GAVO database contains already ten thousands of these, which were calculated with different chemical compositions of the elements H to Ni. In addition to the database, it is possible to calculate individual spectra for hot, compact stars based on the Tübingen NLTE Model-Atmosphere Package (TMAP) via the TMAW service. The TMAW models were, in the pilot phase, restricted to the elements H, He, C, N, and O. Now, TMAW is extended to additionally consider opacities from Ne, Na, and Mg. Soon, TMAW will also be able to include the opacities from the so-called iron-group elements (Ca - Ni). We describe the improvements and show the impact of Ne, Na, Mg, and iron-group elements on the Balmer lines.

Towards new generation spectroscopic models of cool stars

NASA Astrophysics Data System (ADS)

Bergemann, Maria

2018-06-01

Abstract: Spectroscopy is a unique tool to determine the physical parameters of stars. Knowledge of stellar chemical abundances, masses, and ages is the key to understanding the evolution of their host populations. I will focus on the current outstanding problems in spectroscopy of cool stars, which are the most useful objects in studies of our local Galactic neighborhood but also very distant systems, like faint dwarf Spheroidal galaxies. Among the most debated issues is to what extent can we trust the techniques, which rely on the classical assumptions of local thermodynamic equilibrium and hydrostatic balance. I will summarise the ongoing efforts to improve the models of cool stars, with the emphasis on NLTE and 3D modelling. I will then discuss how these exciting observations impact our knowledge of abundances in the Milky Way and in dSph systems, and present outlook for the future studies.

The Abundance of Lithium in an ABG Star in the Globular Cluster M3 (NGC 5272)

NASA Astrophysics Data System (ADS)

Givens, R. A.; Pilachowski, C. A.

2016-12-01

A survey of red giants in the globular cluster M3 with the Hydra multi-object spectrograph on the WIYN 3.5 m telescope indicated a prominent Li i 6707 Å feature in the red giant vZ 1050. Followup spectroscopy with the ARC 3.5 m telescope confirmed this observation and yielded a derived abundance of A(Li)NLTE = 1.6 ± 0.05. In addition, the high oxygen and low sodium abundances measured from the same spectrum suggest that vZ 1050 is a first generation cluster star. The location of vZ 1050 above the horizontal branch and blueward of the red giant branch in the cluster’s color-magnitude diagram places vZ 1050 on M3's asymptotic giant branch. The likely source for the enhanced lithium abundance is the Cameron-Fowler mechanism operating in vZ 1050 itself.

The Impact of Measurement Noise in GPA Diagnostic Analysis of a Gas Turbine Engine

NASA Astrophysics Data System (ADS)

Ntantis, Efstratios L.; Li, Y. G.

2013-12-01

The performance diagnostic analysis of a gas turbine is accomplished by estimating a set of internal engine health parameters from available sensor measurements. No physical measuring instruments however can ever completely eliminate the presence of measurement uncertainties. Sensor measurements are often distorted by noise and bias leading to inaccurate estimation results. This paper explores the impact of measurement noise on Gas Turbine GPA analysis. The analysis is demonstrated with a test case where gas turbine performance simulation and diagnostics code TURBOMATCH is used to build a performance model of a model engine similar to Rolls-Royce Trent 500 turbofan engine, and carry out the diagnostic analysis with the presence of different levels of measurement noise. Conclusively, to improve the reliability of the diagnostic results, a statistical analysis of the data scattering caused by sensor uncertainties is made. The diagnostic tool used to deal with the statistical analysis of measurement noise impact is a model-based method utilizing a non-linear GPA.

Stellar laboratories. IV. New Ga iv, Ga v, and Ga vi oscillator strengths and the gallium abundance in the hot white dwarfs G191-B2B and RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

2015-05-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These atmospheres are strongly dependent on the reliability of the atomic data that are used to calculate them. Aims: Reliable Ga iv-vi oscillator strengths are used to identify Ga lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ga abundances. Methods: We newly calculated Ga iv-vi oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for analyzing of Ga lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: We unambiguously detected 20 isolated and 6 blended (with lines of other species) Ga v lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The identification of Ga iv and Ga vi lines is uncertain because they are weak and partly blended by other lines. The determined Ga abundance is 3.5 ± 0.5 × 10-5 (mass fraction, about 625 times the solar value). The Ga iv/Ga v ionization equilibrium, which is a very sensitive indicator for the effective temperature, is well reproduced in RE 0503-289. We identified the strongest Ga iv lines (at 1258.801, 1338.129 Å) in the HST/STIS spectrum of G191-B2B and measured a Ga abundance of 2.0 ± 0.5 × 10-6 (about 22 times solar). Conclusions: Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. The observed Ga iv-v line profiles in two white dwarf (G191-B2B and RE 0503-289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. For the first time, this allowed us to determine the photospheric Ga abundance in white dwarfs. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Tables 1-6, 11, 12 and 15 are available in electronic form at http://www.aanda.orgTables 7-9 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A6

Dayside temperatures in the Venus upper atmosphere from Venus Express/VIRTIS nadir measurements at 4.3 μm

NASA Astrophysics Data System (ADS)

Peralta, J.; López-Valverde, M. A.; Gilli, G.; Piccialli, A.

2016-01-01

In this work, we analysed nadir observations of atmospheric infrared emissions carried out by VIRTIS, a high-resolution spectrometer on board the European spacecraft Venus Express. We focused on the ro-vibrational band of CO2 at 4.3 μm on the dayside, whose fluorescence originates in the Venus upper mesosphere and above. This is the first time that a systematic sounding of these non-local thermodynamic equilibrium (NLTE) emissions has been carried out in Venus using this geometry. As many as 143,218 spectra have been analysed on the dayside during the period 14/05/2006 to 14/09/2009. We designed an inversion method to obtain the atmospheric temperature from these non-thermal observations, including a NLTE line-by-line forward model and a pre-computed set of spectra for a set of thermal structures and illumination conditions. Our measurements sound a broad region of the upper mesosphere and lower thermosphere of Venus ranging from 10-2-10-5 mb (which in the Venus International Reference Atmosphere, VIRA, is approximately 100-150 km during the daytime) and show a maximum around 195 ± 10 K in the subsolar region, decreasing with latitude and local time towards the terminator. This is in qualitative agreement with predictions by a Venus Thermospheric General Circulation Model (VTGCM) after a proper averaging of altitudes for meaningful comparisons, although our temperatures are colder than the model by about 25 K throughout. We estimate a thermal gradient of about 35 K between the subsolar and antisolar points when comparing our data with nightside temperatures measured at similar altitudes by SPICAV, another instrument on Venus Express (VEx). Our data show a stable temperature structure through five years of measurements, but we also found episodes of strong heating/cooling to occur in the subsolar region of less than two days. The table with numerical data and averaged temperatures displayed in Fig. 7A provided as a CSV data file is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A53

Stellar laboratories . IX. New Se v, Sr iv-vii, Te vi, and I vi oscillator strengths and the Se, Sr, Te, and I abundances in the hot white dwarfs G191-B2B and RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Quinet, P.; Knörzer, M.; Hoyer, D.; Werner, K.; Kruk, J. W.; Demleitner, M.

2017-10-01

Context. To analyze spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model-atmosphere techniques are mandatory. Reliable atomic data is crucial for the calculation of such model atmospheres. Aims: We aim to calculate new Sr iv-vii oscillator strengths to identify for the first time Sr spectral lines in hot white dwarf (WD) stars and to determine the photospheric Sr abundances. To measure the abundances of Se, Te, and I in hot WDs, we aim to compute new Se v, Te vi, and I vi oscillator strengths. Methods: To consider radiative and collisional bound-bound transitions of Se v, Sr iv - vii, Te vi, and I vi in our NLTE atmosphere models, we calculated oscillator strengths for these ions. Results: We newly identified four Se v, 23 Sr v, 1 Te vi, and three I vi lines in the ultraviolet (UV) spectrum of RE 0503-289. We measured a photospheric Sr abundance of 6.5+ 3.8-2.4× 10-4 (mass fraction, 9500-23 800 times solar). We determined the abundances of Se (1.6+ 0.9-0.6× 10-3, 8000-20 000), Te (2.5+ 1.5-0.9× 10-4, 11 000-28 000), and I (1.4+ 0.8-0.5× 10-5, 2700-6700). No Se, Sr, Te, and I line was found in the UV spectra of G191-B2B and we could determine only upper abundance limits of approximately 100 times solar. Conclusions: All identified Se v, Sr v, Te vi, and I vi lines in the UV spectrum of RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. Full Tables A.15 to A.21 are only available via the German Astrophysical Virtual Observatory (GAVO) service TOSS (http://dc.g-vo.org/TOSS).

Comportamiento del Helio en estrellas químicamente peculiares

NASA Astrophysics Data System (ADS)

Malaroda, S. M.; López García, Z.; Leone, F.; Catalano, F.

Las estrellas químicamente peculiares (CP) se caracterizan por tener deficiencias y sobreabundancias de algunos elementos químicos de hasta 106 veces la abundancia solar. Además presentan variaciones en las líneas espectrales. Se piensa que ello se debe a que los campos magnéticos presentes en este tipo de estrellas son principalmente dipolares, con un eje de simetría diferente del eje de rotación. La distribución de los elementos sobreabundantes y deficientes no es homogénea sobre la superficie estelar y las variaciones observadas serían una consecuencia directa de la rotación estelar. Entre los elementos con abundancia anómala se encuentra el Helio, cuyas líneas tienen intensidades que no son consistentes con una abundancia normal, que no puede ser determinada del modo usual, o sea, considerando una atmósfera con composición solar. Con el fin de determinar la abundancia de este elemento, se inició un estudio de estrellas anómalas de Helio, Hew y He strong. Además se determinarán las abundancias de otros elementos anómalos como ser el Si, Cr, Mg, Mn y Fe. Las mismas se determinan del modo tradicional, o sea: a) medida de los anchos equivalentes de las líneas de los distintos elementos analizados; b) adopción de la temperatura efectiva, gravedad y abundancia del Helio; c) cálculo del modelo de atmósfera d) comparación con las observaciones y reinicio de un proceso iterativo hasta lograr un acuerdo entre todos los parámetros analizados. Las observaciones se llevaron a cabo en el Complejo Astronómico El Leoncito. Se observaron setenta y ocho estrellas anómalas de Helio. En este momento se está procediendo a calcular las abundancias correspondientes a los distintos elementos químicos. Para ello se hace uso de los modelos de Kurucz, ATLAS9. Los cálculos NLTE de las líneas de Helio se llevan a cabo con el programa MULTI y se compararán con los realizados con el programa WIDTH9 de Kurucz (LTE), con el objeto de resaltar la importancia de los efectos NLTE.

[Methods of statistical analysis in differential diagnostics of the degree of brain glioma anaplasia during preoperative stage].

PubMed

Glavatskiĭ, A Ia; Guzhovskaia, N V; Lysenko, S N; Kulik, A V

2005-12-01

The authors proposed a possible preoperative diagnostics of the degree of supratentorial brain gliom anaplasia using statistical analysis methods. It relies on a complex examination of 934 patients with I-IV degree anaplasias, which had been treated in the Institute of Neurosurgery from 1990 to 2004. The use of statistical analysis methods for differential diagnostics of the degree of brain gliom anaplasia may optimize a diagnostic algorithm, increase reliability of obtained data and in some cases avoid carrying out irrational operative intrusions. Clinically important signs for the use of statistical analysis methods directed to preoperative diagnostics of brain gliom anaplasia have been defined

Accretion Structures in Algol-Type Interacting Binary Systems

NASA Astrophysics Data System (ADS)

Peters, Geraldine

The physics of mass transfer in interacting binaries of the Algol type will be investigated through an analysis of an extensive collection of FUV spectra from the FUSE spacecraft, Kepler photometry, and FUV spectra from IUE and ORFEUS-SPAS II. The Algols range from close direct impact systems to wider systems that contain prominent accretion disks. Several components of the circumstellar (CS) material have been identified, including the gas stream, splash/outflow domains, a high temperature accretion region (HTAR), accretion disk, and magnetically-controlled flows (cf. Peters 2001, 2007, Richards et al. 2010). Hot spots are sometimes seen at the site where the gas stream impacts the mass gainer's photosphere. Collectively we call these components of mass transfer "accretion structures". The CS material will be studied from an analysis of both line-of-sight FUV absorption features and emission lines. The emission line regions will be mapped in and above/below the orbital plane with 2D and 3D Doppler tomography techniques. We will look for the presence of hot accretion spots in both the Kepler photometry of Algols in the Kepler fields and phase-dependent flux variability in the FUSE spectra. We will also search for evidence of microflaring at the impact site of the gas stream. An abundance study of the mass gainer will reveal the extent to which CNO-processed material from the core of the mass loser is being deposited on the primary. Analysis codes that will be used include 2D and 3D tomography codes, SHELLSPEC, light curve analysis programs such as PHOEBE and Wilson-Devinney, and the NLTE codes TLUSTY/SYNSPEC. This project will transform our understanding of the mass transfer process from a generic to a hydrodynamical one and provide important information on the degree of mass loss from the system which is needed for calculations of the evolution of Algol binaries.

Electromagnetic Analysis of ITER Diagnostic Equatorial Port Plugs During Plasma Disruptions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Y. Zhai, R. Feder, A. Brooks, M. Ulrickson, C.S. Pitcher and G.D. Loesser

2012-08-27

ITER diagnostic port plugs perform many functionsincluding structural support of diagnostic systems under high electromagnetic loads while allowing for diagnostic access to the plasma. The design of diagnostic equatorial port plugs (EPP) are largely driven by electromagnetic loads and associate responses of EPP structure during plasma disruptions and VDEs. This paper summarizes results of transient electromagnetic analysis using Opera 3d in support of the design activities for ITER diagnostic EPP. A complete distribution of disruption loads on the Diagnostic First Walls (DFWs), Diagnostic Shield Modules (DSMs) and the EPP structure, as well as impact on the system design integration duemore » to electrical contact among various EPP structural components are discussed.« less

Feminist identity as a predictor of eating disorder diagnostic status.

PubMed

Green, Melinda A; Scott, Norman A; Riopel, Cori M; Skaggs, Anna K

2008-06-01

Passive Acceptance (PA) and Active Commitment (AC) subscales of the Feminist Identity Development Scale (FIDS) were examined as predictors of eating disorder diagnostic status as assessed by the Questionnaire for Eating Disorder Diagnoses (Q-EDD). Results of a hierarchical regression analysis revealed PA and AC scores were not statistically significant predictors of ED diagnostic status after controlling for diagnostic subtype. Results of a multiple regression analysis revealed FIDS as a statistically significant predictor of ED diagnostic status when failing to control for ED diagnostic subtype. Discrepancies suggest ED diagnostic subtype may serve as a moderator variable in the relationship between ED diagnostic status and FIDS. (c) 2008 Wiley Periodicals, Inc.

The Virtual Observatory Service TheoSSA: Establishing a Database of Synthetic Stellar Flux Standards II. NLTE Spectral Analysis of the OB-Type Subdwarf Feige 110

NASA Technical Reports Server (NTRS)

Rauch, T.; Rudkowski, A.; Kampka, D.; Werner, K.; Kruk, J. W.; Moehler, S.

2014-01-01

Context. In the framework of the Virtual Observatory (VO), the German Astrophysical VO (GAVO) developed the registered service TheoSSA (Theoretical Stellar Spectra Access). It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code, generally for all effective temperatures, surface gravities, and elemental compositions. We will establish a database of SEDs of flux standards that are easily accessible via TheoSSA's web interface. Aims. The OB-type subdwarf Feige 110 is a standard star for flux calibration. State-of-the-art non-local thermodynamic equilibrium stellar-atmosphere models that consider opacities of species up to trans-iron elements will be used to provide a reliable synthetic spectrum to compare with observations. Methods. In case of Feige 110, we demonstrate that the model reproduces not only its overall continuum shape from the far-ultraviolet (FUV) to the optical wavelength range but also the numerous metal lines exhibited in its FUV spectrum. Results. We present a state-of-the-art spectral analysis of Feige 110. We determined Teff =47 250 +/- 2000 K, log g=6.00 +/- 0.20, and the abundances of He, N, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, and Ge. Ti, V, Mn, Co, Zn, and Ge were identified for the first time in this star. Upper abundance limits were derived for C, O, Si, Ca, and Sc. Conclusions. The TheoSSA database of theoretical SEDs of stellar flux standards guarantees that the flux calibration of astronomical data and cross-calibration between different instruments can be based on models and SEDs calculated with state-of-the-art model atmosphere codes.

Measurements and non-local thermodynamic equilibrium modeling of mid-Z plasma emission

NASA Astrophysics Data System (ADS)

Jacquet, L.; Primout, M.; Kaiser, P.; Clouët, J. F.; Girard, F.; Villette, B.; Reverdin, C.; Oudot, G.

2015-12-01

The x-ray yields from laser-irradiated thin foils of iron, copper, zinc, and germanium have been measured in the soft and multi-keV x-ray ranges at the OMEGA laser at the Laboratory for Laser Energetics. The incident laser power had a pre-pulse to enhance the x-ray emission of a 1 ns flat-top main pulse. The experimental results have been compared with post-shot simulations performed with the two-dimensional radiation-hydrodynamics code FCI2. A new non-local thermodynamic equilibrium model, NOO-RAD, have been incorporated into FCI2. In this approach, the plasma ionization state is in-line calculated by the atomic physics NOHEL package. In the soft x-ray bands, both simulations using RADIOM [M. Busquet, Phys. Fluids B 5, 4191 (1993)] and NOO-RAD clearly over-predict the powers and energies measured by a broad-band spectrometer. In one case (the iron foil), the discrepancy between the measured and simulated x-ray output is nevertheless significantly reduced when NOO-RAD is used in the simulations. In the multi-keV x-ray bands, the simulations display a strong sensitivity to the coupling between the electron thermal conductivity and the NLTE models, and for some particular combinations of these, provide a close match to the measured emission. The comparison between the measured and simulated H-like to He-like line-intensity ratios deduced from high-resolution spectra indicates higher experimental electron temperatures were achieved, compared to the simulated ones. Measurements of the plasma conditions have been achieved using the Thomson-scattering diagnostic. The electron temperatures are found to range from 3 to 5 keV at the end of the laser pulse and are greater than predicted by the simulations. The measured flow velocities are in reasonable agreement with the calculated ones. This last finding gives us confidence in our numerical predictions for the plasma parameters, which are over that time mainly determined by hydrodynamics, such as the mass densities and the ion temperatures.

Polarized Continuum Radiation from Stellar Atmospheres

NASA Astrophysics Data System (ADS)

Harrington, J. Patrick

2015-10-01

Continuum scattering by free electrons can be significant in early type stars, while in late type stars Rayleigh scattering by hydrogen atoms or molecules may be important. Computer programs used to construct models of stellar atmospheres generally treat the scattering of the continuum radiation as isotropic and unpolarized, but this scattering has a dipole angular dependence and will produce polarization. We review an accurate method for evaluating the polarization and limb darkening of the radiation from model stellar atmospheres. We use this method to obtain results for: (i) Late type stars, based on the MARCS code models (Gustafsson et al. 2008), and (ii) Early type stars, based on the NLTE code TLUSTY (Lanz and Hubeny 2003). These results are tabulated at http://www.astro.umd.edu/~jph/Stellar_Polarization.html. While the net polarization vanishes for an unresolved spherical star, this symmetry is broken by rapid rotation or by the masking of part of the star by a binary companion or during the transit of an exoplanet. We give some numerical results for these last cases.

MONET, HET and SALT and asteroseismological observations and theory in Göttingen

NASA Astrophysics Data System (ADS)

Schuh, S.; Hessman, F. V.; Dreizler, S.; Kollatschny, W.; Glatzel, W.

2007-06-01

The Göttingen stellar astrophysics group, headed by Stefan Dreizler, conducts research on extrasolar planets and their host stars, on lower-main sequence stars, and on evolved compact objects, in particular hot white dwarfs (including PG 1159 objects, magnetic WDs and cataclysmic variables), and subdwarf B stars. In addition to sophisticated NLTE spectral analyses of these stars, which draw on the extensive stellar atmosphere modelling experience of the group, we actively develop and apply a variety of photometric monitoring and time-resolved spectroscopic techniques to address time-dependent phenomena. With the new instrumentational developments described below, we plan to continue the study of variable white dwarfs (GW Vir, DB and ZZ Ceti variables) and in particular sdB EC 14026 and PG 1617 pulsators which already constitute a main focus, partly within the Whole Earth Telescope (WET/DARC), http://www.physics.udel.edu/~jlp/darc/) collaboration, on a new level. Additional interest is directed towards strange mode instabilities in Wolf Rayet stars.

NLTE opacity calculations: C-Si and C-Ge mixtures

NASA Astrophysics Data System (ADS)

Jarrah, W.; Benredjem, D.; Pain, J.-C.; Dubau, J.

2017-09-01

The opacity is an important issue in the knowledge of the radiative properties of ICF and astrophysical plasmas. We present the opacity of dopants (silicon, germanium) embedded in the ablator of some ICF capsules. In recent works, Hill and Rose calculated the opacity of silicon in LTE and non-LTE plasmas, while Minguez and co-workers focused on the opacity of carbon. We have used the Cowan code to calculate the atomic structure of carbon, silicon and germanium in various ionic stages. The cross-sections of atomic processes (collisional excitation, collisional ionization) are obtained by fitting the values given by the code FAC to the Van Regemorter-like formulas of Sampson and Zhang. A corrected Gaunt factor is then obtained. A collisional-radiative code was developed in order to obtain the ionic populations, the level populations and the opacity. Line broadening and line shift are taken into account. The ionization potential depression is included in our calculations. The effect of a radiation field on the opacity is examined.

Lithium Abundances in the Young Open Cluster IC 2602

NASA Technical Reports Server (NTRS)

Randich, S.; Aharpour, N.; Pallavicini, R.; Prosser, C. F.; Stauffer, J. R.

1997-01-01

We have obtained high-resolution spectra for 28 candidate late-type stars in the 30 Myr old cluster IC 2602. NLTE Li abundances have been derived from measured equivalent widths. The log n(Li) - T(sub eff) and log n(Li) - mass distributions for our sample stars have been compared with those of the Pleiades and alpha Persei. Our data show that F stars in the three clusters have the same lithium content, which corresponds to the initial content for Pop. I stars. G and early-K IC 2602 stars are, on average, somewhat more Li-rich than their counterparts in the two slightly older clusters. Finally, the latest-type IC 2602 stars are heavily Li depleted, with their Li content being as low as the lowest measured among the Pleiades. As in the Pleiades and alpha Per, a star-to-star scatter in lithium is observed among 30 Myr old late-K/early-K dwarfs in IC 2602, indicating that this spread develops in the pre-main sequence phases.

Electromagnetic Analysis For The Design Of ITER Diagnostic Port Plugs During Plasma Disruptions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Y

2014-03-03

ITER diagnostic port plugs perform many functions including structural support of diagnostic systems under high electromagnetic loads while allowing for diagnostic access to plasma. The design of diagnotic equatorial port plugs (EPP) are largely driven by electromagnetic loads and associate response of EPP structure during plasma disruptions and VDEs. This paper summarizes results of transient electromagnetic analysis using Opera 3d in support of the design activities for ITER diagnostic EPP. A complete distribution of disruption loads on the Diagnostic First Walls (DFWs). Diagnostic Shield Modules (DSMs) and the EPP structure, as well as impact on the system design integration duemore » to electrical contact among various EPP structural components are discussed.« less

Comparative genome analysis identifies novel nucleic acid diagnostic targets for use in the specific detection of Haemophilus influenzae.

PubMed

Coughlan, Helena; Reddington, Kate; Tuite, Nina; Boo, Teck Wee; Cormican, Martin; Barrett, Louise; Smith, Terry J; Clancy, Eoin; Barry, Thomas

2015-10-01

Haemophilus influenzae is recognised as an important human pathogen associated with invasive infections, including bloodstream infection and meningitis. Currently used molecular-based diagnostic assays lack specificity in correctly detecting and identifying H. influenzae. As such, there is a need to develop novel diagnostic assays for the specific identification of H. influenzae. Whole genome comparative analysis was performed to identify putative diagnostic targets, which are unique in nucleotide sequence to H. influenzae. From this analysis, we identified 2H. influenzae putative diagnostic targets, phoB and pstA, for use in real-time PCR diagnostic assays. Real-time PCR diagnostic assays using these targets were designed and optimised to specifically detect and identify all 55H. influenzae strains tested. These novel rapid assays can be applied to the specific detection and identification of H. influenzae for use in epidemiological studies and could also enable improved monitoring of invasive disease caused by these bacteria. Copyright © 2015 Elsevier Inc. All rights reserved.

Decision analysis to complete diagnostic research by closing the gap between test characteristics and cost-effectiveness.

PubMed

Schaafsma, Joanna D; van der Graaf, Yolanda; Rinkel, Gabriel J E; Buskens, Erik

2009-12-01

The lack of a standard methodology in diagnostic research impedes adequate evaluation before implementation of constantly developing diagnostic techniques. We discuss the methodology of diagnostic research and underscore the relevance of decision analysis in the process of evaluation of diagnostic tests. Overview and conceptual discussion. Diagnostic research requires a stepwise approach comprising assessment of test characteristics followed by evaluation of added value, clinical outcome, and cost-effectiveness. These multiple goals are generally incompatible with a randomized design. Decision-analytic models provide an important alternative through integration of the best available evidence. Thus, critical assessment of clinical value and efficient use of resources can be achieved. Decision-analytic models should be considered part of the standard methodology in diagnostic research. They can serve as a valid alternative to diagnostic randomized clinical trials (RCTs).

Research of Extension of the Life Cycle of Helicopter Rotor Blade in Hungary

DTIC Science & Technology

2003-02-01

Radiography (DXR), and (iii) Vibration Diagnostics (VD) with Statistical Energy Analysis (SEA) were semi- simultaneously applied [1]. The used three...2.2. Vibration Diagnostics (VD)) Parallel to the NDT measurements the Statistical Energy Analysis (SEA) as a vibration diagnostical tool were...noises were analysed with a dual-channel real time frequency analyser (BK2035). In addition to the Statistical Energy Analysis measurement a small

Multivariate Analysis As a Support for Diagnostic Flowcharts in Allergic Bronchopulmonary Aspergillosis: A Proof-of-Concept Study.

PubMed

Vitte, Joana; Ranque, Stéphane; Carsin, Ania; Gomez, Carine; Romain, Thomas; Cassagne, Carole; Gouitaa, Marion; Baravalle-Einaudi, Mélisande; Bel, Nathalie Stremler-Le; Reynaud-Gaubert, Martine; Dubus, Jean-Christophe; Mège, Jean-Louis; Gaudart, Jean

2017-01-01

Molecular-based allergy diagnosis yields multiple biomarker datasets. The classical diagnostic score for allergic bronchopulmonary aspergillosis (ABPA), a severe disease usually occurring in asthmatic patients and people with cystic fibrosis, comprises succinct immunological criteria formulated in 1977: total IgE, anti- Aspergillus fumigatus ( Af ) IgE, anti- Af "precipitins," and anti- Af IgG. Progress achieved over the last four decades led to multiple IgE and IgG(4) Af biomarkers available with quantitative, standardized, molecular-level reports. These newly available biomarkers have not been included in the current diagnostic criteria, either individually or in algorithms, despite persistent underdiagnosis of ABPA. Large numbers of individual biomarkers may hinder their use in clinical practice. Conversely, multivariate analysis using new tools may bring about a better chance of less diagnostic mistakes. We report here a proof-of-concept work consisting of a three-step multivariate analysis of Af IgE, IgG, and IgG4 biomarkers through a combination of principal component analysis, hierarchical ascendant classification, and classification and regression tree multivariate analysis. The resulting diagnostic algorithms might show the way for novel criteria and improved diagnostic efficiency in Af -sensitized patients at risk for ABPA.

Fundamental Properties of O-Type Stars

NASA Technical Reports Server (NTRS)

Heap, Sara R.; Lanz, Thierry; Hubeny, Ivan

2006-01-01

We present a comprehensive analysis of high-resolution, far-ultraviolet HST STIS, FUSE, and optical spectra of 18 O stars in the Small Magellanic Cloud. Our analysis is based on the OSTAR2002 grid of NLTE metal-line-blanketed model atmospheres calculated with our code TLUSTY. We systematically explore and present the sensitivity of various UV and optical lines to different stellar parameters. We have obtained consistent fits of the UV and the optical spectrum to derive the effective temperature, surface gravity, surface composition, and microturbulent velocity of each star. Stellar radii, masses, and luminosities follow directly. For stars of the same spectral subtype, we find a general good agreement between effective temperature determinations obtained with TLUSTY, CMFGEN, and FASTWIND models, which are all lower than the standard T(sub eff) calibration of O stars. We propose a new calibration between the spectral type and effective temperature based on our results from UV metal lines, as well as optical hydrogen and helium lines. The lower effective temperatures translate into ionizing luminosities that are smaller by a factor of 3 compared to luminosities inferred from previous standard calibrations. The chemical composition analysis reveals that the surface of about 80% of the program stars is moderately to strongly enriched in nitrogen, while showing the original helium, carbon, and oxygen abundances. Our results support the new stellar evolution models that predict that the surface of fast rotating stars becomes nitrogen-rich during the main-sequence phase because of rotationally induced mixing. Enrichment factors are, however, larger than predicted by stellar evolution models. Most stars exhibit the "mass discrepancy" problem, which we interpret as a result of fast rotation that lowers the measured effective gravity. Nitrogen enrichment and low spectroscopic masses are therefore two manifestations of fast rotation. Our study thus emphasizes the importance of rotation in our understanding of the properties of massive stars and provides a framework for investigating populations of low-metallicity massive stars at low and high redshifts.

Diagnostic Classification Models: Are They Necessary? Commentary on Rupp and Templin (2008)

ERIC Educational Resources Information Center

Gorin, Joanna S.

2009-01-01

In their paper "Unique Characteristics of Diagnostic Classification Models: A Comprehensive Review of the Current State-of-the-Art," Andre Rupp and Jonathan Templin (2008) provide a comparative analysis of selected psychometric models useful for the analysis of multidimensional data for purposes of diagnostic score reporting. Recent assessment…

Using Meta-Analysis to Inform the Design of Subsequent Studies of Diagnostic Test Accuracy

ERIC Educational Resources Information Center

Hinchliffe, Sally R.; Crowther, Michael J.; Phillips, Robert S.; Sutton, Alex J.

2013-01-01

An individual diagnostic accuracy study rarely provides enough information to make conclusive recommendations about the accuracy of a diagnostic test; particularly when the study is small. Meta-analysis methods provide a way of combining information from multiple studies, reducing uncertainty in the result and hopefully providing substantial…

[CONTEMPORARY MOLECULAR-GENETIC METHODS USED FOR ETIOLOGIC DIAGNOSTICS OF SEPSIS].

PubMed

Gavrilov, S N; Skachkova, T S; Shipulina, O Yu; Savochkina, Yu A; Shipulin, G A; Maleev, V V

2016-01-01

Etiologic diagnostics of sepsis is one of the most difficult problems of contemporary medicine due to a wide variety of sepsis causative agents, many of which are components of normal human microflora. Disadvantages of contemporary "golden standard" of microbiologic diagnostics of sepsis etiology by seeding of blood for sterility are duration of cultivation, limitation in detection of non-cultivable forms of microorganisms, significant effect of preliminary empiric antibiotics therapy on results of the analysis. Methods of molecular diagnostics that are being actively developed and integrated during the last decade are deprived of these disadvantages. Main contemporary methods of molecular-biological diagnostics are examined in the review, actualdata on their diagnostic characteristic are provided. Special attention is given to methods of PCR-diagnostics, including novel Russian developments. Methods of nucleic acid hybridization and proteomic analysis are examined in comparative aspect. Evaluation of application and perspectives of development of methods of molecular diagnostics of sepsis is given.

Absolute Spectrophotometric Calibration to 1% from the FUV through the near-IR

NASA Astrophysics Data System (ADS)

Finley, David

2006-07-01

We are requesting additional support to complete the work now being carried out under the Cycle 14 archive program, HST-AR-10654. The most critical component of that effort is an accurate determination of the STIS spectrometer LSF, so that we may correctly model the infill of the Balmer line cores by light redistributed from the wings and adjacent continuum. That is the essential input for obtaining accurate and unbiased effective temperatures and gravities, and hence calibrated fluxes, via line profile fitting of the WD calibration standards. To evaluate the published STIS LSF, we investigated the spectral images of the calibration targets, yielding several significant results: a} the STIS LSF varies significantly; b} existing observation-based spectroscopic LSFs or imaging PSFs are inadequate for deriving suitable spectroscopic LSFs; c} accounting for the PSF/LSF variability will improve spectrophotometric accuracy; d} the LSFs used for model fits must be consistent with the extraction process details; and, e} TinyTim-generated PSFs, with some modifications, provide the most suitable basis for producing the required LSFs that are tailored to each individual spectral observation. Based on our current {greatly improved} state of knowlege of the instrumental effects, we are now requesting additional support to complete the work needed to generate correct LSFs, and then carry out the analyses that were the subject of the original proposal.Our goal is the same: to produce a significant improvement to the existing HST calibration. The current calibration is based on three primary DA white dwarf standards, GD 71, GD 153,and G 191-B2B. The standard fluxes are calculated using NLTE models, with effective temperatures and gravities that were derived from Balmer line fits using LTE models. We propose to improve the accuracy and internal consistency of the calibration by deriving corrected effective temperatures and gravities based on fitting the observed line profiles with updated NLTE models, and including the fit results from multiple STIS spectra, rather than the {usually} 1 or 2 ground-based spectra used previously. We will also determine the fluxes for 5 new, fainter primary or secondary standards, extending the standard V magnitude lower limit from 13.4 to 16.5, and extending the wavelength coverage from 0.1 to 2.5 micron. The goal is to achieve an overall flux accuracy of 1%, which will be needed, for example, for the upcoming supernova survey missions to measure the equation of state of the dark energy that is accelerating the expansion of the universe.

Integrated Data Analysis for Fusion: A Bayesian Tutorial for Fusion Diagnosticians

NASA Astrophysics Data System (ADS)

Dinklage, Andreas; Dreier, Heiko; Fischer, Rainer; Gori, Silvio; Preuss, Roland; Toussaint, Udo von

2008-03-01

Integrated Data Analysis (IDA) offers a unified way of combining information relevant to fusion experiments. Thereby, IDA meets with typical issues arising in fusion data analysis. In IDA, all information is consistently formulated as probability density functions quantifying uncertainties in the analysis within the Bayesian probability theory. For a single diagnostic, IDA allows the identification of faulty measurements and improvements in the setup. For a set of diagnostics, IDA gives joint error distributions allowing the comparison and integration of different diagnostics results. Validation of physics models can be performed by model comparison techniques. Typical data analysis applications benefit from IDA capabilities of nonlinear error propagation, the inclusion of systematic effects and the comparison of different physics models. Applications range from outlier detection, background discrimination, model assessment and design of diagnostics. In order to cope with next step fusion device requirements, appropriate techniques are explored for fast analysis applications.

Common pitfalls in statistical analysis: Understanding the properties of diagnostic tests - Part 1.

PubMed

Ranganathan, Priya; Aggarwal, Rakesh

2018-01-01

In this article in our series on common pitfalls in statistical analysis, we look at some of the attributes of diagnostic tests (i.e., tests which are used to determine whether an individual does or does not have disease). The next article in this series will focus on further issues related to diagnostic tests.

Educational Diagnostic Assessment.

ERIC Educational Resources Information Center

Bejar, Isaac I.

1984-01-01

Approaches proposed for educational diagnostic assessment are reviewed and identified as deficit assessment and error analysis. The development of diagnostic instruments may require a reexamination of existing psychometric models and development of alternative ones. The psychometric and content demands of diagnostic assessment all but require test…

To what do psychiatric diagnoses refer? A two-dimensional semantic analysis of diagnostic terms

PubMed Central

Maung, Hane Htut

2016-01-01

In somatic medicine, diagnostic terms often refer to the disease processes that are the causes of patients' symptoms. The language used in some clinical textbooks and health information resources suggests that this is also sometimes assumed to be the case with diagnoses in psychiatry. However, this seems to be in tension with the ways in which psychiatric diagnoses are defined in diagnostic manuals, according to which they refer solely to clusters of symptoms. This paper explores how theories of reference in the philosophy of language can help to resolve this tension. After the evaluation of descriptive and causal theories of reference, I put forward a conceptual framework based on two-dimensional semantics that allows the causal analysis of diagnostic terms in psychiatry, while taking seriously their descriptive definitions in diagnostic manuals. While the framework is presented as a solution to a problem regarding the semantics of psychiatric diagnoses, it can also accommodate the analysis of diagnostic terms in other medical disciplines. PMID:26580354

Develop Advanced Nonlinear Signal Analysis Topographical Mapping System

NASA Technical Reports Server (NTRS)

Jong, Jen-Yi

1997-01-01

During the development of the SSME, a hierarchy of advanced signal analysis techniques for mechanical signature analysis has been developed by NASA and AI Signal Research Inc. (ASRI) to improve the safety and reliability for Space Shuttle operations. These techniques can process and identify intelligent information hidden in a measured signal which is often unidentifiable using conventional signal analysis methods. Currently, due to the highly interactive processing requirements and the volume of dynamic data involved, detailed diagnostic analysis is being performed manually which requires immense man-hours with extensive human interface. To overcome this manual process, NASA implemented this program to develop an Advanced nonlinear signal Analysis Topographical Mapping System (ATMS) to provide automatic/unsupervised engine diagnostic capabilities. The ATMS will utilize a rule-based Clips expert system to supervise a hierarchy of diagnostic signature analysis techniques in the Advanced Signal Analysis Library (ASAL). ASAL will perform automatic signal processing, archiving, and anomaly detection/identification tasks in order to provide an intelligent and fully automated engine diagnostic capability. The ATMS has been successfully developed under this contract. In summary, the program objectives to design, develop, test and conduct performance evaluation for an automated engine diagnostic system have been successfully achieved. Software implementation of the entire ATMS system on MSFC's OISPS computer has been completed. The significance of the ATMS developed under this program is attributed to the fully automated coherence analysis capability for anomaly detection and identification which can greatly enhance the power and reliability of engine diagnostic evaluation. The results have demonstrated that ATMS can significantly save time and man-hours in performing engine test/flight data analysis and performance evaluation of large volumes of dynamic test data.

Designs and adaptive analysis plans for pivotal clinical trials of therapeutics and companion diagnostics.

PubMed

Simon, Richard

2008-06-01

Developments in genomics and biotechnology provide unprecedented opportunities for the development of effective therapeutics and companion diagnostics for matching the right drug to the right patient. Effective co-development involves many new challenges with increased opportunity for success as well as delay and failure. Clinical trial designs and adaptive analysis plans for the prospective design of pivotal trials of new therapeutics and companion diagnostics are reviewed. Effective co-development requires careful prospective planning of the design and analysis strategy for pivotal clinical trials. Randomized clinical trials continue to be important for evaluating the effectiveness of new treatments, but the target populations for analysis should be prospectively specified based on the companion diagnostic. Post hoc analyses of traditionally designed randomized clinical trials are often deeply problematic. Clear separation is generally required of the data used for developing the diagnostic test, including their threshold of positivity, from the data used for evaluating treatment effectiveness in subsets determined by the test. Adaptive analysis can be used to provide flexibility to the analysis but the use of such methods requires careful planning and prospective definition in order to assure that the pivotal trial adequately limits the chance of erroneous conclusions.

2007 Beyond SBIR Phase II: Bringing Technology Edge to the Warfighter

DTIC Science & Technology

2007-08-23

Systems Trade-Off Analysis and Optimization Verification and Validation On-Board Diagnostics and Self - healing Security and Anti-Tampering Rapid...verification; Safety and reliability analysis of flight and mission critical systems On-Board Diagnostics and Self - Healing Model-based monitoring and... self - healing On-board diagnostics and self - healing ; Autonomic computing; Network intrusion detection and prevention Anti-Tampering and Trust

A Predictive Model to Estimate Cost Savings of a Novel Diagnostic Blood Panel for Diagnosis of Diarrhea-predominant Irritable Bowel Syndrome.

PubMed

Pimentel, Mark; Purdy, Chris; Magar, Raf; Rezaie, Ali

2016-07-01

A high incidence of irritable bowel syndrome (IBS) is associated with significant medical costs. Diarrhea-predominant IBS (IBS-D) is diagnosed on the basis of clinical presentation and diagnostic test results and procedures that exclude other conditions. This study was conducted to estimate the potential cost savings of a novel IBS diagnostic blood panel that tests for the presence of antibodies to cytolethal distending toxin B and anti-vinculin associated with IBS-D. A cost-minimization (CM) decision tree model was used to compare the costs of a novel IBS diagnostic blood panel pathway versus an exclusionary diagnostic pathway (ie, standard of care). The probability that patients proceed to treatment was modeled as a function of sensitivity, specificity, and likelihood ratios of the individual biomarker tests. One-way sensitivity analyses were performed for key variables, and a break-even analysis was performed for the pretest probability of IBS-D. Budget impact analysis of the CM model was extrapolated to a health plan with 1 million covered lives. The CM model (base-case) predicted $509 cost savings for the novel IBS diagnostic blood panel versus the exclusionary diagnostic pathway because of the avoidance of downstream testing (eg, colonoscopy, computed tomography scans). Sensitivity analysis indicated that an increase in both positive likelihood ratios modestly increased cost savings. Break-even analysis estimated that the pretest probability of disease would be 0.451 to attain cost neutrality. The budget impact analysis predicted a cost savings of $3,634,006 ($0.30 per member per month). The novel IBS diagnostic blood panel may yield significant cost savings by allowing patients to proceed to treatment earlier, thereby avoiding unnecessary testing. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

The diagnostic performance of perfusion MRI for differentiating glioma recurrence from pseudoprogression: A meta-analysis.

PubMed

Wan, Bing; Wang, Siqi; Tu, Mengqi; Wu, Bo; Han, Ping; Xu, Haibo

2017-03-01

The purpose of this meta-analysis was to evaluate the diagnostic accuracy of perfusion magnetic resonance imaging (MRI) as a method for differentiating glioma recurrence from pseudoprogression. The PubMed, Embase, Cochrane Library, and Chinese Biomedical databases were searched comprehensively for relevant studies up to August 3, 2016 according to specific inclusion and exclusion criteria. The quality of the included studies was assessed according to the quality assessment of diagnostic accuracy studies (QUADAS-2). After performing heterogeneity and threshold effect tests, pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were calculated. Publication bias was evaluated visually by a funnel plot and quantitatively using Deek funnel plot asymmetry test. The area under the summary receiver operating characteristic curve was calculated to demonstrate the diagnostic performance of perfusion MRI. Eleven studies covering 416 patients and 418 lesions were included in this meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 0.88 (95% confidence interval [CI] 0.84-0.92), 0.77 (95% CI 0.69-0.84), 3.93 (95% CI 2.83-5.46), 0.16 (95% CI 0.11-0.22), and 27.17 (95% CI 14.96-49.35), respectively. The area under the summary receiver operating characteristic curve was 0.8899. There was no notable publication bias. Sensitivity analysis showed that the meta-analysis results were stable and credible. While perfusion MRI is not the ideal diagnostic method for differentiating glioma recurrence from pseudoprogression, it could improve diagnostic accuracy. Therefore, further research on combining perfusion MRI with other imaging modalities is warranted.

Tissue microarrays and quantitative tissue-based image analysis as a tool for oncology biomarker and diagnostic development.

PubMed

Dolled-Filhart, Marisa P; Gustavson, Mark D

2012-11-01

Translational oncology has been improved by using tissue microarrays (TMAs), which facilitate biomarker analysis of large cohorts on a single slide. This has allowed for rapid analysis and validation of potential biomarkers for prognostic and predictive value, as well as for evaluation of biomarker prevalence. Coupled with quantitative analysis of immunohistochemical (IHC) staining, objective and standardized biomarker data from tumor samples can further advance companion diagnostic approaches for the identification of drug-responsive or resistant patient subpopulations. This review covers the advantages, disadvantages and applications of TMAs for biomarker research. Research literature and reviews of TMAs and quantitative image analysis methodology have been surveyed for this review (with an AQUA® analysis focus). Applications such as multi-marker diagnostic development and pathway-based biomarker subpopulation analyses are described. Tissue microarrays are a useful tool for biomarker analyses including prevalence surveys, disease progression assessment and addressing potential prognostic or predictive value. By combining quantitative image analysis with TMAs, analyses will be more objective and reproducible, allowing for more robust IHC-based diagnostic test development. Quantitative multi-biomarker IHC diagnostic tests that can predict drug response will allow for greater success of clinical trials for targeted therapies and provide more personalized clinical decision making.

Diagnostic Value of Endorectal Ultrasound in Preoperative Assessment of Lymph Node Involvement in Colorectal Cancer: a Meta-analysis.

PubMed

Li, Li; Chen, Shi; Wang, Ke; Huang, Jiao; Liu, Li; Wei, Sheng; Gao, Hong-Yu

2015-01-01

Nodal invasion by colorectal cancer is a critical determinant in estimating patient survival and in choosing appropriate preoperative treatment. The present meta-analysis was designed to evaluate the diagnostic value of endorectal ultrasound (EUS) in preoperative assessment of lymph node involvement in colorectal cancer. We systematically searched PubMed, Web of Science, Embase, and China National Knowledge Infrastructure (CNKI) databases for relevant studies published on or before December 10th, 2014. The sensitivity, specificity, likelihood ratios, diagnostic odds ratio (DOR) and area under the summary receiver operating characteristics curve (AUC) were assessed to estimate the diagnostic value of EUS. Subgroup analysis and meta-regression were performed to explore heterogeneity across studies. Thirty-three studies covering 3,016 subjects were included. The pooled sensitivity and specificity were 0.69 (95%CI: 0.63-0.75) and 0.77 (95%CI: 0.73-0.82), respectively. The positive and negative likelihood ratios were 3.09 (95%CI: 2.52-3.78) and 0.39 (95%CI: 0.32-0.48), respectively. The DOR was 7.84 (95%CI: 5.56-11.08), and AUC was 0.80 (95%CI: 0.77-0.84). This meta-analysis indicated that EUS has moderate diagnostic value in preoperative assessment of lymph node involvement in colorectal cancer. Further refinements in technology and diagnostic criteria are necessary to improve the diagnostic accuracy of EUS.

Efficient design and verification of diagnostics for impurity transport experiments.

PubMed

Chilenski, M A; Greenwald, M J; Marzouk, Y M; Rice, J E; White, A E

2018-01-01

Recent attempts to measure impurity transport in Alcator C-Mod using an x-ray imaging crystal spectrometer and laser blow-off impurity injector have failed to yield unique reconstructions of the transport coefficient profiles. This paper presents a fast, linearized model which was constructed to estimate diagnostic requirements for impurity transport experiments. The analysis shows that the spectroscopic diagnostics on Alcator C-Mod should be capable of inferring simple profiles of impurity diffusion D Z and convection V Z accurate to better than ±10% uncertainty, suggesting that the failure to infer unique D Z and V Z from experimental data is attributable to an inadequate analysis procedure rather than the result of insufficient diagnostics. Furthermore, the analysis reveals that even a modest spatial resolution can overcome a low time resolution. This approach can be adapted to design and verify diagnostics for transport experiments on any magnetic confinement device.

Argonne Collaborative Center for Energy Storage Science (ACCESS)

Science.gov Websites

Analysis and Diagnostics Laboratory (EADL) Post- Test Facility Access Proven Capabilities Argonne has Analysis, Modeling and Prototyping (CAMP) Electrochemical Analysis and Diagnostics Laboratory (EADL) Post -Test Facility Argonne User Facilities Industries Transportation Consumer Electronics Defense Electric

Diagnostic Accuracy of Coronary Computed Tomography Before Aortic Valve Replacement: Systematic Review and Meta-Analysis.

PubMed

Chaikriangkrai, Kongkiat; Jhun, Hye Yeon; Shantha, Ghanshyam Palamaner Subash; Abdulhak, Aref Bin; Tandon, Rudhir; Alqasrawi, Musab; Klappa, Anthony; Pancholy, Samir; Deshmukh, Abhishek; Bhama, Jay; Sigurdsson, Gardar

2018-07-01

In aortic stenosis patients referred for surgical and transcatheter aortic valve replacement (AVR), the evidence of diagnostic accuracy of coronary computed tomography angiography (CCTA) has been limited. The objective of this study was to investigate the diagnostic accuracy of CCTA for significant coronary artery disease (CAD) in patients referred for AVR using invasive coronary angiography (ICA) as the gold standard. We searched databases for all diagnostic studies of CCTA in patients referred for AVR, which reported diagnostic testing characteristics on patient-based analysis required to pool summary sensitivity, specificity, positive-likelihood ratio, and negative-likelihood ratio. Significant CAD in both CCTA and ICA was defined by >50% stenosis in any coronary artery, coronary stent, or bypass graft. Thirteen studies evaluated 1498 patients (mean age, 74 y; 47% men; 76% transcatheter AVR). The pooled prevalence of significant stenosis determined by ICA was 43%. Hierarchical summary receiver-operating characteristic analysis demonstrated a summary area under curve of 0.96. The pooled sensitivity, specificity, and positive-likelihood and negative-likelihood ratios of CCTA in identifying significant stenosis determined by ICA were 95%, 79%, 4.48, and 0.06, respectively. In subgroup analysis, the diagnostic profiles of CCTA were comparable between surgical and transcatheter AVR. Despite the higher prevalence of significant CAD in patients with aortic stenosis than with other valvular heart diseases, our meta-analysis has shown that CCTA has a suitable diagnostic accuracy profile as a gatekeeper test for ICA. Our study illustrates a need for further study of the potential role of CCTA in preoperative planning for AVR.

What Do Diagnostic Reading Tests Really Diagnose?

ERIC Educational Resources Information Center

Winkley, Carol K.

A study was made of nine reading tests, including both group and individually-administered measures, which are claimed to be chiefly diagnostic. Instruments analyzed were the following: Silent Reading Diagnostic Tests (Bond, Balow, and Hoyt), Botel Reading Inventory, Durrell Analysis of Reading Difficulty, Gates-McKillop Reading Diagnostic Tests,…

The Mysterious sdO X-ray Binary BD+37°442

NASA Astrophysics Data System (ADS)

Heber, U.; Geier, S.; Irrgang, A.; Schneider, D.; Barbu-Barna, I.; Mereghetti, S.; La Palombara, N.

2014-04-01

Pulsed X-ray emission in the luminous, helium-rich sdO BD +37°442 has recently been discovered (La Palombara et al. 2012). It was suggested that the sdO star has a neutron star or white dwarf companion with a spin period of 19.2 s. After HD 49798, which has a massive white dwarf companion spinning at 13.2 s in an 1.55 day orbit, this is only the second O-type subdwarf from which X-ray emission has been detected. We report preliminary results of our ongoing campaign to obtain time-resolved high-resolution spectroscopy using the CAFE instrument at Calar Alto observatory and SARG at the Telescopio Nationale Galileo. Atmospheric parameters were derived via a quantitative NLTE spectral analysis. The line fits hint at an unusually large projected rotation velocity. Therefore it seemed likely that BD +37°442 is a binary similar to HD 49798 and that the orbital period is also similar. The level of X-ray emission from BD +37°442 could be explained by accretion from the sdO wind by a neutron star orbiting at a period of less than ten days. Hence, we embarked on radial velocity monitoring in order to derive the binary parameters of the BD+37°442 system and obtained 41 spectra spread out over several month in 2012. Unlike for HD 49798, no radial velocity variations were found and, hence, there is no dynamical evidence for the existence of a compact companion yet. The origin of the pulsed X-ray emission remains as a mystery.

Parametric Thermal and Flow Analysis of ITER Diagnostic Shield Module

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodak, A.; Zhai, Y.; Wang, W.

As part of the diagnostic port plug assembly, the ITER Diagnostic Shield Module (DSM) is designed to provide mechanical support and the plasma shielding while allowing access to plasma diagnostics. Thermal and hydraulic analysis of the DSM was performed using a conjugate heat transfer approach, in which heat transfer was resolved in both solid and liquid parts, and simultaneously, fluid dynamics analysis was performed only in the liquid part. ITER Diagnostic First Wall (DFW) and cooling tubing were also included in the analysis. This allowed direct modeling of the interface between DSM and DFW, and also direct assessment of themore » coolant flow distribution between the parts of DSM and DFW to ensure DSM design meets the DFW cooling requirements. Design of the DSM included voids filled with Boron Carbide pellets, allowing weight reduction while keeping shielding capability of the DSM. These voids were modeled as a continuous solid with smeared material properties using analytical relation for thermal conductivity. Results of the analysis lead to design modifications improving heat transfer efficiency of the DSM. Furthermore, the effect of design modifications on thermal performance as well as effect of Boron Carbide will be presented.« less

Parametric Thermal and Flow Analysis of ITER Diagnostic Shield Module

DOE PAGES

Khodak, A.; Zhai, Y.; Wang, W.; ...

2017-06-19

As part of the diagnostic port plug assembly, the ITER Diagnostic Shield Module (DSM) is designed to provide mechanical support and the plasma shielding while allowing access to plasma diagnostics. Thermal and hydraulic analysis of the DSM was performed using a conjugate heat transfer approach, in which heat transfer was resolved in both solid and liquid parts, and simultaneously, fluid dynamics analysis was performed only in the liquid part. ITER Diagnostic First Wall (DFW) and cooling tubing were also included in the analysis. This allowed direct modeling of the interface between DSM and DFW, and also direct assessment of themore » coolant flow distribution between the parts of DSM and DFW to ensure DSM design meets the DFW cooling requirements. Design of the DSM included voids filled with Boron Carbide pellets, allowing weight reduction while keeping shielding capability of the DSM. These voids were modeled as a continuous solid with smeared material properties using analytical relation for thermal conductivity. Results of the analysis lead to design modifications improving heat transfer efficiency of the DSM. Furthermore, the effect of design modifications on thermal performance as well as effect of Boron Carbide will be presented.« less

Multiphysics Engineering Analysis for an Integrated Design of ITER Diagnostic First Wall and Diagnostic Shield Module Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Y.; Loesser, G.; Smith, M.

ITER diagnostic first walls (DFWs) and diagnostic shield modules (DSMs) inside the port plugs (PPs) are designed to protect diagnostic instrument and components from a harsh plasma environment and provide structural support while allowing for diagnostic access to the plasma. The design of DFWs and DSMs are driven by 1) plasma radiation and nuclear heating during normal operation 2) electromagnetic loads during plasma events and associate component structural responses. A multi-physics engineering analysis protocol for the design has been established at Princeton Plasma Physics Laboratory and it was used for the design of ITER DFWs and DSMs. The analyses weremore » performed to address challenging design issues based on resultant stresses and deflections of the DFW-DSM-PP assembly for the main load cases. ITER Structural Design Criteria for In-Vessel Components (SDC-IC) required for design by analysis and three major issues driving the mechanical design of ITER DFWs are discussed. The general guidelines for the DSM design have been established as a result of design parametric studies.« less

The experiences of health-related quality of life in patients with nonspecific symptoms who undergo a diagnostic evaluation for cancer: a qualitative interview study.

PubMed

Moseholm, Ellen; Lindhardt, Bjarne Oerskov; Rydahl-Hansen, Susan

2017-09-01

The diagnostic phase of cancer can affect health-related quality of life (HRQoL). The aim of this study was to investigate how patients with nonspecific symptoms experience HRQoL while undergoing diagnostic evaluations for cancer. Twenty-one participants who had completed a fast-track evaluation for possible cancer at one of three hospitals in the Capital Region, Denmark were interviewed 2-4 weeks after completing diagnostic evaluations. The interviews were semi-structured and were supported by an interview guide based on the same themes as in The European Organisation for Research and Treatment of Cancer Quality of Life questionnaire (EORCT-QLQ-C30). Data analysis was based on qualitative content analysis by Krippendorff. The analysis generated six categories: symptoms, physical-, role-, emotional-, cognitive- and social functioning, and the diagnostic fast-track experience. From these categories, a main theme was identified: Health-related quality of life is not solely affected by the diagnostic process. The results provide a comprehensive understanding of HRQoL in the diagnostic phase of possible cancer, which can be used not only to enhance evidence-based care, but also in the interpretation of the EORTC-QLQ-C30 scores. Psycho-social support with a focus on individual informational needs during the diagnostic phase may be warranted. © 2016 Nordic College of Caring Science.

Application of Diagnostic Analysis Tools to the Ares I Thrust Vector Control System

NASA Technical Reports Server (NTRS)

Maul, William A.; Melcher, Kevin J.; Chicatelli, Amy K.; Johnson, Stephen B.

2010-01-01

The NASA Ares I Crew Launch Vehicle is being designed to support missions to the International Space Station (ISS), to the Moon, and beyond. The Ares I is undergoing design and development utilizing commercial-off-the-shelf tools and hardware when applicable, along with cutting edge launch technologies and state-of-the-art design and development. In support of the vehicle s design and development, the Ares Functional Fault Analysis group was tasked to develop an Ares Vehicle Diagnostic Model (AVDM) and to demonstrate the capability of that model to support failure-related analyses and design integration. One important component of the AVDM is the Upper Stage (US) Thrust Vector Control (TVC) diagnostic model-a representation of the failure space of the US TVC subsystem. This paper first presents an overview of the AVDM, its development approach, and the software used to implement the model and conduct diagnostic analysis. It then uses the US TVC diagnostic model to illustrate details of the development, implementation, analysis, and verification processes. Finally, the paper describes how the AVDM model can impact both design and ground operations, and how some of these impacts are being realized during discussions of US TVC diagnostic analyses with US TVC designers.

Effectiveness of urine fibronectin as a non-invasive diagnostic biomarker in bladder cancer patients: a systematic review and meta-analysis.

PubMed

Dong, Fan; Shen, Yifan; Xu, Tianyuan; Wang, Xianjin; Gao, Fengbin; Zhong, Shan; Chen, Shanwen; Shen, Zhoujun

2018-03-21

Previous researches pointed out that the measurement of urine fibronectin (Fn) could be a potential diagnostic test for bladder cancer (BCa). We conducted this meta-analysis to fully assess the diagnostic value of urine Fn for BCa detection. A systematic literature search in PubMed, ISI Web of Science, EMBASE, Cochrane library, and CBM was carried out to identify eligible studies evaluating the urine Fn in diagnosing BCa. Pooled sensitivity, specificity, and diagnostic odds ratio (DOR) with their 95% confidence intervals (CIs) were calculated, and summary receiver operating characteristic (SROC) curves were established. We applied the STATA 13.0, Meta-Disc 1.4, and RevMan 5.3 software to the meta-analysis. Eight separate studies with 744 bladder cancer patients were enrolled in this meta-analysis. The pooled sensitivity, specificity, and DOR were 0.80 (95%CI = 0.77-0.83), 0.79 (95%CI = 0.73-0.84), and 15.18 (95%CI = 10.07-22.87), respectively, and the area under the curve (AUC) of SROC was 0.83 (95%CI = 0.79-0.86). The diagnostic power of a combined method (urine Fn combined with urine cytology) was also evaluated, and its sensitivity and AUC were significantly higher (0.86 (95%CI = 0.82-0.90) and 0.89 (95%CI = 0.86-0.92), respectively). Meta-regression along with subgroup analysis based on various covariates revealed the potential sources of the heterogeneity and the detailed diagnostic value of each subgroup. Sensitivity analysis supported that the result was robust. No threshold effect and publication bias were found in this meta-analysis. Urine Fn may become a promising non-invasive biomarker for bladder cancer with a relatively satisfactory diagnostic power. And the combination of urine Fn with cytology could be an alternative option for detecting BCa in clinical practice. The potential value of urine Fn still needs to be validated in large, multi-center, and prospective studies.

Automated Dermoscopy Image Analysis of Pigmented Skin Lesions

PubMed Central

Baldi, Alfonso; Quartulli, Marco; Murace, Raffaele; Dragonetti, Emanuele; Manganaro, Mario; Guerra, Oscar; Bizzi, Stefano

2010-01-01

Dermoscopy (dermatoscopy, epiluminescence microscopy) is a non-invasive diagnostic technique for the in vivo observation of pigmented skin lesions (PSLs), allowing a better visualization of surface and subsurface structures (from the epidermis to the papillary dermis). This diagnostic tool permits the recognition of morphologic structures not visible by the naked eye, thus opening a new dimension in the analysis of the clinical morphologic features of PSLs. In order to reduce the learning-curve of non-expert clinicians and to mitigate problems inherent in the reliability and reproducibility of the diagnostic criteria used in pattern analysis, several indicative methods based on diagnostic algorithms have been introduced in the last few years. Recently, numerous systems designed to provide computer-aided analysis of digital images obtained by dermoscopy have been reported in the literature. The goal of this article is to review these systems, focusing on the most recent approaches based on content-based image retrieval systems (CBIR). PMID:24281070

The Physical Properties and Effective Temperature Scale of O-Type Stars as a Function of Metallicity. I. A Sample of 20 Stars in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Massey, Philip; Bresolin, Fabio; Kudritzki, Rolf P.; Puls, Joachim; Pauldrach, A. W. A.

2004-06-01

We have obtained Hubble Space Telescope (HST) and ground-based observations of a sample of 20 O-type stars in the LMC and SMC, including six of the hottest massive stars known (subtypes O2-O3) in the R136 cluster. In general, these data include (1) the HST UV spectra in order to measure the terminal velocities of the stellar winds, (2) high signal-to-noise, blue-optical data where the primary temperature- and gravity-sensitive photospheric lines are found, and (3) nebular-free Hα profiles, which provide the mass-loss rates. We find that the older (Faint Object Spectrograph) HST data of the R136 stars (which were obtained without the benefits of sky measurements) suffered from significant nebular emission, which would increase the derived mass-loss rates by factors of ~3, all other factors being equal. We also find several stars in the SMC for which the N III λλ4634, 4642 and He II λ4686 emission ``f'' characteristics do not appear to follow the same pattern as in Galactic stars. Since He II emission is due to the stellar wind (which will be weaker in SMC for stars of the same luminosity), while N III emission is a complex non-LTE (NLTE) effect affected mostly by temperature, it would not be surprising to find that these features do not correlate with each other or with luminosity in SMC stars in the same was as they do in Galactic stars, but theory does not provide a clean answer, and analysis of more stars (both SMC and Galactic) is needed to resolve this issue. The line-blanketed NLTE atmosphere code FASTWIND was then used to determine the physical parameters of this sample of stars. We find good agreement between the synthetic line profiles for the hydrogen, He I, and He II lines in the majority of the stars we analyzed; the three exceptions show evidence of being incipiently resolved spectroscopic binaries or otherwise spectral composites. One such system is apparently an O3 V+O3 V eclipsing binary, and a follow-up radial velocity study is planned to obtain Keplerian masses. Although we did not use them to constrain the fits, good agreement is also found for the He I λ3187 and He II λ3203 lines in the near-UV, which we plan to exploit in future studies. Our effective temperatures are compared with those recently obtained by Repolust, Puls & Herrero for a sample of Galactic stars using the same techniques. We find that the Magellanic Cloud sample is 3000-4000 K hotter than their Galactic counterparts for the early through mid-O typess. These higher temperatures are the consequence of a decreased importance of wind emission, wind blanketing, and metal-line blanketing at lower metallicities. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with programs 6417, 7739, 8633, and 9412. This paper also draws heavily from data obtained from the data archive at STScI.

Fluorescence analysis of ubiquinone and its application in quality control of medical supplies

NASA Astrophysics Data System (ADS)

Timofeeva, Elvira O.; Gorbunova, Elena V.; Chertov, Aleksandr N.

2017-02-01

The presence of antioxidant issues such as redox potential imbalance in human body is a very important question for modern clinical diagnostics. Implementation of fluorescence analysis into optical diagnostics of such wide distributed in a human body antioxidant as ubiquinone is one of the steps for development of the device with a view to clinical diagnostics of redox potential. Recording of fluorescence was carried out with spectrometer using UV irradiation source with thin band (max at 287 and 330 nm) as a background radiation. Concentrations of ubiquinone from 0.25 to 2.5 mmol/l in explored samples were used for investigation. Recording data was processed using correlation analysis and differential analytical technique. The fourth derivative spectrum of fluorescence spectrum provided the basis for a multicomponent analysis of the solutions. As a technique in clinical diagnostics fluorescence analysis with processing method including differential spectrophotometry, it is step forward towards redox potential calculation and quality control in pharmacy for better health care.

The Cloud Feedback Model Intercomparison Project (CFMIP) Diagnostic Codes Catalogue – metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models

DOE PAGES

Tsushima, Yoko; Brient, Florent; Klein, Stephen A.; ...

2017-11-27

The CFMIP Diagnostic Codes Catalogue assembles cloud metrics, diagnostics and methodologies, together with programs to diagnose them from general circulation model (GCM) outputs written by various members of the CFMIP community. This aims to facilitate use of the diagnostics by the wider community studying climate and climate change. Here, this paper describes the diagnostics and metrics which are currently in the catalogue, together with examples of their application to model evaluation studies and a summary of some of the insights these diagnostics have provided into the main shortcomings in current GCMs. Analysis of outputs from CFMIP and CMIP6 experiments willmore » also be facilitated by the sharing of diagnostic codes via this catalogue. Any code which implements diagnostics relevant to analysing clouds – including cloud–circulation interactions and the contribution of clouds to estimates of climate sensitivity in models – and which is documented in peer-reviewed studies, can be included in the catalogue. We very much welcome additional contributions to further support community analysis of CMIP6 outputs.« less

The Cloud Feedback Model Intercomparison Project (CFMIP) Diagnostic Codes Catalogue – metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsushima, Yoko; Brient, Florent; Klein, Stephen A.

The CFMIP Diagnostic Codes Catalogue assembles cloud metrics, diagnostics and methodologies, together with programs to diagnose them from general circulation model (GCM) outputs written by various members of the CFMIP community. This aims to facilitate use of the diagnostics by the wider community studying climate and climate change. Here, this paper describes the diagnostics and metrics which are currently in the catalogue, together with examples of their application to model evaluation studies and a summary of some of the insights these diagnostics have provided into the main shortcomings in current GCMs. Analysis of outputs from CFMIP and CMIP6 experiments willmore » also be facilitated by the sharing of diagnostic codes via this catalogue. Any code which implements diagnostics relevant to analysing clouds – including cloud–circulation interactions and the contribution of clouds to estimates of climate sensitivity in models – and which is documented in peer-reviewed studies, can be included in the catalogue. We very much welcome additional contributions to further support community analysis of CMIP6 outputs.« less

[Companion diagnostics in the era of personalized medicine--chairmen's introductory remarks].

PubMed

Fukutsuka, Katsuhiro; Takubo, Takayuki

2014-04-01

Personalized medicine is a medical model that proposes the customization of treatment for individual patients. In this model, diagnostic tests are essential for selecting safer and more efficacious treatments. The term "companion diagnostics" has been used to describe these tests, whereby molecular assays that measure the levels of proteins or specific gene mutations are used to provide a specific therapy for an individual by stratifying the disease status, selecting the proper medication, and tailoring dosages. Examples of companion diagnostics in the field of cancer medicine for molecular targeted therapy include tests for the ALK-fusion gene in non-small cell lung cancer and expression of CCR4 in adult T-cell leukemia. For breast cancer, the expression of HER2 protein is evaluated by immunohistochemistry (IHC), and gene amplification of HER2 is tested by fluorescence in situ hybridization (FISH); both tests consist of pre-analysis, analysis, and post-analysis processes that require quality control to ensure the reliability of the results. This symposium includes: 1) future aspects of companion diagnostics addressing many of the problems that must be overcome, 2) companion diagnostics using FISH focusing on HER2 amplification and ALK alteration, 3) newly developed diagnostic tests using tumor specimens and cell-free DNA in serum, and 4) CCR4 expression detected by IHC and flow cytometry.

Bolometric Luminosities of Peculiar Type II-P Supernovae: Observational and Theoretical Approaches

NASA Astrophysics Data System (ADS)

Lusk, Jeremy Alexander

2018-01-01

In the three decades since the explosion of SN 1987A, only a handful of other supernovae have been detected which are also thought to originate from blue supergiant progenitors. In this study, we use the five best observed of these supernovae (SNe 1998A, 2000cb, 2006V, 2006au, and 2009E) to examine the bolometric properties of the class through observations and theoretical models. Several techniques for taking photometric observations and inferring bolometric luminosities have been used in the literature. Our newly-improved python package SuperBoL implements many of these techniques. The challenge remains that the true bolometric luminosity of the supernova cannot be directly observed. We must turn to theoretical models in order to examine the validity of the different observationally-based techniques. In this work, we make use of the NLTE generalized atmosphere code PHOENIX to produce synthetic spectra of known luminosity which match the observed supernova spectra. Synthetic photometry of these models is then used as input to SuperBoL to test the different observationally-based bolometric luminosity techniques.

The discovery of Ni V in the photospheres of the hot DA white dwarfs RE 2214-492 and G191-B2B

NASA Technical Reports Server (NTRS)

Holberg, J. B.; Hubeny, I.; Barstow, M. A.; Lanz, T.; Sion, E. M.; Tweedy, R. W.

1994-01-01

We have co-added six recently obtained International Ultraviolet Explorer (IUE) echelle spectra of the hot DA white dwarf RE 2214-492 and 10 existing archive spectra of the well-known hot DA, G191-B2B. We find that both stars contain numerous weak features due to Ni V. Nickel is thus the second iron-group element to be found in the spectra of the very hottest DA white dwarfs. In addition to Ni V, we also observe Al III in both stars and present evidence for the possible presence of Ni IV and Fe IV in RE 2214-492. The presence of Ni and Al, together with previously reported elements, will contribute significantly to both the EUV opacity and to the apparent complexity of the UV spectra of these stars. Using Non-Local Thermodynamic Equilibrium (NLTE) model atmospheres we estimate the Ni abundances in RE 2214-492 the G191-B2B to be log(Ni/H) = -5.5 +/- 0.3 and -6.0 +/- 0.3, respectively.

Confronting the Gaia and NLTE spectroscopic parallaxes for the FGK stars

NASA Astrophysics Data System (ADS)

Sitnova, Tatyana; Mashonkina, Lyudmila; Pakhomov, Yury

2018-04-01

The understanding of the chemical evolution of the Galaxy relies on the stellar chemical composition. Accurate atmospheric parameters is a prerequisite of determination of accurate chemical abundances. For late type stars with known distance, surface gravity (log g) can be calculated from well-known relation between stellar mass, T eff, and absolute bolometric magnitude. This method weakly depends on model atmospheres, and provides reliable log g. However, accurate distances are available for limited number of stars. Another way to determine log g for cool stars is based on ionisation equilibrium, i.e. consistent abundances from lines of neutral and ionised species. In this study we determine atmospheric parameters moving step-by-step from well-studied nearby dwarfs to ultra-metal poor (UMP) giants. In each sample, we select stars with the most reliable T eff based on photometry and the distance-based log g, and compare with spectroscopic gravity calculated taking into account deviations from local thermodinamic equilibrium (LTE). After that, we apply spectroscopic method of log g determination to other stars of the sample with unknown distances.

Long pulse Soft X-ray Emission from Laser Generated Irradiated Gold Foils

NASA Astrophysics Data System (ADS)

Davis, Joshua; Frank, Yechiel; Raicher, Erez; Fraenkel, Moshe; Keiter, Paul; Klein, Sallee; Drake, R. P.; Shvarts, Dov

2016-10-01

Long pulse soft x-ray sources (SXS) allow for flexibility in high-energy-density experimental designs by providing a means of driving matter to the high temperatures needed, for example to study radiation waves in different materials. SXSs can be made by using lasers to heat a high-Z thin foil, which then acts as a quasi-blackbody emitter. Previous studies of the x-ray emission characteristics of gold foils have focused on laser pulses of 1ns or less. We performed experiments using a 6.0ns laser pulse with energy of 2kJ on the Omega-60 system to generate and characterize multi-ns laser heated Au foils of thicknesses between 0.5-2.0 μm. We measured the 2D spatial profile of the emission with a soft x-ray camera and the time history of the emission with the Dante photodiode array . Effective temperatures for the emission were then calculated using the Dante measurements. Discussion of experimental results and a comparison with 1-D Rad-Hydro NLTE simulations will be presented.

Diagnostic value of 3D time-of-flight MRA in trigeminal neuralgia.

PubMed

Cai, Jing; Xin, Zhen-Xue; Zhang, Yu-Qiang; Sun, Jie; Lu, Ji-Liang; Xie, Feng

2015-08-01

The aim of this meta-analysis was to evaluate the diagnostic value of 3D time-of-flight magnetic resonance angiography (3D-TOF-MRA) in trigeminal neuralgia (TN). Relevant studies were identified by computerized database searches supplemented by manual search strategies. The studies were included in accordance with stringent inclusion and exclusion criteria. Following a multistep screening process, high quality studies related to the diagnostic value of 3D-TOF-MRA in TN were selected for meta-analysis. Statistical analyses were conducted using Statistical Analysis Software (version 8.2; SAS Institute, Cary, NC, USA) and Meta Disc (version 1.4; Unit of Clinical Biostatistics, Ramon y Cajal Hospital, Madrid, Spain). For the present meta-analysis, we initially retrieved 95 studies from database searches. A total of 13 studies were eventually enrolled containing a combined total of 1084 TN patients. The meta-analysis results demonstrated that the sensitivity and specificity of the diagnostic value of 3D-TOF-MRA in TN were 95% (95% confidence interval [CI] 0.93-0.96) and 77% (95% CI 0.66-0.86), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 2.72 (95% CI 1.81-4.09) and 0.08 (95% CI 0.06-0.12), respectively. The pooled diagnostic odds ratio of 3D-TOF-MRA in TN was 52.92 (95% CI 26.39-106.11), and the corresponding area under the curve in the summary receiver operating characteristic curve based on the 3D-TOF-MRA diagnostic image of observers was 0.9695 (standard error 0.0165). Our results suggest that 3D-TOF-MRA has excellent sensitivity and specificity as a diagnostic tool for TN, and that it can accurately identify neurovascular compression in TN patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

Levelized cost-benefit analysis of proposed diagnostics for the Ammunition Transfer Arm of the US Army`s Future Armored Resupply Vehicle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilkinson, V.K.; Young, J.M.

1995-07-01

The US Army`s Project Manager, Advanced Field Artillery System/Future Armored Resupply Vehicle (PM-AFAS/FARV) is sponsoring the development of technologies that can be applied to the resupply vehicle for the Advanced Field Artillery System. The Engineering Technology Division of the Oak Ridge National Laboratory has proposed adding diagnostics/prognostics systems to four components of the Ammunition Transfer Arm of this vehicle, and a cost-benefit analysis was performed on the diagnostics/prognostics to show the potential savings that may be gained by incorporating these systems onto the vehicle. Possible savings could be in the form of reduced downtime, less unexpected or unnecessary maintenance, fewermore » regular maintenance checks. and/or tower collateral damage or loss. The diagnostics/prognostics systems are used to (1) help determine component problems, (2) determine the condition of the components, and (3) estimate the remaining life of the monitored components. The four components on the arm that are targeted for diagnostics/prognostics are (1) the electromechanical brakes, (2) the linear actuators, (3) the wheel/roller bearings, and (4) the conveyor drive system. These would be monitored using electrical signature analysis, vibration analysis, or a combination of both. Annual failure rates for the four components were obtained along with specifications for vehicle costs, crews, number of missions, etc. Accident scenarios based on component failures were postulated, and event trees for these scenarios were constructed to estimate the annual loss of the resupply vehicle, crew, arm. or mission aborts. A levelized cost-benefit analysis was then performed to examine the costs of such failures, both with and without some level of failure reduction due to the diagnostics/prognostics systems. Any savings resulting from using diagnostics/prognostics were calculated.« less

Pulmonary Infiltrates in Immunosuppressed Patients: Analysis of a Diagnostic Protocol

PubMed Central

Danés, Cristina; González-Martín, Julián; Pumarola, Tomàs; Rañó, Ana; Benito, Natividad; Torres, Antoni; Moreno, Asunción; Rovira, Montserrat; Puig de la Bellacasa, Jorge

2002-01-01

A diagnostic protocol was started to study the etiology of pulmonary infiltrates in immunosuppressed patients. The diagnostic yields of the different techniques were analyzed, with special emphasis on the importance of the sample quality and the role of rapid techniques in the diagnostic strategy. In total, 241 patients with newly developed pulmonary infiltrates within a period of 19 months were included. Noninvasive or invasive evaluation was performed according to the characteristics of the infiltrates. Diagnosis was achieved in 202 patients (84%); 173 patients (72%) had pneumonia, and specific etiologic agents were found in 114 (66%). Bronchoaspirate and bronchoalveolar lavage showed the highest yields, either on global analysis (23 of 35 specimens [66%] and 70 of 134 specimens [52%], respectively) or on analysis of each type of pneumonia. A tendency toward better results with optimal-quality samples was observed, and a statistically significant difference was found in sputum bacterial culture. Rapid diagnostic tests yielded results in 71 of 114 (62.2%) diagnoses of etiological pneumonia. PMID:12037077

Using Fault Trees to Advance Understanding of Diagnostic Errors.

PubMed

Rogith, Deevakar; Iyengar, M Sriram; Singh, Hardeep

2017-11-01

Diagnostic errors annually affect at least 5% of adults in the outpatient setting in the United States. Formal analytic techniques are only infrequently used to understand them, in part because of the complexity of diagnostic processes and clinical work flows involved. In this article, diagnostic errors were modeled using fault tree analysis (FTA), a form of root cause analysis that has been successfully used in other high-complexity, high-risk contexts. How factors contributing to diagnostic errors can be systematically modeled by FTA to inform error understanding and error prevention is demonstrated. A team of three experts reviewed 10 published cases of diagnostic error and constructed fault trees. The fault trees were modeled according to currently available conceptual frameworks characterizing diagnostic error. The 10 trees were then synthesized into a single fault tree to identify common contributing factors and pathways leading to diagnostic error. FTA is a visual, structured, deductive approach that depicts the temporal sequence of events and their interactions in a formal logical hierarchy. The visual FTA enables easier understanding of causative processes and cognitive and system factors, as well as rapid identification of common pathways and interactions in a unified fashion. In addition, it enables calculation of empirical estimates for causative pathways. Thus, fault trees might provide a useful framework for both quantitative and qualitative analysis of diagnostic errors. Future directions include establishing validity and reliability by modeling a wider range of error cases, conducting quantitative evaluations, and undertaking deeper exploration of other FTA capabilities. Copyright © 2017 The Joint Commission. Published by Elsevier Inc. All rights reserved.

[Analysis of characteristics and influence factors of diagnostic delay of endometriosis].

PubMed

Han, X T; Guo, H Y; Kong, D L; Han, J S; Zhang, L F

2018-02-25

Objective: To access the influence factors of diagnostic delay of endometriosis. Methods: We designed a questionnaire of diagnostic delay of endometriosis. From February 2014 to February 2016, 400 patients who had dysmenorrhea and diagnosed with endometriosis by surgery in Peking University Third Hospital were surveyed retrospectively. Time and risk factors of diagnostic delay were analyzed. Results: The diagnostic delay of 400 patients was 13.0 years (0.2-43.0 years), 78.5%(314/400) patients thought pain was a normal phenomenon and didn't see the doctor. Patients who suffered dysmenorrhea at menarche experienced longer diagnostic delay than those who had dysmenorrhea after menarche (18.0 vs 4.5 years; Z= 191.800, P< 0.01) . Patients who suffered aggravating dysmenorrhea experienced shorter delay time than those who suffered stable or relieving dysmenorrhea (11.0 vs 12.5 vs 18.0 years; Z= 8.270, P< 0.05) , with the difference statistically significant, single factor analysis shows. Severe dysmenorrhea, deep infiltration endometriosis (DIE) , family history of dysmenorrhea or endometriosis, previous surgical history of endometriosis, high stage, with infertility, adenomyoma or other symptoms, could help to shorten diagnostic delay with no significant difference ( P> 0.05) . By multiple logistic regression analysis, the results shown that whether have dysmenorrhea at menarche and clinical diagnosis time were the independent factors affecting delayed diagnosis ( P< 0.01) . Conclusions: Diagnostic delay of endometriosis is common and the mean delay time is 13.0 years mainly due to the unawareness of dysmenorrhea. Dysmenorrhea at menarche, clinical diagnosis time and dysmenorrhea intensity are the factors affecting time of diagnostic delay.

A Practical Illustration of Multidimensional Diagnostic Skills Profiling: Comparing Results from Confirmatory Factor Analysis and Diagnostic Classification Models

ERIC Educational Resources Information Center

Kunina-Habenicht, Olga; Rupp, Andre A.; Wilhelm, Oliver

2009-01-01

In recent years there has been an increasing international interest in fine-grained diagnostic inferences on multiple skills for formative purposes. A successful provision of such inferences that support meaningful instructional decision-making requires (a) careful diagnostic assessment design coupled with (b) empirical support for the structure…

[Gene expression analyses of kidney biopsies: the European renal cDNA bank--Kröner-Fresenius biopsy bank].

PubMed

Cohen, C D; Kretzler, M

2009-03-01

Histological analysis of kidney biopsies is an essential part of our current diagnostic workup of patients with renal disease. Besides the already established diagnostic tools, new methods allow extensive analysis of the sample tissue's gene expression. Using results from a European multicenter study on gene expression analysis of renal biopsies, in this review we demonstrate that this novel approach not only expands the scope of so-called basic research but also might supplement future biopsy diagnostics. The goals are improved diagnosis and more specific therapy choice and prognosis estimates.

Diagnostic accuracy of imaging devices in glaucoma: A meta-analysis.

PubMed

Fallon, Monica; Valero, Oliver; Pazos, Marta; Antón, Alfonso

Imaging devices such as the Heidelberg retinal tomograph-3 (HRT3), scanning laser polarimetry (GDx), and optical coherence tomography (OCT) play an important role in glaucoma diagnosis. A systematic search for evidence-based data was performed for prospective studies evaluating the diagnostic accuracy of HRT3, GDx, and OCT. The diagnostic odds ratio (DOR) was calculated. To compare the accuracy among instruments and parameters, a meta-analysis considering the hierarchical summary receiver-operating characteristic model was performed. The risk of bias was assessed using quality assessment of diagnostic accuracy studies, version 2. Studies in the context of screening programs were used for qualitative analysis. Eighty-six articles were included. The DOR values were 29.5 for OCT, 18.6 for GDx, and 13.9 for HRT. The heterogeneity analysis demonstrated statistically a significant influence of degree of damage and ethnicity. Studies analyzing patients with earlier glaucoma showed poorer results. The risk of bias was high for patient selection. Screening studies showed lower sensitivity values and similar specificity values when compared with those included in the meta-analysis. The classification capabilities of GDx, HRT, and OCT were high and similar across the 3 instruments. The highest estimated DOR was obtained with OCT. Diagnostic accuracy could be overestimated in studies including prediagnosed groups of subjects. Copyright © 2017 Elsevier Inc. All rights reserved.

Vitrectomy for the diagnosis and management of uveitis of unknown cause.

PubMed

Margolis, Ron; Brasil, Oswaldo F M; Lowder, Careen Y; Singh, Rishi P; Kaiser, Peter K; Smith, Scott D; Perez, Victor L; Sonnie, Christine; Sears, Jonathan E

2007-10-01

To determine the diagnostic yield of tests commonly used for vitreous fluid analysis in eyes with suspected intraocular infection or malignancy. Noncomparative interventional case series. Forty-four consecutive patients (45 eyes) treated from 1998 through 2006 with posterior segment inflammation who underwent pars plana vitrectomy for diagnostic purposes. Vitreous specimens obtained via pars plana vitrectomy were analyzed by microbiologic culture, cytologic analysis, and flow cytometry. Diagnostic yield and sensitivity of each test performed on vitreous specimens and visual outcomes of eyes that underwent diagnostic vitrectomy (DVx). Preoperative diagnoses were infection in 15 eyes and malignancy in 30 eyes. Overall, vitreous analysis identified a specific cause in 9 (20%) of 45 eyes. The overall sensitivity of DVx was 63.6%. The sensitivities of individual tests were: culture, 50%; cytologic analysis, 66.7%; and flow cytometry, 83.3%. The yields of diagnostic tests were: culture, 5.7%; cytologic analysis, 14.3%; and flow cytometry, 20.6%. Final diagnoses were infection in 6 eyes, malignancy in 9 eyes, and idiopathic in 30 eyes. Mean visual acuity improved significantly in the first 6 months after DVx. Visual acuity improved in 60% of eyes, with 37.8% of eyes improving by 3 lines or more. Analysis of vitreous fluid by widely available tests is useful in identifying intraocular infection or malignancy. Most patients experienced a substantial improvement in vision.

Mobile diagnostics: next-generation technologies for in vitro diagnostics.

PubMed

Shin, Joonchul; Chakravarty, Sudesna; Choi, Wooseok; Lee, Kyungyeon; Han, Dongsik; Hwang, Hyundoo; Choi, Jaekyu; Jung, Hyo-Il

2018-03-26

The emergence of a wide range of applications of smartphones along with advances in 'liquid biopsy' has significantly propelled medical research particularly in the field of in vitro diagnostics (IVD). Herein, we have presented a detailed analysis of IVD, its associated critical concerns and probable solutions. It also demonstrates the transition in terms of analytes from minimally invasive (blood) to non-invasive (urine, saliva and sweat) and depicts how the different features of a smartphone can be integrated for specific diagnostic purposes. This review basically highlights recent advances in the applications of smartphone-based biosensors in IVD taking into account the following factors: accuracy and portability; quantitative and qualitative analysis; and centralization and decentralization tests. Furthermore, the critical concerns and future direction of diagnostics based on smartphones are also discussed.

Case-Deletion Diagnostics for Maximum Likelihood Multipoint Quantitative Trait Locus Linkage Analysis

PubMed Central

Mendoza, Maria C.B.; Burns, Trudy L.; Jones, Michael P.

2009-01-01

Objectives Case-deletion diagnostic methods are tools that allow identification of influential observations that may affect parameter estimates and model fitting conclusions. The goal of this paper was to develop two case-deletion diagnostics, the exact case deletion (ECD) and the empirical influence function (EIF), for detecting outliers that can affect results of sib-pair maximum likelihood quantitative trait locus (QTL) linkage analysis. Methods Subroutines to compute the ECD and EIF were incorporated into the maximum likelihood QTL variance estimation components of the linkage analysis program MAPMAKER/SIBS. Performance of the diagnostics was compared in simulation studies that evaluated the proportion of outliers correctly identified (sensitivity), and the proportion of non-outliers correctly identified (specificity). Results Simulations involving nuclear family data sets with one outlier showed EIF sensitivities approximated ECD sensitivities well for outlier-affected parameters. Sensitivities were high, indicating the outlier was identified a high proportion of the time. Simulations also showed the enormous computational time advantage of the EIF. Diagnostics applied to body mass index in nuclear families detected observations influential on the lod score and model parameter estimates. Conclusions The EIF is a practical diagnostic tool that has the advantages of high sensitivity and quick computation. PMID:19172086

Efficient genome-wide association in biobanks using topic modeling identifies multiple novel disease loci.

PubMed

McCoy, Thomas H; Castro, Victor M; Snapper, Leslie A; Hart, Kamber L; Perlis, Roy H

2017-08-31

Biobanks and national registries represent a powerful tool for genomic discovery, but rely on diagnostic codes that may be unreliable and fail to capture the relationship between related diagnoses. We developed an efficient means of conducting genome-wide association studies using combinations of diagnostic codes from electronic health records (EHR) for 10845 participants in a biobanking program at two large academic medical centers. Specifically, we applied latent Dirichilet allocation to fit 50 disease topics based on diagnostic codes, then conducted genome-wide common-variant association for each topic. In sensitivity analysis, these results were contrasted with those obtained from traditional single-diagnosis phenome-wide association analysis, as well as those in which only a subset of diagnostic codes are included per topic. In meta-analysis across three biobank cohorts, we identified 23 disease-associated loci with p<1e-15, including previously associated autoimmune disease loci. In all cases, observed significant associations were of greater magnitude than for single phenome-wide diagnostic codes, and incorporation of less strongly-loading diagnostic codes enhanced association. This strategy provides a more efficient means of phenome-wide association in biobanks with coded clinical data.

Efficient Genome-wide Association in Biobanks Using Topic Modeling Identifies Multiple Novel Disease Loci

PubMed Central

McCoy, Thomas H; Castro, Victor M; Snapper, Leslie A; Hart, Kamber L; Perlis, Roy H

2017-01-01

Biobanks and national registries represent a powerful tool for genomic discovery, but rely on diagnostic codes that can be unreliable and fail to capture relationships between related diagnoses. We developed an efficient means of conducting genome-wide association studies using combinations of diagnostic codes from electronic health records for 10,845 participants in a biobanking program at two large academic medical centers. Specifically, we applied latent Dirichilet allocation to fit 50 disease topics based on diagnostic codes, then conducted a genome-wide common-variant association for each topic. In sensitivity analysis, these results were contrasted with those obtained from traditional single-diagnosis phenome-wide association analysis, as well as those in which only a subset of diagnostic codes were included per topic. In meta-analysis across three biobank cohorts, we identified 23 disease-associated loci with p < 1e-15, including previously associated autoimmune disease loci. In all cases, observed significant associations were of greater magnitude than single phenome-wide diagnostic codes, and incorporation of less strongly loading diagnostic codes enhanced association. This strategy provides a more efficient means of identifying phenome-wide associations in biobanks with coded clinical data. PMID:28861588

Meta-analysis for the comparison of two diagnostic tests to a common gold standard: A generalized linear mixed model approach.

PubMed

Hoyer, Annika; Kuss, Oliver

2018-05-01

Meta-analysis of diagnostic studies is still a rapidly developing area of biostatistical research. Especially, there is an increasing interest in methods to compare different diagnostic tests to a common gold standard. Restricting to the case of two diagnostic tests, in these meta-analyses the parameters of interest are the differences of sensitivities and specificities (with their corresponding confidence intervals) between the two diagnostic tests while accounting for the various associations across single studies and between the two tests. We propose statistical models with a quadrivariate response (where sensitivity of test 1, specificity of test 1, sensitivity of test 2, and specificity of test 2 are the four responses) as a sensible approach to this task. Using a quadrivariate generalized linear mixed model naturally generalizes the common standard bivariate model of meta-analysis for a single diagnostic test. If information on several thresholds of the tests is available, the quadrivariate model can be further generalized to yield a comparison of full receiver operating characteristic (ROC) curves. We illustrate our model by an example where two screening methods for the diagnosis of type 2 diabetes are compared.

Conversion-Integration of MSFC Nonlinear Signal Diagnostic Analysis Algorithms for Realtime Execution of MSFC's MPP Prototype System

NASA Technical Reports Server (NTRS)

Jong, Jen-Yi

1996-01-01

NASA's advanced propulsion system Small Scale Magnetic Disturbances/Advanced Technology Development (SSME/ATD) has been undergoing extensive flight certification and developmental testing, which involves large numbers of health monitoring measurements. To enhance engine safety and reliability, detailed analysis and evaluation of the measurement signals are mandatory to assess its dynamic characteristics and operational condition. Efficient and reliable signal detection techniques will reduce the risk of catastrophic system failures and expedite the evaluation of both flight and ground test data, and thereby reduce launch turn-around time. During the development of SSME, ASRI participated in the research and development of several advanced non- linear signal diagnostic methods for health monitoring and failure prediction in turbomachinery components. However, due to the intensive computational requirement associated with such advanced analysis tasks, current SSME dynamic data analysis and diagnostic evaluation is performed off-line following flight or ground test with a typical diagnostic turnaround time of one to two days. The objective of MSFC's MPP Prototype System is to eliminate such 'diagnostic lag time' by achieving signal processing and analysis in real-time. Such an on-line diagnostic system can provide sufficient lead time to initiate corrective action and also to enable efficient scheduling of inspection, maintenance and repair activities. The major objective of this project was to convert and implement a number of advanced nonlinear diagnostic DSP algorithms in a format consistent with that required for integration into the Vanderbilt Multigraph Architecture (MGA) Model Based Programming environment. This effort will allow the real-time execution of these algorithms using the MSFC MPP Prototype System. ASRI has completed the software conversion and integration of a sequence of nonlinear signal analysis techniques specified in the SOW for real-time execution on MSFC's MPP Prototype. This report documents and summarizes the results of the contract tasks; provides the complete computer source code; including all FORTRAN/C Utilities; and all other utilities/supporting software libraries that are required for operation.

The role of molecular genetic analysis in the diagnosis of primary ciliary dyskinesia.

PubMed

Kim, Raymond H; A Hall, David; Cutz, Ernest; Knowles, Michael R; Nelligan, Kathleen A; Nykamp, Keith; Zariwala, Maimoona A; Dell, Sharon D

2014-03-01

Primary ciliary dyskinesia (PCD) is an autosomal recessive genetic disorder of motile cilia. The diagnosis of PCD has previously relied on ciliary analysis with transmission electron microscopy or video microscopy. However, patients with PCD may have normal ultrastructural appearance, and ciliary analysis has limited accessibility. Alternatively, PCD can be diagnosed by demonstrating biallelic mutations in known PCD genes. Genetic testing is emerging as a diagnostic tool to complement ciliary analysis where interpretation and access may delay diagnosis. To determine the diagnostic yield of genetic testing of patients with a confirmed or suspected diagnosis of PCD in a multiethnic urban center. Twenty-eight individuals with confirmed PCD on transmission electron microscopy of ciliary ultrastructure and 24 individuals with a probable diagnosis of PCD based on a classical PCD phenotype and low nasal nitric oxide had molecular analysis of 12 genes associated with PCD. Of 49 subjects who underwent ciliary biopsy, 28 (57%) were diagnosed with PCD through an ultrastructural defect. Of the 52 individuals who underwent molecular genetic analysis, 22 (42%) individuals had two mutations in known PCD genes. Twenty-four previously unreported mutations in known PCD genes were observed. Combining both diagnostic modalities of biopsy and molecular genetics, the diagnostic yield increased to 69% compared with 57% based on biopsy alone. The diagnosis of PCD is challenging and has traditionally relied on ciliary biopsy, which is unreliable as the sole criterion for a definitive diagnosis. Molecular genetic analysis can be used as a complementary test to increase the diagnostic yield.

How does study quality affect the results of a diagnostic meta-analysis?

PubMed Central

Westwood, Marie E; Whiting, Penny F; Kleijnen, Jos

2005-01-01

Background The use of systematic literature review to inform evidence based practice in diagnostics is rapidly expanding. Although the primary diagnostic literature is extensive, studies are often of low methodological quality or poorly reported. There has been no rigorously evaluated, evidence based tool to assess the methodological quality of diagnostic studies. The primary objective of this study was to determine the extent to which variations in the quality of primary studies impact the results of a diagnostic meta-analysis and whether this differs with diagnostic test type. A secondary objective was to contribute to the evaluation of QUADAS, an evidence-based tool for the assessment of quality in diagnostic accuracy studies. Methods This study was conducted as part of large systematic review of tests used in the diagnosis and further investigation of urinary tract infection (UTI) in children. All studies included in this review were assessed using QUADAS, an evidence-based tool for the assessment of quality in systematic reviews of diagnostic accuracy studies. The impact of individual components of QUADAS on a summary measure of diagnostic accuracy was investigated using regression analysis. The review divided the diagnosis and further investigation of UTI into the following three clinical stages: diagnosis of UTI, localisation of infection, and further investigation of the UTI. Each stage used different types of diagnostic test, which were considered to involve different quality concerns. Results Many of the studies included in our review were poorly reported. The proportion of QUADAS items fulfilled was similar for studies in different sections of the review. However, as might be expected, the individual items fulfilled differed between the three clinical stages. Regression analysis found that different items showed a strong association with test performance for the different tests evaluated. These differences were observed both within and between the three clinical stages assessed by the review. The results of regression analyses were also affected by whether or not a weighting (by sample size) was applied. Our analysis was severely limited by the completeness of reporting and the differences between the index tests evaluated and the reference standards used to confirm diagnoses in the primary studies. Few tests were evaluated by sufficient studies to allow meaningful use of meta-analytic pooling and investigation of heterogeneity. This meant that further analysis to investigate heterogeneity could only be undertaken using a subset of studies, and that the findings are open to various interpretations. Conclusion Further work is needed to investigate the influence of methodological quality on the results of diagnostic meta-analyses. Large data sets of well-reported primary studies are needed to address this question. Without significant improvements in the completeness of reporting of primary studies, progress in this area will be limited. PMID:15943861

KIC 9821622: An interesting lithium-rich giant in the Kepler field

NASA Astrophysics Data System (ADS)

Jofré, E.; Petrucci, R.; García, L.; Gómez, M.

2015-12-01

We report the discovery of a new exceptional young lithium-rich giant, KIC 9821622, in the Kepler field that exhibits an unusually large enhancement of α, Fe-peak, and r-process elements. From high-resolution spectra obtained with GRACES at Gemini North, we derived fundamental parameters and detailed chemical abundances of 23 elements from equivalent widths and synthesis analysis. By combining atmospheric stellar parameters with available asteroseismic data, we obtained the stellar mass, radius, and age. The data analysis reveals that KIC 9821622 is a Li-rich (A(Li)NLTE = 1.80 ± 0.2) intermediate-mass giant star (M = 1.64 M⊙) located at the red giant branch near the luminosity bump. We find unexpectedly elevated abundances of Fe-peak and r-process elements. In addition, as previously reported, we find that this is a young star (2.37 Gyr) with unusually high abundances of α-elements ([α/Fe] = 0.31). The evolutionary status of KIC 9821622 suggests that its Li-rich nature is the result of internal fresh Li that is synthesized through the Cameron-Fowler mechanism near the luminosity bump. However, its peculiar enhancement of α, Fe-peak, and r-process elements opens the possibility of external contamination by material enriched by a supernova explosion. Although it is less likely, planet accretion cannot be ruled out. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).Appendix A is available in electronic form at http://www.aanda.org

WEIGHING THE GALACTIC DARK MATTER HALO: A LOWER MASS LIMIT FROM THE FASTEST HALO STAR KNOWN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Przybilla, Norbert; Tillich, Alfred; Heber, Ulrich

2010-07-20

The mass of the Galactic dark matter halo is under vivid discussion. A recent study by Xue et al. revised the Galactic halo mass downward by a factor of {approx}2 relative to previous work, based on the line-of-sight velocity distribution of {approx}2400 blue horizontal-branch (BHB) halo stars. The observations were interpreted with a statistical approach using cosmological galaxy formation simulations, as only four of the six-dimensional phase-space coordinates were determined. Here we concentrate on a close investigation of the stars with the highest negative radial velocity from that sample. For one star, SDSSJ153935.67+023909.8 (J1539+0239 for short), we succeed in measuringmore » a significant proper motion, i.e., full phase-space information is obtained. We confirm the star to be a Population II BHB star from an independent quantitative analysis of the Sloan Digital Sky Survey (SDSS) spectrum-providing the first non-LTE (NLTE) study of any halo BHB star-and reconstruct its three-dimensional trajectory in the Galactic potential. J1539+0239 turns out to be the fastest halo star known to date, with a Galactic rest-frame velocity of 694{sup +300}{sub -221} km s{sup -1} (full uncertainty range from Monte Carlo error propagation) at its current position. The extreme kinematics of the star allows a significant lower limit to be put on the halo mass in order to keep it bound, of M {sub halo} {>=} 1.7{sup +2.3}{sub -1.1} x 10{sup 12} M{sub sun}. We conclude that the Xue et al. results tend to underestimate the true halo mass as their most likely mass value is consistent with our analysis only at a level of 4%. However, our result confirms other studies that make use of the full phase-space information.« less

Evidence-Based Diagnostic Algorithm for Glioma: Analysis of the Results of Pathology Panel Review and Molecular Parameters of EORTC 26951 and 26882 Trials.

PubMed

Kros, Johan M; Huizer, Karin; Hernández-Laín, Aurelio; Marucci, Gianluca; Michotte, Alex; Pollo, Bianca; Rushing, Elisabeth J; Ribalta, Teresa; French, Pim; Jaminé, David; Bekka, Nawal; Lacombe, Denis; van den Bent, Martin J; Gorlia, Thierry

2015-06-10

With the rapid discovery of prognostic and predictive molecular parameters for glioma, the status of histopathology in the diagnostic process should be scrutinized. Our project aimed to construct a diagnostic algorithm for gliomas based on molecular and histologic parameters with independent prognostic values. The pathology slides of 636 patients with gliomas who had been included in EORTC 26951 and 26882 trials were reviewed using virtual microscopy by a panel of six neuropathologists who independently scored 18 histologic features and provided an overall diagnosis. The molecular data for IDH1, 1p/19q loss, EGFR amplification, loss of chromosome 10 and chromosome arm 10q, gain of chromosome 7, and hypermethylation of the promoter of MGMT were available for some of the cases. The slides were divided in discovery (n = 426) and validation sets (n = 210). The diagnostic algorithm resulting from analysis of the discovery set was validated in the latter. In 66% of cases, consensus of overall diagnosis was present. A diagnostic algorithm consisting of two molecular markers and one consensus histologic feature was created by conditional inference tree analysis. The order of prognostic significance was: 1p/19q loss, EGFR amplification, and astrocytic morphology, which resulted in the identification of four diagnostic nodes. Validation of the nodes in the validation set confirmed the prognostic value (P < .001). We succeeded in the creation of a timely diagnostic algorithm for anaplastic glioma based on multivariable analysis of consensus histopathology and molecular parameters. © 2015 by American Society of Clinical Oncology.

ROC curves in clinical chemistry: uses, misuses, and possible solutions.

PubMed

Obuchowski, Nancy A; Lieber, Michael L; Wians, Frank H

2004-07-01

ROC curves have become the standard for describing and comparing the accuracy of diagnostic tests. Not surprisingly, ROC curves are used often by clinical chemists. Our aims were to observe how the accuracy of clinical laboratory diagnostic tests is assessed, compared, and reported in the literature; to identify common problems with the use of ROC curves; and to offer some possible solutions. We reviewed every original work using ROC curves and published in Clinical Chemistry in 2001 or 2002. For each article we recorded phase of the research, prospective or retrospective design, sample size, presence/absence of confidence intervals (CIs), nature of the statistical analysis, and major analysis problems. Of 58 articles, 31% were phase I (exploratory), 50% were phase II (challenge), and 19% were phase III (advanced) studies. The studies increased in sample size from phase I to III and showed a progression in the use of prospective designs. Most phase I studies were powered to assess diagnostic tests with ROC areas >/=0.70. Thirty-eight percent of studies failed to include CIs for diagnostic test accuracy or the CIs were constructed inappropriately. Thirty-three percent of studies provided insufficient analysis for comparing diagnostic tests. Other problems included dichotomization of the gold standard scale and inappropriate analysis of the equivalence of two diagnostic tests. We identify available software and make some suggestions for sample size determination, testing for equivalence in diagnostic accuracy, and alternatives to a dichotomous classification of a continuous-scale gold standard. More methodologic research is needed in areas specific to clinical chemistry.

European Thyroid Association Guidelines regarding Thyroid Nodule Molecular Fine-Needle Aspiration Cytology Diagnostics.

PubMed

Paschke, Ralf; Cantara, Silvia; Crescenzi, Anna; Jarzab, Barbara; Musholt, Thomas J; Sobrinho Simoes, Manuel

2017-07-01

Molecular fine-needle aspiration (FNA) cytology diagnostics has the potential to address the inherent limitation of FNA cytology which is an indeterminate (atypia of undetermined significance/follicular lesion of undetermined significance follicular neoplasm) cytology. Because of the emerging role of molecular FNA cytology diagnostics, the European Thyroid Association convened a panel of international experts to review methodological aspects, indications, results, and limitations of molecular FNA cytology diagnostics. The panel reviewed the evidence for the diagnostic value of mutation panel assessment (including at least BRAF , NRAS , HRAS , KRAS , PAX8/PPARG , RET/PTC ) of targeted next generation sequencing and of a microarray gene expression classifier (GEC) test in the diagnostic assessment of an indeterminate cytology thyroid nodule. Moreover, possible surgical consequences of molecular FNA diagnostic results of thyroid nodules and the evidence that analysis of a molecular FNA diagnostic panel of somatic mutations or a microarray GEC test can alter the follow-up were reviewed. Molecular tests may help clinicians to drive patient care and the surgical decision if the analysis is performed in specialized laboratories. These molecular tests require standardization of performance characteristics and appropriate calibration as well as analytic validation before clinical interpretation.

European Thyroid Association Guidelines regarding Thyroid Nodule Molecular Fine-Needle Aspiration Cytology Diagnostics

PubMed Central

Paschke, Ralf; Cantara, Silvia; Crescenzi, Anna; Jarzab, Barbara; Musholt, Thomas J.; Sobrinho Simoes, Manuel

2017-01-01

Molecular fine-needle aspiration (FNA) cytology diagnostics has the potential to address the inherent limitation of FNA cytology which is an indeterminate (atypia of undetermined significance/follicular lesion of undetermined significance follicular neoplasm) cytology. Because of the emerging role of molecular FNA cytology diagnostics, the European Thyroid Association convened a panel of international experts to review methodological aspects, indications, results, and limitations of molecular FNA cytology diagnostics. The panel reviewed the evidence for the diagnostic value of mutation panel assessment (including at least BRAF, NRAS, HRAS, KRAS, PAX8/PPARG, RET/PTC) of targeted next generation sequencing and of a microarray gene expression classifier (GEC) test in the diagnostic assessment of an indeterminate cytology thyroid nodule. Moreover, possible surgical consequences of molecular FNA diagnostic results of thyroid nodules and the evidence that analysis of a molecular FNA diagnostic panel of somatic mutations or a microarray GEC test can alter the follow-up were reviewed. Molecular tests may help clinicians to drive patient care and the surgical decision if the analysis is performed in specialized laboratories. These molecular tests require standardization of performance characteristics and appropriate calibration as well as analytic validation before clinical interpretation. PMID:28785538

Diagnostic performance of semi-quantitative and quantitative stress CMR perfusion analysis: a meta-analysis.

PubMed

van Dijk, R; van Assen, M; Vliegenthart, R; de Bock, G H; van der Harst, P; Oudkerk, M

2017-11-27

Stress cardiovascular magnetic resonance (CMR) perfusion imaging is a promising modality for the evaluation of coronary artery disease (CAD) due to high spatial resolution and absence of radiation. Semi-quantitative and quantitative analysis of CMR perfusion are based on signal-intensity curves produced during the first-pass of gadolinium contrast. Multiple semi-quantitative and quantitative parameters have been introduced. Diagnostic performance of these parameters varies extensively among studies and standardized protocols are lacking. This study aims to determine the diagnostic accuracy of semi- quantitative and quantitative CMR perfusion parameters, compared to multiple reference standards. Pubmed, WebOfScience, and Embase were systematically searched using predefined criteria (3272 articles). A check for duplicates was performed (1967 articles). Eligibility and relevance of the articles was determined by two reviewers using pre-defined criteria. The primary data extraction was performed independently by two researchers with the use of a predefined template. Differences in extracted data were resolved by discussion between the two researchers. The quality of the included studies was assessed using the 'Quality Assessment of Diagnostic Accuracy Studies Tool' (QUADAS-2). True positives, false positives, true negatives, and false negatives were subtracted/calculated from the articles. The principal summary measures used to assess diagnostic accuracy were sensitivity, specificity, andarea under the receiver operating curve (AUC). Data was pooled according to analysis territory, reference standard and perfusion parameter. Twenty-two articles were eligible based on the predefined study eligibility criteria. The pooled diagnostic accuracy for segment-, territory- and patient-based analyses showed good diagnostic performance with sensitivity of 0.88, 0.82, and 0.83, specificity of 0.72, 0.83, and 0.76 and AUC of 0.90, 0.84, and 0.87, respectively. In per territory analysis our results show similar diagnostic accuracy comparing anatomical (AUC 0.86(0.83-0.89)) and functional reference standards (AUC 0.88(0.84-0.90)). Only the per territory analysis sensitivity did not show significant heterogeneity. None of the groups showed signs of publication bias. The clinical value of semi-quantitative and quantitative CMR perfusion analysis remains uncertain due to extensive inter-study heterogeneity and large differences in CMR perfusion acquisition protocols, reference standards, and methods of assessment of myocardial perfusion parameters. For wide spread implementation, standardization of CMR perfusion techniques is essential. CRD42016040176 .

Implementation of Point-of-Care Diagnostics in Rural Primary Healthcare Clinics in South Africa: Perspectives of Key Stakeholders.

PubMed

Mashamba-Thompson, Tivani P; Jama, Ngcwalisa A; Sartorius, Benn; Drain, Paul K; Thompson, Rowan M

2017-01-08

Key stakeholders' involvement is crucial to the sustainability of quality point-of-care (POC) diagnostics services in low-and-middle income countries. The aim of this study was to explore key stakeholder perceptions on the implementation of POC diagnostics in rural primary healthcare (PHC) clinics in South Africa. We conducted a qualitative study encompassing in-depth interviews with multiple key stakeholders of POC diagnostic services for rural and resource-limited PHC clinics. Interviews were digitally recorded and transcribed verbatim prior to thematic content analysis. Thematic content analysis was conducted using themes guided by the World Health Organisation (WHO) quality-ASSURED (Affordable, Sensitive, Specific, User friendly, Rapid and to enable treatment at first visit and Robust, Equipment free and Delivered to those who need it) criteria for POC diagnostic services in resource-limited settings. 11 key stakeholders participated in the study. All stakeholders perceived the main advantage of POC diagnostics as enabling access to healthcare for rural patients. Stakeholders perceived the current POC diagnostic services to have an ability to meet patients' needs, but recommended further improvement of the following areas: research on cost-effectiveness; improved quality management systems; development of affordable POC diagnostic and clinic-based monitoring and evaluation. Key stakeholders of POC diagnostics in rural PHC clinics in South Africa highlighted the need to assess affordability and ensure quality assurance of current services before adopting new POC diagnostics and scaling up current POC diagnostics.

Implementation of Point-of-Care Diagnostics in Rural Primary Healthcare Clinics in South Africa: Perspectives of Key Stakeholders

PubMed Central

Mashamba-Thompson, Tivani P.; Jama, Ngcwalisa A.; Sartorius, Benn; Drain, Paul K.; Thompson, Rowan M.

2017-01-01

Introduction: Key stakeholders’ involvement is crucial to the sustainability of quality point-of-care (POC) diagnostics services in low-and-middle income countries. The aim of this study was to explore key stakeholder perceptions on the implementation of POC diagnostics in rural primary healthcare (PHC) clinics in South Africa. Method: We conducted a qualitative study encompassing in-depth interviews with multiple key stakeholders of POC diagnostic services for rural and resource-limited PHC clinics. Interviews were digitally recorded and transcribed verbatim prior to thematic content analysis. Thematic content analysis was conducted using themes guided by the World Health Organisation (WHO) quality-ASSURED (Affordable, Sensitive, Specific, User friendly, Rapid and to enable treatment at first visit and Robust, Equipment free and Delivered to those who need it) criteria for POC diagnostic services in resource-limited settings. Results: 11 key stakeholders participated in the study. All stakeholders perceived the main advantage of POC diagnostics as enabling access to healthcare for rural patients. Stakeholders perceived the current POC diagnostic services to have an ability to meet patients’ needs, but recommended further improvement of the following areas: research on cost-effectiveness; improved quality management systems; development of affordable POC diagnostic and clinic-based monitoring and evaluation. Conclusions: Key stakeholders of POC diagnostics in rural PHC clinics in South Africa highlighted the need to assess affordability and ensure quality assurance of current services before adopting new POC diagnostics and scaling up current POC diagnostics. PMID:28075337

Agreement between admission and discharge diagnoses: Analysis by the groups of international classification of diseases, 10th revision.

PubMed

Mihailović, Nataša; Trajković, Goran; Simić-Vukomanović, Ivana; Ristić, Svetlana; Kocić, Sanja

2016-12-01

Admission diagnosis represents the diagnosis of an illness, injury or condition due to which a patient is referred to hospital to be admitted. Discharge diagnosis represents the main reason of illness or condition due to which a patient is admitted. The aim of this study was to analyze the agreement between admission diagnostic groups and discharge diagnostic groups of patients in the Clinical Center Kragujevac in the period from January 1, 2006 to December 31, 2013 on the basis of the hospitalization report. From the basic set of reports, 5% of random samples were singled out and they contained 20,422 reports. Out of the given number of reports, 18,173 hospitalization reports were complete and then further analyzed in the paper. Admission diagnostic groups given by the primary care doctor were compared with discharge diagnostic groups filled out by the practicing physician in the hospital ward from which a patient was discharged. The agreement of these two diagnostic groups was an indication of the high-quality performance of the primary care doctor. Agreement analysis was conducted using Cohen’s Kappa statistics. Agreement analysis showed that the values of the Kappa coefficient for the five leading admission diagnostic groups were in the range of κ = 0.61 to κ = 0.94. The values of the Kappa coefficient for the five most common discharge diagnostic groups were in the range of κ = 0.55 to κ = 0.81. Hospitalization report is a reliable individual report on inpatient care, so it could be used in determining the degree of agreement between admission diagnostic groups and discharge diagnostic groups.

A fluctuation-induced plasma transport diagnostic based upon fast-Fourier transform spectral analysis

NASA Technical Reports Server (NTRS)

Powers, E. J.; Kim, Y. C.; Hong, J. Y.; Roth, J. R.; Krawczonek, W. M.

1978-01-01

A diagnostic, based on fast Fourier-transform spectral analysis techniques, that provides experimental insight into the relationship between the experimentally observable spectral characteristics of the fluctuations and the fluctuation-induced plasma transport is described. The model upon which the diagnostic technique is based and its experimental implementation is discussed. Some characteristic results obtained during the course of an experimental study of fluctuation-induced transport in the electric field dominated NASA Lewis bumpy torus plasma are presented.

Simplified diagnostic coding sheet for computerized data storage and analysis in ophthalmology.

PubMed

Tauber, J; Lahav, M

1987-11-01

A review of currently-available diagnostic coding systems revealed that most are either too abbreviated or too detailed. We have compiled a simplified diagnostic coding sheet based on the International Coding and Diagnosis (ICD-9), which is both complete and easy to use in a general practice. The information is transferred to a computer, which uses the relevant (ICD-9) diagnoses as database and can be retrieved later for display of patients' problems or analysis of clinical data.

Diagnostics of red-shifted H-alpha line emission from a C-class flare with full non-LTE radiative and hydrodynamic approach

NASA Astrophysics Data System (ADS)

Druett, M. K.; Zharkova, V. V.; Scullion, E.; Zharkov, S.; Matthews, S. A.

2016-12-01

We analyse H-alpha line profiles with strong redshifts during the C1.8 flare on 1st July 2012 obtained from the Swedish Solar Telescope (SST) closely resembling the previous observations (Wuelser and Marti, 1989). The flare has a magnetic field configuration with two levels of loop structures. The kernels with red shifts are observed in one of the H-alpha ribbons in the south-west location formed after the main impulse recorded in the north-east. The locations of H-alpha kernels with red shifts reveal close temporal and spatial correlation with weaker HXR signatures and coincide with the locations of coronal jets observed with AIA/SDO. For interpretation we apply a revised 1D hydrodynamic and non-LTE (NLTE) radiative model for 5 level plus continuum model hydrogen atom (Druett & Zharkova, 2016) considering radiative, thermal and non-thermal excitation and ionisation by beam electrons with the updated beam densities (Zharkova & Dobranskis, 2016) and analytical excitation/ionisation rates (Zharkova& Kobylinskijj, 1993). We find the simultaneous solutions of steady state and radiative transfer equations in all optically-thick lines and continua. The electron and ion temperatures, ambient density and macrovelocity of the ambient plasma are derived from a 1D hydrodynamic model with initial condition of the pre-flaring photosphere for the two fluid ambient plasma heated by beam electrons (Zharkova & Zharkov, 2007). We simulate distributions over precipitation depth of ionisation and departure coefficients for all the hydrogen atom transitions including the deviation of ionisation from Saha equation affected by non-thermal electron beams. We show that in the very first seconds after the beam onset Balmer line profiles are sensitive to the effect of beam electrons. The combination of the additional ionisation caused by beam electrons leading to a very strong Stark effect in Balmer lines with the hydrodynamic heating and formation of a low temperature shock in the chromosphere is shown to closely account for the visible asymmetric H-alpha line profiles with strong red shifts observed now and in the past. The interplay between the ambient plasma heating and non-thermal collisional excitation and ionisation rates by beam electrons is shown to define the Balmer line red shifts and continuum enhancements.

Clinical Factors and Disease Course Related to Diagnostic Delay in Korean Crohn's Disease Patients: Results from the CONNECT Study.

PubMed

Moon, Chang Mo; Jung, Sung-Ae; Kim, Seong-Eun; Song, Hyun Joo; Jung, Yunho; Ye, Byong Duk; Cheon, Jae Hee; Kim, You Sun; Kim, Young-Ho; Kim, Joo Sung; Han, Dong Soo

2015-01-01

Diagnostic delay frequently occurs in Crohn's disease (CD) patients because of diagnostic limitations. However, diagnostic delay and its related factors remain poorly defined. Therefore, we aimed to identify the predictors associated with diagnostic delay and to evaluate the impact of diagnostic delay on clinical course in a Korean CD patient cohort. We performed a multicenter retrospective analysis of 1,047 CD patients registered in the Crohn's Disease Clinical Network and Cohort study in Korea. The mean interval of diagnostic delay was 16.0 ± 33.1 months. Multivariate analysis showed that older age at diagnosis (≥40 years) (p = 0.014), concomitant upper gastrointestinal (UGI) disease (p = 0.012) and penetrating disease behavior at diagnosis (p = 0.001) were positively associated with long diagnostic delay (≥18 months). During the longitudinal follow-up, long diagnostic delay was independently predictive of further development of intestinal stenosis (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.07-1.93; p = 0.017), internal fistulas (HR, 1.62; 95% CI, 1.12-2.33; p = 0.011), and perianal fistulas (HR, 1.38; 95% CI, 1.06-1.80; p = 0.016). However, as for the risk of abscess formation, bowel perforation, and CD-related abdominal surgery, no significant association with diagnostic delay was observed. Older age at diagnosis, UGI involvement, and penetrating behavior are associated with long diagnostic delay in Korean CD patients. Moreover, diagnostic delay is associated with an increased risk of CD-related complications such as intestinal stenosis, internal fistulas, and perianal fistulas.

Diagnostics of wear in aeronautical systems

NASA Technical Reports Server (NTRS)

Wedeven, L. D.

1979-01-01

The use of appropriate diagnostic tools for aircraft oil wetted components is reviewed, noting that it can reduce direct operating costs through reduced unscheduled maintenance, particularly in helicopter engine and transmission systems where bearing failures are a significant cost factor. Engine and transmission wear modes are described, and diagnostic methods for oil and wet particle analysis, the spectrometric oil analysis program, chip detectors, ferrography, in-line oil monitor and radioactive isotope tagging are discussed, noting that they are effective over a limited range of particle sizes but compliment each other if used in parallel. Fine filtration can potentially increase time between overhauls, but reduces the effectiveness of conventional oil monitoring techniques so that alternative diagnostic techniques must be used. It is concluded that the development of a diagnostic system should be parallel and integral with the development of a mechanical system.

Benefit-risk Evaluation for Diagnostics: A Framework (BED-FRAME).

PubMed

Evans, Scott R; Pennello, Gene; Pantoja-Galicia, Norberto; Jiang, Hongyu; Hujer, Andrea M; Hujer, Kristine M; Manca, Claudia; Hill, Carol; Jacobs, Michael R; Chen, Liang; Patel, Robin; Kreiswirth, Barry N; Bonomo, Robert A

2016-09-15

The medical community needs systematic and pragmatic approaches for evaluating the benefit-risk trade-offs of diagnostics that assist in medical decision making. Benefit-Risk Evaluation of Diagnostics: A Framework (BED-FRAME) is a strategy for pragmatic evaluation of diagnostics designed to supplement traditional approaches. BED-FRAME evaluates diagnostic yield and addresses 2 key issues: (1) that diagnostic yield depends on prevalence, and (2) that different diagnostic errors carry different clinical consequences. As such, evaluating and comparing diagnostics depends on prevalence and the relative importance of potential errors. BED-FRAME provides a tool for communicating the expected clinical impact of diagnostic application and the expected trade-offs of diagnostic alternatives. BED-FRAME is a useful fundamental supplement to the standard analysis of diagnostic studies that will aid in clinical decision making. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Can and should value-based pricing be applied to molecular diagnostics?

PubMed

Garau, Martina; Towse, Adrian; Garrison, Louis; Housman, Laura; Ossa, Diego

2013-01-01

Current pricing and reimbursement systems for diagnostics are not efficient. Prices for diagnostics are often driven by administrative practices and expected production cost. The purpose of the paper is to discuss how a value-based pricing framework being used to ensure efficient use and price of medicines could also be applied to diagnostics. Diagnostics not only facilitates health gain and cost savings, but also information to guide patients' decisions on interventions and their future 'behaviors'. For value assessment processes we recommend a two-part approach. Companion diagnostics introduced at the launch of the drug should be assessed through new drug assessment processes considering a broad range of value elements and a balanced analysis of diagnostic impacts. A separate diagnostic-dedicated committee using value-based pricing principles should review other diagnostics lying outside the companion diagnostics-and-drug 'at-launch' situation.

Thermal image analysis using the serpentine method

NASA Astrophysics Data System (ADS)

Koprowski, Robert; Wilczyński, Sławomir

2018-03-01

Thermal imaging is an increasingly widespread alternative to other imaging methods. As a supplementary method in diagnostics, it can be used both statically and with dynamic temperature changes. The paper proposes a new image analysis method that allows for the acquisition of new diagnostic information as well as object segmentation. The proposed serpentine analysis uses known and new methods of image analysis and processing proposed by the authors. Affine transformations of an image and subsequent Fourier analysis provide a new diagnostic quality. The method is fully repeatable and automatic and independent of inter-individual variability in patients. The segmentation results are by 10% better than those obtained from the watershed method and the hybrid segmentation method based on the Canny detector. The first and second harmonics of serpentine analysis enable to determine the type of temperature changes in the region of interest (gradient, number of heat sources etc.). The presented serpentine method provides new quantitative information on thermal imaging and more. Since it allows for image segmentation and designation of contact points of two and more heat sources (local minimum), it can be used to support medical diagnostics in many areas of medicine.

Diagnostics of oral lichen planus based on analysis of volatile organic compounds in saliva

NASA Astrophysics Data System (ADS)

Kistenev, Yury; Borisov, Alexey; Shapovalov, Alexander; Baydik, Olga; Titarenko, Maria

2017-03-01

The ability of diagnostics of oral lichen planus (OLP) based on spectral analysis of saliva using the THz spectroscopy is presented. The study included 8 patients with clinically proven OLP. The comparison group consisted of 8 healthy volunteers. Absorption spectra of the saliva was measured using time-domain spectrometer T-spec (EXPLA) in the range 0.2-3THz and have been considered as the feature vectors of the state. The spatial distribution of the objects under study in the feature space was analyzed using principle component analysis. The groups under study were shown to separate in full. Thus, the saliva analysis by the THz spectroscopy technique can be potentially used as a method of noninvasive diagnostics of the OLP.

Noncontact techniques for diesel engine diagnostics using exhaust waveform analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gore, D.A.; Cooke, G.J.

1987-01-01

RCA Corporation's continuing efforts to develop noncontact test techniques for diesel engines have led to recent advancements in deep engine diagnostics. The U.S. Army Tank-Automotive Command (TACOM) has been working with RCA for the development of new noncontact sensors and test techniques which use these sensors in conjunction with their family of Simplified Test Equipment (STE) to perform vehicle diagnostics. The STE systems are microprocessor-based maintenance tools that assist the Army mechanic in diagnosing malfunctions in both tactical and combat vehicles. The test systems support the mechanic by providing the sophisticated signal processing capabilities necessary for a wide range ofmore » diagnostic testing including exhaust waveform analysis.« less

Development and Testing of an LED-Based Near-Infrared Sensor for Human Kidney Tumor Diagnostics

PubMed Central

Zabarylo, Urszula; Kirsanov, Dmitry; Belikova, Valeria; Ageev, Vladimir; Usenov, Iskander; Galyanin, Vladislav; Minet, Olaf; Sakharova, Tatiana; Danielyan, Georgy; Feliksberger, Elena; Artyushenko, Viacheslav

2017-01-01

Optical spectroscopy is increasingly used for cancer diagnostics. Tumor detection feasibility in human kidney samples using mid- and near-infrared (NIR) spectroscopy, fluorescence spectroscopy, and Raman spectroscopy has been reported (Artyushenko et al., Spectral fiber sensors for cancer diagnostics in vitro. In Proceedings of the European Conference on Biomedical Optics, Munich, Germany, 21–25 June 2015). In the present work, a simplification of the NIR spectroscopic analysis for cancer diagnostics was studied. The conventional high-resolution NIR spectroscopic method of kidney tumor diagnostics was replaced by a compact optical sensing device constructively represented by a set of four light-emitting diodes (LEDs) at selected wavelengths and one detecting photodiode. Two sensor prototypes were tested using 14 in vitro clinical samples of 7 different patients. Statistical data evaluation using principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) confirmed the general applicability of the LED-based sensing approach to kidney tumor detection. An additional validation of the results was performed by means of sample permutation. PMID:28825612

bcROCsurface: an R package for correcting verification bias in estimation of the ROC surface and its volume for continuous diagnostic tests.

PubMed

To Duc, Khanh

2017-11-18

Receiver operating characteristic (ROC) surface analysis is usually employed to assess the accuracy of a medical diagnostic test when there are three ordered disease status (e.g. non-diseased, intermediate, diseased). In practice, verification bias can occur due to missingness of the true disease status and can lead to a distorted conclusion on diagnostic accuracy. In such situations, bias-corrected inference tools are required. This paper introduce an R package, named bcROCsurface, which provides utility functions for verification bias-corrected ROC surface analysis. The shiny web application of the correction for verification bias in estimation of the ROC surface analysis is also developed. bcROCsurface may become an important tool for the statistical evaluation of three-class diagnostic markers in presence of verification bias. The R package, readme and example data are available on CRAN. The web interface enables users less familiar with R to evaluate the accuracy of diagnostic tests, and can be found at http://khanhtoduc.shinyapps.io/bcROCsurface_shiny/ .

Noninvasive prostate cancer screening based on serum surface-enhanced Raman spectroscopy and support vector machine

NASA Astrophysics Data System (ADS)

Li, Shaoxin; Zhang, Yanjiao; Xu, Junfa; Li, Linfang; Zeng, Qiuyao; Lin, Lin; Guo, Zhouyi; Liu, Zhiming; Xiong, Honglian; Liu, Songhao

2014-09-01

This study aims to present a noninvasive prostate cancer screening methods using serum surface-enhanced Raman scattering (SERS) and support vector machine (SVM) techniques through peripheral blood sample. SERS measurements are performed using serum samples from 93 prostate cancer patients and 68 healthy volunteers by silver nanoparticles. Three types of kernel functions including linear, polynomial, and Gaussian radial basis function (RBF) are employed to build SVM diagnostic models for classifying measured SERS spectra. For comparably evaluating the performance of SVM classification models, the standard multivariate statistic analysis method of principal component analysis (PCA) is also applied to classify the same datasets. The study results show that for the RBF kernel SVM diagnostic model, the diagnostic accuracy of 98.1% is acquired, which is superior to the results of 91.3% obtained from PCA methods. The receiver operating characteristic curve of diagnostic models further confirm above research results. This study demonstrates that label-free serum SERS analysis technique combined with SVM diagnostic algorithm has great potential for noninvasive prostate cancer screening.

Using meta-analysis to inform the design of subsequent studies of diagnostic test accuracy.

PubMed

Hinchliffe, Sally R; Crowther, Michael J; Phillips, Robert S; Sutton, Alex J

2013-06-01

An individual diagnostic accuracy study rarely provides enough information to make conclusive recommendations about the accuracy of a diagnostic test; particularly when the study is small. Meta-analysis methods provide a way of combining information from multiple studies, reducing uncertainty in the result and hopefully providing substantial evidence to underpin reliable clinical decision-making. Very few investigators consider any sample size calculations when designing a new diagnostic accuracy study. However, it is important to consider the number of subjects in a new study in order to achieve a precise measure of accuracy. Sutton et al. have suggested previously that when designing a new therapeutic trial, it could be more beneficial to consider the power of the updated meta-analysis including the new trial rather than of the new trial itself. The methodology involves simulating new studies for a range of sample sizes and estimating the power of the updated meta-analysis with each new study added. Plotting the power values against the range of sample sizes allows the clinician to make an informed decision about the sample size of a new trial. This paper extends this approach from the trial setting and applies it to diagnostic accuracy studies. Several meta-analytic models are considered including bivariate random effects meta-analysis that models the correlation between sensitivity and specificity. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

[The experience of implementation of system of quality management in the Department of Laboratory Diagnostic of the N.V. Sklifosofskiy Research Institute of Emergency Care of Moscow Health Department: a lecture].

PubMed

Zenina, L P; Godkov, M A

2013-08-01

The article presents the experience of implementation of system of quality management into the practice of multi-field laboratory of emergency medical care hospital. The analysis of laboratory errors is applied and the modes of their prevention are demonstrated. The ratings of department of laboratory diagnostic of the N. V. Sklifosofskiy research institute of emergency care in the program EQAS (USA) Monthly Clinical Chemistry from 2007 are presented. The implementation of the system of quality management of laboratory analysis into department of laboratory diagnostic made it possible to support physicians of clinical departments with reliable information. The confidence of clinicians to received results increased. The effectiveness of laboratory diagnostic increased due to lowering costs of analysis without negative impact to quality of curative process.

How to Perform a Systematic Review and Meta-analysis of Diagnostic Imaging Studies.

PubMed

Cronin, Paul; Kelly, Aine Marie; Altaee, Duaa; Foerster, Bradley; Petrou, Myria; Dwamena, Ben A

2018-05-01

A systematic review is a comprehensive search, critical evaluation, and synthesis of all the relevant studies on a specific (clinical) topic that can be applied to the evaluation of diagnostic and screening imaging studies. It can be a qualitative or a quantitative (meta-analysis) review of available literature. A meta-analysis uses statistical methods to combine and summarize the results of several studies. In this review, a 12-step approach to performing a systematic review (and meta-analysis) is outlined under the four domains: (1) Problem Formulation and Data Acquisition, (2) Quality Appraisal of Eligible Studies, (3) Statistical Analysis of Quantitative Data, and (4) Clinical Interpretation of the Evidence. This review is specifically geared toward the performance of a systematic review and meta-analysis of diagnostic test accuracy (imaging) studies. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Network meta-analysis of diagnostic test accuracy studies identifies and ranks the optimal diagnostic tests and thresholds for health care policy and decision-making.

PubMed

Owen, Rhiannon K; Cooper, Nicola J; Quinn, Terence J; Lees, Rosalind; Sutton, Alex J

2018-07-01

Network meta-analyses (NMA) have extensively been used to compare the effectiveness of multiple interventions for health care policy and decision-making. However, methods for evaluating the performance of multiple diagnostic tests are less established. In a decision-making context, we are often interested in comparing and ranking the performance of multiple diagnostic tests, at varying levels of test thresholds, in one simultaneous analysis. Motivated by an example of cognitive impairment diagnosis following stroke, we synthesized data from 13 studies assessing the efficiency of two diagnostic tests: Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA), at two test thresholds: MMSE <25/30 and <27/30, and MoCA <22/30 and <26/30. Using Markov chain Monte Carlo (MCMC) methods, we fitted a bivariate network meta-analysis model incorporating constraints on increasing test threshold, and accounting for the correlations between multiple test accuracy measures from the same study. We developed and successfully fitted a model comparing multiple tests/threshold combinations while imposing threshold constraints. Using this model, we found that MoCA at threshold <26/30 appeared to have the best true positive rate, whereas MMSE at threshold <25/30 appeared to have the best true negative rate. The combined analysis of multiple tests at multiple thresholds allowed for more rigorous comparisons between competing diagnostics tests for decision making. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

A Systematic Review and Aggregated Analysis on the Impact of Amyloid PET Brain Imaging on the Diagnosis, Diagnostic Confidence, and Management of Patients being Evaluated for Alzheimer's Disease.

PubMed

Fantoni, Enrico R; Chalkidou, Anastasia; O' Brien, John T; Farrar, Gill; Hammers, Alexander

2018-01-01

Amyloid PET (aPET) imaging could improve patient outcomes in clinical practice, but the extent of impact needs quantification. To provide an aggregated quantitative analysis of the value added by aPET in cognitively impaired subjects. Systematic literature searches were performed in Embase and Medline until January 2017. 1,531 cases over 12 studies were included (1,142 cases over seven studies in the primary analysis where aPET was the key biomarker; the remaining cases included as defined groups in the secondary analysis). Data was abstracted by consensus among two observers and assessed for bias. Clinical utility was measured by diagnostic change, diagnostic confidence, and patient management before and after aPET. Three groups were further analyzed: control patients for whom feedback of aPET scan results was delayed; aPET Appropriate Use Criteria (AUC+) cases; and patients undergoing additional FDG/CSF testing. For 1,142 cases with only aPET, 31.3% of diagnoses were revised, whereas 3.2% of diagnoses changed in the delayed aPET control group (p < 0.0001). Increased diagnostic confidence following aPET was found for 62.1% of 870 patients. Management changes with aPET were found in 72.2% of 740 cases and in 55.5% of 299 cases in the control group (p < 0.0001). The diagnostic value of aPET in AUC+ patients or when FDG/CSF were additionally available did not substantially differ from the value of aPET alone in the wider population. Amyloid PET contributed to diagnostic revision in almost a third of cases and demonstrated value in increasing diagnostic confidence and refining management plans.

Cost-effectiveness analysis of acute kidney injury biomarkers in pediatric cardiac surgery.

PubMed

Petrovic, Stanislava; Bogavac-Stanojevic, Natasa; Lakic, Dragana; Peco-Antic, Amira; Vulicevic, Irena; Ivanisevic, Ivana; Kotur-Stevuljevic, Jelena; Jelic-Ivanovic, Zorana

2015-01-01

Acute kidney injury (AKI) is significant problem in children with congenital heart disease (CHD) who undergo cardiac surgery. The economic impact of a biomarker-based diagnostic strategy for AKI in pediatric populations undergoing CHD surgery is unknown. The aim of this study was to perform the cost effectiveness analysis of using serum cystatin C (sCysC), urine neutrophil gelatinase-associated lipocalin (uNGAL) and urine liver fatty acid-binding protein (uL-FABP) for the diagnosis of AKI in children after cardiac surgery compared with current diagnostic method (monitoring of serum creatinine (sCr) level). We developed a decision analytical model to estimate incremental cost-effectiveness of different biomarker-based diagnostic strategies compared to current diagnostic strategy. The Markov model was created to compare the lifetime cost associated with using of sCysC, uNGAL, uL-FABP with monitoring of sCr level for the diagnosis of AKI. The utility measurement included in the analysis was quality-adjusted life years (QALY). The results of the analysis are presented as the incremental cost-effectiveness ratio (ICER). Analysed biomarker-based diagnostic strategies for AKI were cost-effective compared to current diagnostic method. However, uNGAL and sCys C strategies yielded higher costs and lower effectiveness compared to uL-FABP strategy. uL-FABP added 1.43 QALY compared to current diagnostic method at an additional cost of $8521.87 per patient. Therefore, ICER for uL-FABP compared to sCr was $5959.35/QALY. Our results suggest that the use of uL-FABP would represent cost effective strategy for early diagnosis of AKI in children after cardiac surgery.

A Systematic Review and Aggregated Analysis on the Impact of Amyloid PET Brain Imaging on the Diagnosis, Diagnostic Confidence, and Management of Patients being Evaluated for Alzheimer’s Disease

PubMed Central

Fantoni, Enrico R.; Chalkidou, Anastasia; O’ Brien, John T.; Farrar, Gill; Hammers, Alexander

2018-01-01

Background: Amyloid PET (aPET) imaging could improve patient outcomes in clinical practice, but the extent of impact needs quantification. Objective: To provide an aggregated quantitative analysis of the value added by aPET in cognitively impaired subjects. Methods: Systematic literature searches were performed in Embase and Medline until January 2017. 1,531 cases over 12 studies were included (1,142 cases over seven studies in the primary analysis where aPET was the key biomarker; the remaining cases included as defined groups in the secondary analysis). Data was abstracted by consensus among two observers and assessed for bias. Clinical utility was measured by diagnostic change, diagnostic confidence, and patient management before and after aPET. Three groups were further analyzed: control patients for whom feedback of aPET scan results was delayed; aPET Appropriate Use Criteria (AUC+) cases; and patients undergoing additional FDG/CSF testing. Results: For 1,142 cases with only aPET, 31.3% of diagnoses were revised, whereas 3.2% of diagnoses changed in the delayed aPET control group (p < 0.0001). Increased diagnostic confidence following aPET was found for 62.1% of 870 patients. Management changes with aPET were found in 72.2% of 740 cases and in 55.5% of 299 cases in the control group (p < 0.0001). The diagnostic value of aPET in AUC+ patients or when FDG/CSF were additionally available did not substantially differ from the value of aPET alone in the wider population. Conclusions: Amyloid PET contributed to diagnostic revision in almost a third of cases and demonstrated value in increasing diagnostic confidence and refining management plans. PMID:29689725

Diagnostic Performance of Mammographic Texture Analysis in the Differential Diagnosis of Benign and Malignant Breast Tumors.

PubMed

Li, Zhiming; Yu, Lan; Wang, Xin; Yu, Haiyang; Gao, Yuanxiang; Ren, Yande; Wang, Gang; Zhou, Xiaoming

2017-11-09

The purpose of this study was to investigate the diagnostic performance of mammographic texture analysis in the differential diagnosis of benign and malignant breast tumors. Digital mammography images were obtained from the Picture Archiving and Communication System at our institute. Texture features of mammographic images were calculated. Mann-Whitney U test was used to identify differences between the benign and malignant group. The receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic performance of texture features. Significant differences of texture features of histogram, gray-level co-occurrence matrix (GLCM) and run length matrix (RLM) were found between the benign and malignant breast group (P < .05). The area under the ROC (AUROC) of histogram, GLCM, and RLM were 0.800, 0.787, and 0.761, with no differences between them (P > .05). The AUROCs of imaging-based diagnosis, texture analysis, and imaging-based diagnosis combined with texture analysis were 0.873, 0.863, and 0.961, respectively. When imaging-based diagnosis was combined with texture analysis, the AUROC was higher than that of imaging-based diagnosis or texture analysis (P < .05). Mammographic texture analysis is a reliable technique for differential diagnosis of benign and malignant breast tumors. Furthermore, the combination of imaging-based diagnosis and texture analysis can significantly improve diagnostic performance. Copyright © 2017 Elsevier Inc. All rights reserved.

Diagnostic value of FIB-4 for liver fibrosis in patients with hepatitis B: a meta-analysis of diagnostic test.

PubMed

Yin, Zhi; Zou, Jin; Li, Qiongxuan; Chen, Lizhang

2017-04-04

This study is aimed at evaluating the diagnostic value of FIB-4 for liver fibrosis in patients with hepatitis B through a meta-analysis of diagnostic test. We conducted a comprehensive search in the Pubmed, Embase, Web of Science, and Chinese National Knowledge Infrastructure before October 31, 2016. Stata 14.0 software was used for calculation and statistical analyses. We used the sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR), diagnostic odds ratio (DOR) and 95% confidence intervals (CIs) to evaluate the diagnostic value of FIB-4 for liver fibrosis in patients with hepatitis B. Twenty-six studies were included in the final analyses, with a total of 8274 individuals. The pooled parameters are calculated from all studies: sensitivity of 0.69 (95%CI:0.63-0.75), specificity of 0.81 (95%CI: 0.73-0.87), PLR of 3.63 (95%CI:2.66-4.94), NLR of 0.38 (95%CI:0.32-0.44), DOR of 9.57 (95%CI: 6.67-13.74), and area under the curve (AUC) of 0.80 (95%CI: 0.76-0.83). We also conducted subgroup based on the range of cut-off values. Results from subgroup analysis showed that cut-off was the source of heterogeneity in the present study. The sensitivity and specificity of cut-off>2 were 0.69 and 0.95 with the AUC of 0.90 (95%CI: 0.87-0.92). The overall diagnostic value of FIB-4 is not very high for liver fibrosis in patients with hepatitis B. However, the diagnostic value is affected by the cut-off value. FIB-4 has relatively high diagnostic value for detecting liver fibrosis in patients with hepatitis B when the diagnostic threshold value is more than 2.0.

Diagnostic evaluation of distributed physically based model at the REW scale (THREW) using rainfall-runoff event analysis

NASA Astrophysics Data System (ADS)

Tian, F.; Sivapalan, M.; Li, H.; Hu, H.

2007-12-01

The importance of diagnostic analysis of hydrological models is increasingly recognized by the scientific community (M. Sivapalan, et al., 2003; H. V. Gupta, et al., 2007). Model diagnosis refers to model structures and parameters being identified not only by statistical comparison of system state variables and outputs but also by process understanding in a specific watershed. Process understanding can be gained by the analysis of observational data and model results at the specific watershed as well as through regionalization. Although remote sensing technology can provide valuable data about the inputs, state variables, and outputs of the hydrological system, observational rainfall-runoff data still constitute the most accurate, reliable, direct, and thus a basic component of hydrology related database. One critical question in model diagnostic analysis is, therefore, what signature characteristic can we extract from rainfall and runoff data. To this date only a few studies have focused on this question, such as Merz et al. (2006) and Lana-Renault et al. (2007), still none of these studies related event analysis with model diagnosis in an explicit, rigorous, and systematic manner. Our work focuses on the identification of the dominant runoff generation mechanisms from event analysis of rainfall-runoff data, including correlation analysis and analysis of timing pattern. The correlation analysis involves the identification of the complex relationship among rainfall depth, intensity, runoff coefficient, and antecedent conditions, and the timing pattern analysis aims to identify the clustering pattern of runoff events in relation to the patterns of rainfall events. Our diagnostic analysis illustrates the changing pattern of runoff generation mechanisms in the DMIP2 test watersheds located in Oklahoma region, which is also well recognized by numerical simulations based on TsingHua Representative Elementary Watershed (THREW) model. The result suggests the usefulness of rainfall-runoff event analysis for model development as well as model diagnostics.

Diagnostic value of tumor markers for lung adenocarcinoma-associated malignant pleural effusion: a validation study and meta-analysis.

PubMed

Feng, Mei; Zhu, Jing; Liang, Liqun; Zeng, Ni; Wu, Yanqiu; Wan, Chun; Shen, Yongchun; Wen, Fuqiang

2017-04-01

Pleural effusion is one of the most common complications of lung adenocarcinoma and is diagnostically challenging. This study aimed to investigate the diagnostic performance of carcinoembryonic antigen (CEA), cytokeratin fragment (CYFRA) 21-1, and cancer antigen (CA) 19-9 for lung adenocarcinoma-associated malignant pleural effusion (MPE) through a validation study and meta-analysis. Pleural effusion samples were collected from 81 lung adenocarcinoma-associated MPEs and 96 benign pleural effusions. CEA, CYFRA 21-1, and CA19-9 were measured by electrochemiluminescence immunoassay. The capacity of tumor markers was assessed with receiver operating characteristic curve analyses and the area under the curve (AUC) was calculated. Standard methods for meta-analysis of diagnostic studies were used to summarize the diagnostic performance of CEA, CYFRA 21-1, and CA19-9 for lung adenocarcinoma-associated MPE. The pleural levels of CEA, CYFRA 21-1, and CA19-9 were significantly increased in lung adenocarcinoma-associated MPE compared to benign pleural effusion. The cut-off points for CEA, CYFRA 21-1, and CA19-9 were optimally set at 4.55 ng/ml, 43.10 μg/ml, and 12.89 U/ml, and corresponding AUCs were 0.93, 0.85, and 0.81, respectively. The combination of CEA, CYFRA 21-1, and CA19-9 increased the sensitivity to 95.06%, with an AUC of 0.95. Eight studies were included in this meta-analysis. CEA showed the best diagnostic performance with pooled sensitivity, specificity, positive/negative likelihood ratio, and diagnostic odds ratio of 0.75, 0.96, 16.01, 0.23, and 81.49, respectively. The AUC was 0.93. CEA, CYFRA 21-1, and CA19-9 play a role in the diagnosis of lung adenocarcinoma-associated MPE. The combination of these tumor markers increases the diagnostic accuracy.

An update on the use of cerebrospinal fluid analysis as a diagnostic tool in multiple sclerosis.

PubMed

Gastaldi, Matteo; Zardini, Elisabetta; Franciotta, Diego

2017-01-01

Intrathecal B-lymphocyte activation is a hallmark of multiple sclerosis (MS), a multi-factorial inflammatory-demyelinating disease of the central nervous system. Such activation has a counterpart in the cerebrospinal fluid (CSF) oligoclonal IgG bands (OCB), whose diagnostic role in MS has been downgraded within the current McDonald's criteria. With a theoretico-practical approach, the authors review the physiopathological basis of the CSF dynamics, and the state-of-the-art of routine CSF analysis and CSF biomarkers in MS. Areas covered: The authors discuss pros and cons of CSF analysis, including critical evaluations of both well-established, and promising diagnostic and prognostic laboratory tools. New acquisitions on the CSF and cerebral interstitial fluid dynamics are also presented. The authors searched the PubMed database for English-language articles reported between January 2010 and June 2016, using the key words 'multiple sclerosis', 'cerebrospinal fluid', 'oligoclonal bands'. Reference lists of relevant articles were scanned for additional studies. Expert commentary: The availability of performing high-quality, routine CSF tests in specialized laboratories, the emerging potential of novel CSF biomarkers, and the trend for early treatments should induce a reappraisal of CSF analysis for diagnostic and prognostic purposes in MS. Further procedural and methodological improvements seem to be necessary in both research and translational diagnostic CSF settings.

Improving utility of brain tumor confocal laser endomicroscopy: objective value assessment and diagnostic frame detection with convolutional neural networks

NASA Astrophysics Data System (ADS)

Izadyyazdanabadi, Mohammadhassan; Belykh, Evgenii; Martirosyan, Nikolay; Eschbacher, Jennifer; Nakaji, Peter; Yang, Yezhou; Preul, Mark C.

2017-03-01

Confocal laser endomicroscopy (CLE), although capable of obtaining images at cellular resolution during surgery of brain tumors in real time, creates as many non-diagnostic as diagnostic images. Non-useful images are often distorted due to relative motion between probe and brain or blood artifacts. Many images, however, simply lack diagnostic features immediately informative to the physician. Examining all the hundreds or thousands of images from a single case to discriminate diagnostic images from nondiagnostic ones can be tedious. Providing a real time diagnostic value assessment of images (fast enough to be used during the surgical acquisition process and accurate enough for the pathologist to rely on) to automatically detect diagnostic frames would streamline the analysis of images and filter useful images for the pathologist/surgeon. We sought to automatically classify images as diagnostic or non-diagnostic. AlexNet, a deep-learning architecture, was used in a 4-fold cross validation manner. Our dataset includes 16,795 images (8572 nondiagnostic and 8223 diagnostic) from 74 CLE-aided brain tumor surgery patients. The ground truth for all the images is provided by the pathologist. Average model accuracy on test data was 91% overall (90.79 % accuracy, 90.94 % sensitivity and 90.87 % specificity). To evaluate the model reliability we also performed receiver operating characteristic (ROC) analysis yielding 0.958 average for area under ROC curve (AUC). These results demonstrate that a deeply trained AlexNet network can achieve a model that reliably and quickly recognizes diagnostic CLE images.

Quantitative Myocardial Perfusion Imaging Versus Visual Analysis in Diagnosing Myocardial Ischemia: A CE-MARC Substudy.

PubMed

Biglands, John D; Ibraheem, Montasir; Magee, Derek R; Radjenovic, Aleksandra; Plein, Sven; Greenwood, John P

2018-05-01

This study sought to compare the diagnostic accuracy of visual and quantitative analyses of myocardial perfusion cardiovascular magnetic resonance against a reference standard of quantitative coronary angiography. Visual analysis of perfusion cardiovascular magnetic resonance studies for assessing myocardial perfusion has been shown to have high diagnostic accuracy for coronary artery disease. However, only a few small studies have assessed the diagnostic accuracy of quantitative myocardial perfusion. This retrospective study included 128 patients randomly selected from the CE-MARC (Clinical Evaluation of Magnetic Resonance Imaging in Coronary Heart Disease) study population such that the distribution of risk factors and disease status was proportionate to the full population. Visual analysis results of cardiovascular magnetic resonance perfusion images, by consensus of 2 expert readers, were taken from the original study reports. Quantitative myocardial blood flow estimates were obtained using Fermi-constrained deconvolution. The reference standard for myocardial ischemia was a quantitative coronary x-ray angiogram stenosis severity of ≥70% diameter in any coronary artery of >2 mm diameter, or ≥50% in the left main stem. Diagnostic performance was calculated using receiver-operating characteristic curve analysis. The area under the curve for visual analysis was 0.88 (95% confidence interval: 0.81 to 0.95) with a sensitivity of 81.0% (95% confidence interval: 69.1% to 92.8%) and specificity of 86.0% (95% confidence interval: 78.7% to 93.4%). For quantitative stress myocardial blood flow the area under the curve was 0.89 (95% confidence interval: 0.83 to 0.96) with a sensitivity of 87.5% (95% confidence interval: 77.3% to 97.7%) and specificity of 84.5% (95% confidence interval: 76.8% to 92.3%). There was no statistically significant difference between the diagnostic performance of quantitative and visual analyses (p = 0.72). Incorporating rest myocardial blood flow values to generate a myocardial perfusion reserve did not significantly increase the quantitative analysis area under the curve (p = 0.79). Quantitative perfusion has a high diagnostic accuracy for detecting coronary artery disease but is not superior to visual analysis. The incorporation of rest perfusion imaging does not improve diagnostic accuracy in quantitative perfusion analysis. Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Role of Arrival Time Difference Between Lesions and Lung Tissue on Contrast-Enhanced Sonography in the Differential Diagnosis of Subpleural Pulmonary Lesions.

PubMed

Bai, Jing; Yang, Wei; Wang, Song; Guan, Rui-Hong; Zhang, Hui; Fu, Jing-Jing; Wu, Wei; Yan, Kun

2016-07-01

The purpose of this study was to explore the diagnostic value of the arrival time difference between lesions and surrounding lung tissue on contrast-enhanced sonography of subpleural pulmonary lesions. A total of 110 patients with subpleural pulmonary lesions who underwent both conventional and contrast-enhanced sonography and had a definite diagnosis were enrolled. After contrast agent injection, the arrival times in the lesion, lung, and chest wall were recorded. The arrival time differences between various tissues were also calculated. Statistical analysis showed a significant difference in the lesion arrival time, the arrival time difference between the lesion and lung, and the arrival time difference between the chest wall and lesion (all P < .001) for benign and malignant lesions. Receiver operating characteristic curve analysis revealed that the optimal diagnostic criterion was the arrival time difference between the lesion and lung, and that the best cutoff point was 2.5 seconds (later arrival signified malignancy). This new diagnostic criterion showed superior diagnostic accuracy (97.1%) compared to conventional diagnostic criteria. The individualized diagnostic method based on an arrival time comparison using contrast-enhanced sonography had high diagnostic accuracy (97.1%) with good feasibility and could provide useful diagnostic information for subpleural pulmonary lesions.

Likelihood-Based Clustering of Meta-Analytic SROC Curves

ERIC Educational Resources Information Center

Holling, Heinz; Bohning, Walailuck; Bohning, Dankmar

2012-01-01

Meta-analysis of diagnostic studies experience the common problem that different studies might not be comparable since they have been using a different cut-off value for the continuous or ordered categorical diagnostic test value defining different regions for which the diagnostic test is defined to be positive. Hence specificities and…

Problem Representation, Background Evidence, Analysis, Recommendation: An Oral Case Presentation Tool to Promote Diagnostic Reasoning.

PubMed

Carter, Cristina; Akar-Ghibril, Nicole; Sestokas, Jeff; Dixon, Gabrina; Bradford, Wilhelmina; Ottolini, Mary

2018-03-01

Oral case presentations provide an opportunity for trainees to communicate diagnostic reasoning at the bedside. However, few tools exist to enable faculty to provide effective feedback. We developed a tool to assess diagnostic reasoning and communication during oral case presentations. Published by Elsevier Inc.

Clinical Factors and Disease Course Related to Diagnostic Delay in Korean Crohn’s Disease Patients: Results from the CONNECT Study

PubMed Central

Moon, Chang Mo; Jung, Sung-Ae; Kim, Seong-Eun; Song, Hyun Joo; Jung, Yunho; Ye, Byong Duk; Cheon, Jae Hee; Kim, You Sun; Kim, Young-Ho; Kim, Joo Sung; Han, Dong Soo

2015-01-01

Diagnostic delay frequently occurs in Crohn’s disease (CD) patients because of diagnostic limitations. However, diagnostic delay and its related factors remain poorly defined. Therefore, we aimed to identify the predictors associated with diagnostic delay and to evaluate the impact of diagnostic delay on clinical course in a Korean CD patient cohort. We performed a multicenter retrospective analysis of 1,047 CD patients registered in the Crohn’s Disease Clinical Network and Cohort study in Korea. The mean interval of diagnostic delay was 16.0 ± 33.1 months. Multivariate analysis showed that older age at diagnosis (≥40 years) (p = 0.014), concomitant upper gastrointestinal (UGI) disease (p = 0.012) and penetrating disease behavior at diagnosis (p = 0.001) were positively associated with long diagnostic delay (≥18 months). During the longitudinal follow-up, long diagnostic delay was independently predictive of further development of intestinal stenosis (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.07–1.93; p = 0.017), internal fistulas (HR, 1.62; 95% CI, 1.12–2.33; p = 0.011), and perianal fistulas (HR, 1.38; 95% CI, 1.06–1.80; p = 0.016). However, as for the risk of abscess formation, bowel perforation, and CD-related abdominal surgery, no significant association with diagnostic delay was observed. Older age at diagnosis, UGI involvement, and penetrating behavior are associated with long diagnostic delay in Korean CD patients. Moreover, diagnostic delay is associated with an increased risk of CD-related complications such as intestinal stenosis, internal fistulas, and perianal fistulas. PMID:26647084

Wavenumber selection based analysis in Raman spectroscopy improves skin cancer diagnostic specificity at high sensitivity levels (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhao, Jianhua; Zeng, Haishan; Kalia, Sunil; Lui, Harvey

2017-02-01

Background: Raman spectroscopy is a non-invasive optical technique which can measure molecular vibrational modes within tissue. A large-scale clinical study (n = 518) has demonstrated that real-time Raman spectroscopy could distinguish malignant from benign skin lesions with good diagnostic accuracy; this was validated by a follow-up independent study (n = 127). Objective: Most of the previous diagnostic algorithms have typically been based on analyzing the full band of the Raman spectra, either in the fingerprint or high wavenumber regions. Our objective in this presentation is to explore wavenumber selection based analysis in Raman spectroscopy for skin cancer diagnosis. Methods: A wavenumber selection algorithm was implemented using variably-sized wavenumber windows, which were determined by the correlation coefficient between wavenumbers. Wavenumber windows were chosen based on accumulated frequency from leave-one-out cross-validated stepwise regression or least and shrinkage selection operator (LASSO). The diagnostic algorithms were then generated from the selected wavenumber windows using multivariate statistical analyses, including principal component and general discriminant analysis (PC-GDA) and partial least squares (PLS). A total cohort of 645 confirmed lesions from 573 patients encompassing skin cancers, precancers and benign skin lesions were included. Lesion measurements were divided into training cohort (n = 518) and testing cohort (n = 127) according to the measurement time. Result: The area under the receiver operating characteristic curve (ROC) improved from 0.861-0.891 to 0.891-0.911 and the diagnostic specificity for sensitivity levels of 0.99-0.90 increased respectively from 0.17-0.65 to 0.20-0.75 by selecting specific wavenumber windows for analysis. Conclusion: Wavenumber selection based analysis in Raman spectroscopy improves skin cancer diagnostic specificity at high sensitivity levels.

Potential diagnostic value of serum p53 antibody for detecting colorectal cancer: A meta-analysis.

PubMed

Meng, Rongqin; Wang, Yang; He, Liang; He, Yuanqing; Du, Zedong

2018-04-01

Numerous studies have assessed the diagnostic value of serum p53 (s-p53) antibody in patients with colorectal cancer (CRC); however, results remain controversial. The present study aimed to comprehensively and quantitatively summarize the potential diagnostic value of s-p53 antibody in CRC. The present study utilized databases, including PubMed and EmBase, systematically regarding s-p53 antibody diagnosis in CRC, accessed on and prior to 31 July 2016. The quality of all the included studies was assessed using quality assessment of studies of diagnostic accuracy (QUADAS). The result of pooled sensitivity, pooled specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were analyzed and compared with overall accuracy measures using diagnostic odds ratios (DORs) and area under the curve (AUC) analysis. Publication bias and heterogeneity were also assessed. A total of 11 trials that enrolled a combined 3,392 participants were included in the meta-analysis. Approximately 72.73% (8/11) of the included studies were of high quality (QUADAS score >7), and all were retrospective case-control studies. The pooled sensitivity was 0.19 [95% confidence interval (CI), 0.18-0.21] and pooled specificity was 0.93 (95% CI, 0.92-0.94). Results also demonstrated a PLR of 4.56 (95% CI, 3.27-6.34), NLR of 0.78 (95% CI, 0.71-0.85) and DOR of 6.70 (95% CI, 4.59-9.76). The symmetrical summary receiver operating characteristic curve was 0.73. Furthermore, no evidence of publication bias or heterogeneity was observed in the meta-analysis. Meta-analysis data indicated that s-p53 antibody possesses potential diagnostic value for CRC. However, discrimination power was somewhat limited due to the low sensitivity.

A tutorial on the use of ROC analysis for computer-aided diagnostic systems.

PubMed

Scheipers, Ulrich; Perrey, Christian; Siebers, Stefan; Hansen, Christian; Ermert, Helmut

2005-07-01

The application of the receiver operating characteristic (ROC) curve for computer-aided diagnostic systems is reviewed. A statistical framework is presented and different methods of evaluating the classification performance of computer-aided diagnostic systems, and, in particular, systems for ultrasonic tissue characterization, are derived. Most classifiers that are used today are dependent on a separation threshold, which can be chosen freely in many cases. The separation threshold separates the range of output values of the classification system into different target groups, thus conducting the actual classification process. In the first part of this paper, threshold specific performance measures, e.g., sensitivity and specificity, are presented. In the second part, a threshold-independent performance measure, the area under the ROC curve, is reviewed. Only the use of separation threshold-independent performance measures provides classification results that are overall representative for computer-aided diagnostic systems. The following text was motivated by the lack of a complete and definite discussion of the underlying subject in available textbooks, references and publications. Most manuscripts published so far address the theme of performance evaluation using ROC analysis in a manner too general to be practical for everyday use in the development of computer-aided diagnostic systems. Nowadays, the user of computer-aided diagnostic systems typically handles huge amounts of numerical data, not always distributed normally. Many assumptions made in more or less theoretical works on ROC analysis are no longer valid for real-life data. The paper aims at closing the gap between theoretical works and real-life data. The review provides the interested scientist with information needed to conduct ROC analysis and to integrate algorithms performing ROC analysis into classification systems while understanding the basic principles of classification.

A Review of Diagnostic Techniques for ISHM Applications

NASA Technical Reports Server (NTRS)

Patterson-Hine, Ann; Biswas, Gautam; Aaseng, Gordon; Narasimhan, Sriam; Pattipati, Krishna

2005-01-01

System diagnosis is an integral part of any Integrated System Health Management application. Diagnostic applications make use of system information from the design phase, such as safety and mission assurance analysis, failure modes and effects analysis, hazards analysis, functional models, fault propagation models, and testability analysis. In modern process control and equipment monitoring systems, topological and analytic , models of the nominal system, derived from design documents, are also employed for fault isolation and identification. Depending on the complexity of the monitored signals from the physical system, diagnostic applications may involve straightforward trending and feature extraction techniques to retrieve the parameters of importance from the sensor streams. They also may involve very complex analysis routines, such as signal processing, learning or classification methods to derive the parameters of importance to diagnosis. The process that is used to diagnose anomalous conditions from monitored system signals varies widely across the different approaches to system diagnosis. Rule-based expert systems, case-based reasoning systems, model-based reasoning systems, learning systems, and probabilistic reasoning systems are examples of the many diverse approaches ta diagnostic reasoning. Many engineering disciplines have specific approaches to modeling, monitoring and diagnosing anomalous conditions. Therefore, there is no "one-size-fits-all" approach to building diagnostic and health monitoring capabilities for a system. For instance, the conventional approaches to diagnosing failures in rotorcraft applications are very different from those used in communications systems. Further, online and offline automated diagnostic applications are integrated into an operations framework with flight crews, flight controllers and maintenance teams. While the emphasis of this paper is automation of health management functions, striking the correct balance between automated and human-performed tasks is a vital concern.

Image quality enhancement for skin cancer optical diagnostics

NASA Astrophysics Data System (ADS)

Bliznuks, Dmitrijs; Kuzmina, Ilona; Bolocko, Katrina; Lihachev, Alexey

2017-12-01

The research presents image quality analysis and enhancement proposals in biophotonic area. The sources of image problems are reviewed and analyzed. The problems with most impact in biophotonic area are analyzed in terms of specific biophotonic task - skin cancer diagnostics. The results point out that main problem for skin cancer analysis is the skin illumination problems. Since it is often not possible to prevent illumination problems, the paper proposes image post processing algorithm - low frequency filtering. Practical results show diagnostic results improvement after using proposed filter. Along that, filter do not reduces diagnostic results' quality for images without illumination defects. Current filtering algorithm requires empirical tuning of filter parameters. Further work needed to test the algorithm in other biophotonic applications and propose automatic filter parameter selection.

Diagnostic performance of traditional hepatobiliary biomarkers of drug-induced liver injury in the rat.

PubMed

Ennulat, Daniela; Magid-Slav, Michal; Rehm, Sabine; Tatsuoka, Kay S

2010-08-01

Nonclinical studies provide the opportunity to anchor biochemical with morphologic findings; however, liver injury is often complex and heterogeneous, confounding the ability to relate biochemical changes with specific patterns of injury. The aim of the current study was to compare diagnostic performance of hepatobiliary markers for specific manifestations of drug-induced liver injury in rat using data collected in a recent hepatic toxicogenomics initiative in which rats (n = 3205) were given 182 different treatments for 4 or 14 days. Diagnostic accuracy of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (Tbili), serum bile acids (SBA), alkaline phosphatase (ALP), gamma glutamyl transferase (GGT), total cholesterol (Chol), and triglycerides (Trig) was evaluated for specific types of liver histopathology by Receiver Operating Characteristic (ROC) analysis. To assess the relationship between biochemical and morphologic changes in the absence of hepatocellular necrosis, a second ROC analysis was performed on a subset of rats (n = 2504) given treatments (n = 152) that did not cause hepatocellular necrosis. In the initial analysis, ALT, AST, Tbili, and SBA had the greatest diagnostic utility for manifestations of hepatocellular necrosis and biliary injury, with comparable magnitude of area under the ROC curve and serum hepatobiliary marker changes for both. In the absence of hepatocellular necrosis, ALT increases were observed with biochemical or morphologic evidence of cholestasis. In both analyses, diagnostic utility of ALP and GGT for biliary injury was limited; however, ALP had modest diagnostic value for peroxisome proliferation, and ALT, AST, and total Chol had moderate diagnostic utility for phospholipidosis. None of the eight markers evaluated had diagnostic value for manifestations of hypertrophy, cytoplasmic rarefaction, inflammation, or lipidosis.

Impact of point-of-care diagnostics on maternal outcomes in HIV-infected women: systematic review and meta-analysis protocol

PubMed Central

Mashamba-Thompson, T P; Sartorius, B; Thabane, L; Shi, C X; Drain, P K

2016-01-01

Introduction Studies indicate substandard diagnostic care, delayed and missed diagnosis as some of the contributing factors to maternal mortality. The clinical impact of point-of-care (POC) diagnostics has been shown in the monitoring and treatment of a variety of infectious diseases, including HIV/AIDS and tuberculosis. The objective of this systematic review is to investigate the impact of POC diagnostics on maternal outcomes for HIV-infected women. Methods We will conduct a systematic review to evaluate the impact of POC diagnostics for improving desired healthcare outcomes for HIV-infected women. The search strategy will involve electronic databases including: Cochrane Infectious Disease Group Specialised Register; Cochrane Central Register of Control Trials, published in The Cochrane Library; PubMed; EBSCOhost and LILACS. The studies will be mapped in 2 stages: stage 1 will map studies descriptively by focus and method; stage 2 will involve additional inclusion criteria, quality assessment and data extraction undertaken by 2 reviewers in parallel. Evidence will be synthesised using relevant systematic research tools: meta-analysis and subgroup analysis will be conducted using RevMan and Stata 13 will be used for meta-regressions. We will follow recommendations described in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and the Cochrane Handbook for Intervention Reviews. Ethics and dissemination We anticipate finding a large number of studies on POC diagnostic interventions on maternal outcomes in HIV-infected women, which, once summarised, will be useful to guide future diagnostic interventions. The protocol for the systematic review has been registered in PROSPERO. The study will be disseminated electronically and in print. It will also be presented to conferences related to HIV/AIDS, POC diagnostics and maternal health. Trial registration number PROSPERO CRD42014015439. PMID:26817633

Diagnostic accuracy of ultrasonography, MRI and MR arthrography in the characterisation of rotator cuff disorders: a systematic review and meta-analysis

PubMed Central

Roy, Jean-Sébastien; Braën, Caroline; Leblond, Jean; Desmeules, François; Dionne, Clermont E; MacDermid, Joy C; Bureau, Nathalie J; Frémont, Pierre

2015-01-01

Background Different diagnostic imaging modalities, such as ultrasonography (US), MRI, MR arthrography (MRA) are commonly used for the characterisation of rotator cuff (RC) disorders. Since the most recent systematic reviews on medical imaging, multiple diagnostic studies have been published, most using more advanced technological characteristics. The first objective was to perform a meta-analysis on the diagnostic accuracy of medical imaging for characterisation of RC disorders. Since US is used at the point of care in environments such as sports medicine, a secondary analysis assessed accuracy by radiologists and non-radiologists. Methods A systematic search in three databases was conducted. Two raters performed data extraction and evaluation of risk of bias independently, and agreement was achieved by consensus. Hierarchical summary receiver-operating characteristic package was used to calculate pooled estimates of included diagnostic studies. Results Diagnostic accuracy of US, MRI and MRA in the characterisation of full-thickness RC tears was high with overall estimates of sensitivity and specificity over 0.90. As for partial RC tears and tendinopathy, overall estimates of specificity were also high (>0.90), while sensitivity was lower (0.67–0.83). Diagnostic accuracy of US was similar whether a trained radiologist, sonographer or orthopaedist performed it. Conclusions Our results show the diagnostic accuracy of US, MRI and MRA in the characterisation of full-thickness RC tears. Since full thickness tear constitutes a key consideration for surgical repair, this is an important characteristic when selecting an imaging modality for RC disorder. When considering accuracy, cost, and safety, US is the best option. PMID:25677796

Fusing Symbolic and Numerical Diagnostic Computations

NASA Technical Reports Server (NTRS)

James, Mark

2007-01-01

X-2000 Anomaly Detection Language denotes a developmental computing language, and the software that establishes and utilizes the language, for fusing two diagnostic computer programs, one implementing a numerical analysis method, the other implementing a symbolic analysis method into a unified event-based decision analysis software system for realtime detection of events (e.g., failures) in a spacecraft, aircraft, or other complex engineering system. The numerical analysis method is performed by beacon-based exception analysis for multi-missions (BEAMs), which has been discussed in several previous NASA Tech Briefs articles. The symbolic analysis method is, more specifically, an artificial-intelligence method of the knowledge-based, inference engine type, and its implementation is exemplified by the Spacecraft Health Inference Engine (SHINE) software. The goal in developing the capability to fuse numerical and symbolic diagnostic components is to increase the depth of analysis beyond that previously attainable, thereby increasing the degree of confidence in the computed results. In practical terms, the sought improvement is to enable detection of all or most events, with no or few false alarms.

Global foot-and-mouth disease research update and gap analysis: 4 - diagnostics

USDA-ARS?s Scientific Manuscript database

In 2014, the Global Foot-And-Mouth Disease Research Alliance (GFRA) conducted a gap analysis of FMD research. Published as a series of seven papers, in this paper, we report updated findings in the field of diagnostics. The paper consists of the following four sections: 1. Research priorities identi...

The Application of Strength of Association Statistics to the Item Analysis of an In-Training Examination in Diagnostic Radiology.

ERIC Educational Resources Information Center

Diamond, James J.; McCormick, Janet

1986-01-01

Using item responses from an in-training examination in diagnostic radiology, the application of a strength of association statistic to the general problem of item analysis is illustrated. Criteria for item selection, general issues of reliability, and error of measurement are discussed. (Author/LMO)

An Energy Analysis of the Pseudo Wigner-Ville Distribution in Support of Machinery Monitoring and Diagnostics

DTIC Science & Technology

1992-06-01

AD-A256 202 NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS - _ ’. AN ENERGY ANALYSIS OF THE PSEUDO WIGNER - VILLE DISTRIBUTION IN SUPPORT OF...NO 11 TITLE (Include Security Classification) AN ENERGY ANALYSIS OF THE PSEUDO WIGNER - VILLE DISTRIBUTION IN SUPPORT OF MACHINERY MONITORING AND...block number) FIELD GROUP SUB-GROUP machinery monitoring, transient, pseudo wigner - ville distribution , machinery diagnostics 19 ABSTRACT (Continue on

Comparison of the diagnostic ability of blue laser imaging magnification versus pit pattern analysis for colorectal polyps.

PubMed

Nakano, Arihiro; Hirooka, Yoshiki; Yamamura, Takeshi; Watanabe, Osamu; Nakamura, Masanao; Funasaka, Kohei; Ohno, Eizaburo; Kawashima, Hiroki; Miyahara, Ryoji; Goto, Hidemi

2017-04-01

Background and study aims  There have been few evaluations of the diagnostic ability of new narrow band light observation blue laser imaging (BLI). The present prospective study compared the diagnostic ability of BLI magnification and pit pattern analysis for colorectal polyps. Patients and methods  We collected lesions prospectively, and the analysis of images was made by two endoscopists, retrospectively. A total of 799 colorectal polyps were examined by BLI magnification and pit pattern analysis at Nagoya University Hospital. The Hiroshima narrow-band imaging classification was used for BLI. Differentiation of neoplastic from non-neoplastic lesions and diagnosis of deeply invasive submucosal cancer (dSM) were compared between BLI magnification and pit pattern analysis. Type C2 in the Hiroshima classification was evaluated separately, because application of this category as an index of the depth of cancer invasion was considered difficult. Results  We analyzed 748 colorectal polyps, excluding 51 polyps that were inflammatory polyps, sessile serrated adenoma/polyps, serrated adenomas, advanced colorectal cancers, or other lesions. The accuracy of differential diagnosis between neoplastic and non-neoplastic lesions was 98.4 % using BLI magnification and 98.7 % with pit pattern analysis. In addition, the diagnostic accuracy of BLI magnification and pit pattern analysis for dSM for cancer was 89.5 % and 92.1 %, respectively. When type C2 lesions were excluded, the diagnostic accuracy of BLI for dSM was 95.9 %. The 18 type C2 lesions comprised 1 adenoma, 9 intramucosal or slightly invasive submucosal cancers, and 8 dSM. Pit pattern analysis allowed accurate diagnosis of the depth of invasion in 13 lesions (72.2 %). Conclusions  Most colorectal polyps could be diagnosed accurately by BLI magnification without pit pattern analysis, but we should add pit pattern analysis for type C2 lesions in the Hiroshima classification.

Diagnostic accuracy of HLA-B*57:01 screening for the prediction of abacavir hypersensitivity and clinical utility of the test: a meta-analytic review.

PubMed

Cargnin, Sarah; Jommi, Claudio; Canonico, Pier Luigi; Genazzani, Armando A; Terrazzino, Salvatore

2014-05-01

To determine diagnostic accuracy of HLA-B*57:01 testing for prediction of abacavir-induced hypersensitivity and to quantify the clinical benefit of pretreatment screening through a meta-analytic review of published studies. A comprehensive search was performed up to June 2013. The methodological quality of relevant studies was assessed by the QUADAS-2 tool. The pooled diagnostic estimates were calculated using a random effect model. Despite the presence of heterogeneity in sensitivity or specificity estimates, the pooled diagnostic odds ratio to detect abacavir-induced hypersensitivity on the basis of clinical criteria was 33.07 (95% CI: 22.33-48.97, I(2): 13.9%), while diagnostic odds ratio for detection of immunologically confirmed abacavir hypersensitivity was 1141 (95% CI: 409-3181, I(2): 0%). Pooled analysis of risk ratio showed that prospective HLA-B*57:01 testing significantly reduced the incidence of abacavir-induced hypersensitivity. This meta-analysis demonstrates an excellent diagnostic accuracy of HLA-B*57:01 testing to detect immunologically confirmed abacavir hypersensitivity and corroborates existing recommendations.

A Meta-Analysis of Typhoid Diagnostic Accuracy Studies: A Recommendation to Adopt a Standardized Composite Reference

PubMed Central

Storey, Helen L.; Huang, Ying; Crudder, Chris; Golden, Allison; de los Santos, Tala; Hawkins, Kenneth

2015-01-01

Novel typhoid diagnostics currently under development have the potential to improve clinical care, surveillance, and the disease burden estimates that support vaccine introduction. Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard. If no single gold standard test exists, use of a composite reference standard (CRS) can improve estimation of diagnostic accuracy. Numerous studies have used a CRS to evaluate new typhoid diagnostics; however, there is no consensus on an appropriate CRS. In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed. We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality. This wide-ranging meta-analysis suggests that no single test has sufficiently good performance but some existing diagnostics may be useful as part of a CRS. Additionally, based on findings from the meta-analysis and a constructed numerical example demonstrating the use of CRS, we proposed necessary criteria and potential components of a typhoid CRS to guide future recommendations. Agreement and adoption by all investigators of a standardized CRS is requisite, and would improve comparison of new diagnostics across independent studies, leading to the identification of a better reference test and improved confidence in prevalence estimates. PMID:26566275

Value of circulating cell-free DNA analysis as a diagnostic tool for breast cancer: a meta-analysis

PubMed Central

Ma, Xuelei; Zhang, Jing; Hu, Xiuying

2017-01-01

Objectives The aim of this study was to systematically evaluate the diagnostic value of cell free DNA (cfDNA) for breast cancer. Results Among 308 candidate articles, 25 with relevant diagnostic screening qualified for final analysis. The mean sensitivity, specificity and area under the curve (AUC) of SROC plots for 24 studies that distinguished breast cancer patients from healthy controls were 0.70, 0.87, and 0.9314, yielding a DOR of 32.31. When analyzed in subgroups, the 14 quantitative studies produced sensitivity, specificity, AUC, and a DOR of 0.78, 0.83, 0.9116, and 24.40. The 10 qualitative studies produced 0.50, 0.98, 0.9919, and 68.45. For 8 studies that distinguished malignant breast cancer from benign diseases, the specificity, sensitivity, AUC and DOR were 0.75, 0.79, 0.8213, and 9.49. No covariate factors had a significant correlation with relative DOR. Deek's funnel plots indicated an absence of publication bias. Materials and Methods Databases were searched for studies involving the use of cfDNA to diagnose breast cancer. The studies were analyzed to determine sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio (DOR), and the summary receiver operating characteristic (SROC). Covariates were evaluated for effect on relative DOR. Deek's Funnel plots were generated to measure publication bias. Conclusions Our analysis suggests a promising diagnostic potential of using cfDNA for breast cancer screening, but this diagnostic method is not yet independently sufficient. Further work refining qualitative cfDNA assays will improve the correct diagnosis of breast cancers. PMID:28460452

Breast-specific gamma camera imaging with 99mTc-MIBI has better diagnostic performance than magnetic resonance imaging in breast cancer patients: A meta-analysis.

PubMed

Zhang, Aimi; Li, Panli; Liu, Qiufang; Song, Shaoli

2017-01-01

This study aimed to evaluate the diagnostic role of breast-specific gamma camera imaging (BSGI) with technetium-99m-methoxy isobutyl isonitrile ( 99m Tc-MIBI) and magnetic resonance imaging (MRI) in patients with breast cancer through a meta-analysis. Three reviewers searched articles published in medical journals before June 2016 in MEDLINE, EMBASE and Springer Databases; the references listed in original articles were also retrieved. We used the quality assessment of diagnostic accuracy studies (QUADAS) tool to assess the quality of the included studies. Heterogeneity, pooled sensitivity and specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio (DOR) and summary receiver operating characteristic (SROC) curves were calculated by Meta-DiSc software to estimate the diagnostic performance of BSGI and MRI. Ten studies with 517 patients were included after meeting the inclusion criteria. We did a subgroup analysis of the same data type. The pooled sensitivities of BSGI and MRI were: 0.84 (95% CI, 0.79-0.88) and 0.89 (95% CI, 0.84-0.92) respectively, and the pooled specificities of BSGI and MRI were: 0.82 (95% CI, 0.74-0.88) and 0.39 (95% CI, 0.30-0.49) respectively. The areas under the SROC curve of BSGI and MRI were 0.93 and 0.72 respectively. The results of our meta-analysis indicated that compared with MRI, BSGI has similar sensitivity, higher specificity, better diagnostic performance, and can be widely used in clinical practice.

The diagnostic value of polymerase chain reaction for Mycobacterium tuberculosis to distinguish intestinal tuberculosis from crohn's disease: A meta-analysis.

PubMed

Jin, Ting; Fei, Baoying; Zhang, Yu; He, Xujun

2017-01-01

Intestinal tuberculosis (ITB) and Crohn's disease (CD) are important differential diagnoses that can be difficult to distinguish. Polymerase chain reaction (PCR) for Mycobacterium tuberculosis (MTB) is an efficient and promising tool. This meta-analysis was performed to systematically and objectively assess the potential diagnostic accuracy and clinical value of PCR for MTB in distinguishing ITB from CD. We searched PubMed, Embase, Web of Science, Science Direct, and the Cochrane Library for eligible studies, and nine articles with 12 groups of data were identified. The included studies were subjected to quality assessment using the revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The summary estimates were as follows: sensitivity 0.47 (95% CI: 0.42-0.51); specificity 0.95 (95% CI: 0.93-0.97); the positive likelihood ratio (PLR) 10.68 (95% CI: 6.98-16.35); the negative likelihood ratio (NLR) 0.49 (95% CI: 0.33-0.71); and diagnostic odds ratio (DOR) 21.92 (95% CI: 13.17-36.48). The area under the curve (AUC) was 0.9311, with a Q* value of 0.8664. Heterogeneity was found in the NLR. The heterogeneity of the studies was evaluated by meta-regression analysis and subgroup analysis. The current evidence suggests that PCR for MTB is a promising and highly specific diagnostic method to distinguish ITB from CD. However, physicians should also keep in mind that negative results cannot exclude ITB for its low sensitivity. Additional prospective studies are needed to further evaluate the diagnostic accuracy of PCR.

Diagnostic accuracy of clinical tests of the hip: a systematic review with meta-analysis.

PubMed

Reiman, Michael P; Goode, Adam P; Hegedus, Eric J; Cook, Chad E; Wright, Alexis A

2013-09-01

Hip Physical Examination (HPE) tests have long been used to diagnose a myriad of intra-and extra-articular pathologies of the hip joint. Useful clinical utility is necessary to support diagnostic imaging and subsequent surgical decision making. Summarise and evaluate the current research and utility on the diagnostic accuracy of HPE tests for the hip joint germane to sports related injuries and pathology. A computer-assisted literature search of MEDLINE, CINHAL and EMBASE databases (January 1966 to January 2012) using keywords related to diagnostic accuracy of the hip joint. This systematic review with meta-analysis utilised the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for the search and reporting phases of the study. Der-Simonian and Laird random effects models were used to summarise sensitivities (SN), specificities (SP), likelihood ratios and diagnostic OR. The employed search strategy revealed 25 potential articles, with 10 demonstrating high quality. Fourteen articles qualified for meta-analysis. The meta-analysis demonstrated that most tests possess weak diagnostic properties with the exception of the patellar-pubic percussion test, which had excellent pooled SN 95 (95% CI 92 to 97%) and good specificity 86 (95% CI 78 to 92%). Several studies have investigated pathology in the hip. Few of the current studies are of substantial quality to dictate clinical decision-making. Currently, only the patellar-pubic percussion test is supported by the data as a stand-alone HPE test. Further studies involving high quality designs are needed to fully assess the value of HPE tests for patients with intra- and extra-articular hip dysfunction.

Addressing the challenges of diagnostics demand and supply: insights from an online global health discussion platform.

PubMed

Engel, Nora; Wachter, Keri; Pai, Madhukar; Gallarda, Jim; Boehme, Catharina; Celentano, Isabelle; Weintraub, Rebecca

2016-01-01

Several barriers challenge development, adoption and scale-up of diagnostics in low and middle income countries. An innovative global health discussion platform allows capturing insights from the global health community on factors driving demand and supply for diagnostics. We conducted a qualitative content analysis of the online discussion 'Advancing Care Delivery: Driving Demand and Supply of Diagnostics' organised by the Global Health Delivery Project (GHD) (http://www.ghdonline.org/) at Harvard University. The discussion, driven by 12 expert panellists, explored what must be done to develop delivery systems, business models, new technologies, interoperability standards, and governance mechanisms to ensure that patients receive the right diagnostic at the right time. The GHD Online (GHDonline) platform reaches over 19 000 members from 185 countries. Participants (N=99) in the diagnostics discussion included academics, non-governmental organisations, manufacturers, policymakers, and physicians. Data was coded and overarching categories analysed using qualitative data analysis software. Participants considered technical characteristics of diagnostics as smaller barriers to effective use of diagnostics compared with operational and health system challenges, such as logistics, poor fit with user needs, cost, workforce, infrastructure, access, weak regulation and political commitment. Suggested solutions included: health system strengthening with patient-centred delivery; strengthened innovation processes; improved knowledge base; harmonised guidelines and evaluation; supply chain innovations; and mechanisms for ensuring quality and capacity. Engaging and connecting different actors involved with diagnostic development and use is paramount for improving diagnostics. While the discussion participants were not representative of all actors involved, the platform enabled a discussion between globally acknowledged experts and physicians working in different countries.

Rocket Engine Oscillation Diagnostics

NASA Technical Reports Server (NTRS)

Nesman, Tom; Turner, James E. (Technical Monitor)

2002-01-01

Rocket engine oscillating data can reveal many physical phenomena ranging from unsteady flow and acoustics to rotordynamics and structural dynamics. Because of this, engine diagnostics based on oscillation data should employ both signal analysis and physical modeling. This paper describes an approach to rocket engine oscillation diagnostics, types of problems encountered, and example problems solved. Determination of design guidelines and environments (or loads) from oscillating phenomena is required during initial stages of rocket engine design, while the additional tasks of health monitoring, incipient failure detection, and anomaly diagnostics occur during engine development and operation. Oscillations in rocket engines are typically related to flow driven acoustics, flow excited structures, or rotational forces. Additional sources of oscillatory energy are combustion and cavitation. Included in the example problems is a sampling of signal analysis tools employed in diagnostics. The rocket engine hardware includes combustion devices, valves, turbopumps, and ducts. Simple models of an oscillating fluid system or structure can be constructed to estimate pertinent dynamic parameters governing the unsteady behavior of engine systems or components. In the example problems it is shown that simple physical modeling when combined with signal analysis can be successfully employed to diagnose complex rocket engine oscillatory phenomena.

Turning the Page: Advancing Paper-Based Microfluidics for Broad Diagnostic Application.

PubMed

Gong, Max M; Sinton, David

2017-06-28

Infectious diseases are a major global health issue. Diagnosis is a critical first step in effectively managing their spread. Paper-based microfluidic diagnostics first emerged in 2007 as a low-cost alternative to conventional laboratory testing, with the goal of improving accessibility to medical diagnostics in developing countries. In this review, we examine the advances in paper-based microfluidic diagnostics for medical diagnosis in the context of global health from 2007 to 2016. The theory of fluid transport in paper is first presented. The next section examines the strategies that have been employed to control fluid and analyte transport in paper-based assays. Tasks such as mixing, timing, and sequential fluid delivery have been achieved in paper and have enabled analytical capabilities comparable to those of conventional laboratory methods. The following section examines paper-based sample processing and analysis. The most impactful advancement here has been the translation of nucleic acid analysis to a paper-based format. Smartphone-based analysis is another exciting development with potential for wide dissemination. The last core section of the review highlights emerging health applications, such as male fertility testing and wearable diagnostics. We conclude the review with the future outlook, remaining challenges, and emerging opportunities.

Time-dependent analysis of visible helium line-ratios for electron temperature and density diagnostic using synthetic simulations on NSTX-U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muñoz Burgos, J. M.; Barbui, T.; Schmitz, O.

Helium line-ratios for electron temperature (T e) and density (n e) plasma diagnostic in the Scrape-Off-Layer (SOL) and Edge regions of tokamaks are widely used. Due to their intensities and proximity of wavelengths, the singlet 667.8 and 728.1 nm, and triplet 706.5 nm visible lines have been typically preferred. Time-dependency of the triplet line (706.5 nm) has been previously analyzed in detail by including transient effects on line-ratios during gas-puff diagnostic applications. In this work, several line-ratio combinations within each of the two spin systems are analyzed with the purpose of eliminating transient effects to extend the application of thismore » powerful diagnostic to high temporal resolution characterization of plasmas. The analysis is done using synthetic emission modeling and diagnostic for low electron density NSTX SOL plasma conditions by several visible lines. Quasi-static equilibrium, and time-dependent models are employed to evaluate transient effects of the atomic population levels that may affect the derived electron temperatures and densities as the helium gas-puff penetrates the plasma. Ultimately, the analysis of a wider range of spectral lines will help to extend this powerful diagnostic to experiments where the wavelength range of the measured spectra may be constrained either by limitations of the spectrometer, or by other conflicting lines from different ions.« less

Time-dependent analysis of visible helium line-ratios for electron temperature and density diagnostic using synthetic simulations on NSTX-U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muñoz Burgos, J. M., E-mail: jmunozbu@pppl.gov; Stutman, D.; Tritz, K.

Helium line-ratios for electron temperature (T{sub e}) and density (n{sub e}) plasma diagnostic in the Scrape-Off-Layer (SOL) and edge regions of tokamaks are widely used. Due to their intensities and proximity of wavelengths, the singlet, 667.8 and 728.1 nm, and triplet, 706.5 nm, visible lines have been typically preferred. Time-dependency of the triplet line (706.5 nm) has been previously analyzed in detail by including transient effects on line-ratios during gas-puff diagnostic applications. In this work, several line-ratio combinations within each of the two spin systems are analyzed with the purpose of eliminating transient effects to extend the application of thismore » powerful diagnostic to high temporal resolution characterization of plasmas. The analysis is done using synthetic emission modeling and diagnostic for low electron density NSTX SOL plasma conditions by several visible lines. Quasi-static equilibrium and time-dependent models are employed to evaluate transient effects of the atomic population levels that may affect the derived electron temperatures and densities as the helium gas-puff penetrates the plasma. The analysis of a wider range of spectral lines will help to extend this powerful diagnostic to experiments where the wavelength range of the measured spectra may be constrained either by limitations of the spectrometer or by other conflicting lines from different ions.« less

Time-dependent analysis of visible helium line-ratios for electron temperature and density diagnostic using synthetic simulations on NSTX-U

DOE PAGES

Muñoz Burgos, J. M.; Barbui, T.; Schmitz, O.; ...

2016-07-11

Helium line-ratios for electron temperature (T e) and density (n e) plasma diagnostic in the Scrape-Off-Layer (SOL) and Edge regions of tokamaks are widely used. Due to their intensities and proximity of wavelengths, the singlet 667.8 and 728.1 nm, and triplet 706.5 nm visible lines have been typically preferred. Time-dependency of the triplet line (706.5 nm) has been previously analyzed in detail by including transient effects on line-ratios during gas-puff diagnostic applications. In this work, several line-ratio combinations within each of the two spin systems are analyzed with the purpose of eliminating transient effects to extend the application of thismore » powerful diagnostic to high temporal resolution characterization of plasmas. The analysis is done using synthetic emission modeling and diagnostic for low electron density NSTX SOL plasma conditions by several visible lines. Quasi-static equilibrium, and time-dependent models are employed to evaluate transient effects of the atomic population levels that may affect the derived electron temperatures and densities as the helium gas-puff penetrates the plasma. Ultimately, the analysis of a wider range of spectral lines will help to extend this powerful diagnostic to experiments where the wavelength range of the measured spectra may be constrained either by limitations of the spectrometer, or by other conflicting lines from different ions.« less

Evaluation and construction of diagnostic criteria for inclusion body myositis

PubMed Central

Mammen, Andrew L.; Amato, Anthony A.; Weiss, Michael D.; Needham, Merrilee

2014-01-01

Objective: To use patient data to evaluate and construct diagnostic criteria for inclusion body myositis (IBM), a progressive disease of skeletal muscle. Methods: The literature was reviewed to identify all previously proposed IBM diagnostic criteria. These criteria were applied through medical records review to 200 patients diagnosed as having IBM and 171 patients diagnosed as having a muscle disease other than IBM by neuromuscular specialists at 2 institutions, and to a validating set of 66 additional patients with IBM from 2 other institutions. Machine learning techniques were used for unbiased construction of diagnostic criteria. Results: Twenty-four previously proposed IBM diagnostic categories were identified. Twelve categories all performed with high (≥97%) specificity but varied substantially in their sensitivities (11%–84%). The best performing category was European Neuromuscular Centre 2013 probable (sensitivity of 84%). Specialized pathologic features and newly introduced strength criteria (comparative knee extension/hip flexion strength) performed poorly. Unbiased data-directed analysis of 20 features in 371 patients resulted in construction of higher-performing data-derived diagnostic criteria (90% sensitivity and 96% specificity). Conclusions: Published expert consensus–derived IBM diagnostic categories have uniformly high specificity but wide-ranging sensitivities. High-performing IBM diagnostic category criteria can be developed directly from principled unbiased analysis of patient data. Classification of evidence: This study provides Class II evidence that published expert consensus–derived IBM diagnostic categories accurately distinguish IBM from other muscle disease with high specificity but wide-ranging sensitivities. PMID:24975859

Software Users Manual (SUM): Extended Testability Analysis (ETA) Tool

NASA Technical Reports Server (NTRS)

Maul, William A.; Fulton, Christopher E.

2011-01-01

This software user manual describes the implementation and use the Extended Testability Analysis (ETA) Tool. The ETA Tool is a software program that augments the analysis and reporting capabilities of a commercial-off-the-shelf (COTS) testability analysis software package called the Testability Engineering And Maintenance System (TEAMS) Designer. An initial diagnostic assessment is performed by the TEAMS Designer software using a qualitative, directed-graph model of the system being analyzed. The ETA Tool utilizes system design information captured within the diagnostic model and testability analysis output from the TEAMS Designer software to create a series of six reports for various system engineering needs. The ETA Tool allows the user to perform additional studies on the testability analysis results by determining the detection sensitivity to the loss of certain sensors or tests. The ETA Tool was developed to support design and development of the NASA Ares I Crew Launch Vehicle. The diagnostic analysis provided by the ETA Tool was proven to be valuable system engineering output that provided consistency in the verification of system engineering requirements. This software user manual provides a description of each output report generated by the ETA Tool. The manual also describes the example diagnostic model and supporting documentation - also provided with the ETA Tool software release package - that were used to generate the reports presented in the manual

HIDRA-MAT: A Material Analysis Tool for Fusion Devices

NASA Astrophysics Data System (ADS)

Andruczyk, Daniel; Rizkallah, Rabel; Bedoya, Felipe; Kapat, Aveek; Schamis, Hanna; Allain, Jean Paul

2017-10-01

The former WEGA stellarator which is now operating as HIDRA at the University of Illinois will be almost exclusively used to study the intimate relationship between the plasma interacting with surfaces of different materials. A Material Analysis Tool (HIDRA-MAT) is being designed and will be built based on the successful Material Analysis and Particle Probe (MAPP) which is currently used on NSTX-U at PPPL. This will be an in-situ material diagnostic probe, meaning that all analysis can be done without breaking vacuum. This allows surface changes to be studied in real-time. HIDRA-MAT will consist of several in-situ diagnostics including Langmuir probes (LP), Thermal Desorption Spectroscopy (TDS), X-ray Photo Spectroscopy (XPS) and Ion Scattering Spectroscopy (ISS). This presentation will outline the HIDRA-MAT diagnostic and initial design, as well as its integration into the HIDRA system.

Mobile Diagnostics Based on Motion? A Close Look at Motility Patterns in the Schistosome Life Cycle

PubMed Central

Linder, Ewert; Varjo, Sami; Thors, Cecilia

2016-01-01

Imaging at high resolution and subsequent image analysis with modified mobile phones have the potential to solve problems related to microscopy-based diagnostics of parasitic infections in many endemic regions. Diagnostics using the computing power of “smartphones” is not restricted by limited expertise or limitations set by visual perception of a microscopist. Thus diagnostics currently almost exclusively dependent on recognition of morphological features of pathogenic organisms could be based on additional properties, such as motility characteristics recognizable by computer vision. Of special interest are infectious larval stages and “micro swimmers” of e.g., the schistosome life cycle, which infect the intermediate and definitive hosts, respectively. The ciliated miracidium, emerges from the excreted egg upon its contact with water. This means that for diagnostics, recognition of a swimming miracidium is equivalent to recognition of an egg. The motility pattern of miracidia could be defined by computer vision and used as a diagnostic criterion. To develop motility pattern-based diagnostics of schistosomiasis using simple imaging devices, we analyzed Paramecium as a model for the schistosome miracidium. As a model for invasive nematodes, such as strongyloids and filaria, we examined a different type of motility in the apathogenic nematode Turbatrix, the “vinegar eel.” The results of motion time and frequency analysis suggest that target motility may be expressed as specific spectrograms serving as “diagnostic fingerprints.” PMID:27322330

Evaluation of spectral domain optical coherence tomography parameters in ocular hypertension, preperimetric, and early glaucoma.

PubMed

Aydogan, Tuğba; Akçay, BetÜl İlkay Sezgin; Kardeş, Esra; Ergin, Ahmet

2017-11-01

The objective of this study is to evaluate the diagnostic ability of retinal nerve fiber layer (RNFL), macular, optic nerve head (ONH) parameters in healthy subjects, ocular hypertension (OHT), preperimetric glaucoma (PPG), and early glaucoma (EG) patients, to reveal factors affecting the diagnostic ability of spectral domain-optical coherence tomography (SD-OCT) parameters and risk factors for glaucoma. Three hundred and twenty-six eyes (89 healthy, 77 OHT, 94 PPG, and 66 EG eyes) were analyzed. RNFL, macular, and ONH parameters were measured with SD-OCT. The area under the receiver operating characteristic curve (AUC) and sensitivity at 95% specificity was calculated. Logistic regression analysis was used to determine the glaucoma risk factors. Receiver operating characteristic regression analysis was used to evaluate the influence of covariates on the diagnostic ability of parameters. In PPG patients, parameters that had the largest AUC value were average RNFL thickness (0.83) and rim volume (0.83). In EG patients, parameter that had the largest AUC value was average RNFL thickness (0.98). The logistic regression analysis showed average RNFL thickness was a risk factor for both PPG and EG. Diagnostic ability of average RNFL and average ganglion cell complex thickness increased as disease severity increased. Signal strength index did not affect diagnostic abilities. Diagnostic ability of average RNFL and rim area increased as disc area increased. When evaluating patients with glaucoma, patients at risk for glaucoma, and healthy controls RNFL parameters deserve more attention in clinical practice. Further studies are needed to fully understand the influence of covariates on the diagnostic ability of OCT parameters.

Receiver operating characteristic analysis of eyewitness memory: comparing the diagnostic accuracy of simultaneous versus sequential lineups.

PubMed

Mickes, Laura; Flowe, Heather D; Wixted, John T

2012-12-01

A police lineup presents a real-world signal-detection problem because there are two possible states of the world (the suspect is either innocent or guilty), some degree of information about the true state of the world is available (the eyewitness has some degree of memory for the perpetrator), and a decision is made (identifying the suspect or not). A similar state of affairs applies to diagnostic tests in medicine because, in a patient, the disease is either present or absent, a diagnostic test yields some degree of information about the true state of affairs, and a decision is made about the presence or absence of the disease. In medicine, receiver operating characteristic (ROC) analysis is the standard method for assessing diagnostic accuracy. By contrast, in the eyewitness memory literature, this powerful technique has never been used. Instead, researchers have attempted to assess the diagnostic performance of different lineup procedures using methods that cannot identify the better procedure (e.g., by computing a diagnosticity ratio). Here, we describe the basics of ROC analysis, explaining why it is needed and showing how to use it to measure the performance of different lineup procedures. To illustrate the unique advantages of this technique, we also report 3 ROC experiments that were designed to investigate the diagnostic accuracy of simultaneous versus sequential lineups. According to our findings, the sequential procedure appears to be inferior to the simultaneous procedure in discriminating between the presence versus absence of a guilty suspect in a lineup.

Smartphone-Based Accurate Analysis of Retinal Vasculature towards Point-of-Care Diagnostics

PubMed Central

Xu, Xiayu; Ding, Wenxiang; Wang, Xuemin; Cao, Ruofan; Zhang, Maiye; Lv, Peilin; Xu, Feng

2016-01-01

Retinal vasculature analysis is important for the early diagnostics of various eye and systemic diseases, making it a potentially useful biomarker, especially for resource-limited regions and countries. Here we developed a smartphone-based retinal image analysis system for point-of-care diagnostics that is able to load a fundus image, segment retinal vessels, analyze individual vessel width, and store or uplink results. The proposed system was not only evaluated on widely used public databases and compared with the state-of-the-art methods, but also validated on clinical images directly acquired with a smartphone. An Android app is also developed to facilitate on-site application of the proposed methods. Both visual assessment and quantitative assessment showed that the proposed methods achieved comparable results to the state-of-the-art methods that require high-standard workstations. The proposed system holds great potential for the early diagnostics of various diseases, such as diabetic retinopathy, for resource-limited regions and countries. PMID:27698369

Diagnostic performance of neck circumference to identify overweight and obesity as defined by body mass index in children and adolescents: systematic review and meta-analysis.

PubMed

Ma, Chunming; Wang, Rui; Liu, Yue; Lu, Qiang; Liu, Xiaoli; Yin, Fuzai

2017-05-01

The neck circumference (NC) has been shown to be an accurate index for screening overweight and obesity in children and adolescents. To perform a meta-analysis to assess the performance of NC for the assessment of overweight and obesity. Data sources were PubMed and EMBASE up to March 2016. Studies providing measures of diagnostic performance of NC and using body mass index as reference standard were included. Six eligible studies that evaluated 11 214 children and adolescents aged 6-18 years were included in the meta-analysis. NC showed pooled sensitivity to detect high body mass index of 0.780 (95% confidence interval [CI] = 0.765-0.794), specificity of 0.746 (95% CI =  0.736-0.756) and a diagnostic odds ratio of 17.343 (95% CI =  8.743-34.405). The NC had moderate diagnostic accuracy for identifying overweight and obesity in children and adolescents.

Instrument for evaluation of sedentary lifestyle in patients with high blood pressure.

PubMed

Lopes, Marcos Venícios de Oliveira; da Silva, Viviane Martins; de Araujo, Thelma Leite; Guedes, Nirla Gomes; Martins, Larissa Castelo Guedes; Teixeira, Iane Ximenes

2015-01-01

this article describes the diagnostic accuracy of the International Physical Activity Questionnaire to identify the nursing diagnosis of sedentary lifestyle. a diagnostic accuracy study was developed with 240 individuals with established high blood pressure. The analysis of diagnostic accuracy was based on measures of sensitivity, specificity, predictive values, likelihood ratios, efficiency, diagnostic odds ratio, Youden index, and area under the receiver-operating characteristic curve. statistical differences between genders were observed for activities of moderate intensity and for total physical activity. Age was negatively correlated with activities of moderate intensity and total physical activity. the analysis of area under the receiver-operating characteristic curve for moderate intensity activities, walking, and total physical activity showed that the International Physical Activity Questionnaire present moderate capacity to correctly classify individuals with and without sedentary lifestyle.

A fuzzy logic intelligent diagnostic system for spacecraft integrated vehicle health management

NASA Technical Reports Server (NTRS)

Wu, G. Gordon

1995-01-01

Due to the complexity of future space missions and the large amount of data involved, greater autonomy in data processing is demanded for mission operations, training, and vehicle health management. In this paper, we develop a fuzzy logic intelligent diagnostic system to perform data reduction, data analysis, and fault diagnosis for spacecraft vehicle health management applications. The diagnostic system contains a data filter and an inference engine. The data filter is designed to intelligently select only the necessary data for analysis, while the inference engine is designed for failure detection, warning, and decision on corrective actions using fuzzy logic synthesis. Due to its adaptive nature and on-line learning ability, the diagnostic system is capable of dealing with environmental noise, uncertainties, conflict information, and sensor faults.

A qualitative approach to systemic diagnosis of the SSME

NASA Technical Reports Server (NTRS)

Bickmore, Timothy W.; Maul, William A.

1993-01-01

A generic software architecture has been developed for posttest diagnostics of rocket engines, and is presently being applied to the posttest analysis of the SSME. This investigation deals with the Systems Section module of the architecture, which is presently under development. Overviews of the manual SSME systems analysis process and the overall SSME diagnostic system architecture are presented.

Statistical analysis and interpretation of prenatal diagnostic imaging studies, Part 2: descriptive and inferential statistical methods.

PubMed

Tuuli, Methodius G; Odibo, Anthony O

2011-08-01

The objective of this article is to discuss the rationale for common statistical tests used for the analysis and interpretation of prenatal diagnostic imaging studies. Examples from the literature are used to illustrate descriptive and inferential statistics. The uses and limitations of linear and logistic regression analyses are discussed in detail.

Correction of the near threshold behavior of electron collisional excitation cross-sections in the plane-wave Born approximation

NASA Astrophysics Data System (ADS)

Kilcrease, D. P.; Brookes, S.

2013-12-01

The modeling of NLTE plasmas requires the solution of population rate equations to determine the populations of the various atomic levels relevant to a particular problem. The equations require many cross sections for excitation, de-excitation, ionization and recombination. A simple and computational fast way to calculate electron collisional excitation cross-sections for ions is by using the plane-wave Born approximation. This is essentially a high-energy approximation and the cross section suffers from the unphysical problem of going to zero near threshold. Various remedies for this problem have been employed with varying degrees of success. We present a correction procedure for the Born cross-sections that employs the Elwert-Sommerfeld factor to correct for the use of plane waves instead of Coulomb waves in an attempt to produce a cross-section similar to that from using the more time consuming Coulomb Born approximation. We compare this new approximation with other, often employed correction procedures. We also look at some further modifications to our Born Elwert procedure and its combination with Y.K. Kim's correction of the Coulomb Born approximation for singly charged ions that more accurately approximate convergent close coupling calculations.

On the 3He anomaly in hot subdwarf B stars

NASA Astrophysics Data System (ADS)

Schneider, David; Irrgang, Andreas; Heber, Ulrich; Nieva, Maria F.; Przybilla, Norbert

2017-12-01

Decades ago, 3He isotope enrichment in helium-weak B-type main-sequence, in blue horizontal branch and in hot subdwarf B (sdB) stars, i.e., helium-core burning stars of the extreme horizontal branch, were discovered. Diffusion processes in the atmosphere of these stars lead to the observed abundance anomalies. Quantitative spectral analyses of high-resolution spectra to derive photospheric isotopic helium abundance ratios for known 3He sdBs have not been performed yet. We present preliminary results of high-resolution and high S/N spectra to determine the 3He and 4He abundances of nine known 3He sdBs. We used a hybrid local/non-local thermodynamic equilibrium (LTE/NLTE) approach for B-type stars investigating multiple He i lines, including λ4922 Å and λ6678 Å, which show the strongest isotopic shifts in the optical spectral range.We also report the discovery of four new 3He sdBs from the ESO Supernova Progenitor survey. Most of the 3He sdBs cluster in a narrow temperature strip between ˜ 26000 K and ˜ 30000 K and have almost no atmospheric 4He at all. Interestingly, three 3He sdBs show evidence for vertical helium stratification.

The application of quasi-steady approximation in atomic kinetics in simulation of hohlraum radiation drive

NASA Astrophysics Data System (ADS)

Ren, Guoli; Pei, Wenbing; Lan, Ke; Li, Xin; Hohlraum Physics Team

2014-10-01

In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum-number (n-level) average atom model (AAM) in NLTE plasma description. The more sophisticated atomic kinetics description is better choice, but the in-line calculation consumes much more resource. By distinguishing the much more fast bound-bound atomic processes from the relative slow bound-free atomic processes, we found a method to built up a bound electron distribution (n-level or nl-level) using in-line n-level calculated plasma condition (such as temperature, density, average ionization degree). We name this method ``quasi-steady approximation.'' Using this method and the plasma condition calculated under n-level, we re-build the nl-level bound electron distribution (Pnl), and acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more-detailed frequency-dependant structures. Also we use this method in the benchmark gold sphere experiment, the constructed nl-level radiation drive resembles the experimental results and DCA results, while the n-level raditation does not.

To acquire more detailed radiation drive by use of ``quasi-steady'' approximation in atomic kinetics

NASA Astrophysics Data System (ADS)

Ren, Guoli; Pei, Wenbing; Lan, Ke; Gu, Peijun; Li, Xin

2012-10-01

In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum- number(n-level) average atom model(AAM) in NLTE plasma description. However, the detailed experimental frequency-dependant radiative drive differs from our n-level simulated drive, which reminds us the need of a more detailed atomic kinetics description. The orbital-quantum- number(nl-level) average atom model is a natural consideration, however the nl-level in-line calculation needs much more computational resource. By distinguishing the rapid bound-bound atomic processes from the relative slow bound-free atomic processes, we found a method to build up a more detailed bound electron distribution(nl-level even nlm-level) using in-line n-level calculated plasma conditions(temperature, density, and average ionization degree). We name this method ``quasi-steady approximation'' in atomic kinetics. Using this method, we re-build the nl-level bound electron distribution (Pnl), and acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more fine frequency-denpending spectrum structure which appears only in nl-level transition with same n number(n=0) .

Radar analysis of free oscillations of rail for diagnostics defects

NASA Astrophysics Data System (ADS)

Shaydurov, G. Y.; Kudinov, D. S.; Kokhonkova, E. A.; Potylitsyn, V. S.

2018-05-01

One of the tasks of developing and implementing defectoscopy devices is the minimal influence of the human factor in their exploitation. At present, rail inspection systems do not have sufficient depth of rail research, and ultrasonic diagnostics systems need to contact the sensor with the surface being studied, which leads to low productivity. The article gives a comparative analysis of existing noncontact methods of flaw detection, offers a contactless method of diagnostics by excitation of acoustic waves and extraction of information about defects from the frequency of free rail oscillations using the radar method.

New laboratory atomic data for neutral, singly and doubly ionised iron group elements for astrophysics applications

NASA Astrophysics Data System (ADS)

Pickering, Juliet C.; Nave, Gillian; Liggins, Florence; Clear, Christian; Ruffoni, Matthew; Sansonetti, Craig

2015-08-01

We present new laboratory spectroscopic measurements to produce atomic data for astrophysically important species: neutral, singly and doubly ionised iron group elements.We use high resolution Fourier Transform Spectrometry (FTS) (resolving power up to 2x106 at 200nm) to measure atomic spectra, giving accurate line wavelengths (to a few parts in 108), atomic energy levels, hyperfine structure splitting and log gfs (accurate to a few %) (Ruffoni et al this meeting). These data are vital for astrophysical spectral analyses for: line identification, spectrum synthesis, elemental abundance determinations [eg 1], and disentangling of blends etc. It is not possible to theoretically calculate these atomic data to the accuracy needed for modern astrophysics applications.At Imperial College we have a unique visible-VUV FT spectrometer with short wavelength cut-off of 135nm. We supplement FTS data at shorter wavelengths with spectra recorded on the NIST 10.7m grating spectrograph (with phosphor image or photographic plates) and at longer wavelengths in the IR we use the NIST IR FT spectrometer.An elemental spectrum may contain thousands of spectral lines from the IR to VUV. We use these wavelengths to correct known atomic energy levels, and search for new atomic levels. The result is a classified linelist and accurate atomic energy levels.We present progress on iron group element atomic energy levels and wavelengths for V I and V II [2,3], Co III [4], Cr I, Mn I and Mn II, and Ni II.This work is supported by STFC(UK), The Leverhulme Trust, The Royal Society and NASA.References[1] Bergemann M, Pickering JC & Gehren T,“NLTE analysis of Co I/Co II lines in spectra of cool stars with new laboratory hyperfine splitting constants",MNRAS 401(2) 1334 (2010)[2] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V II”, ApJS 207,13 (2013)[3] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V I",ApJS 192,11 (2011)[4] Smillie DG, Pickering JC, Nave G & Smith PL,“The Spectrum and Term Analysis of Co III Measured using Fourier Transform and Grating Spectroscopy”,ApJS submitted

An abundance analysis from the STIS-HST UV spectrum of the non-magnetic Bp star HR 6000

NASA Astrophysics Data System (ADS)

Castelli, F.; Cowley, C. R.; Ayres, T. R.; Catanzaro, G.; Leone, F.

2017-05-01

Context. The sharp-line spectrum of the non-magnetic, main-sequence Bp star HR 6000 has peculiarities that distinguish it from those of the HgMn stars with which it is sometimes associated. The position of the star close to the center of the Lupus 3 molecular cloud, whose estimated age is on the order of 9.1 ± 2.1 Myr, has lead to the hypothesis that the anomalous peculiarities of HR 6000 can be explained by the young age of the star. Aims: Observational material from the Hubble Space Telescope (HST) provides the opportunity to extend the abundance analysis previously performed for the optical region and clarify the properties of this remarkable peculiar star. Our aim was to obtain the atmospheric abundances for all the elements observed in a broad region from 1250 to 10 000 Å. Methods: An LTE synthetic spectrum was compared with a high-resolution spectrum observed with the Space Telescope Imaging Spectrograph (STIS) equipment in the 1250-3040 Å interval. Abundances were changed until the synthetic spectrum fit the observed spectrum. The assumed model is an LTE, plane-parallel, line-blanketed ATLAS12 model already used for the abundance analysis of a high-resolution optical spectrum observed at ESO with the Ultraviolet and Visual Echelle Spectrograph (UVES). The stellar parameters are Teff = 13450 K, log g = 4.3, and zero microturbulent velocity. Results: Abundances for 28 elements and 7 upper limits were derived from the ultraviolet spectrum. Adding results from previous work, we have now quantitative results for 37 elements, some of which show striking contrasts with those of a broad sample of HgMn stars. The analysis has pointed out numerous abundance anomalies, such as ionization anomalies and line-to-line variation in the derived abundances, in particular for silicon. The inferred discrepancies could be explained by non-LTE effects and with the occurrence of diffusion and vertical abundance stratification. In the framework of the last hypothesis, we obtained, by means of trial and error, empirical step functions of abundance versus optical depth log (τ5000) for carbon, nitrogen, silicon, manganese, and gold, while we failed to find such a function for phosphorous. The poor results for carbon, and mostly for phosphorus, suggest the possible importance in this star of NLTE effects to be investigated in future works.

The ITER bolometer diagnostic: Status and plansa)

NASA Astrophysics Data System (ADS)

Meister, H.; Giannone, L.; Horton, L. D.; Raupp, G.; Zeidner, W.; Grunda, G.; Kalvin, S.; Fischer, U.; Serikov, A.; Stickel, S.; Reichle, R.

2008-10-01

A consortium consisting of four EURATOM Associations has been set up to develop the project plan for the full development of the ITER bolometer diagnostic and to continue urgent R&D activities. An overview of the current status is given, including detector development, line-of-sight optimization, performance analysis as well as the design of the diagnostic components and their integration in ITER. This is complemented by the presentation of plans for future activities required to successfully implement the bolometer diagnostic, ranging from the detector development over diagnostic design and prototype testing to RH tools for calibration.

The DSM and the Dangerous School Child

ERIC Educational Resources Information Center

Bailey, Simon

2010-01-01

The history of ADHD is in part a history of children who have not fitted in at school. Yet until recently, surges in diagnostic levels had not prompted a questioning of the school's complicity in the trend. Through an analysis of the Diagnostic and Statistical Manual for Mental Disorders (DSM), the principal diagnostic guideline relating to ADHD,…

Seizure, Fit or Attack? The Use of Diagnostic Labels by Patients with Epileptic or Non-Epileptic Seizures

ERIC Educational Resources Information Center

Plug, Leendert; Sharrack, Basil; Reuber, Markus

2010-01-01

We present an analysis of the use of diagnostic labels such as "seizure", "attack", "fit", and "blackout" by patients who experience seizures. While previous research on patients' preferences for diagnostic terminology has relied on questionnaires, we assess patients' own preferences and their responses to a doctor's use of different labels…

CT Bronchus Sign and the Diagnostic Yield of Guided Bronchoscopy for Peripheral Pulmonary Lesions: A Systematic Review and Meta-Analysis.

PubMed

Ali, Muhammad S; Sethi, Jaskaran; Taneja, Amit; Musani, Ali; Maldonado, Fabien

2018-06-07

Indeterminate peripheral pulmonary lesions often require tissue diagnosis. If non-surgical biopsy techniques are considered, deciding between bronchoscopic transbronchial vs. CT guided transthoracic biopsy can be difficult. The former has a low diagnostic yield with a low complication risk, while the latter has a better diagnostic yield but a higher complication rate. Investigators have looked at various lesion characteristics that can predict the diagnostic yield of guided bronchoscopic biopsies. While consensus exists that larger size and proximity to the hilum increase the diagnostic yield, there is ongoing debate about the association between CT bronchus sign (air-filled bronchus in close proximity of the lesion as seen on CT) and the diagnostic yield of guided bronchoscopic modalities. To perform a meta-analysis and systematic review, determining the association between CT bronchus sign and the diagnostic yield of guided bronchoscopy for peripheral pulmonary lesions. MEDLINE, Embase, Scopus and Google Scholar were searched in January 2018 for guided bronchoscopy studies that had assessed the impact of CT bronchus sign on the diagnostic yield. The quality of included studies was assessed using Quality Assessment, Data Abstraction and Synthesis-2 tool. Meta-analysis was performed using MedCalc (version 18). Odds ratios were used to compare yield of lesions with and without bronchus sign. Random effects model was used when significant heterogeneity was observed (I2>40%). For 2199 lesions with CT bronchus sign, the overall weighted diagnostic yield was 74.1% (95% CI: 68.3-79.5%). For 971 lesions without CT bronchus sign, the overall weighted diagnostic yield was 49.6% (95% CI: 39.6-59.5%). The odds ratio for successfully diagnosing a lesion with CT bronchus was 3.4 (95% CI: 2.4-5.0). Possible sources of heterogeneity in the meta-analysis included differences in study designs, guidance modalities and cancer prevalence. The odds ratio for successfully diagnosing a lesion with CT bronchus sign was relatively lower for prospective studies. Peripheral pulmonary lesions with CT bronchus sign are more likely to be diagnosed with guided bronchoscopy as compared to the lesions without CT bronchus sign. Clinicians should consider this along with the lesion size and distance from hilum, when contemplating guided bronchoscopy for peripheral pulmonary lesions. To perform a meta-analysis and systematic review, determining the impact of CT bronchus sign on the diagnostic yield of guided bronchoscopy for peripheral pulmonary lesions. MEDLINE, Embase, Scopus and Google Scholar were searched in January 2018 for guided bronchoscopy studies that had assessed the impact of CT bronchus sign on the diagnostic yield. The quality of included studies was assessed using Quality Assessment, Data Abstraction and Synthesis-2 tool. Meta-analysis was performed using MedCalc (version 18). Odds ratios were used to compare yield of lesions with and without bronchus sign. Random effects model was used when significant heterogeneity was observed (I2>40%). For 2199 lesions with CT bronchus sign, the overall weighted diagnostic yield was 74.1% (95% CI: 68.3-79.5%). For 971 lesions without CT bronchus, the overall weighted diagnostic yield was 49.6% (95% CI: 39.6-59.5%). The odds ratio for successfully diagnosing a lesion with CT bronchus was 3.4 (95% CI: 2.4-5.0). I² index was 62.1 therefore random effects model was used. Peripheral pulmonary lesions with CT bronchus sign are much more likely to be successfully diagnosed with guided bronchoscopy as compared to the lesions without CT bronchus sign. Clinicians should consider the presence (or absence) of CT bronchus sign along with the size of the lesion and distance from the hilum, when contemplating guided bronchoscopic modalities for peripheral pulmonary lesions.

Role of CFTR mutation analysis in the diagnostic algorithm for cystic fibrosis.

PubMed

Ratkiewicz, Michelle; Pastore, Matthew; McCoy, Karen Sharrock; Thompson, Rohan; Hayes, Don; Sheikh, Shahid Ijaz

2017-04-01

The cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation identification is being used with increased frequency to aid in the diagnosis of cystic fibrosis (CF) in those suspected with CF. Aim of this study was to identify diagnostic outcomes when CFTR mutational analysis was used in CF diagnosis. CFTR mutational analysis results were also compared with sweat chloride results. This study was done on all patients at our institution who had CFTR mutation analysis over a sevenyear period since August 2006. A total of 315 patients underwent CFTR mutational analysis. Fifty-one (16.2%) patients had two mutations identified. Among them 32 had positive sweat chloride levels (≥60 mmol/L), while seven had borderline sweat chloride levels (40-59 mmol/L). An additional 70 patients (22.3%) had only one mutation identified. Among them eight had positive sweat chloride levels, and 17 had borderline sweat chloride levels. Fifty-five patients (17.5%) without CFTR mutations had either borderline (n=45) or positive (n=10) sweat chloride results. Three patients with a CF phenotype had negative CFTR analysis but elevated sweat chloride levels. In eighty-three patients (26.4%) CFTR mutational analysis was done without corresponding sweat chloride testing. Although CFTR mutation analysis has improved the diagnostic capability for CF, its use either as the first step or the only test to diagnose CFTR dysfunction should be discouraged and CF diagnostic guidelines need to be followed.

Delirium diagnosis defined by cluster analysis of symptoms versus diagnosis by DSM and ICD criteria: diagnostic accuracy study.

PubMed

Sepulveda, Esteban; Franco, José G; Trzepacz, Paula T; Gaviria, Ana M; Meagher, David J; Palma, José; Viñuelas, Eva; Grau, Imma; Vilella, Elisabet; de Pablo, Joan

2016-05-26

Information on validity and reliability of delirium criteria is necessary for clinicians, researchers, and further developments of DSM or ICD. We compare four DSM and ICD delirium diagnostic criteria versions, which were developed by consensus of experts, with a phenomenology-based natural diagnosis delineated using cluster analysis of delirium features in a sample with a high prevalence of dementia. We also measured inter-rater reliability of each system when applied by two evaluators from distinct disciplines. Cross-sectional analysis of 200 consecutive patients admitted to a skilled nursing facility, independently assessed within 24-48 h after admission with the Delirium Rating Scale-Revised-98 (DRS-R98) and for DSM-III-R, DSM-IV, DSM-5, and ICD-10 criteria for delirium. Cluster analysis (CA) delineated natural delirium and nondelirium reference groups using DRS-R98 items and then diagnostic systems' performance were evaluated against the CA-defined groups using logistic regression and crosstabs for discriminant analysis (sensitivity, specificity, percentage of subjects correctly classified by each diagnostic system and their individual criteria, and performance for each system when excluding each individual criterion are reported). Kappa Index (K) was used to report inter-rater reliability for delirium diagnostic systems and their individual criteria. 117 (58.5 %) patients had preexisting dementia according to the Informant Questionnaire on Cognitive Decline in the Elderly. CA delineated 49 delirium subjects and 151 nondelirium. Against these CA groups, delirium diagnosis accuracy was highest using DSM-III-R (87.5 %) followed closely by DSM-IV (86.0 %), ICD-10 (85.5 %) and DSM-5 (84.5 %). ICD-10 had the highest specificity (96.0 %) but lowest sensitivity (53.1 %). DSM-III-R had the best sensitivity (81.6 %) and the best sensitivity-specificity balance. DSM-5 had the highest inter-rater reliability (K =0.73) while DSM-III-R criteria were the least reliable. Using our CA-defined, phenomenologically-based delirium designations as the reference standard, we found performance discordance among four diagnostic systems when tested in subjects where comorbid dementia was prevalent. The most complex diagnostic systems have higher accuracy and the newer DSM-5 have higher reliability. Our novel phenomenological approach to designing a delirium reference standard may be preferred to guide revisions of diagnostic systems in the future.

Community-based benchmarking of the CMIP DECK experiments

NASA Astrophysics Data System (ADS)

Gleckler, P. J.

2015-12-01

A diversity of community-based efforts are independently developing "diagnostic packages" with little or no coordination between them. A short list of examples include NCAR's Climate Variability Diagnostics Package (CVDP), ORNL's International Land Model Benchmarking (ILAMB), LBNL's Toolkit for Extreme Climate Analysis (TECA), PCMDI's Metrics Package (PMP), the EU EMBRACE ESMValTool, the WGNE MJO diagnostics package, and CFMIP diagnostics. The full value of these efforts cannot be realized without some coordination. As a first step, a WCRP effort has initiated a catalog to document candidate packages that could potentially be applied in a "repeat-use" fashion to all simulations contributed to the CMIP DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. Some coordination of community-based diagnostics has the additional potential to improve how CMIP modeling groups analyze their simulations during model-development. The fact that most modeling groups now maintain a "CMIP compliant" data stream means that in principal without much effort they could readily adopt a set of well organized diagnostic capabilities specifically designed to operate on CMIP DECK experiments. Ultimately, a detailed listing of and access to analysis codes that are demonstrated to work "out of the box" with CMIP data could enable model developers (and others) to select those codes they wish to implement in-house, potentially enabling more systematic evaluation during the model development process.

The role of molecular diagnostic testing in the management of thyroid nodules.

PubMed

Moore, Maureen D; Panjwani, Suraj; Gray, Katherine D; Finnerty, Brendan M; Zarnegar, Rasa; Fahey, Thomas J

2017-06-01

Fine needle aspiration (FNA) with cytologic examination remains the standard of care for investigation of thyroid nodules. However, as many as 30% of FNA samples are cytologically indeterminate for malignancy, which confounds clinical management. To reduce the burden of repeat diagnostic testing and unnecessary surgery, there has been extensive investigation into molecular markers that can be detected on FNA specimens to more accurately stratify a patient's risk of malignancy. Areas covered: In this review, the authors discuss recent evidence and progress in molecular markers used in the diagnosis of thyroid cancer highlighting somatic gene alterations, molecular technologies and microRNA analysis. Expert commentary: The goal of molecular markers is to improve diagnostic accuracy and aid clinicians in the preoperative management of thyroid lesions. Modalities such as direct mutation analysis, mRNA gene expression profiling, next-generation sequencing, and miRNA expression profiling have been explored to improve the diagnostic accuracy of thyroid nodule FNA. Although no perfect test has been discovered, molecular diagnostic testing has revolutionized the management of thyroid nodules.

Recent developments in Förster resonance energy transfer (FRET) diagnostics using quantum dots.

PubMed

Geißler, Daniel; Hildebrandt, Niko

2016-07-01

The exceptional photophysical properties and the nanometric dimensions of colloidal semiconductor quantum dots (QD) have strongly attracted the bioanalytical community over the last approximately 20 y. In particular, the integration of QDs in the analysis of biological components and interactions, and the related diagnostics using Förster resonance energy transfer (FRET), have allowed researchers to significantly improve and diversify fluorescence-based biosensing. In this TRENDS article, we review some recent developments in QD-FRET biosensing that have implemented this technology in electronic consumer products, multiplexed analysis, and detection without light excitation for diagnostic applications. In selected examples of smartphone-based imaging, single- and multistep FRET, steady-state and time-resolved spectroscopy, and bio/chemiluminescence detection of QDs used as both FRET donors and acceptors, we highlight the advantages of QD-based FRET biosensing for multiplexed and sensitive diagnostics. Graphical Abstract Quantum dots (QDs) can be applied as donors and/or acceptors for Förster resonance energy transfer- (FRET-) based biosensing for multiplexed and sensitive diagnostics in various assay formats.

Application of computer-aided diagnosis (CAD) in MR-mammography (MRM): do we really need whole lesion time curve distribution analysis?

PubMed

Baltzer, Pascal Andreas Thomas; Renz, Diane M; Kullnig, Petra E; Gajda, Mieczyslaw; Camara, Oumar; Kaiser, Werner A

2009-04-01

The identification of the most suspect enhancing part of a lesion is regarded as a major diagnostic criterion in dynamic magnetic resonance mammography. Computer-aided diagnosis (CAD) software allows the semi-automatic analysis of the kinetic characteristics of complete enhancing lesions, providing additional information about lesion vasculature. The diagnostic value of this information has not yet been quantified. Consecutive patients from routine diagnostic studies (1.5 T, 0.1 mmol gadopentetate dimeglumine, dynamic gradient-echo sequences at 1-minute intervals) were analyzed prospectively using CAD. Dynamic sequences were processed and reduced to a parametric map. Curve types were classified by initial signal increase (not significant, intermediate, and strong) and the delayed time course of signal intensity (continuous, plateau, and washout). Lesion enhancement was measured using CAD. The most suspect curve, the curve-type distribution percentage, and combined dynamic data were compared. Statistical analysis included logistic regression analysis and receiver-operating characteristic analysis. Fifty-one patients with 46 malignant and 44 benign lesions were enrolled. On receiver-operating characteristic analysis, the most suspect curve showed diagnostic accuracy of 76.7 +/- 5%. In comparison, the curve-type distribution percentage demonstrated accuracy of 80.2 +/- 4.9%. Combined dynamic data had the highest diagnostic accuracy (84.3 +/- 4.2%). These differences did not achieve statistical significance. With appropriate cutoff values, sensitivity and specificity, respectively, were found to be 80.4% and 72.7% for the most suspect curve, 76.1% and 83.6% for the curve-type distribution percentage, and 78.3% and 84.5% for both parameters. The integration of whole-lesion dynamic data tends to improve specificity. However, no statistical significance backs up this finding.

[Meta-analysis of diagnostic capability of frequency-doubling technology (FDT) for primary glaucoma].

PubMed

Liu, Ting; He, Xiang-ge

2006-05-01

To evaluate the overall diagnostic capabilities of frequency-doubling technology (FDT) in patients of primary glaucoma, with standard automated perimetry (SAP) and/or optic disc appearance as the gold standard. A comprehensive electric search in MEDLINE, EMBASE, Cochrane Library, BIOSIS, Previews, HMIC, IPA, OVID, CNKI, CBMdisc, VIP information, CMCC, CCPD, SSreader and 21dmedia and a manual search in related textbooks, journals, congress articles and their references were performed to identify relevant English and Chinese language articles. Criteria for adaptability were established according to validity criteria for diagnostic research published by the Cochrane Methods Group on Screening and Diagnostic Tests. Quality of the included articles was assessed and relevant materials were extracted for studying. Statistical analysis was performed with Meta Test version 0.6 software. Heterogeneity of the included articles was tested, which was used to select appropriate effect model to calculate pooled weighted sensitivity and specificity. Summary Receiver Operating Characteristic (SROC) curve was established and the area under the curve (AUC) was calculated. Finally, sensitivity analysis was performed. Fifteen English articles (21 studies) of 206 retrieved articles were included in the present study, with a total of 3172 patients. The reported sensitivity of FDT ranged from 0.51 to 1.00, and specificity from 0.58 to 1.00. The pooled weighted sensitivity and specificity for FDT with 95% confidence intervals (95% CI) after correction for standard error were 0.86 (0.80 - 0.90), 0.87 (0.81 - 0.91), respectively. The AUC of SROC was 93.01%. Sensitivity analysis demonstrated no disproportionate influences of individual study. The included articles are of good quality and FDT can be a highly efficient diagnostic test for primary glaucoma based on Meta-analysis. However, a high quality perspective study is still required for further analysis.

Diagnosis of periprosthetic joint infection in Medicare patients: multicriteria decision analysis.

PubMed

Diaz-Ledezma, Claudio; Lichstein, Paul M; Dolan, James G; Parvizi, Javad

2014-11-01

In the setting of finite healthcare resources, developing cost-efficient strategies for periprosthetic joint infection (PJI) diagnosis is paramount. The current levels of knowledge allow for PJI diagnostic recommendations based on scientific evidence but do not consider the benefits, opportunities, costs, and risks of the different diagnostic alternatives. We determined the best diagnostic strategy for knee and hip PJI in the ambulatory setting for Medicare patients, utilizing benefits, opportunities, costs, and risks evaluation through multicriteria decision analysis (MCDA). The PJI diagnostic definition supported by the Musculoskeletal Infection Society was employed for the MCDA. Using a preclinical model, we evaluated three diagnostic strategies that can be conducted in a Medicare patient seen in the outpatient clinical setting complaining of a painful TKA or THA. Strategies were (1) screening with serum markers (erythrocyte sedimentation rate [ESR]/C-reactive protein [CRP]) followed by arthrocentesis in positive cases, (2) immediate arthrocentesis, and (3) serum markers requested simultaneously with arthrocentesis. MCDA was conducted through the analytic hierarchy process, comparing the diagnostic strategies in terms of benefits, opportunities, costs, and risks. Strategy 1 was the best alternative to diagnose knee PJI among Medicare patients (normalized value: 0.490), followed by Strategy 3 (normalized value: 0.403) and then Strategy 2 (normalized value: 0.106). The same ranking of alternatives was observed for the hip PJI model (normalized value: 0.487, 0.405, and 0.107, respectively). The sensitivity analysis found this sequence to be robust with respect to benefits, opportunities, and risks. However, if during the decision-making process, cost savings was given a priority of higher than 54%, the ranking for the preferred diagnostic strategy changed. After considering the benefits, opportunities, costs, and risks of the different available alternatives, our preclinical model supports the American Academy of Orthopaedic Surgeons recommendations regarding the use of serum markers (ESR/CRP) before arthrocentesis as the best diagnostic strategy for PJI among Medicare patients. Level II, economic and decision analysis. See Instructions to Authors for a complete description of levels of evidence.

ECM1 and TMPRSS4 Are Diagnostic Markers of Malignant Thyroid Neoplasms and Improve the Accuracy of Fine Needle Aspiration Biopsy

PubMed Central

Kebebew, Electron; Peng, Miao; Reiff, Emily; Duh, Quan-Yang; Clark, Orlo H.; McMillan, Alex

2005-01-01

Objective: The objective of this study was to determine whether genes that regulate cellular invasion and metastasis are differentially expressed and could serve as diagnostic markers of malignant thyroid nodules. Summary and Background Data: Patients whose thyroid nodules have indeterminate or suspicious cytologic features on fine needle aspiration (FNA) biopsy require thyroidectomy because of a 20% to 30% risk of thyroid cancer. Cell invasion and metastasis is a hallmark of malignant phenotype; therefore, genes that regulate these processes might be differentially expressed and could serve as diagnostic markers of malignancy. Methods: Differentially expressed genes (2-fold higher or lower) in malignant versus benign thyroid neoplasms were identified by extracellular matrix and adhesion molecule cDNA array analysis and confirmed by real-time quantitative polymerase chain reaction (PCR). The area under the receiver operating characteristic (AUC) curve was calculated to determine diagnostic accuracy of gene expression level cutoffs established by logistic regression analysis. Results: By cDNA array analysis, ADAMTS8, ECM1, MMP8, PLAU, SELP, and TMPRSS4 were upregulated, and by quantitative PCR, ECM1, SELP, and TMPRSS4 mRNA expression was higher in malignant (n = 57) than in benign (n = 38) thyroid neoplasms (P< 0.002). ECM1 and TMPRSS4 mRNA expression levels were independent predictors of a malignant thyroid neoplasm (P < 0.003). The AUC was 0.956 for ECM1 and 0.926 for TMPRSS4. Combining both markers improved their diagnostic use (AUC 0.985; sensitivity, 91.7%; specificity, 89.8%; positive predictive value, 85.7%; negative predictive value, 82.8%). ECM1 and TMPRSS4 expression analysis improved the diagnostic accuracy of FNA biopsy in 35 of 38 indeterminate or suspicious results. The level of ECM1 mRNA expression was higher in TNM stage I differentiated thyroid cancers than in stage II and III tumors (P ≤ 0.031). Conclusions: ECM1 and TMPRSS4 are excellent diagnostic markers of malignant thyroid nodules and may be used to improve the diagnostic accuracy of FNA biopsy. ECM1 is also a marker of the extent of disease in differentiated thyroid cancers. PMID:16135921

Definition of periprosthetic joint infection: is there a consensus?

PubMed

Parvizi, Javad; Jacovides, Christina; Zmistowski, Benjamin; Jung, Kwang Am

2011-11-01

The diagnosis of periprosthetic joint infection (PJI) continues to pose a challenge. While many diagnostic criteria have been proposed, a gold standard for diagnosis is lacking. Use of multiple diagnostic criteria within the joint arthroplasty community raises concerns in patient treatment and comparison of research pertaining to PJI. We (1) determined the variation in existing diagnostic criteria, (2) compared the existing criteria to a proposed new set of criteria that incorporates aspirate cell count analysis, and (3) investigated the variations between the existing criteria and the proposed criteria. We retrospectively identified 182 patients undergoing 192 revision knee arthroplasties who had a preoperative joint aspiration analysis at our institution between April 2002 and November 2009. We excluded 20 cases due to insufficient laboratory parameters, leaving 172 cases for analysis. We applied six previously published sets of diagnostic criteria for PJI to determine the variation in its incidence using each set of criteria. We then compared these diagnostic criteria to our proposed new criteria and investigated cases where disagreement occurred. We identified 41 cases (24%) in which at least one established criteria set classified the case as infected while at least one other criteria set classified the case as uninfected. With our proposed criteria, the infected/uninfected ratio was 92/80. The proposed criteria had a large variance in sensitivity (54%-100%), specificity (39%-100%), and accuracy (53%-100%) when using each of the established criteria sets as the reference standard. The discrepancy between definitions of infection complicates interpretation of the literature and the treatment of failed TKAs owing to PJI. Based on our findings, we suggest establishing a common set of diagnostic criteria utilizing aspirate analysis to improve the treatment of PJI and facilitate interpretation of the literature. Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Diagnostic reasoning strategies and diagnostic success.

PubMed

Coderre, S; Mandin, H; Harasym, P H; Fick, G H

2003-08-01

Cognitive psychology research supports the notion that experts use mental frameworks or "schemes", both to organize knowledge in memory and to solve clinical problems. The central purpose of this study was to determine the relationship between problem-solving strategies and the likelihood of diagnostic success. Think-aloud protocols were collected to determine the diagnostic reasoning used by experts and non-experts when attempting to diagnose clinical presentations in gastroenterology. Using logistic regression analysis, the study found that there is a relationship between diagnostic reasoning strategy and the likelihood of diagnostic success. Compared to hypothetico-deductive reasoning, the odds of diagnostic success were significantly greater when subjects used the diagnostic strategies of pattern recognition and scheme-inductive reasoning. Two other factors emerged as independent determinants of diagnostic success: expertise and clinical presentation. Not surprisingly, experts outperformed novices, while the content area of the clinical cases in each of the four clinical presentations demonstrated varying degrees of difficulty and thus diagnostic success. These findings have significant implications for medical educators. It supports the introduction of "schemes" as a means of enhancing memory organization and improving diagnostic success.

Applying Diagnostics to Enhance Cable System Reliability (Cable Diagnostic Focused Initiative, Phase II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartlein, Rick; Hampton, Nigel; Perkel, Josh

2016-02-01

The Cable Diagnostic Focused Initiative (CDFI) played a significant and powerful role in clarifying the concerns and understanding the benefits of performing diagnostic tests on underground power cable systems. This project focused on the medium and high voltage cable systems used in utility transmission and distribution (T&D) systems. While many of the analysis techniques and interpretations are applicable to diagnostics and cable systems outside of T&D, areas such as generating stations (nuclear, coal, wind, etc.) and other industrial environments were not the focus. Many large utilities in North America now deploy diagnostics or have changed their diagnostic testing approach asmore » a result of this project. Previous to the CDFI, different diagnostic technology providers individually promoted their approach as the “the best” or “the only” means of detecting cable system defects.« less

[Evaluation of diagnostic criteria of syphilitic infection by means of gas chromatography and mass-spectrometry].

PubMed

Vorob'ev, A A; Mironov, A Iu; Istratov, V G; Osman, K A

2005-01-01

In order to estimate possibility of chromatographic criteria application in diagnostics of syphilitic infection, the authors researched in three directions: evaluation of dysmetabolism of carbohydrate, lipid and amino acid components in patients' serum; search of signal compounds that serve as microbe "cooperative sensitivity" activators (lactones, quinolones, furan boron ethers) with evaluation of the risk of luetic infection generalization; indication of organ lesion markers (the brain, liver, bone structures). The factor analysis performed by the researchers allowed to determine priorities of clinical, laboratory and chromatographic data according to their value. The diagnostic value of various diagnostic chromatographic criteria was estimated as follows: the diagnostic sensitivity was 79.6% to 97.2%, the diagnostic specificity was 50.0% to 92.7%, the positive diagnostic predictability was 61.8% to 94.7% and the negative diagnostic predictability was 60.9% to 95.1%.

Assessing the effectiveness of problem-based learning in physical diagnostics education in China: a meta-analysis

PubMed Central

Wang, Jianmiao; Xu, Yongjian; Liu, Xiansheng; Xiong, Weining; Xie, Jungang; Zhao, Jianping

2016-01-01

Problem-based learning (PBL) has been extensively applied as an experimental educational method in Chinese medical schools over the past decade. A meta-analysis was performed to assess the effectiveness of PBL on students’ learning outcomes in physical diagnostics education. Related databases were searched for eligible studies evaluating the effects of PBL compared to traditional teaching on students’ knowledge and/or skill scores of physical diagnostics. Standardized mean difference (SMD) with 95% confidence interval (CI) was estimated. Thirteen studies with a total of 2086 medical students were included in this meta-analysis. All of these studies provided usable data on knowledge scores, and the pooled analysis showed a significant difference in favor of PBL compared to the traditional teaching (SMD = 0.76, 95%CI = 0.33–1.19). Ten studies provided usable data on skill scores, and a significant difference in favor of PBL was also observed (SMD = 1.46, 95%CI = 0.89–2.02). Statistically similar results were obtained in the sensitivity analysis, and there was no significant evidence of publication bias. These results suggested that PBL in physical diagnostics education in China appeared to be more effective than traditional teaching method in improving knowledge and skills. PMID:27808158

Assessing the effectiveness of problem-based learning in physical diagnostics education in China: a meta-analysis.

PubMed

Wang, Jianmiao; Xu, Yongjian; Liu, Xiansheng; Xiong, Weining; Xie, Jungang; Zhao, Jianping

2016-11-03

Problem-based learning (PBL) has been extensively applied as an experimental educational method in Chinese medical schools over the past decade. A meta-analysis was performed to assess the effectiveness of PBL on students' learning outcomes in physical diagnostics education. Related databases were searched for eligible studies evaluating the effects of PBL compared to traditional teaching on students' knowledge and/or skill scores of physical diagnostics. Standardized mean difference (SMD) with 95% confidence interval (CI) was estimated. Thirteen studies with a total of 2086 medical students were included in this meta-analysis. All of these studies provided usable data on knowledge scores, and the pooled analysis showed a significant difference in favor of PBL compared to the traditional teaching (SMD = 0.76, 95%CI = 0.33-1.19). Ten studies provided usable data on skill scores, and a significant difference in favor of PBL was also observed (SMD = 1.46, 95%CI = 0.89-2.02). Statistically similar results were obtained in the sensitivity analysis, and there was no significant evidence of publication bias. These results suggested that PBL in physical diagnostics education in China appeared to be more effective than traditional teaching method in improving knowledge and skills.

Diagnostic value of blood-derived microRNAs for schizophrenia: results of a meta-analysis and validation.

PubMed

Liu, Sha; Zhang, Fuquan; Wang, Xijin; Shugart, Yin Yao; Zhao, Yingying; Li, Xinrong; Liu, Zhifen; Sun, Ning; Yang, Chunxia; Zhang, Kerang; Yue, Weihua; Yu, Xin; Xu, Yong

2017-11-10

There is an increasing interest in searching biomarkers for schizophrenia (SZ) diagnosis, which overcomes the drawbacks inherent with the subjective diagnostic methods. MicroRNA (miRNA) fingerprints have been explored for disease diagnosis. We performed a meta-analysis to examine miRNA diagnostic value for SZ and further validated the meta-analysis results. Using following terms: schizophrenia/SZ, microRNA/miRNA, diagnosis, sensitivity and specificity, we searched databases restricted to English language and reviewed all articles published from January 1990 to October 2016. All extracted data were statistically analyzed and the results were further validated with peripheral blood mononuclear cells (PBMNCs) isolated from patients and healthy controls using RT-qPCR and receiver operating characteristic (ROC) analysis. A total of 6 studies involving 330 patients and 202 healthy controls were included for meta-analysis. The pooled sensitivity, specificity and diagnostic odds ratio were 0.81 (95% CI: 0.75-0.86), 0.81 (95% CI: 0.72-0.88) and 18 (95% CI: 9-34), respectively; the positive and negative likelihood ratio was 4.3 and 0.24 respectively; the area under the curve in summary ROC was 0.87 (95% CI: 0.84-0.90). Validation revealed that miR-181b-5p, miR-21-5p, miR-195-5p, miR-137, miR-346 and miR-34a-5p in PBMNCs had high diagnostic sensitivity and specificity in the context of schizophrenia. In conclusion, blood-derived miRNAs might be promising biomarkers for SZ diagnosis.

Improved Diagnostic Accuracy of SPECT Through Statistical Analysis and the Detection of Hot Spots at the Primary Sensorimotor Area for the Diagnosis of Alzheimer Disease in a Community-Based Study: "The Osaki-Tajiri Project".

PubMed

Kaneta, Tomohiro; Nakatsuka, Masahiro; Nakamura, Kei; Seki, Takashi; Yamaguchi, Satoshi; Tsuboi, Masahiro; Meguro, Kenichi

2016-01-01

SPECT is an important diagnostic tool for dementia. Recently, statistical analysis of SPECT has been commonly used for dementia research. In this study, we evaluated the accuracy of visual SPECT evaluation and/or statistical analysis for the diagnosis (Dx) of Alzheimer disease (AD) and other forms of dementia in our community-based study "The Osaki-Tajiri Project." Eighty-nine consecutive outpatients with dementia were enrolled and underwent brain perfusion SPECT with 99mTc-ECD. Diagnostic accuracy of SPECT was tested using 3 methods: visual inspection (SPECT Dx), automated diagnostic tool using statistical analysis with easy Z-score imaging system (eZIS Dx), and visual inspection plus eZIS (integrated Dx). Integrated Dx showed the highest sensitivity, specificity, and accuracy, whereas eZIS was the second most accurate method. We also observed that a higher than expected rate of SPECT images indicated false-negative cases of AD. Among these, 50% showed hypofrontality and were diagnosed as frontotemporal lobar degeneration. These cases typically showed regional "hot spots" in the primary sensorimotor cortex (ie, a sensorimotor hot spot sign), which we determined were associated with AD rather than frontotemporal lobar degeneration. We concluded that the diagnostic abilities were improved by the integrated use of visual assessment and statistical analysis. In addition, the detection of a sensorimotor hot spot sign was useful to detect AD when hypofrontality is present and improved the ability to properly diagnose AD.

Whole Genome Sequencing Increases Molecular Diagnostic Yield Compared with Current Diagnostic Testing for Inherited Retinal Disease.

PubMed

Ellingford, Jamie M; Barton, Stephanie; Bhaskar, Sanjeev; Williams, Simon G; Sergouniotis, Panagiotis I; O'Sullivan, James; Lamb, Janine A; Perveen, Rahat; Hall, Georgina; Newman, William G; Bishop, Paul N; Roberts, Stephen A; Leach, Rick; Tearle, Rick; Bayliss, Stuart; Ramsden, Simon C; Nemeth, Andrea H; Black, Graeme C M

2016-05-01

To compare the efficacy of whole genome sequencing (WGS) with targeted next-generation sequencing (NGS) in the diagnosis of inherited retinal disease (IRD). Case series. A total of 562 patients diagnosed with IRD. We performed a direct comparative analysis of current molecular diagnostics with WGS. We retrospectively reviewed the findings from a diagnostic NGS DNA test for 562 patients with IRD. A subset of 46 of 562 patients (encompassing potential clinical outcomes of diagnostic analysis) also underwent WGS, and we compared mutation detection rates and molecular diagnostic yields. In addition, we compared the sensitivity and specificity of the 2 techniques to identify known single nucleotide variants (SNVs) using 6 control samples with publically available genotype data. Diagnostic yield of genomic testing. Across known disease-causing genes, targeted NGS and WGS achieved similar levels of sensitivity and specificity for SNV detection. However, WGS also identified 14 clinically relevant genetic variants through WGS that had not been identified by NGS diagnostic testing for the 46 individuals with IRD. These variants included large deletions and variants in noncoding regions of the genome. Identification of these variants confirmed a molecular diagnosis of IRD for 11 of the 33 individuals referred for WGS who had not obtained a molecular diagnosis through targeted NGS testing. Weighted estimates, accounting for population structure, suggest that WGS methods could result in an overall 29% (95% confidence interval, 15-45) uplift in diagnostic yield. We show that WGS methods can detect disease-causing genetic variants missed by current NGS diagnostic methodologies for IRD and thereby demonstrate the clinical utility and additional value of WGS. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

How do gut feelings feature in tutorial dialogues on diagnostic reasoning in GP traineeship?

PubMed

Stolper, C F; Van de Wiel, M W J; Hendriks, R H M; Van Royen, P; Van Bokhoven, M A; Van der Weijden, T; Dinant, G J

2015-05-01

Diagnostic reasoning is considered to be based on the interaction between analytical and non-analytical cognitive processes. Gut feelings, a specific form of non-analytical reasoning, play a substantial role in diagnostic reasoning by general practitioners (GPs) and may activate analytical reasoning. In GP traineeships in the Netherlands, trainees mostly see patients alone but regularly consult with their supervisors to discuss patients and problems, receive feedback, and improve their competencies. In the present study, we examined the discussions of supervisors and their trainees about diagnostic reasoning in these so-called tutorial dialogues and how gut feelings feature in these discussions. 17 tutorial dialogues focussing on diagnostic reasoning were video-recorded and transcribed and the protocols were analysed using a detailed bottom-up and iterative content analysis and coding procedure. The dialogues were segmented into quotes. Each quote received a content code and a participant code. The number of words per code was used as a unit of analysis to quantitatively compare the contributions to the dialogues made by supervisors and trainees, and the attention given to different topics. The dialogues were usually analytical reflections on a trainee's diagnostic reasoning. A hypothetico-deductive strategy was often used, by listing differential diagnoses and discussing what information guided the reasoning process and might confirm or exclude provisional hypotheses. Gut feelings were discussed in seven dialogues. They were used as a tool in diagnostic reasoning, inducing analytical reflection, sometimes on the entire diagnostic reasoning process. The emphasis in these tutorial dialogues was on analytical components of diagnostic reasoning. Discussing gut feelings in tutorial dialogues seems to be a good educational method to familiarize trainees with non-analytical reasoning. Supervisors need specialised knowledge about these aspects of diagnostic reasoning and how to deal with them in medical education.

Diagnostic accuracy of magnetic resonance imaging techniques for treatment response evaluation in patients with high-grade glioma, a systematic review and meta-analysis.

PubMed

van Dijken, Bart R J; van Laar, Peter Jan; Holtman, Gea A; van der Hoorn, Anouk

2017-10-01

Treatment response assessment in high-grade gliomas uses contrast enhanced T1-weighted MRI, but is unreliable. Novel advanced MRI techniques have been studied, but the accuracy is not well known. Therefore, we performed a systematic meta-analysis to assess the diagnostic accuracy of anatomical and advanced MRI for treatment response in high-grade gliomas. Databases were searched systematically. Study selection and data extraction were done by two authors independently. Meta-analysis was performed using a bivariate random effects model when ≥5 studies were included. Anatomical MRI (five studies, 166 patients) showed a pooled sensitivity and specificity of 68% (95%CI 51-81) and 77% (45-93), respectively. Pooled apparent diffusion coefficients (seven studies, 204 patients) demonstrated a sensitivity of 71% (60-80) and specificity of 87% (77-93). DSC-perfusion (18 studies, 708 patients) sensitivity was 87% (82-91) with a specificity of 86% (77-91). DCE-perfusion (five studies, 207 patients) sensitivity was 92% (73-98) and specificity was 85% (76-92). The sensitivity of spectroscopy (nine studies, 203 patients) was 91% (79-97) and specificity was 95% (65-99). Advanced techniques showed higher diagnostic accuracy than anatomical MRI, the highest for spectroscopy, supporting the use in treatment response assessment in high-grade gliomas. • Treatment response assessment in high-grade gliomas with anatomical MRI is unreliable • Novel advanced MRI techniques have been studied, but diagnostic accuracy is unknown • Meta-analysis demonstrates that advanced MRI showed higher diagnostic accuracy than anatomical MRI • Highest diagnostic accuracy for spectroscopy and perfusion MRI • Supports the incorporation of advanced MRI in high-grade glioma treatment response assessment.

Method of Testing and Predicting Failures of Electronic Mechanical Systems

NASA Technical Reports Server (NTRS)

Iverson, David L.; Patterson-Hine, Frances A.

1996-01-01

A method employing a knowledge base of human expertise comprising a reliability model analysis implemented for diagnostic routines is disclosed. The reliability analysis comprises digraph models that determine target events created by hardware failures human actions, and other factors affecting the system operation. The reliability analysis contains a wealth of human expertise information that is used to build automatic diagnostic routines and which provides a knowledge base that can be used to solve other artificial intelligence problems.

Capsule Endoscopy in the Assessment of Obscure Gastrointestinal Bleeding: An Evidence-Based Analysis

PubMed Central

2015-01-01

Background Obscure gastrointestinal bleeding (OGIB) is defined as persistent or recurrent bleeding associated with negative findings on upper and lower gastrointestinal (GI) endoscopic evaluations. The diagnosis and management of patients with OGIB is particularly challenging because of the length and complex loops of the small intestine. Capsule endoscopy (CE) is 1 diagnostic modality that is used to determine the etiology of bleeding. Objectives The objective of this analysis was to review the diagnostic accuracy, safety, and impact on health outcomes of CE in patients with OGIB in comparison with other diagnostic modalities. Data Sources A literature search was performed using Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid Embase, the Wiley Cochrane Library, and the Centre for Reviews and Dissemination database, for studies published between 2007 and 2013. Review Methods Data on diagnostic accuracy, safety, and impact on health outcomes were abstracted from included studies. Quality of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Results The search yielded 1,189 citations, and 24 studies were included. Eight studies reported diagnostic accuracy comparing CE with other diagnostic modalities. Capsule endoscopy has a higher sensitivity and lower specificity than magnetic resonance enteroclysis, computed tomography, and push enteroscopy. Capsule endoscopy has a good safety profile with few adverse events, although comparative safety data with other diagnostic modalities are limited. Capsule endoscopy is associated with no difference in patient health-related outcomes such as rebleeding or follow-up treatment compared with push enteroscopy, small-bowel follow-through, and angiography. Limitations There was significant heterogeneity in estimates of diagnostic accuracy, which prohibited a statistical summary of findings. The analysis was also limited by the fact that there is no established reference standard to which the diagnostic accuracy of CE can be compared. Conclusions There is very-low-quality evidence that CE has a higher sensitivity but a lower specificity than other diagnostic modalities. Capsule endoscopy has few adverse events, with capsule retention being the most serious complication. Capsule endoscopy is perceived by patients as less painful and less burdensome compared with other modalities. There is low-quality evidence that patients who undergo CE have similar rates of rebleeding, further therapeutic interventions, and hospitalization compared with other diagnostic modalities. PMID:26357529

Development and Application of a Two-Tier Multiple Choice Diagnostic Instrument To Assess High School Students' Understanding of Inorganic Chemistry Qualitative Analysis.

ERIC Educational Resources Information Center

Tan, Kim Chwee Daniel; Goh, Ngoh Khang; Chia, Lian Sai; Treagust, David F.

2002-01-01

Describes the development and application of a two-tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis. Shows that the Grade 10 students had difficulty understanding the reactions involved in the identification of cations and anions, for example, double decomposition…

Diagnostic Yield of Chromosomal Microarray Analysis in a Cohort of Patients with Autism Spectrum Disorders from a Highly Consanguineous Population

ERIC Educational Resources Information Center

Al-Mamari, Watfa; Al-Saegh, Abeer; Al-Kindy, Adila; Bruwer, Zandre; Al-Murshedi, Fathiya; Al-Thihli, Khalid

2015-01-01

Autism Spectrum Disorders are a complicated group of disorders characterized with heterogeneous genetic etiologies. The genetic investigations for this group of disorders have expanded considerably over the past decade. In our study we designed a tired approach and studied the diagnostic yield of chromosomal microarray analysis on patients…

Diagnostic Performance of Narrow Band Imaging for Laryngeal Cancer: A Systematic Review and Meta-analysis.

PubMed

Sun, Changling; Han, Xue; Li, Xiaoying; Zhang, Yayun; Du, Xiaodong

2017-04-01

Objective To evaluate the performance of narrow band imaging (NBI) for the diagnosis of laryngeal cancer and to compare the diagnostic value of NBI with that of white light endoscopy. Data Sources PubMed, Embase, Cochrane Library, and CNKI databases. Review Methods Data analyses were performed with Meta-DiSc. The updated Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess study quality and potential bias. Publication bias was assessed with the Deeks's asymmetry test. The protocol used in this article has been published on PROSPERO and is in accordance with the PRISMA checklist. The registry number for this study is CRD42015025866. Results Six studies including 716 lesions were included in this meta-analysis. The pooled sensitivity, specificity, and diagnostic odds ratio for the NBI diagnosis of laryngeal cancer were 0.94 (95% confidence interval [95% CI]: 0.91-0.96), 0.89 (95% CI: 0.85-0.92), and 142.12 (95% CI: 46.42-435.15), respectively, and the area under receiver operating characteristics curve was 0.97. Among the 6 studies, 3 evaluated the diagnostic value of white light endoscopy, with a sensitivity of 0.81 (95% CI: 0.76-0.86), a specificity of 0.92 (95% CI: 0.88-0.95), and a diagnostic odds ratio of 33.82 (95% CI: 14.76-77.49). The evaluation of heterogeneity, calculated per the diagnostic odds ratio, gave an I 2 of 66%. No marked publication bias ( P = .84) was detected in this meta-analysis. Conclusion The sensitivity of NBI is superior to white light endoscopy, and the potential value of NBI needs to be validated in future studies.

Evaluation of spectral domain optical coherence tomography parameters in ocular hypertension, preperimetric, and early glaucoma

PubMed Central

Aydoğan, Tuğba; Akçay, Betül İlkay Sezgin; Kardeş, Esra; Ergin, Ahmet

2017-01-01

Purpose: The objective of this study is to evaluate the diagnostic ability of retinal nerve fiber layer (RNFL), macular, optic nerve head (ONH) parameters in healthy subjects, ocular hypertension (OHT), preperimetric glaucoma (PPG), and early glaucoma (EG) patients, to reveal factors affecting the diagnostic ability of spectral domain-optical coherence tomography (SD-OCT) parameters and risk factors for glaucoma. Methods: Three hundred and twenty-six eyes (89 healthy, 77 OHT, 94 PPG, and 66 EG eyes) were analyzed. RNFL, macular, and ONH parameters were measured with SD-OCT. The area under the receiver operating characteristic curve (AUC) and sensitivity at 95% specificity was calculated. Logistic regression analysis was used to determine the glaucoma risk factors. Receiver operating characteristic regression analysis was used to evaluate the influence of covariates on the diagnostic ability of parameters. Results: In PPG patients, parameters that had the largest AUC value were average RNFL thickness (0.83) and rim volume (0.83). In EG patients, parameter that had the largest AUC value was average RNFL thickness (0.98). The logistic regression analysis showed average RNFL thickness was a risk factor for both PPG and EG. Diagnostic ability of average RNFL and average ganglion cell complex thickness increased as disease severity increased. Signal strength index did not affect diagnostic abilities. Diagnostic ability of average RNFL and rim area increased as disc area increased. Conclusion: When evaluating patients with glaucoma, patients at risk for glaucoma, and healthy controls RNFL parameters deserve more attention in clinical practice. Further studies are needed to fully understand the influence of covariates on the diagnostic ability of OCT parameters. PMID:29133640

Diagnostic ability of macular ganglion cell asymmetry for glaucoma.

PubMed

Hwang, Young Hoon; Ahn, Sang Il; Ko, Sung Ju

2015-11-01

Using spectral-domain optical coherence tomography (OCT), this study aims to investigate the glaucoma diagnostic ability of macular ganglion cell asymmetry analysis. A cross-sectional study was conducted. This study was performed to investigate glaucoma diagnostic ability of macular ganglion cell asymmetry analysis in eyes with various degrees of glaucoma. We enrolled 181 healthy eyes and 265 glaucomatous eyes. Glaucomatous eyes were subdivided into pre-perimetric, early, moderate and advanced-to-severe glaucoma based on visual field test results. For each eye, macular ganglion cell-inner plexiform layer (GCIPL) thickness was measured using OCT. Average GCIPL thickness, GCIPL thicknesses in superior and inferior hemispheres, absolute difference in GCIPL thickness between superior and inferior hemispheres and GCIPL asymmetry index calculated as the absolute value of log10 (inferior hemisphere thickness/superior hemisphere thickness) were analysed. Areas under the receiver operating characteristics curves (AUCs) of GCIPL parameter were calculated and compared. All of the GCIPL parameters showed good glaucoma diagnostic ability (AUCs ≥ 0.817, P < 0.01). AUCs of average, superior and inferior GCIPL thickness increased as the severity of glaucoma increased. GCIPL thickness difference and asymmetry index showed the highest AUCs in early and moderate glaucoma and lower AUCs in pre-perimetric and advanced-to-severe glaucoma. GCIPL thickness difference and asymmetry index showed better glaucoma diagnostic ability than other GCIPL parameters only in early stage of glaucoma (P < 0.05); in other stages, these parameters had similar to or worse glaucoma diagnostic ability than other GCIPL parameters. Macular ganglion cell asymmetry analysis showed good glaucoma diagnostic ability, especially in early-stage glaucoma. However, it has limited usefulness in other stages of glaucoma. © 2015 Royal Australian and New Zealand College of Ophthalmologists.

The Effects of Diagnostic Definitions in Claims Data on Healthcare Cost Estimates: Evidence from a Large-Scale Panel Data Analysis of Diabetes Care in Japan.

PubMed

Fukuda, Haruhisa; Ikeda, Shunya; Shiroiwa, Takeru; Fukuda, Takashi

2016-10-01

Inaccurate estimates of diabetes-related healthcare costs can undermine the efficiency of resource allocation for diabetes care. The quantification of these costs using claims data may be affected by the method for defining diagnoses. The aims were to use panel data analysis to estimate diabetes-related healthcare costs and to comparatively evaluate the effects of diagnostic definitions on cost estimates. Monthly panel data analysis of Japanese claims data. The study included a maximum of 141,673 patients with type 2 diabetes who received treatment between 2005 and 2013. Additional healthcare costs associated with diabetes and diabetes-related complications were estimated for various diagnostic definition methods using fixed-effects panel data regression models. The average follow-up period per patient ranged from 49.4 to 52.3 months. The number of patients identified as having type 2 diabetes varied widely among the diagnostic definition methods, ranging from 14,743 patients to 141,673 patients. The fixed-effects models showed that the additional costs per patient per month associated with diabetes ranged from US$180 [95 % confidence interval (CI) 178-181] to US$223 (95 % CI 221-224). When the diagnostic definition excluded rule-out diagnoses, the diabetes-related complications associated with higher additional healthcare costs were ischemic heart disease with surgery (US$13,595; 95 % CI 13,568-13,622), neuropathy/extremity disease with surgery (US$4594; 95 % CI 3979-5208), and diabetic nephropathy with dialysis (US$3689; 95 % CI 3667-3711). Diabetes-related healthcare costs are sensitive to diagnostic definition methods. Determining appropriate diagnostic definitions can further advance healthcare cost research for diabetes and its applications in healthcare policies.

Effect of routine diagnostic imaging for patients with musculoskeletal disorders: A meta-analysis.

PubMed

Karel, Yasmaine H J M; Verkerk, Karin; Endenburg, Silvio; Metselaar, Sven; Verhagen, Arianne P

2015-10-01

The increasing use of diagnostic imaging has led to high expenditures, unnecessary invasive procedures and/or false-positive diagnoses, without certainty that the patients actually benefit from these imaging procedures. This review explores whether diagnostic imaging leads to better patient-reported outcomes in individuals with musculoskeletal disorders. Databases were searched from inception to September 2013, together with scrutiny of selected bibliographies. Trials were eligible when: 1) a diagnostic imaging procedure was compared with any control group not getting or not receiving the results of imaging; 2) the population included individuals suffering from musculoskeletal disorders, and 3) if patient-reported outcomes were available. Primary outcome measures were pain and function. Secondary outcome measures were satisfaction and quality of life. Subgroup analysis was done for different musculoskeletal complaints and high technological medical imaging (MRI/CT). Eleven trials were eligible. The effects of diagnostic imaging were only evaluated in patients with low back pain (n=7) and knee complaints (n=4). Overall, there was a moderate level of evidence for no benefit of diagnostic imaging on all outcomes compared with controls. A significant but clinically irrelevant effect was found in favor of no (routine) imaging in low back pain patients in terms of pain severity at short [SMD 0.17 (0.04-0.31)] and long-term follow-up [SMD 0.13 (0.02-0.24)], and for overall improvement [RR 1.15 (1.03-1.28)]. Subgroup analysis did not significantly change these results. These results strengthen the available evidence that routine referral to diagnostic imaging by general practitioners for patients with knee and low back pain yields little to no benefit. Copyright © 2015 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

A meta-analysis of use of Prostate Imaging Reporting and Data System Version 2 (PI-RADS V2) with multiparametric MR imaging for the detection of prostate cancer.

PubMed

Zhang, Li; Tang, Min; Chen, Sipan; Lei, Xiaoyan; Zhang, Xiaoling; Huan, Yi

2017-12-01

This meta-analysis was undertaken to review the diagnostic accuracy of PI-RADS V2 for prostate cancer (PCa) detection with multiparametric MR (mp-MR). A comprehensive literature search of electronic databases was performed by two observers independently. Inclusion criteria were original research using the PI-RADS V2 system in reporting prostate MRI. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Data necessary to complete 2 × 2 contingency tables were obtained from the included studies. Thirteen studies (2,049 patients) were analysed. This is an initial meta-analysis of PI-RADs V2 and the overall diagnostic accuracy in diagnosing PCa was as follows: pooled sensitivity, 0.85 (0.78-0.91); pooled specificity, 0.71 (0.60-0.80); pooled positive likelihood ratio (LR+), 2.92 (2.09-4.09); pooled negative likelihood ratio (LR-), 0.21 (0.14-0.31); pooled diagnostic odds ratio (DOR), 14.08 (7.93-25.01), respectively. Positive predictive values ranged from 0.54 to 0.97 and negative predictive values ranged from 0.26 to 0.92. Currently available evidence indicates that PI-RADS V2 appears to have good diagnostic accuracy in patients with PCa lesions with high sensitivity and moderate specificity. However, no recommendation regarding the best threshold can be provided because of heterogeneity. • PI-RADS V2 shows good diagnostic accuracy for PCa detection. • Initially pooled specificity of PI-RADS v2 remains moderate. • PCa detection is increased by experienced radiologists. • There is currently a high heterogeneity in prostate diagnostics with MRI.

Accuracy of stroke volume variation in predicting fluid responsiveness: a systematic review and meta-analysis.

PubMed

Zhang, Zhongheng; Lu, Baolong; Sheng, Xiaoyan; Jin, Ni

2011-12-01

Stroke volume variation (SVV) appears to be a good predictor of fluid responsiveness in critically ill patients. However, a wide range of its predictive values has been reported in recent years. We therefore undertook a systematic review and meta-analysis of clinical trials that investigated the diagnostic value of SVV in predicting fluid responsiveness. Clinical investigations were identified from several sources, including MEDLINE, EMBASE, WANFANG, and CENTRAL. Original articles investigating the diagnostic value of SVV in predicting fluid responsiveness were considered to be eligible. Participants included critically ill patients in the intensive care unit (ICU) or operating room (OR) who require hemodynamic monitoring. A total of 568 patients from 23 studies were included in our final analysis. Baseline SVV was correlated to fluid responsiveness with a pooled correlation coefficient of 0.718. Across all settings, we found a diagnostic odds ratio of 18.4 for SVV to predict fluid responsiveness at a sensitivity of 0.81 and specificity of 0.80. The SVV was of diagnostic value for fluid responsiveness in OR or ICU patients monitored with the PiCCO or the FloTrac/Vigileo system, and in patients ventilated with tidal volume greater than 8 ml/kg. SVV is of diagnostic value in predicting fluid responsiveness in various settings.

Digital Pathology: Data-Intensive Frontier in Medical Imaging

PubMed Central

Cooper, Lee A. D.; Carter, Alexis B.; Farris, Alton B.; Wang, Fusheng; Kong, Jun; Gutman, David A.; Widener, Patrick; Pan, Tony C.; Cholleti, Sharath R.; Sharma, Ashish; Kurc, Tahsin M.; Brat, Daniel J.; Saltz, Joel H.

2013-01-01

Pathology is a medical subspecialty that practices the diagnosis of disease. Microscopic examination of tissue reveals information enabling the pathologist to render accurate diagnoses and to guide therapy. The basic process by which anatomic pathologists render diagnoses has remained relatively unchanged over the last century, yet advances in information technology now offer significant opportunities in image-based diagnostic and research applications. Pathology has lagged behind other healthcare practices such as radiology where digital adoption is widespread. As devices that generate whole slide images become more practical and affordable, practices will increasingly adopt this technology and eventually produce an explosion of data that will quickly eclipse the already vast quantities of radiology imaging data. These advances are accompanied by significant challenges for data management and storage, but they also introduce new opportunities to improve patient care by streamlining and standardizing diagnostic approaches and uncovering disease mechanisms. Computer-based image analysis is already available in commercial diagnostic systems, but further advances in image analysis algorithms are warranted in order to fully realize the benefits of digital pathology in medical discovery and patient care. In coming decades, pathology image analysis will extend beyond the streamlining of diagnostic workflows and minimizing interobserver variability and will begin to provide diagnostic assistance, identify therapeutic targets, and predict patient outcomes and therapeutic responses. PMID:25328166

Dental and dental hygiene students' diagnostic accuracy in oral radiology: effect of diagnostic strategy and instructional method.

PubMed

Baghdady, Mariam T; Carnahan, Heather; Lam, Ernest W N; Woods, Nicole N

2014-09-01

There has been much debate surrounding diagnostic strategies and the most appropriate training models for novices in oral radiology. It has been argued that an analytic approach, using a step-by-step analysis of the radiographic features of an abnormality, is ideal. Alternative research suggests that novices can successfully employ non-analytic reasoning. Many of these studies do not take instructional methodology into account. This study evaluated the effectiveness of non-analytic and analytic strategies in radiographic interpretation and explored the relationship between instructional methodology and diagnostic strategy. Second-year dental and dental hygiene students were taught four radiographic abnormalities using basic science instructions or a step-by-step algorithm. The students were tested on diagnostic accuracy and memory immediately after learning and one week later. A total of seventy-three students completed both immediate and delayed sessions and were included in the analysis. Students were randomly divided into two instructional conditions: one group provided a diagnostic hypothesis for the image and then identified specific features to support it, while the other group first identified features and then provided a diagnosis. Participants in the diagnosis-first condition (non-analytic reasoning) had higher diagnostic accuracy then those in the features-first condition (analytic reasoning), regardless of their learning condition. No main effect of learning condition or interaction with diagnostic strategy was observed. Educators should be mindful of the potential influence of analytic and non-analytic approaches on the effectiveness of the instructional method.

Impact of CT perfusion imaging on the assessment of peripheral chronic pulmonary thromboembolism: clinical experience in 62 patients.

PubMed

Le Faivre, Julien; Duhamel, Alain; Khung, Suonita; Faivre, Jean-Baptiste; Lamblin, Nicolas; Remy, Jacques; Remy-Jardin, Martine

2016-11-01

To evaluate the impact of CT perfusion imaging on the detection of peripheral chronic pulmonary embolisms (CPE). 62 patients underwent a dual-energy chest CT angiographic examination with (a) reconstruction of diagnostic and perfusion images; (b) enabling depiction of vascular features of peripheral CPE on diagnostic images and perfusion defects (20 segments/patient; total: 1240 segments examined). The interpretation of diagnostic images was of two types: (a) standard (i.e., based on cross-sectional images alone) or (b) detailed (i.e., based on cross-sectional images and MIPs). The segment-based analysis showed (a) 1179 segments analyzable on both imaging modalities and 61 segments rated as nonanalyzable on perfusion images; (b) the percentage of diseased segments was increased by 7.2 % when perfusion imaging was compared to the detailed reading of diagnostic images, and by 26.6 % when compared to the standard reading of images. At a patient level, the extent of peripheral CPE was higher on perfusion imaging, with a greater impact when compared to the standard reading of diagnostic images (number of patients with a greater number of diseased segments: n = 45; 72.6 % of the study population). Perfusion imaging allows recognition of a greater extent of peripheral CPE compared to diagnostic imaging. • Dual-energy computed tomography generates standard diagnostic imaging and lung perfusion analysis. • Depiction of CPE on central arteries relies on standard diagnostic imaging. • Detection of peripheral CPE is improved by perfusion imaging.

Radiation effects in IFMIF Li target diagnostic systems

NASA Astrophysics Data System (ADS)

Molla, J.; Vila, R.; Shikama, T.; Horiike, H.; Simakov, S.; Ciotti, M.; Ibarra, A.

2009-04-01

Diagnostics for the lithium target will be crucial for the operation of IFMIF. Several parameters as the lithium temperature, target thickness or wave pattern must be monitored during operation. Radiation effects may produce malfunctioning in any of these diagnostics due to the exposure to high radiation fields. The main diagnostic systems proposed for the operation of IFMIF are reviewed in this paper from the point of view of radiation damage. The main tools for the assessment of the performance of these diagnostics are the neutronics calculations by using specialised codes and the information accumulated during the last decades on the radiation effects in functional materials, components and diagnostics for ITER. This analysis allows to conclude that the design of some of the diagnostic systems must be revised to assure the high availability required for the target system.

Bayesian multivariate hierarchical transformation models for ROC analysis.

PubMed

O'Malley, A James; Zou, Kelly H

2006-02-15

A Bayesian multivariate hierarchical transformation model (BMHTM) is developed for receiver operating characteristic (ROC) curve analysis based on clustered continuous diagnostic outcome data with covariates. Two special features of this model are that it incorporates non-linear monotone transformations of the outcomes and that multiple correlated outcomes may be analysed. The mean, variance, and transformation components are all modelled parametrically, enabling a wide range of inferences. The general framework is illustrated by focusing on two problems: (1) analysis of the diagnostic accuracy of a covariate-dependent univariate test outcome requiring a Box-Cox transformation within each cluster to map the test outcomes to a common family of distributions; (2) development of an optimal composite diagnostic test using multivariate clustered outcome data. In the second problem, the composite test is estimated using discriminant function analysis and compared to the test derived from logistic regression analysis where the gold standard is a binary outcome. The proposed methodology is illustrated on prostate cancer biopsy data from a multi-centre clinical trial.

Bayesian multivariate hierarchical transformation models for ROC analysis

PubMed Central

O'Malley, A. James; Zou, Kelly H.

2006-01-01

SUMMARY A Bayesian multivariate hierarchical transformation model (BMHTM) is developed for receiver operating characteristic (ROC) curve analysis based on clustered continuous diagnostic outcome data with covariates. Two special features of this model are that it incorporates non-linear monotone transformations of the outcomes and that multiple correlated outcomes may be analysed. The mean, variance, and transformation components are all modelled parametrically, enabling a wide range of inferences. The general framework is illustrated by focusing on two problems: (1) analysis of the diagnostic accuracy of a covariate-dependent univariate test outcome requiring a Box–Cox transformation within each cluster to map the test outcomes to a common family of distributions; (2) development of an optimal composite diagnostic test using multivariate clustered outcome data. In the second problem, the composite test is estimated using discriminant function analysis and compared to the test derived from logistic regression analysis where the gold standard is a binary outcome. The proposed methodology is illustrated on prostate cancer biopsy data from a multi-centre clinical trial. PMID:16217836

Meta-analysis of diagnostic accuracy studies accounting for disease prevalence: alternative parameterizations and model selection.

PubMed

Chu, Haitao; Nie, Lei; Cole, Stephen R; Poole, Charles

2009-08-15

In a meta-analysis of diagnostic accuracy studies, the sensitivities and specificities of a diagnostic test may depend on the disease prevalence since the severity and definition of disease may differ from study to study due to the design and the population considered. In this paper, we extend the bivariate nonlinear random effects model on sensitivities and specificities to jointly model the disease prevalence, sensitivities and specificities using trivariate nonlinear random-effects models. Furthermore, as an alternative parameterization, we also propose jointly modeling the test prevalence and the predictive values, which reflect the clinical utility of a diagnostic test. These models allow investigators to study the complex relationship among the disease prevalence, sensitivities and specificities; or among test prevalence and the predictive values, which can reveal hidden information about test performance. We illustrate the proposed two approaches by reanalyzing the data from a meta-analysis of radiological evaluation of lymph node metastases in patients with cervical cancer and a simulation study. The latter illustrates the importance of carefully choosing an appropriate normality assumption for the disease prevalence, sensitivities and specificities, or the test prevalence and the predictive values. In practice, it is recommended to use model selection techniques to identify a best-fitting model for making statistical inference. In summary, the proposed trivariate random effects models are novel and can be very useful in practice for meta-analysis of diagnostic accuracy studies. Copyright 2009 John Wiley & Sons, Ltd.

Noninvasive express diagnostics of pulmonary diseases based on control of patient's gas emission using methods of IR and terahertz laser spectroscopy

NASA Astrophysics Data System (ADS)

Starikova, M. K.; Bulanova, A. A.; Bukreeva, E. B.; Karapuzikov, A. A.; Karapuzikov, A. I.; Kistenev, Y. V.; Klementyev, V. M.; Kolker, D. B.; Kuzmin, D. A.; Nikiforova, O. Y.; Ponomarev, Yu. N.; Sherstov, I. V.; Boyko, A. A.

2013-11-01

Pulmonary diseases diagnostics always occupies one of the key positions in medicine practices. A large variety of high technology methods are used today, but none of them cannot be used for early screening of pulmonary diseases. We discuss abilities of methods of IR and terahertz laser spectroscopy for noninvasive express diagnostics of pulmonary diseases on a base of analysis of absorption spectra of patient's gas emission, in particular, exhaled air. Experience in the field of approaches to experimental data analysis and hard-ware realization of gas analyzers for medical applications is also discussed.

Diagnostic Accuracy of Natriuretic Peptides for Heart Failure in Patients with Pleural Effusion: A Systematic Review and Updated Meta-Analysis

PubMed Central

Cheng, Juan-Juan; Zhao, Shi-Di; Gao, Ming-Zhu; Huang, Hong-Yu; Gu, Bing; Ma, Ping; Chen, Yan; Wang, Jun-Hong; Yang, Cheng-Jian; Yan, Zi-He

2015-01-01

Background Previous studies have reported that natriuretic peptides in the blood and pleural fluid (PF) are effective diagnostic markers for heart failure (HF). These natriuretic peptides include N-terminal pro-brain natriuretic peptide (NT-proBNP), brain natriuretic peptide (BNP), and midregion pro-atrial natriuretic peptide (MR-proANP). This systematic review and meta-analysis evaluates the diagnostic accuracy of blood and PF natriuretic peptides for HF in patients with pleural effusion. Methods PubMed and EMBASE databases were searched to identify articles published in English that investigated the diagnostic accuracy of BNP, NT-proBNP, and MR-proANP for HF. The last search was performed on 9 October 2014. The quality of the eligible studies was assessed using the revised Quality Assessment of Diagnostic Accuracy Studies tool. The diagnostic performance characteristics (sensitivity, specificity, and other measures of accuracy) were pooled and examined using a bivariate model. Results In total, 14 studies were included in the meta-analysis, including 12 studies reporting the diagnostic accuracy of PF NT-proBNP and 4 studies evaluating blood NT-proBNP. The summary estimates of PF NT-proBNP for HF had a diagnostic sensitivity of 0.94 (95% confidence interval [CI]: 0.90–0.96), specificity of 0.91 (95% CI: 0.86–0.95), positive likelihood ratio of 10.9 (95% CI: 6.4–18.6), negative likelihood ratio of 0.07 (95% CI: 0.04–0.12), and diagnostic odds ratio of 157 (95% CI: 57–430). The overall sensitivity of blood NT-proBNP for diagnosis of HF was 0.92 (95% CI: 0.86–0.95), with a specificity of 0.88 (95% CI: 0.77–0.94), positive likelihood ratio of 7.8 (95% CI: 3.7–16.3), negative likelihood ratio of 0.10 (95% CI: 0.06–0.16), and diagnostic odds ratio of 81 (95% CI: 27–241). The diagnostic accuracy of PF MR-proANP and blood and PF BNP was not analyzed due to the small number of related studies. Conclusions BNP, NT-proBNP, and MR-proANP, either in blood or PF, are effective tools for diagnosis of HF. Additional studies are needed to rigorously evaluate the diagnostic accuracy of PF and blood MR-proANP and BNP for the diagnosis of HF. PMID:26244664

Diagnostic accuracy of atypical p-ANCA in autoimmune hepatitis using ROC- and multivariate regression analysis.

PubMed

Terjung, B; Bogsch, F; Klein, R; Söhne, J; Reichel, C; Wasmuth, J-C; Beuers, U; Sauerbruch, T; Spengler, U

2004-09-29

Antineutrophil cytoplasmic antibodies (atypical p-ANCA) are detected at high prevalence in sera from patients with autoimmune hepatitis (AIH), but their diagnostic relevance for AIH has not been systematically evaluated so far. Here, we studied sera from 357 patients with autoimmune (autoimmune hepatitis n=175, primary sclerosing cholangitis (PSC) n=35, primary biliary cirrhosis n=45), non-autoimmune chronic liver disease (alcoholic liver cirrhosis n=62; chronic hepatitis C virus infection (HCV) n=21) or healthy controls (n=19) for the presence of various non-organ specific autoantibodies. Atypical p-ANCA, antinuclear antibodies (ANA), antibodies against smooth muscles (SMA), antibodies against liver/kidney microsomes (anti-Lkm1) and antimitochondrial antibodies (AMA) were detected by indirect immunofluorescence microscopy, antibodies against the M2 antigen (anti-M2), antibodies against soluble liver antigen (anti-SLA/LP) and anti-Lkm1 by using enzyme linked immunosorbent assays. To define the diagnostic precision of the autoantibodies, results of autoantibody testing were analyzed by receiver operating characteristics (ROC) and forward conditional logistic regression analysis. Atypical p-ANCA were detected at high prevalence in sera from patients with AIH (81%) and PSC (94%). ROC- and logistic regression analysis revealed atypical p-ANCA and SMA, but not ANA as significant diagnostic seromarkers for AIH (atypical p-ANCA: AUC 0.754+/-0.026, odds ratio [OR] 3.4; SMA: 0.652+/-0.028, OR 4.1). Atypical p-ANCA also emerged as the only diagnostically relevant seromarker for PSC (AUC 0.690+/-0.04, OR 3.4). None of the tested antibodies yielded a significant diagnostic accuracy for patients with alcoholic liver cirrhosis, HCV or healthy controls. Atypical p-ANCA along with SMA represent a seromarker with high diagnostic accuracy for AIH and should be explicitly considered in a revised version of the diagnostic score for AIH.

Statistical analysis of Turbine Engine Diagnostic (TED) field test data

NASA Astrophysics Data System (ADS)

Taylor, Malcolm S.; Monyak, John T.

1994-11-01

During the summer of 1993, a field test of turbine engine diagnostic (TED) software, developed jointly by U.S. Army Research Laboratory and the U.S. Army Ordnance Center and School, was conducted at Fort Stuart, GA. The data were collected in conformance with a cross-over design, some of whose considerations are detailed. The initial analysis of the field test data was exploratory, followed by a more formal investigation. Technical aspects of the data analysis insights that were elicited are reported.

An Efficient Reachability Analysis Algorithm

NASA Technical Reports Server (NTRS)

Vatan, Farrokh; Fijany, Amir

2008-01-01

A document discusses a new algorithm for generating higher-order dependencies for diagnostic and sensor placement analysis when a system is described with a causal modeling framework. This innovation will be used in diagnostic and sensor optimization and analysis tools. Fault detection, diagnosis, and prognosis are essential tasks in the operation of autonomous spacecraft, instruments, and in-situ platforms. This algorithm will serve as a power tool for technologies that satisfy a key requirement of autonomous spacecraft, including science instruments and in-situ missions.

An Instructor's Diagnostic Aid for Feedback in Training.

ERIC Educational Resources Information Center

Andrews, Dee H.; Uliano, Kevin C.

1988-01-01

Instructor's Diagnostic Aid for Feedback in Training (IDAFT) is a computer-assisted method based on error analysis, domains of learning, and events of instruction. Its use with Navy team instructors is currently being explored. (JOW)

DATAS Hardware Diagnostic Tests

DOT National Transportation Integrated Search

1990-10-01

This document is reference material for personnel using the Data Link and : Analysis System (DATAS) for hardware diagnostic testing. Included in this : document is a brief overall description of the DATAS, and a thorough : description of how to opera...

Accuracy of magnetic resonance venography in diagnosing cerebral venous sinus thrombosis.

PubMed

Gao, Liansheng; Xu, Weilin; Li, Tao; Yu, Xiaobo; Cao, Shenglong; Xu, Hangzhe; Yan, Feng; Chen, Gao

2018-05-17

The non-specific clinical manifestations and lack of effective diagnostic techniques have made cerebral venous sinus thrombosis (CVST) difficult to recognize and easy to misdiagnose. Several studies have suggested that different types of magnetic resonance venography (MRV) have advantages in diagnosing CVST. We conducted this meta-analysis to assess the accuracy of MRV in identifying CVST. We searched the Embase, PubMed, and Chinese Biomedical (CBM) databases comprehensively to retrieve eligible articles up to Mar 31, 2018. The methodological quality of each article was evaluated individually. The summary diagnostic accuracy of MRV for CVST was obtained from pooled analysis with random-effects models. Sensitivity analysis, subgroup analysis, and meta-regression were used to explore the sources of heterogeneity. A trim and fill analysis was conducted to correct the funnel plot asymmetry. The meta-analysis synthesized 12 articles containing 27 cohorts with a total of 1933 cases. The pooled sensitivity and specificity were 0.86 (95% CI: 0.83, 0.89) and 0.94 (95% CI: 0.93, 0.95), respectively. The pooled diagnostic odds ratio (DOR) was 75.24 (95% CI: 38.33, 147.72). The area under the curve (AUC) was 0.9472 (95% CI: 0.9229, 0.9715). Subgroup analysis and meta-regression analysis revealed the technical types of MRV and the methods of counting cases contributing to the heterogeneity. The trim and fill method confirmed that publication bias has little effect on our results. MRV has excellent diagnostic performance and is accurate in confirming CVST. Copyright © 2018 Elsevier Ltd. All rights reserved.

Wavelet analysis in two-dimensional tomography

NASA Astrophysics Data System (ADS)

Burkovets, Dimitry N.

2002-02-01

The diagnostic possibilities of wavelet-analysis of coherent images of connective tissue in its pathological changes diagnostics. The effectiveness of polarization selection in obtaining wavelet-coefficients' images is also shown. The wavelet structures, characterizing the process of skin psoriasis, bone-tissue osteoporosis have been analyzed. The histological sections of physiological normal and pathologically changed samples of connective tissue of human skin and spongy bone tissue have been analyzed.

Diagnostic value of stool DNA testing for multiple markers of colorectal cancer and advanced adenoma: a meta-analysis.

PubMed

Yang, Hua; Xia, Bing-Qing; Jiang, Bo; Wang, Guozhen; Yang, Yi-Peng; Chen, Hao; Li, Bing-Sheng; Xu, An-Gao; Huang, Yun-Bo; Wang, Xin-Ying

2013-08-01

The diagnostic value of stool DNA (sDNA) testing for colorectal neoplasms remains controversial. To compensate for the lack of large-scale unbiased population studies, a meta-analysis was performed to evaluate the diagnostic value of sDNA testing for multiple markers of colorectal cancer (CRC) and advanced adenoma. The PubMed, Science Direct, Biosis Review, Cochrane Library and Embase databases were systematically searched in January 2012 without time restriction. Meta-analysis was performed using a random-effects model using sensitivity, specificity, diagnostic OR (DOR), summary ROC curves, area under the curve (AUC), and 95% CIs as effect measures. Heterogeneity was measured using the χ(2) test and Q statistic; subgroup analysis was also conducted. A total of 20 studies comprising 5876 individuals were eligible. There was no heterogeneity for CRC, but adenoma and advanced adenoma harboured considerable heterogeneity influenced by risk classification and various detection markers. Stratification analysis according to risk classification showed that multiple markers had a high DOR for the high-risk subgroups of both CRC (sensitivity 0.759 [95% CI 0.711 to 0.804]; specificity 0.883 [95% CI 0.846 to 0.913]; AUC 0.906) and advanced adenoma (sensitivity 0.683 [95% CI 0.584 to 0.771]; specificity 0.918 [95% CI 0.866 to 0.954]; AUC 0.946) but not for the average-risk subgroups of either. In the methylation subgroup, sDNA testing had significantly higher DOR for CRC (sensitivity 0.753 [95% CI 0.685 to 0.812]; specificity 0.913 [95% CI 0.860 to 0.950]; AUC 0.918) and advanced adenoma (sensitivity 0.623 [95% CI 0.527 to 0.712]; specificity 0.926 [95% CI 0.882 to 0.958]; AUC 0.910) compared with the mutation subgroup. There was no significant heterogeneity among studies for subgroup analysis. sDNA testing for multiple markers had strong diagnostic significance for CRC and advanced adenoma in high-risk subjects. Methylation makers had more diagnostic value than mutation markers.

Integrating Oil Debris and Vibration Measurements for Intelligent Machine Health Monitoring. Degree awarded by Toledo Univ., May 2002

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.

2003-01-01

A diagnostic tool for detecting damage to gears was developed. Two different measurement technologies, oil debris analysis and vibration were integrated into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual measurement technologies. This diagnostic tool was developed and evaluated experimentally by collecting vibration and oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig. An oil debris sensor and the two vibration algorithms were adapted as the diagnostic tools. An inductance type oil debris sensor was selected for the oil analysis measurement technology. Gear damage data for this type of sensor was limited to data collected in the NASA Glenn test rigs. For this reason, this analysis included development of a parameter for detecting gear pitting damage using this type of sensor. The vibration data was used to calculate two previously available gear vibration diagnostic algorithms. The two vibration algorithms were selected based on their maturity and published success in detecting damage to gears. Oil debris and vibration features were then developed using fuzzy logic analysis techniques, then input into a multi sensor data fusion process. Results show combining the vibration and oil debris measurement technologies improves the detection of pitting damage on spur gears. As a result of this research, this new diagnostic tool has significantly improved detection of gear damage in the NASA Glenn Spur Gear Fatigue Rigs. This research also resulted in several other findings that will improve the development of future health monitoring systems. Oil debris analysis was found to be more reliable than vibration analysis for detecting pitting fatigue failure of gears and is capable of indicating damage progression. Also, some vibration algorithms are as sensitive to operational effects as they are to damage. Another finding was that clear threshold limits must be established for diagnostic tools. Based on additional experimental data obtained from the NASA Glenn Spiral Bevel Gear Fatigue Rig, the methodology developed in this study can be successfully implemented on other geared systems.

Meta-analysis of diagnostic test data: a bivariate Bayesian modeling approach.

PubMed

Verde, Pablo E

2010-12-30

In the last decades, the amount of published results on clinical diagnostic tests has expanded very rapidly. The counterpart to this development has been the formal evaluation and synthesis of diagnostic results. However, published results present substantial heterogeneity and they can be regarded as so far removed from the classical domain of meta-analysis, that they can provide a rather severe test of classical statistical methods. Recently, bivariate random effects meta-analytic methods, which model the pairs of sensitivities and specificities, have been presented from the classical point of view. In this work a bivariate Bayesian modeling approach is presented. This approach substantially extends the scope of classical bivariate methods by allowing the structural distribution of the random effects to depend on multiple sources of variability. Meta-analysis is summarized by the predictive posterior distributions for sensitivity and specificity. This new approach allows, also, to perform substantial model checking, model diagnostic and model selection. Statistical computations are implemented in the public domain statistical software (WinBUGS and R) and illustrated with real data examples. Copyright © 2010 John Wiley & Sons, Ltd.

Toward DSM-V: An Item Response Theory Analysis of the Diagnostic Process for DSM-IV Alcohol Abuse and Dependence in Adolescents

ERIC Educational Resources Information Center

Gelhorn, Heather; Hartman, Christie; Sakai, Joseph; Stallings, Michael; Young, Susan; Rhee, So Hyun; Corley, Robin; Hewitt, John; Hopger, Christian; Crowley, Thomas D.

2008-01-01

Clinical interviews of approximately 5,587 adolescents revealed that DSM-IV diagnostic categories were found to be different in terms of the severity of alcohol use disorders (AUDs). However, a substantial inconsistency and overlap was found in severity of AUDs across categories. The need for an alternative diagnostic algorithm which considers all…

Real-time Raman spectroscopy for in vivo, online gastric cancer diagnosis during clinical endoscopic examination.

PubMed

Duraipandian, Shiyamala; Sylvest Bergholt, Mads; Zheng, Wei; Yu Ho, Khek; Teh, Ming; Guan Yeoh, Khay; Bok Yan So, Jimmy; Shabbir, Asim; Huang, Zhiwei

2012-08-01

Optical spectroscopic techniques including reflectance, fluorescence and Raman spectroscopy have shown promising potential for in vivo precancer and cancer diagnostics in a variety of organs. However, data-analysis has mostly been limited to post-processing and off-line algorithm development. In this work, we develop a fully automated on-line Raman spectral diagnostics framework integrated with a multimodal image-guided Raman technique for real-time in vivo cancer detection at endoscopy. A total of 2748 in vivo gastric tissue spectra (2465 normal and 283 cancer) were acquired from 305 patients recruited to construct a spectral database for diagnostic algorithms development. The novel diagnostic scheme developed implements on-line preprocessing, outlier detection based on principal component analysis statistics (i.e., Hotelling's T2 and Q-residuals) for tissue Raman spectra verification as well as for organ specific probabilistic diagnostics using different diagnostic algorithms. Free-running optical diagnosis and processing time of < 0.5 s can be achieved, which is critical to realizing real-time in vivo tissue diagnostics during clinical endoscopic examination. The optimized partial least squares-discriminant analysis (PLS-DA) models based on the randomly resampled training database (80% for learning and 20% for testing) provide the diagnostic accuracy of 85.6% [95% confidence interval (CI): 82.9% to 88.2%] [sensitivity of 80.5% (95% CI: 71.4% to 89.6%) and specificity of 86.2% (95% CI: 83.6% to 88.7%)] for the detection of gastric cancer. The PLS-DA algorithms are further applied prospectively on 10 gastric patients at gastroscopy, achieving the predictive accuracy of 80.0% (60/75) [sensitivity of 90.0% (27/30) and specificity of 73.3% (33/45)] for in vivo diagnosis of gastric cancer. The receiver operating characteristics curves further confirmed the efficacy of Raman endoscopy together with PLS-DA algorithms for in vivo prospective diagnosis of gastric cancer. This work successfully moves biomedical Raman spectroscopic technique into real-time, on-line clinical cancer diagnosis, especially in routine endoscopic diagnostic applications.

Real-time Raman spectroscopy for in vivo, online gastric cancer diagnosis during clinical endoscopic examination

NASA Astrophysics Data System (ADS)

Duraipandian, Shiyamala; Sylvest Bergholt, Mads; Zheng, Wei; Yu Ho, Khek; Teh, Ming; Guan Yeoh, Khay; Bok Yan So, Jimmy; Shabbir, Asim; Huang, Zhiwei

2012-08-01

Optical spectroscopic techniques including reflectance, fluorescence and Raman spectroscopy have shown promising potential for in vivo precancer and cancer diagnostics in a variety of organs. However, data-analysis has mostly been limited to post-processing and off-line algorithm development. In this work, we develop a fully automated on-line Raman spectral diagnostics framework integrated with a multimodal image-guided Raman technique for real-time in vivo cancer detection at endoscopy. A total of 2748 in vivo gastric tissue spectra (2465 normal and 283 cancer) were acquired from 305 patients recruited to construct a spectral database for diagnostic algorithms development. The novel diagnostic scheme developed implements on-line preprocessing, outlier detection based on principal component analysis statistics (i.e., Hotelling's T2 and Q-residuals) for tissue Raman spectra verification as well as for organ specific probabilistic diagnostics using different diagnostic algorithms. Free-running optical diagnosis and processing time of < 0.5 s can be achieved, which is critical to realizing real-time in vivo tissue diagnostics during clinical endoscopic examination. The optimized partial least squares-discriminant analysis (PLS-DA) models based on the randomly resampled training database (80% for learning and 20% for testing) provide the diagnostic accuracy of 85.6% [95% confidence interval (CI): 82.9% to 88.2%] [sensitivity of 80.5% (95% CI: 71.4% to 89.6%) and specificity of 86.2% (95% CI: 83.6% to 88.7%)] for the detection of gastric cancer. The PLS-DA algorithms are further applied prospectively on 10 gastric patients at gastroscopy, achieving the predictive accuracy of 80.0% (60/75) [sensitivity of 90.0% (27/30) and specificity of 73.3% (33/45)] for in vivo diagnosis of gastric cancer. The receiver operating characteristics curves further confirmed the efficacy of Raman endoscopy together with PLS-DA algorithms for in vivo prospective diagnosis of gastric cancer. This work successfully moves biomedical Raman spectroscopic technique into real-time, on-line clinical cancer diagnosis, especially in routine endoscopic diagnostic applications.

Neural Network Analysis of Different Segmentation Strategies of Nerve Fiber Layer Assessment for Glaucoma Diagnosis.

PubMed

Larrosa, Jose M; Polo, Vicente; Ferreras, Antonio; García-Martín, Elena; Calvo, Pilar; Pablo, Luis E

2015-12-01

To compare the diagnostic performance of different segmentations of the nerve fiber layer (NFL) thickness measurements using an artificial neural network and to define the optimal number of sectors with best diagnostic ability for glaucoma diagnosis. A total of 117 glaucoma patients and 123 normal subjects were included in the study. NFL thickness measurements were performed using the Spectralis-OCT (Heidelberg Engineering) to obtain the NFL thickness average; measurements from 2 semicircles, 4 quadrants, and 6, 8, 12, 16, 24, 32, and 64 sectors; and 768 uniformly divided locations around the peripapillary NFL. An artificial neural network evaluation was performed to compare the influence of sector analysis on the diagnostic performance of optical coherence tomography. Receiver operating characteristic curves were used to compare the diagnostic ability of the different segmentation analyses. The 6 sectors divided by the horizontal division of the nasal and temporal quadrants were better than the 6 sectors divided by the vertical line through the superior and inferior quadrants [areas under curve, 0.778; 95% confidence interval (CI), 0.720-0.829 and 0.814; 95% CI, 0.759-0.861, respectively]. In the case of quadrants, clock quadrants (area under curve 0.770; 95% CI, 0.712-0.822) were better than the ISNT (inferior-superior-nasal-temporal) quadrants (area under curve, 0.770; 95% CI, 0.712-0.822; P=0.003). The first segmentation strategy that improved the diagnostic value of 4 ISNT quadrants was the 12-sector analysis (area under curve, 0.845; 95% CI, 0.793-0.889; P=0.001). The 2 best candidate strategies for the OCT report were the 12-sector analysis and the 4 planimetric quadrant (alternatively, the 4 clock quadrants) analysis.

Developments in label-free microfluidic methods for single-cell analysis and sorting.

PubMed

Carey, Thomas R; Cotner, Kristen L; Li, Brian; Sohn, Lydia L

2018-04-24

Advancements in microfluidic technologies have led to the development of many new tools for both the characterization and sorting of single cells without the need for exogenous labels. Label-free microfluidics reduce the preparation time, reagents needed, and cost of conventional methods based on fluorescent or magnetic labels. Furthermore, these devices enable analysis of cell properties such as mechanical phenotype and dielectric parameters that cannot be characterized with traditional labels. Some of the most promising technologies for current and future development toward label-free, single-cell analysis and sorting include electronic sensors such as Coulter counters and electrical impedance cytometry; deformation analysis using optical traps and deformation cytometry; hydrodynamic sorting such as deterministic lateral displacement, inertial focusing, and microvortex trapping; and acoustic sorting using traveling or standing surface acoustic waves. These label-free microfluidic methods have been used to screen, sort, and analyze cells for a wide range of biomedical and clinical applications, including cell cycle monitoring, rapid complete blood counts, cancer diagnosis, metastatic progression monitoring, HIV and parasite detection, circulating tumor cell isolation, and point-of-care diagnostics. Because of the versatility of label-free methods for characterization and sorting, the low-cost nature of microfluidics, and the rapid prototyping capabilities of modern microfabrication, we expect this class of technology to continue to be an area of high research interest going forward. New developments in this field will contribute to the ongoing paradigm shift in cell analysis and sorting technologies toward label-free microfluidic devices, enabling new capabilities in biomedical research tools as well as clinical diagnostics. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices. © 2018 Wiley Periodicals, Inc.

Accurate ECG diagnosis of atrial tachyarrhythmias using quantitative analysis: a prospective diagnostic and cost-effectiveness study.

PubMed

Krummen, David E; Patel, Mitul; Nguyen, Hong; Ho, Gordon; Kazi, Dhruv S; Clopton, Paul; Holland, Marian C; Greenberg, Scott L; Feld, Gregory K; Faddis, Mitchell N; Narayan, Sanjiv M

2010-11-01

Quantitative ECG Analysis. Optimal atrial tachyarrhythmia management is facilitated by accurate electrocardiogram interpretation, yet typical atrial flutter (AFl) may present without sawtooth F-waves or RR regularity, and atrial fibrillation (AF) may be difficult to separate from atypical AFl or rapid focal atrial tachycardia (AT). We analyzed whether improved diagnostic accuracy using a validated analysis tool significantly impacts costs and patient care. We performed a prospective, blinded, multicenter study using a novel quantitative computerized algorithm to identify atrial tachyarrhythmia mechanism from the surface ECG in patients referred for electrophysiology study (EPS). In 122 consecutive patients (age 60 ± 12 years) referred for EPS, 91 sustained atrial tachyarrhythmias were studied. ECGs were also interpreted by 9 physicians from 3 specialties for comparison and to allow healthcare system modeling. Diagnostic accuracy was compared to the diagnosis at EPS. A Markov model was used to estimate the impact of improved arrhythmia diagnosis. We found 13% of typical AFl ECGs had neither sawtooth flutter waves nor RR regularity, and were misdiagnosed by the majority of clinicians (0/6 correctly diagnosed by consensus visual interpretation) but correctly by quantitative analysis in 83% (5/6, P = 0.03). AF diagnosis was also improved through use of the algorithm (92%) versus visual interpretation (primary care: 76%, P < 0.01). Economically, we found that these improvements in diagnostic accuracy resulted in an average cost-savings of $1,303 and 0.007 quality-adjusted-life-years per patient. Typical AFl and AF are frequently misdiagnosed using visual criteria. Quantitative analysis improves diagnostic accuracy and results in improved healthcare costs and patient outcomes. © 2010 Wiley Periodicals, Inc.

Ultrasound for Distal Forearm Fracture: A Systematic Review and Diagnostic Meta-Analysis

PubMed Central

Douma-den Hamer, Djoke; Blanker, Marco H.; Edens, Mireille A.; Buijteweg, Lonneke N.; Boomsma, Martijn F.; van Helden, Sven H.; Mauritz, Gert-Jan

2016-01-01

Study Objective To determine the diagnostic accuracy of ultrasound for detecting distal forearm fractures. Methods A systematic review and diagnostic meta-analysis was performed according to the PRISMA statement. We searched MEDLINE, Web of Science and the Cochrane Library from inception to September 2015. All prospective studies of the diagnostic accuracy of ultrasound versus radiography as the reference standard were included. We excluded studies with a retrospective design and those with evidence of verification bias. We assessed the methodological quality of the included studies with the QUADAS-2 tool. We performed a meta-analysis of studies evaluating ultrasound to calculate the pooled sensitivity and specificity with 95% confidence intervals (CI95%) using a bivariate model with random effects. Subgroup and sensitivity analysis were used to examine the effect of methodological differences and other study characteristics. Results Out of 867 publications we included 16 studies with 1,204 patients and 641 fractures. The pooled test characteristics for ultrasound were: sensitivity 97% (CI95% 93–99%), specificity 95% (CI95% 89–98%), positive likelihood ratio (LR) 20.0 (8.5–47.2) and negative LR 0.03 (0.01–0.08). The corresponding pooled diagnostic odds ratio (DOR) was 667 (142–3,133). Apparent differences were shown for method of viewing, with the 6-view method showing higher specificity, positive LR, and DOR, compared to the 4-view method. Conclusion The present meta-analysis showed that ultrasound has a high accuracy for the diagnosis of distal forearm fractures in children when used by proper viewing method. Based on this, ultrasound should be considered a reliable alternative, which has the advantages of being radiation free. PMID:27196439

Semen Analysis

MedlinePlus

... Booklets Pruebas diagnósticas para la infertilidad masculina (Diagnostic tests for male infertility) From: Spanish Fact Sheets & Info Booklets Assisted reproductive technology 辅助生殖技术辅助生殖技术 From: Chinese Fact Sheets & Info Booklets Diagnostic ...

Pharmacometabolomics Informs Quantitative Radiomics for Glioblastoma Diagnostic Innovation.

PubMed

Katsila, Theodora; Matsoukas, Minos-Timotheos; Patrinos, George P; Kardamakis, Dimitrios

2017-08-01

Applications of omics systems biology technologies have enormous promise for radiology and diagnostics in surgical fields. In this context, the emerging fields of radiomics (a systems scale approach to radiology using a host of technologies, including omics) and pharmacometabolomics (use of metabolomics for patient and disease stratification and guiding precision medicine) offer much synergy for diagnostic innovation in surgery, particularly in neurosurgery. This synthesis of omics fields and applications is timely because diagnostic accuracy in central nervous system tumors still challenges decision-making. Considering the vast heterogeneity in brain tumors, disease phenotypes, and interindividual variability in surgical and chemotherapy outcomes, we believe that diagnostic accuracy can be markedly improved by quantitative radiomics coupled to pharmacometabolomics and related health information technologies while optimizing economic costs of traditional diagnostics. In this expert review, we present an innovation analysis on a systems-level multi-omics approach toward diagnostic accuracy in central nervous system tumors. For this, we suggest that glioblastomas serve as a useful application paradigm. We performed a literature search on PubMed for articles published in English between 2006 and 2016. We used the search terms "radiomics," "glioblastoma," "biomarkers," "pharmacogenomics," "pharmacometabolomics," "pharmacometabonomics/pharmacometabolomics," "collaborative informatics," and "precision medicine." A list of the top 4 insights we derived from this literature analysis is presented in this study. For example, we found that (i) tumor grading needs to be better refined, (ii) diagnostic precision should be improved, (iii) standardization in radiomics is lacking, and (iv) quantitative radiomics needs to prove clinical implementation. We conclude with an interdisciplinary call to the metabolomics, pharmacy/pharmacology, radiology, and surgery communities that pharmacometabolomics coupled to information technologies (chemoinformatics tools, databases, collaborative systems) can inform quantitative radiomics, thus translating Big Data and information growth to knowledge growth, rational drug development and diagnostics innovation for glioblastomas, and possibly in other brain tumors.

The market trend analysis and prospects of cancer molecular diagnostics kits.

PubMed

Seo, Ju Hwan; Lee, Joon Woo; Cho, Daemyeong

2018-01-01

The molecular diagnostics market can be broadly divided into PCR (rt-PCR, d-PCR), NGS(Next Generation Sequencing), Microarray, FISH(Fluorescent in situ-hybridization) and other categories, based on the diagnostic technique. Also, depending on the disease being diagnosed, the market can also be divided into cancer, infectious diseases, HIV/STDs (herpes, syphilis), and women's health issues such as breast cancer, cervical cancer, ovarian cancer, HPV(human papillomavirus), and vaginitis.Chromosome analysis (including Fluorescent In-situ Hybridization) is one type of blood cancer diagnostic method, which involves the direct detection of individual cells with chromosomal translocation, but there have been problems of sensitivity when using this method. PCR targeting individual genes or the RT (reverse transcription)-PCR method offers outstanding sensitivity, but one drawback is the risk of false-positive reaction caused by contamination of samples, etc. Blood cancer molecular diagnostics kits allow us to overcome these shortcomings, and related products have been under development, with a focus on improving detection sensitivity, enabling multiple tests, and reducing the cost and diagnostic time. Blood cancer molecular diagnostics is usually performed based on platforms such as PCR. The global market for blood cancer molecular diagnostics kits is $ 335.9 million as of 2016 and is expected to reach $ 6980 million in 2026 with an average annual growth rate of 32.9%. The market in South Korea is anticipated to grow at an average annual rate of 28.9%, from $ 3.75 million as of 2016 to $ 60.89 million in 2026. The Market for blood cancer molecular diagnostics kits is judged to be higher in growth possibility due to the increase in the number of cancer patients.

An international comparative family medicine study of the Transition Project data from the Netherlands, Malta, Japan and Serbia. An analysis of diagnostic odds ratios aggregated across age bands, years of observation and individual practices.

PubMed

Soler, Jean K; Okkes, Inge; Oskam, Sibo; van Boven, Kees; Zivotic, Predrag; Jevtic, Milan; Dobbs, Frank; Lamberts, Henk

2012-06-01

This is a study of the process of diagnosis in family medicine (FM) in four practice populations from the Netherlands, Malta, Serbia and Japan. Diagnostic odds ratios (ORs) for common reasons for encounter (RfEs) and episode titles are used to study the process of diagnosis in international FM and to test the assumption that data can be aggregated across different age bands, practices and years of observation. Participating family doctors (FDs) recorded details of all their patient contacts in an episode of care (EoC) structure using the International Classification of Primary Care (ICPC). RfEs presented by the patient and the diagnostic labels (EoC titles) recorded for each encounter were classified with ICPC. The relationships between RfEs and episode titles were expressed as ORs using Bayesian probability analysis to calculate the posterior (post-test) odds of an episode title given an RfE, at the start of a new EoC. The distributions of diagnostic ORs from the four population databases are tabled across age groups, years of observation and practices. There is a lot of congruence in diagnostic process and concepts between populations, across age groups, years of observation and FD practices, despite differences in the strength of such diagnostic associations. There is particularly little variability of diagnostic ORs across years of observation and between individual FD practices. Given our findings, it makes sense to aggregate diagnostic data from different FD practices and years of observation. Our findings support the existence of common core diagnostic concepts in international FM.

A new dump system design for stray light reduction of Thomson scattering diagnostic system on EAST.

PubMed

Xiao, Shumei; Zang, Qing; Han, Xiaofeng; Wang, Tengfei; Yu, Jin; Zhao, Junyu

2016-07-01

Thomson scattering (TS) diagnostic is an important diagnostic for measuring electron temperature and density during plasma discharge. However, the measurement of Thomson scattering signal is disturbed by the stray light easily. The stray light sources in the Experimental Advanced Superconducting Tokamak (EAST) TS diagnostic system were analyzed by a simulation model of the diagnostic system, and simulation results show that the dump system is the primary stray light source. Based on the optics theory and the simulation analysis, a novel dump system including an improved beam trap was proposed and installed. The measurement results indicate that the new dump system can reduce more than 60% of the stray light for the diagnostic system, and the influence of stray light on the error of measured density decreases.

Development of stimulation diagnostic technology. Annual report, May 1990--December 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warpinski, N.R.; Lorenz, J.C.

The objective of this project is to apply Sandia`s expertise and technology towards the development of stimulation diagnostic technology in the areas of in situ stress, natural fracturing, stimulation processes and instrumentation systems. Initial work has concentrated on experiment planning for a site where hydraulic fracturing could be evaluated and design models and fracture diagnostics could be validated and improved. Important issues have been defined and new diagnostics, such as inclinometers, identified. In the area of in situ stress, circumferential velocity analysis is proving to be a useful diagnostic for stress orientation. Natural fracture studies of the Frontier formation aremore » progressing; two fracture sets have been found and their relation to tectonic events have been hypothesized. Analyses of stimulation data have been performed for several sites, primarily for in situ stress information. Some new ideas in stimulation diagnostics have been proposed; these ideas may significantly improve fracture diagnostic capabilities.« less

Development of stimulation diagnostic technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warpinski, N.R.; Lorenz, J.C.

The objective of this project is to apply Sandia's expertise and technology towards the development of stimulation diagnostic technology in the areas of in situ stress, natural fracturing, stimulation processes and instrumentation systems. Initial work has concentrated on experiment planning for a site where hydraulic fracturing could be evaluated and design models and fracture diagnostics could be validated and improved. Important issues have been defined and new diagnostics, such as inclinometers, identified. In the area of in situ stress, circumferential velocity analysis is proving to be a useful diagnostic for stress orientation. Natural fracture studies of the Frontier formation aremore » progressing; two fracture sets have been found and their relation to tectonic events have been hypothesized. Analyses of stimulation data have been performed for several sites, primarily for in situ stress information. Some new ideas in stimulation diagnostics have been proposed; these ideas may significantly improve fracture diagnostic capabilities.« less

Mapping the literature of diagnostic medical sonography.

PubMed Central

Walcott, B M

1999-01-01

Diagnostic medical sonography has been evolving as a recognized allied health occupation since the early 1970s, but no bibliometric studies of the literature of the field have been published. This study, part of the Medical Library Association Nursing and Allied Health Resources Section's Project for Mapping the Literature of Allied Health, attempted to identify the core journals in diagnostic medical sonography and determine how well these journals are indexed by MEDLINE, EMBASE/Excerpta Medica, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). Citation analysis was done using the three journals listed for the field by the Brandon/Hill list. Characteristics of two of these three journals affected the results to the extent that more data should be gathered to reach conclusions about the literature of diagnostic medical sonography as a whole. Results of the analysis do suggest that the literature of echocardiography, which is a special area of diagnostic medical sonography, is indexed much more completely by MEDLINE and EMBASE/Excerpta Medica than by CINAHL. Suggestions are made for librarians making collection development decisions in this area of allied health. PMID:10427429

X-ray power and yield measurements at the refurbished Z machine

DOE PAGES

Jones, M. C.; Ampleford, D. J.; Cuneo, M. E.; ...

2014-08-04

Advancements have been made in the diagnostic techniques to measure accurately the total radiated x-ray yield and power from z-pinch loads at the Z Machine with high accuracy. The Z-accelerator is capable of outputting 2MJ and 330 TW of x-ray yield and power, and accurately measuring these quantities is imperative. We will describe work over the past several years which include the development of new diagnostics, improvements to existing diagnostics, and implementation of automated data analysis routines. A set of experiments were conducted on the Z machine where the load and machine configuration were held constant. During this shot series,more » it was observed that total z-pinch x-ray emission power determined from the two common techniques for inferring the x-ray power, Kimfol filtered x-ray diode diagnostic and the Total Power and Energy diagnostic gave 450 TW and 327 TW respectively. Our analysis shows the latter to be the more accurate interpretation. More broadly, the comparison demonstrates the necessity to consider spectral response and field of view when inferring xray powers from z-pinch sources.« less

Gender differences in the diagnostic accuracy of SPECT myocardial perfusion imaging: a bivariate meta-analysis.

PubMed

Iskandar, Aline; Limone, Brendan; Parker, Matthew W; Perugini, Andrew; Kim, Hyejin; Jones, Charles; Calamari, Brian; Coleman, Craig I; Heller, Gary V

2013-02-01

It remains controversial whether the diagnostic accuracy of single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) is different in men as compared to women. We performed a meta-analysis to investigate gender differences of SPECT MPI for the diagnosis of CAD (≥50% stenosis). Two investigators independently performed a systematic review of the MEDLINE and EMBASE databases from inception through January 2012 for English-language studies determining the diagnostic accuracy of SPECT MPI. We included prospective studies that compared SPECT MPI with conventional coronary angiography which provided sufficient data to calculate gender-specific true and false positives and negatives. Data from studies evaluating <20 patients of one gender were excluded. Bivariate meta-analysis was used to create summary receiver operating curves. Twenty-six studies met inclusion criteria, representing 1,148 women and 1,142 men. Bivariate meta-analysis yielded a mean sensitivity and specificity of 84.2% (95% confidence interval [CI] 78.7%-88.6%) and 78.7% (CI 70.0%-85.3%) for SPECT MPI in women and 89.1% (CI 84.0%-92.7%) and 71.2% (CI 60.8%-79.8%) for SPECT MPI in men. There was no significant difference in the sensitivity (P = .15) or specificity (P = .23) between male and female subjects. In a bivariate meta-analysis of the available literature, the diagnostic accuracy of SPECT MPI is similar for both men and women.

Automated fluorescent miscroscopic image analysis of PTBP1 expression in glioma

PubMed Central

Becker, Aline; Elder, Brad; Puduvalli, Vinay; Winter, Jessica; Gurcan, Metin

2017-01-01

Multiplexed immunofluorescent testing has not entered into diagnostic neuropathology due to the presence of several technical barriers, amongst which includes autofluorescence. This study presents the implementation of a methodology capable of overcoming the visual challenges of fluorescent microscopy for diagnostic neuropathology by using automated digital image analysis, with long term goal of providing unbiased quantitative analyses of multiplexed biomarkers for solid tissue neuropathology. In this study, we validated PTBP1, a putative biomarker for glioma, and tested the extent to which immunofluorescent microscopy combined with automated and unbiased image analysis would permit the utility of PTBP1 as a biomarker to distinguish diagnostically challenging surgical biopsies. As a paradigm, we utilized second resections from patients diagnosed either with reactive brain changes (pseudoprogression) and recurrent glioblastoma (true progression). Our image analysis workflow was capable of removing background autofluorescence and permitted quantification of DAPI-PTBP1 positive cells. PTBP1-positive nuclei, and the mean intensity value of PTBP1 signal in cells. Traditional pathological interpretation was unable to distinguish between groups due to unacceptably high discordance rates amongst expert neuropathologists. Our data demonstrated that recurrent glioblastoma showed more DAPI-PTBP1 positive cells and a higher mean intensity value of PTBP1 signal compared to resections from second surgeries that showed only reactive gliosis. Our work demonstrates the potential of utilizing automated image analysis to overcome the challenges of implementing fluorescent microscopy in diagnostic neuropathology. PMID:28282372

Diagnostic Performance of DNA Hypermethylation Markers in Peripheral Blood for the Detection of Colorectal Cancer: A Meta-Analysis and Systematic Review

PubMed Central

Li, Bingsheng; Gan, Aihua; Chen, Xiaolong; Wang, Xinying; He, Weifeng; Zhang, Xiaohui; Huang, Renxiang; Zhou, Shuzhu; Song, Xiaoxiao; Xu, Angao

2016-01-01

DNA hypermethylation in blood is becoming an attractive candidate marker for colorectal cancer (CRC) detection. To assess the diagnostic accuracy of blood hypermethylation markers for CRC in different clinical settings, we conducted a meta-analysis of published reports. Of 485 publications obtained in the initial literature search, 39 studies were included in the meta-analysis. Hypermethylation markers in peripheral blood showed a high degree of accuracy for the detection of CRC. The summary sensitivity was 0.62 [95% confidence interval (CI), 0.56–0.67] and specificity was 0.91 (95% CI, 0.89–0.93). Subgroup analysis showed significantly greater sensitivity for the methylated Septin 9 gene (SEPT9) subgroup (0.75; 95% CI, 0.67–0.81) than for the non-methylated SEPT9 subgroup (0.58; 95% CI, 0.52–0.64). Sensitivity and specificity were not affected significantly by target gene number, CRC staging, study region, or methylation analysis method. These findings show that hypermethylation markers in blood are highly sensitive and specific for CRC detection, with methylated SEPT9 being particularly robust. The diagnostic performance of hypermethylation markers, which have varied across different studies, can be improved by marker optimization. Future research should examine variation in diagnostic accuracy according to non-neoplastic factors. PMID:27158984

Vacuum system design and tritium inventory for the TFTR charge exchange diagnostic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medley, S.S.

The charge exchange diagnostic for the TFTR is comprised of two analyzer systems which contain a total of twenty independent mass/energy analyzers and one diagnostic neutral beam tentatively rated at 80 keV, 15 A. The associated vacuum systems were analyzed using the Vacuum System Transient Simulator (VSTS) computer program which models the transient transport of multi-gas species through complex networks of ducts, valves, traps, vacuum pumps, and other related vacuum system components. In addition to providing improved design performance at reduced cost, the analysis yields estimates for the exchange of tritium from the torus to the diagnostic components and ofmore » the diagnostic working gases to the torus.« less

Regularities in eyewitness identification.

PubMed

Clark, Steven E; Howell, Ryan T; Davey, Sherrie L

2008-06-01

What do eyewitness identification experiments typically show? We address this question through a meta-analysis of 94 comparisons between target-present and target-absent lineups. The analyses showed that: (a) correct identifications and correct-nonidentifications were uncorrelated, (b) suspect identifications were more diagnostic with respect to the suspect's guilt or innocence than any other response, (c) nonidentifications were diagnostic of the suspect's innocence, (d) the diagnosticity of foil identifications depended on lineup composition, and (e) don't know responses were nondiagnostic with respect to guilt or innocence. Results of diagnosticity analyses for simultaneous and sequential lineups varied for full-sample versus direct-comparison analyses. Diagnosticity patterns also varied as a function of lineup composition. Theoretical, forensic, and legal implications are discussed.

Peers without fears? Barriers to effective communication among primary care physicians and oncologists about diagnostic delays in cancer

PubMed Central

Lipitz-Snyderman, Allison; Kale, Minal; Robbins, Laura; Pfister, David; Fortier, Elizabeth; Pocus, Valerie; Chimonas, Susan; Weingart, Saul N

2018-01-01

Objective Relatively little attention has been devoted to the role of communication between physicians as a mechanism for individual and organisational learning about diagnostic delays. This study’s objective was to elicit physicians’ perceptions about and experiences with communication among physicians regarding diagnostic delays in cancer. Design, setting, participants Qualitative analysis based on seven focus groups. Fifty-one physicians affiliated with three New York-based academic medical centres participated, with six to nine subjects per group. We used content analysis to identify commonalities among primary care physicians and specialists (ie, medical and surgical oncologists). Primary outcome measure Perceptions and experiences with physician-to-physician communication about delays in cancer diagnosis. Results Our analysis identified five major themes: openness to communication, benefits of communication, fears about giving and receiving feedback, infrastructure barriers to communication and overcoming barriers to communication. Subjects valued communication about cancer diagnostic delays, but they had many concerns and fears about providing and receiving feedback in practice. Subjects expressed reluctance to communicate if there was insufficient information to attribute responsibility, if it would have no direct benefit or if it would jeopardise their existing relationships. They supported sensitive approaches to conveying information, as they feared eliciting or being subject to feelings of incompetence or shame. Subjects also cited organisational barriers. They offered suggestions that might facilitate communication about delays. Conclusions Addressing the barriers to communication among physicians about diagnostic delays is needed to promote a culture of learning across specialties and institutions. Supporting open and honest discussions about diagnostic delays may help build safer health systems. PMID:28655713

KRAS mutation analysis of washing fluid from endoscopic ultrasound-guided fine needle aspiration improves cytologic diagnosis of pancreatic ductal adenocarcinoma.

PubMed

Park, Joo Kyung; Lee, Yoon Jung; Lee, Jong Kyun; Lee, Kyu Taek; Choi, Yoon-La; Lee, Kwang Hyuck

2017-01-10

EUS-FNA becomes one of the most important diagnostic modalities for PDACs. However, acquired tissue specimens were sometimes insufficient to make a definite cytological diagnosis. On the other hand, KRAS mutation is the most frequently acquired genetic alteration found more than 90% of PDACs. To investigate the way to improve diagnostic accuracy for PDACs using both cytological examination and KRAS mutation analysis would be a great help. Therefore, the aims of this study were to evaluate usefulness of conventional cytological examination combined with KRAS mutation analysis with modified PCR technology to improve the sensitivity and the accuracy. We enrolled 43 patients with solid pancreatic masses and 86 EUS-FNA specimens were obtained. During the EUS-FNA, the needle catheter was flushed with 2 cc of saline and the washed fluid was collected for KRAS mutation analysis for the first 2 passes; PNAClamp™ KRAS Mutation Detection Kit. There were 46 specimens from the 23 PDACs and 40 specimens from the 20 other pancreatic diseases. The sensitivity, specificity and accuracy were as follows; conventional cytopathologic examination: 63%, 100% and 80%; combination of cytopathologic examination and K-ras mutation analysis: 87%, 100% and 93%. Furthermore, KRAS mutation was detected 11 out of 17 PDAC samples whose cytopathology results were inconclusive. KRAS mutation analysis with PNAClamp™ technique using washing fluid from EUS-FNA along with cytological examination may not only improve the diagnostic accuracy of PDACs, but also establish the platform using genetic analysis which would be helpful as diagnostic modality for PDACs.

[THE RESULTS OF CLINICAL AND PSYCHOPATHOLOGICAL AND PSYCHOLOGICAL DIAGNOSTIC INVESTIGATIONS EMPLOYEES OF FINANCIAL INSTITUTIONS WHICH WERE IDENTIFIED NEUROTIC DISORDERS].

PubMed

Solovyova, M

2014-12-01

The article presents the results of the clinical and psychopathological and psychological diagnostic, investigations mental health employees of financial institutions, description and analysis of clinical forms identified disorders.

Evaluating Utility in Diagnostic Decision Making.

ERIC Educational Resources Information Center

Harber, Jean R.

1981-01-01

The utility of the procedures special educators apply in making decisions about the identification of handicapped individuals has not been thoroughly studied. The paper examines the utility of diagnostic decision making from the perspective of receiver operating curve analysis. (Author)

Validation of Quantitative Multimodality Analysis of Telomerase Activity in Urine Cells as a Noninvasive Diagnostic and Prognostic Tool for Prostate Cancer

DTIC Science & Technology

2005-08-01

present study, who was previously misdiagnosed with BPH and inflammation, eventually has revealed the prostate cancer with the Gleason score 7. Therefore...Noninvasive Diagnostic and Prognostic Tool for Prostate Cancer ...5a. CONTRACT NUMBER Urine Cells as a Noninvasive Diagnostic and Prognostic Tool for Prostate Cancer 5b. GRANT NUMBER W81XWH-04-1-0774 5c

Malaria surveillance in the Democratic Republic of the Congo: comparison of microscopy, PCR, and rapid diagnostic test.

PubMed

Doctor, Stephanie M; Liu, Yunhao; Whitesell, Amy; Thwai, Kyaw L; Taylor, Steve M; Janko, Mark; Emch, Michael; Kashamuka, Melchior; Muwonga, Jérémie; Tshefu, Antoinette; Meshnick, Steven R

2016-05-01

Malaria surveillance is critical for control efforts, but diagnostic methods frequently disagree. Here, we compare microscopy, PCR, and a rapid diagnostic test in 7137 samples from children in the Democratic Republic of the Congo using latent class analysis. PCR had the highest sensitivity (94.6%) and microscopy had the lowest (76.7%). Copyright © 2016 Elsevier Inc. All rights reserved.

Diagnostic accuracy of serological diagnosis of hepatitis C and B using dried blood spot samples (DBS): two systematic reviews and meta-analyses.

PubMed

Lange, Berit; Cohn, Jennifer; Roberts, Teri; Camp, Johannes; Chauffour, Jeanne; Gummadi, Nina; Ishizaki, Azumi; Nagarathnam, Anupriya; Tuaillon, Edouard; van de Perre, Philippe; Pichler, Christine; Easterbrook, Philippa; Denkinger, Claudia M

2017-11-01

Dried blood spots (DBS) are a convenient tool to enable diagnostic testing for viral diseases due to transport, handling and logistical advantages over conventional venous blood sampling. A better understanding of the performance of serological testing for hepatitis C (HCV) and hepatitis B virus (HBV) from DBS is important to enable more widespread use of this sampling approach in resource limited settings, and to inform the 2017 World Health Organization (WHO) guidance on testing for HBV/HCV. We conducted two systematic reviews and meta-analyses on the diagnostic accuracy of HCV antibody (HCV-Ab) and HBV surface antigen (HBsAg) from DBS samples compared to venous blood samples. MEDLINE, EMBASE, Global Health and Cochrane library were searched for studies that assessed diagnostic accuracy with DBS and agreement between DBS and venous sampling. Heterogeneity of results was assessed and where possible a pooled analysis of sensitivity and specificity was performed using a bivariate analysis with maximum likelihood estimate and 95% confidence intervals (95%CI). We conducted a narrative review on the impact of varying storage conditions or limits of detection in subsets of samples. The QUADAS-2 tool was used to assess risk of bias. For the diagnostic accuracy of HBsAg from DBS compared to venous blood, 19 studies were included in a quantitative meta-analysis, and 23 in a narrative review. Pooled sensitivity and specificity were 98% (95%CI:95%-99%) and 100% (95%CI:99-100%), respectively. For the diagnostic accuracy of HCV-Ab from DBS, 19 studies were included in a pooled quantitative meta-analysis, and 23 studies were included in a narrative review. Pooled estimates of sensitivity and specificity were 98% (CI95%:95-99) and 99% (CI95%:98-100), respectively. Overall quality of studies and heterogeneity were rated as moderate in both systematic reviews. HCV-Ab and HBsAg testing using DBS compared to venous blood sampling was associated with excellent diagnostic accuracy. However, generalizability is limited as no uniform protocol was applied and most studies did not use fresh samples. Future studies on diagnostic accuracy should include an assessment of impact of environmental conditions common in low resource field settings. Manufacturers also need to formally validate their assays for DBS for use with their commercial assays.

[Physical, chemical and morphological urine examination guidelines for the Analytical Phase from the Intersociety Urinalysis Group].

PubMed

Manoni, Fabio; Gessoni, Gianluca; Fogazzi, Giovanni Battista; Alessio, Maria Grazia; Caleffi, Alberta; Gambaro, Giovanni; Epifani, Maria Grazia; Pieretti, Barbara; Perego, Angelo; Ottomano, Cosimo; Saccani, Graziella; Valverde, Sara; Secchiero, Sandra

2016-01-01

With these guidelines the Intersociety Urinalysis Group (GIAU) aims to stimulate the following aspects: Improvement and standardization of the analytical approach to physical, chemical and morphological urine examination (ECMU). Improvement of the chemical analysis of urine with particular regard to the reconsideration of the diagnostic significance of the parameters that are traditionally evaluated in dipstick analysis together with an increasing awareness of the limits of sensitivity and specificity of this analytical method. Increase the awareness of the importance of professional skills in the field of urinary morphology and the relationship with the clinicians. Implement a policy of evaluation of the analytical quality by using, in addition to traditional internal and external controls, a program for the evaluation of morphological competence. Stimulate the diagnostics industry to focus research efforts and development methodology and instrumental catering on the needs of clinical diagnosis. The hope is to revalue the enormous diagnostic potential of 'ECMU, implementing a urinalysis on personalized diagnostic needs for each patient. Emphasize the value added to ECMU by automated analyzers for the study of the morphology of the corpuscular fraction urine. The hope is to revalue the enormous potential diagnostic of 'ECMU, implementing a urinalysis on personalized diagnostic needs that each patient brings with it.

The Diagnostic Value of Gastrin-17 Detection in Atrophic Gastritis

PubMed Central

Wang, Xu; Ling, Li; Li, Shanshan; Qin, Guiping; Cui, Wei; Li, Xiang; Ni, Hong

2016-01-01

Abstract A meta-analysis was performed to assess the diagnostic value of gastrin-17 (G-17) for the early detection of chronic atrophic gastritis (CAG). An extensive literature search was performed, with the aim of selecting publications that reported the accuracy of G-17 in predicting CAG, in the following databases: PubMed, Science Direct, Web of Science, Chinese Biological Medicine, Chinese National Knowledge Infrastructure, Wanfang, and VIP. To assess the diagnostic value of G-17, the following statistics were estimated and described: sensitivity, specificity, diagnostic odds ratios (DOR), summary receiver operating characteristic curves, area under the curve (AUC), and 95% confidence intervals (CIs). Thirteen studies that met the inclusion criteria were included in this meta-analysis, comprising 894 patients and 1950 controls. The pooled sensitivity and specificity of these studies were 0.48 (95% CI: 0.45–0.51) and 0.79 (95% CI: 0.77–0.81), respectively. The DOR was 5.93 (95% CI: 2.93–11.99), and the AUC was 0.82. G-17 may have potential diagnostic value because it has good specificity and a moderate DOR and AUC for CAG. However, more studies are needed to improve the sensitivity of this diagnostic tool in the future. PMID:27149493

Mean cerebral blood volume is an effective diagnostic index of recurrent and radiation injury in glioma patients: A meta-analysis of diagnostic test.

PubMed

Li, Zhanzhan; Zhou, Qin; Li, Yanyan; Yan, Shipeng; Fu, Jun; Huang, Xinqiong; Shen, Liangfang

2017-02-28

We conducted a meta-analysis to evaluate the diagnostic values of mean cerebral blood volume for recurrent and radiation injury in glioma patients. We performed systematic electronic searches for eligible study up to August 8, 2016. Bivariate mixed effects models were used to estimate the combined sensitivity, specificity, positive likelihood ratios, negative likelihood ratios, diagnostic odds ratios and their 95% confidence intervals (CIs). Fifteen studies with a total number of 576 participants were enrolled. The pooled sensitivity and specificity of diagnostic were 0.88 (95%CI: 0.82-0.92) and 0.85 (95%CI: 0.68-0.93). The pooled positive likelihood ratio is 5.73 (95%CI: 2.56-12.81), negative likelihood ratio is 0.15 (95%CI: 0.10-0.22), and the diagnostic odds ratio is 39.34 (95%CI:13.96-110.84). The summary receiver operator characteristic is 0.91 (95%CI: 0.88-0.93). However, the Deek's plot suggested publication bias may exist (t=2.30, P=0.039). Mean cerebral blood volume measurement methods seems to be very sensitive and highly specific to differentiate recurrent and radiation injury in glioma patients. The results should be interpreted with caution because of the potential bias.

Advances in Optical Fiber-Based Faraday Rotation Diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, A D; McHale, G B; Goerz, D A

2009-07-27

In the past two years, we have used optical fiber-based Faraday Rotation Diagnostics (FRDs) to measure pulsed currents on several dozen capacitively driven and explosively driven pulsed power experiments. We have made simplifications to the necessary hardware for quadrature-encoded polarization analysis, including development of an all-fiber analysis scheme. We have developed a numerical model that is useful for predicting and quantifying deviations from the ideal diagnostic response. We have developed a method of analyzing quadrature-encoded FRD data that is simple to perform and offers numerous advantages over several existing methods. When comparison has been possible, we have seen good agreementmore » with our FRDs and other current sensors.« less

System of Mueller-Jones matrix polarizing mapping of blood plasma films in breast pathology

NASA Astrophysics Data System (ADS)

Zabolotna, Natalia I.; Radchenko, Kostiantyn O.; Tarnovskiy, Mykola H.

2017-08-01

The combined method of Jones-Mueller matrix mapping and blood plasma films analysis based on the system that proposed in this paper. Based on the obtained data about the structure and state of blood plasma samples the diagnostic conclusions can be make about the state of breast cancer patients ("normal" or "pathology"). Then, by using the statistical analysis obtain statistical and correlational moments for every coordinate distributions; these indicators are served as diagnostic criterias. The final step is to comparing results and choosing the most effective diagnostic indicators. The paper presents the results of Mueller-Jones matrix mapping of optically thin (attenuation coefficient ,τ≤0,1) blood plasma layers.

Towards advanced OCT clinical applications

NASA Astrophysics Data System (ADS)

Kirillin, Mikhail; Panteleeva, Olga; Agrba, Pavel; Pasukhin, Mikhail; Sergeeva, Ekaterina; Plankina, Elena; Dudenkova, Varvara; Gubarkova, Ekaterina; Kiseleva, Elena; Gladkova, Natalia; Shakhova, Natalia; Vitkin, Alex

2015-07-01

In this paper we report on our recent achievement in application of conventional and cross-polarization OCT (CP OCT) modalities for in vivo clinical diagnostics in different medical areas including gynecology, dermatology, and stomatology. In gynecology, CP OCT was employed for diagnosing fallopian tubes and cervix; in dermatology OCT for monitoring of treatment of psoriasis, scleroderma and atopic dermatitis; and in stomatology for diagnosis of oral diseases. For all considered application, we propose and develop different image processing methods which enhance the diagnostic value of the technique. In particular, we use histogram analysis, Fourier analysis and neural networks, thus calculating different tissue characteristics as revealed by OCT's polarization evolution. These approaches enable improved OCT image quantification and increase its resultant diagnostic accuracy.

Serum and urine metabolomics study reveals a distinct diagnostic model for cancer cachexia

PubMed Central

Yang, Quan‐Jun; Zhao, Jiang‐Rong; Hao, Juan; Li, Bin; Huo, Yan; Han, Yong‐Long; Wan, Li‐Li; Li, Jie; Huang, Jinlu; Lu, Jin

2017-01-01

Abstract Background Cachexia is a multifactorial metabolic syndrome with high morbidity and mortality in patients with advanced cancer. The diagnosis of cancer cachexia depends on objective measures of clinical symptoms and a history of weight loss, which lag behind disease progression and have limited utility for the early diagnosis of cancer cachexia. In this study, we performed a nuclear magnetic resonance‐based metabolomics analysis to reveal the metabolic profile of cancer cachexia and establish a diagnostic model. Methods Eighty‐four cancer cachexia patients, 33 pre‐cachectic patients, 105 weight‐stable cancer patients, and 74 healthy controls were included in the training and validation sets. Comparative analysis was used to elucidate the distinct metabolites of cancer cachexia, while metabolic pathway analysis was employed to elucidate reprogramming pathways. Random forest, logistic regression, and receiver operating characteristic analyses were used to select and validate the biomarker metabolites and establish a diagnostic model. Results Forty‐six cancer cachexia patients, 22 pre‐cachectic patients, 68 weight‐stable cancer patients, and 48 healthy controls were included in the training set, and 38 cancer cachexia patients, 11 pre‐cachectic patients, 37 weight‐stable cancer patients, and 26 healthy controls were included in the validation set. All four groups were age‐matched and sex‐matched in the training set. Metabolomics analysis showed a clear separation of the four groups. Overall, 45 metabolites and 18 metabolic pathways were associated with cancer cachexia. Using random forest analysis, 15 of these metabolites were identified as highly discriminating between disease states. Logistic regression and receiver operating characteristic analyses were used to create a distinct diagnostic model with an area under the curve of 0.991 based on three metabolites. The diagnostic equation was Logit(P) = −400.53 – 481.88 × log(Carnosine) −239.02 × log(Leucine) + 383.92 × log(Phenyl acetate), and the result showed 94.64% accuracy in the validation set. Conclusions This metabolomics study revealed a distinct metabolic profile of cancer cachexia and established and validated a diagnostic model. This research provided a feasible diagnostic tool for identifying at‐risk populations through the detection of serum metabolites. PMID:29152916

An Investigation of Diagnostic Accuracy and Confidence Associated with Diagnostic Checklists as Well as Gender Biases in Relation to Mental Disorders.

PubMed

Cwik, Jan C; Papen, Fabienne; Lemke, Jan-Erik; Margraf, Jürgen

2016-01-01

This study examines the utility of checklists in attaining more accurate diagnoses in the context of diagnostic decision-making for mental disorders. The study also aimed to replicate results from a meta-analysis indicating that there is no association between patients' gender and misdiagnoses. To this end, 475 psychotherapists were asked to judge three case vignettes describing patients with Major Depressive Disorder (MDD), Generalized Anxiety Disorder, and Borderline Personality Disorder. Therapists were randomly assigned to experimental conditions in a 2 (diagnostic method: with using diagnostic checklists vs. without using diagnostic checklists) × 2 (gender: male vs. female case vignettes) between-subjects design. Multinomial logistic and linear regression analyses were used to examine the association between the usage of diagnostic checklists as well as patients' gender and diagnostic decisions. The results showed that when checklists were used, fewer incorrect co-morbid diagnoses were made, but clinicians were less likely to diagnose MDD even when the criteria were met. Additionally, checklists improved therapists' confidence with diagnostic decisions, but were not associated with estimations of patients' characteristics. As expected, there were no significant associations between gender and diagnostic decisions.

Aerospike Engine Post-Test Diagnostic System Delivered to Rocketdyne

NASA Technical Reports Server (NTRS)

Meyer, Claudia M.

2000-01-01

The NASA Glenn Research Center at Lewis Field, in cooperation with Rocketdyne, has designed, developed, and implemented an automated Post-Test Diagnostic System (PTDS) for the X-33 linear aerospike engine. The PTDS was developed to reduce analysis time and to increase the accuracy and repeatability of rocket engine ground test fire and flight data analysis. This diagnostic system provides a fast, consistent, first-pass data analysis, thereby aiding engineers who are responsible for detecting and diagnosing engine anomalies from sensor data. It uses analytical methods modeled after the analysis strategies used by engineers. Glenn delivered the first version of PTDS in September of 1998 to support testing of the engine s power pack assembly. The system was used to analyze all 17 power pack tests and assisted Rocketdyne engineers in troubleshooting both data acquisition and test article anomalies. The engine version of PTDS, which was delivered in June of 1999, will support all single-engine, dual-engine, and flight firings of the aerospike engine.

Dielectrophoresis-Based Sample Handling in General-Purpose Programmable Diagnostic Instruments

PubMed Central

Gascoyne, Peter R. C.; Vykoukal, Jody V.

2009-01-01

As the molecular origins of disease are better understood, the need for affordable, rapid, and automated technologies that enable microscale molecular diagnostics has become apparent. Widespread use of microsystems that perform sample preparation and molecular analysis could ensure that the benefits of new biomedical discoveries are realized by a maximum number of people, even those in environments lacking any infrastructure. While progress has been made in developing miniaturized diagnostic systems, samples are generally processed off-device using labor-intensive and time-consuming traditional sample preparation methods. We present the concept of an integrated programmable general-purpose sample analysis processor (GSAP) architecture where raw samples are routed to separation and analysis functional blocks contained within a single device. Several dielectrophoresis-based methods that could serve as the foundation for building GSAP functional blocks are reviewed including methods for cell and particle sorting, cell focusing, cell ac impedance analysis, cell lysis, and the manipulation of molecules and reagent droplets. PMID:19684877

Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data

DOE PAGES

Strait, E. J.; King, J. D.; Hanson, J. M.; ...

2016-08-11

An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric "3D" features of tokamak plasmas, with typical amplitudes ~10 -3 to 10 -5 of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Lastly, applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.

Diagnostic Performance of (18)F-Fluorodeoxyglucose in 162 Small Pulmonary Nodules Incidentally Detected in Subjects Without a History of Malignancy.

PubMed

Calcagni, Maria Lucia; Taralli, Silvia; Cardillo, Giuseppe; Graziano, Paolo; Ialongo, Pasquale; Mattoli, Maria Vittoria; Di Franco, Davide; Caldarella, Carmelo; Carleo, Francesco; Indovina, Luca; Giordano, Alessandro

2016-04-01

Solitary pulmonary nodule (SPN) still represents a diagnostic challenge. The aim of our study was to evaluate the diagnostic performance of (18)F-fluorodeoxyglucose positron emission tomography-computed tomography in one of the largest samples of small SPNs, incidentally detected in subjects without a history of malignancy (nonscreening population) and undetermined at computed tomography. One-hundred and sixty-two small (>0.8 to 1.5 cm) and, for comparison, 206 large nodules (>1.5 to 3 cm) were retrospectively evaluated. Diagnostic performance of (18)F-fluorodeoxyglucose visual analysis, receiver-operating characteristic (ROC) analysis for maximum standardized uptake value (SUVmax), and Bayesian analysis were assessed using histology or radiological follow-up as a golden standard. In 162 small nodules, (18)F-fluorodeoxyglucose visual and ROC analyses (SUVmax = 1.3) provided 72.6% and 77.4% sensitivity and 88.0% and 82.0% specificity, respectively. The prevalence of malignancy was 38%; Bayesian analysis provided 78.8% positive and 16.0% negative posttest probabilities of malignancy. In 206 large nodules (18)F-fluorodeoxyglucose visual and ROC analyses (SUVmax = 1.9) provided 89.5% and 85.1% sensitivity and 70.8% and 79.2% specificity, respectively. The prevalence of malignancy was 65%; Bayesian analysis provided 85.0% positive and 21.6% negative posttest probabilities of malignancy. In both groups, malignant nodules had a significant higher SUVmax (p < 0.0001) than benign nodules. Only in the small group, malignant nodules were significantly larger (p = 0.0054) than benign ones. (18)F-fluorodeoxyglucose can be clinically relevant to rule in and rule out malignancy in undetermined small SPNs, incidentally detected in nonscreening population with intermediate pretest probability of malignancy, as well as in larger ones. Visual analysis can be considered an optimal diagnostic criterion, adequately detecting a wide range of malignant nodules with different metabolic activity. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Diagnostic value of sTREM-1 in bronchoalveolar lavage fluid in ICU patients with bacterial lung infections: a bivariate meta-analysis.

PubMed

Shi, Jia-Xin; Li, Jia-Shu; Hu, Rong; Li, Chun-Hua; Wen, Yan; Zheng, Hong; Zhang, Feng; Li, Qin

2013-01-01

The serum soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is a useful biomarker in differentiating bacterial infections from others. However, the diagnostic value of sTREM-1 in bronchoalveolar lavage fluid (BALF) in lung infections has not been well established. We performed a meta-analysis to assess the accuracy of sTREM-1 in BALF for diagnosis of bacterial lung infections in intensive care unit (ICU) patients. We searched PUBMED, EMBASE and Web of Knowledge (from January 1966 to October 2012) databases for relevant studies that reported diagnostic accuracy data of BALF sTREM-1 in the diagnosis of bacterial lung infections in ICU patients. Pooled sensitivity, specificity, and positive and negative likelihood ratios were calculated by a bivariate regression analysis. Measures of accuracy and Q point value (Q*) were calculated using summary receiver operating characteristic (SROC) curve. The potential between-studies heterogeneity was explored by subgroup analysis. Nine studies were included in the present meta-analysis. Overall, the prevalence was 50.6%; the sensitivity was 0.87 (95% confidence interval (CI), 0.72-0.95); the specificity was 0.79 (95% CI, 0.56-0.92); the positive likelihood ratio (PLR) was 4.18 (95% CI, 1.78-9.86); the negative likelihood ratio (NLR) was 0.16 (95% CI, 0.07-0.36), and the diagnostic odds ratio (DOR) was 25.60 (95% CI, 7.28-89.93). The area under the SROC curve was 0.91 (95% CI, 0.88-0.93), with a Q* of 0.83. Subgroup analysis showed that the assay method and cutoff value influenced the diagnostic accuracy of sTREM-1. BALF sTREM-1 is a useful biomarker of bacterial lung infections in ICU patients. Further studies are needed to confirm the optimized cutoff value.

Meta-Analyses of Diagnostic Accuracy in Imaging Journals: Analysis of Pooling Techniques and Their Effect on Summary Estimates of Diagnostic Accuracy.

PubMed

McGrath, Trevor A; McInnes, Matthew D F; Korevaar, Daniël A; Bossuyt, Patrick M M

2016-10-01

Purpose To determine whether authors of systematic reviews of diagnostic accuracy studies published in imaging journals used recommended methods for meta-analysis, and to evaluate the effect of traditional methods on summary estimates of sensitivity and specificity. Materials and Methods Medline was searched for published systematic reviews that included meta-analysis of test accuracy data limited to imaging journals published from January 2005 to May 2015. Two reviewers independently extracted study data and classified methods for meta-analysis as traditional (univariate fixed- or random-effects pooling or summary receiver operating characteristic curve) or recommended (bivariate model or hierarchic summary receiver operating characteristic curve). Use of methods was analyzed for variation with time, geographical location, subspecialty, and journal. Results from reviews in which study authors used traditional univariate pooling methods were recalculated with a bivariate model. Results Three hundred reviews met the inclusion criteria, and in 118 (39%) of those, authors used recommended meta-analysis methods. No change in the method used was observed with time (r = 0.54, P = .09); however, there was geographic (χ(2) = 15.7, P = .001), subspecialty (χ(2) = 46.7, P < .001), and journal (χ(2) = 27.6, P < .001) heterogeneity. Fifty-one univariate random-effects meta-analyses were reanalyzed with the bivariate model; the average change in the summary estimate was -1.4% (P < .001) for sensitivity and -2.5% (P < .001) for specificity. The average change in width of the confidence interval was 7.7% (P < .001) for sensitivity and 9.9% (P ≤ .001) for specificity. Conclusion Recommended methods for meta-analysis of diagnostic accuracy in imaging journals are used in a minority of reviews; this has not changed significantly with time. Traditional (univariate) methods allow overestimation of diagnostic accuracy and provide narrower confidence intervals than do recommended (bivariate) methods. (©) RSNA, 2016 Online supplemental material is available for this article.

A new dump system design for stray light reduction of Thomson scattering diagnostic system on EAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Shumei; Zang, Qing, E-mail: zangq@ipp.ac.cn; Han, Xiaofeng

Thomson scattering (TS) diagnostic is an important diagnostic for measuring electron temperature and density during plasma discharge. However, the measurement of Thomson scattering signal is disturbed by the stray light easily. The stray light sources in the Experimental Advanced Superconducting Tokamak (EAST) TS diagnostic system were analyzed by a simulation model of the diagnostic system, and simulation results show that the dump system is the primary stray light source. Based on the optics theory and the simulation analysis, a novel dump system including an improved beam trap was proposed and installed. The measurement results indicate that the new dump systemmore » can reduce more than 60% of the stray light for the diagnostic system, and the influence of stray light on the error of measured density decreases.« less

[Validity of three methods for inmuno-diagnostic of neurocysticercosis: systematic review of the literature with meta-analysis 1960-2014].

PubMed

Cardona-Arias, Jaiberth Antonio; Carrasquilla-Agudelo, Yoneida Elena; Restrepo-Posada, Deisy Cristina

2017-02-01

The screening of neurocysticercosis is complex and immunological methods have varying validity. To evaluate the validity of ELISA for antigen and antibody, and EITB for antibody in the screening of neurocysticercosis. Meta-analysis of diagnostic tests with an ex-ante protocol implemented in five databases with 15 search strategies, ensuring reproducibility in the selection and extraction of information. Sensitivity, specificity, likelihood ratios (LR), diagnostic odds ratio and ROC curve were estimated in MetaDiSc, and predictive values, and Youden index were estimated in Epidat. EITB presented sensitivity of 85.7% (95% CI 83.5-87.7), specificity 93.9% (95% CI = 92.7-95.0), PLR 19.6 (95% CI = 8,6-44.6), NLR 0.16 (95% CI = 0.12-0.21), OR diagnostic 136.2 (95% CI = 54.7-342.6) and area under the curve 0.926. In ELISA for antibody sensitivity was 87.5% (95% CI = 86.1-88.8), specificity 92.2% (95% CI = 91.4-93.0), PLR 11.3 (95% CI = 8.45-15.11), NLR 0.15 (95% CI = 0.13-0.18), diagnostic OR 87.4 (95% CI = 60.1-127.1) and area under the curve 0.950. ELISA for antigen showed low diagnostic validity. No differences were found in these parameters by sample, antigen or antibody type. ELISA for antibodies and EITB have a similar diagnostic value, detection of serum and CSF showed a similar validity.

The diagnostic performance of shear-wave elastography for liver fibrosis in children and adolescents: A systematic review and diagnostic meta-analysis.

PubMed

Kim, Jeong Rye; Suh, Chong Hyun; Yoon, Hee Mang; Lee, Jin Seong; Cho, Young Ah; Jung, Ah Young

2018-03-01

To assess the diagnostic performance of shear-wave elastography for determining the severity of liver fibrosis in children and adolescents. An electronic literature search of PubMed and EMBASE was conducted. Bivariate modelling and hierarchical summary receiver-operating-characteristic modelling were performed to evaluate the diagnostic performance of shear-wave elastography. Meta-regression and subgroup analyses according to the modality of shear-wave imaging and the degree of liver fibrosis were also performed. Twelve eligible studies with 550 patients were included. Shear-wave elastography showed a summary sensitivity of 81 % (95 % CI: 71-88) and a specificity of 91 % (95 % CI: 83-96) for the prediction of significant liver fibrosis. The number of measurements of shear-wave elastography performed was a significant factor influencing study heterogeneity. Subgroup analysis revealed shear-wave elastography to have an excellent diagnostic performance according to each degree of liver fibrosis. Supersonic shear imaging (SSI) had a higher sensitivity (p<.01) and specificity (p<.01) than acoustic radiation force impulse imaging (ARFI). Shear-wave elastography is an excellent modality for the evaluation of the severity of liver fibrosis in children and adolescents. Compared with ARFI, SSI showed better diagnostic performance for prediction of significant liver fibrosis. • Shear-wave elastography is beneficial for determining liver fibrosis severity in children. • Shear-wave elastography showed summary sensitivity of 81 %, specificity of 91 %. • SSI showed better diagnostic performance than ARFI for significant liver fibrosis.

Diagnostic utility of abdominal ultrasonography in dogs with chronic vomiting.

PubMed

Leib, M S; Larson, M M; Panciera, D L; Troy, G C; Monroe, W E; Rossmeisl, J H; Forrester, S D; Herring, E S

2010-01-01

Chronic vomiting is a common problem in dogs that has many causes. Ultrasonographic descriptions of many gastrointestinal (GI) diseases have been published. However, diagnostic utility of ultrasonography in dogs with chronic vomiting has not been investigated. Diagnostic utility of abdominal ultrasound will be highest in dogs with GI neoplasia and lowest in those with inflammatory disorders. Eighty-nine pet dogs with chronic vomiting. Medical records were reviewed and the contribution of abdominal ultrasound to the clinical diagnosis was subjectively scored. In 68.5% of dogs, the reviewers thought that the same diagnosis would have been reached without performing ultrasonography. In 22.5% of dogs, the ultrasound examination was considered to be vital or beneficial to the diagnosis. Univariable analysis identified that increased diagnostic utility was associated with increasing age, a greater number of vomiting episodes per week, presence of weight loss, a greater percentage of lost body weight, and a final diagnosis of GI lymphoma or gastric adenocarcinoma. However, multivariate analysis only identified increasing age and a final diagnosis of gastric adenocarcinoma or GI lymphoma to be associated with increased diagnostic utility. In 12.4% of dogs, additional benefits of ultrasonography to case management, excluding the contribution to the vomiting problem, were identified. The diagnostic utility of abdominal ultrasonography was high in 27% of dogs. The presence of factors that are associated with high diagnostic utility is an indication to perform abdominal ultrasonography in dogs with chronic vomiting.

Evaluation of a diagnostic flow chart applying medical thoracoscopy, adenosine deaminase and T-SPOT.TB in diagnosis of tuberculous pleural effusion.

PubMed

He, Y; Zhang, W; Huang, T; Wang, X; Wang, M

2015-10-01

To evaluate a diagnostic flow chart applying medical thoracoscoy (MT), adenosine deaminase (ADA) and T-SPOT.TB in diagnosis of tuberculous pleural effusion (TPE) at a high TB burden country. 136 patients with pleural effusion (PE) were enrolled and divided into TPE and Non-TPE group. MT (histology), PE ADA and T-SPOT.TB were conducted on all patients. ROC analysis was performed for the best cut-off value of PE ADA in detection of TPE. The diagnostic flow chart applying MT, ADA and T-SPOT.TB was evaluated for improving the limitations of each diagnostic method. ROC analysis showed that the best cut-off value of PE ADA was 30U/L. The sensitivity and specificity of these tests were calculated respectively to be: 71.4% (58.5%-81.6%) and 100% (95.4-100.0%) for MT, 92.9% (83.0-97.2%) and 68.8% (57.9-77.9%) for T-SPOT.TB, and 80.0% (69.6-88.1%) and 92.9% (82.7-98.0%) for PE ADA. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, positive predictive value and negative predictive value of the diagnostic flow chart were 96.4% (87.9-99.0%), 96.3% (89.6-98.7%), 25.714, 0.037, 97.4 and 94.9, respectively. The diagnostic flow chart applying MT, ADA and T-SPOT.TB is an accurate and rapid diagnostic method in detection of TPE.

Can CT imaging features of ground-glass opacity predict invasiveness? A meta-analysis.

PubMed

Dai, Jian; Yu, Guoyou; Yu, Jianqiang

2018-04-01

A meta-analysis was conducted to investigate the diagnostic performance of computed tomography (CT) imaging features of ground-glass opacity (GGO) to predict invasiveness. Two reviewers independently searched PubMed, Medline, Web of Science, Cochrane Embase and CNKI for relevant studies. CT imaging signs of bubble lucency, speculation, lobulated margin, and pleural indentation were used as diagnostic references to discriminate pre-invasive and invasive disease. The sensitivity, specificity, diagnostic odds ratio (DOR), summary receiver operating characteristic (SROC) curves, and the area under the SROC curve (AUC) were calculated to evaluate diagnostic efficiency. Twelve studies were finally included. Diagnostic performance ranged from 0.41 to 0.52 for sensitivity and 0.56 to 0.63 for specificity. The diagnostic positive and negative likelihood ratios ranged from 1.03 to 2.13 and 0.52 to 1.05, respectively. The DORs of the GGO CT features for discriminating invasive disease ranged from 1.02 to 4.00. The area under the ROC curve was also low, with a range of 0.60 to 0.67 for discriminating pre-invasive and invasive disease. The diagnostic value of a single CT imaging sign of GGO, such as bubble lucency, speculation, lobulated margin, or pleural indentation is limited for discriminating pre-invasive and invasive disease because of low sensitivity, specificity, and AUC. © 2018 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.

Diagnostic accuracy of dual-source computed tomography angiography for the detection of coronary in-stent restenosis: A systematic review and meta-analysis.

PubMed

Liu, Wen-Jun; Li, Gui-Zhen; Liu, Hai-Feng; Lei, Jun-Qiang

2018-04-01

We sought to perform a meta-analysis to comprehensively evaluate the diagnostic accuracy of dual-source computed tomography angiography (DSCTA) in detecting coronary in-stent restenosis (CISR) when compared to invasive coronary angiography. The stent-based research studies in which DSCTA was used as diagnostic tool for CISR, as recent as of October 2017, from several reputed scientific libraries (PubMed, Embase, Scopus, The Cochrane Library, and Web of Science) were evaluated. Study inclusion, data extraction, and risk bias assessment were conducted by two researchers independently. Pooled sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under summary receiver operator characteristics (SROC) curve (AUC) were calculated to assess the diagnostic value. In addition, heterogeneity and subgroup analysis were also carried out. A total of 13 studies with a total of 894 patients and 1384 assessable stents were included. The pooled results of DSCTA diagnosing CISR were as follows: SEN 0.92 (95% confidence interval [CI] 0.87-0.96), SPE 0.91 (95% CI 0.87-0.94), PLR 9.83 (95% CI 6.93-13.94), NLR 0.09 (95% CI 0.05-0.15), DOR 114.73 (95% CI 64.12-205.28), and AUC 0.97 (95% CI 0.95-0.98), respectively. The subgroup analysis result suggested that DSTCA performed significantly better in CISR detection when the stent diameter was ≥3 mm compared with the stent diameter <3 mm: (0.98 [0.97-0.99] vs 0.82 [0.79-0.86]) with P < .05. This study revealed that DSCTA has excellent diagnostic performance for detecting CISR and may serve as an alternative for further patient evaluation with CISR, especially for stent diameter ≥3 mm. © 2018 Wiley Periodicals, Inc.

Who Is at Risk for Diagnostic Discrepancies? Comparison of Pre- and Postmortal Diagnoses in 1800 Patients of 3 Medical Decades in East and West Berlin

PubMed Central

Wittschieber, Daniel; Klauschen, Frederick; Kimmritz, Anna-Christin; von Winterfeld, Moritz; Kamphues, Carsten; Scholman, Hans-Joachim; Erbersdobler, Andreas; Pfeiffer, Heidi; Denkert, Carsten; Dietel, Manfred; Weichert, Wilko

2012-01-01

Background Autopsy rates in Western countries consistently decline to an average of <5%, although clinical autopsies represent a reasonable tool for quality control in hospitals, medically and economically. Comparing pre- and postmortal diagnoses, diagnostic discrepancies as uncovered by clinical autopsies supply crucial information on how to improve clinical treatment. The study aimed at analyzing current diagnostic discrepancy rates, investigating their influencing factors and identifying risk profiles of patients that could be affected by a diagnostic discrepancy. Methods and Findings Of all adult autopsy cases of the Charité Institute of Pathology from the years 1988, 1993, 1998, 2003 and 2008, the pre- and postmortal diagnoses and all demographic data were analyzed retrospectively. Based on power analysis, 1,800 cases were randomly selected to perform discrepancy classification (class I-VI) according to modified Goldman criteria. The rate of discrepancies in major diagnoses (class I) was 10.7% (95% CI: 7.7%–14.7%) in 2008 representing a reduction by 15.1%. Subgroup analysis revealed several influencing factors to significantly correlate with the discrepancy rate. Cardiovascular diseases had the highest frequency among class-I-discrepancies. Comparing the 1988-data of East- and West-Berlin, no significant differences were found in diagnostic discrepancies despite an autopsy rate differing by nearly 50%. A risk profile analysis visualized by intuitive heatmaps revealed a significantly high discrepancy rate in patients treated in low or intermediate care units at community hospitals. In this collective, patients with genitourinary/renal or infectious diseases were at particularly high risk. Conclusions This is the current largest and most comprehensive study on diagnostic discrepancies worldwide. Our well-powered analysis revealed a significant rate of class-I-discrepancies indicating that autopsies are still of value. The identified risk profiles may aid both pathologists and clinicians to identify patients at increased risk for a discrepant diagnosis and possibly suboptimal treatment intra vitam. PMID:22629399

A Hybrid Stochastic-Neuro-Fuzzy Model-Based System for In-Flight Gas Turbine Engine Diagnostics

DTIC Science & Technology

2001-04-05

Margin (ADM) and (ii) Fault Detection Margin (FDM). Key Words: ANFIS, Engine Health Monitoring , Gas Path Analysis, and Stochastic Analysis Adaptive Network...The paper illustrates the application of a hybrid Stochastic- Fuzzy -Inference Model-Based System (StoFIS) to fault diagnostics and prognostics for both...operational history monitored on-line by the engine health management (EHM) system. To capture the complex functional relationships between different

Analysis of significantly mutated genes as a clinical tool for the diagnosis in a case of lung cancer.

PubMed

Miyashita, Yoshihiro; Hirotsu, Yosuke; Tsutsui, Toshiharu; Higashi, Seishi; Sogami, Yusuke; Kakizaki, Yumiko; Goto, Taichiro; Amemiya, Kenji; Oyama, Toshio; Omata, Masao

2017-01-01

Bronchoendoscopic examination is not necessarily comfortable procedure and limited by its sensitivity, depending on the location and size of the tumor lesion. Patients with a non-diagnostic bronchoendoscopic examination often undergo further invasive examinations. Non-invasive diagnostic tool of lung cancer is desired. A 72-year-old man had a 3.0 cm × 2.5 cm mass lesion in the segment B1 of right lung. Cytological examination of sputum, bronchial washing and curetted samples were all "negative". We could confirm a diagnosis of lung cancer after right upper lung lobe resection pathologically, and also obtained concordant results by genomic analysis using cytological negative samples from airways collected before operation. Genetic analysis showed mutational profiles of both resected specimens and samples from airways were identical. These data clearly indicated the next generation sequencing (NGS) may yield a diagnostic tool to conduct "precision medicine".

Expert diagnostics system as a part of analysis software for power mission operations

NASA Technical Reports Server (NTRS)

Harris, Jennifer A.; Bahrami, Khosrow A.

1993-01-01

The operation of interplanetary spacecraft at JPL has become an increasingly complex activity. This complexity is due to advanced spacecraft designs and ambitious mission objectives which lead to operations requirements that are more demanding than those of any previous mission. For this reason, several productivity enhancement measures are underway at JPL within mission operations, particularly in the spacecraft analysis area. These measures aimed at spacecraft analysis include: the development of a multi-mission, multi-subsystem operations environment; the introduction of automated tools into this environment; and the development of an expert diagnostics system. This paper discusses an effort to integrate the above mentioned productivity enhancement measures. A prototype was developed that integrates an expert diagnostics system into a multi-mission, multi-subsystem operations environment using the Galileo Power / Pyro Subsystem as a testbed. This prototype will be discussed in addition to background information associated with it.

Debris characterization diagnostic for the NIF

NASA Astrophysics Data System (ADS)

Miller, M. C.; Celeste, J. R.; Stoyer, M. A.; Suter, L. J.; Tobin, M. T.; Grun, J.; Davis, J. F.; Barnes, C. W.; Wilson, D. C.

2001-01-01

Generation of debris from targets and by x-ray ablation of surrounding materials will be a matter of concern for experimenters and National Ignition Facility (NIF) operations. Target chamber and final optics protection, for example debris shield damage, drive the interest for NIF operations. Experimenters are primarily concerned with diagnostic survivability, separation of mechanical versus radiation induced test object response in the case of effects tests, and radiation transport through the debris field when the net radiation output is used to benchmark computer codes. In addition, radiochemical analysis of activated capsule debris during ignition shots can provide a measure of the ablator <ρr>. Conceptual design of the Debris Monitor and Rad-Chem Station, one of the NIF core diagnostics, is presented. Methods of debris collection, particle size and mass analysis, impulse measurement, and radiochemical analysis are given. A description of recent experiments involving debris collection and impulse measurement on the OMEGA and Pharos lasers is also provided.

High-throughput cell analysis and sorting technologies for clinical diagnostics and therapeutics

NASA Astrophysics Data System (ADS)

Leary, James F.; Reece, Lisa M.; Szaniszlo, Peter; Prow, Tarl W.; Wang, Nan

2001-05-01

A number of theoretical and practical limits of high-speed flow cytometry/cell sorting are important for clinical diagnostics and therapeutics. Three applications include: (1) stem cell isolation with tumor purging for minimal residual disease monitoring and treatment, (2) identification and isolation of human fetal cells from maternal blood for prenatal diagnostics and in-vitro therapeutics, and (3) high-speed library screening for recombinant vaccine production against unknown pathogens.

Implementation of a multichannel soft x-ray diagnostic for electron temperature measurements in TJ-II high-density plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baiao, D.; Varandas, C.; Medina, F.

2012-10-15

Based on the multi-foil technique, a multichannel soft x-ray diagnostic for electron temperature measurements has been recently implemented in the TJ-II stellarator. The diagnostic system is composed by four photodiodes arrays with beryllium filters of different thickness. An in-vacuum amplifier board is coupled to each array, aiming at preventing induced noise currents. The Thomson scattering and the vacuum ultraviolet survey diagnostics are used for assessing plasma profiles and composition, being the analysis carried out with the radiation code IONEQ. The electron temperature is determined through the different signal-pair ratios with temporal and spatial resolution. The design and preliminary results frommore » the diagnostic are presented.« less

The prevalence of depressive symptoms in frontotemporal dementia: a meta-analysis.

PubMed

Chakrabarty, Trisha; Sepehry, Amir A; Jacova, Claudia; Hsiung, Ging-Yuek Robin

2015-01-01

Depression is common in Alzheimer's and vascular dementia and is associated with poorer outcomes; however, less is known about the impact of depression on frontotemporal dementia (FTD). Here, we conducted a meta-analysis of diagnostic methods and the prevalence of depressive symptoms in FTD. PubMed, EMBASE and PsychINFO were queried for 'depression' and/or 'depressive mood' in behavioral- and language-variant FTD. The prevalence and diagnosis of depressive symptoms were extracted from relevant studies and the results pooled using a random-effects model. We included 29 studies in this meta-analysis, with sample sizes ranging from 3 to 73 (n = 870). The omnibus estimated event rate of depressed mood was 0.334 (33%; 95% CI: 0.268-0.407). Symptoms were most commonly assessed via standardized neuropsychiatric rating scales, with other methods including subjective caregiver reports and chart reviews. The study results were heterogeneous due to the variability in diagnostic methods. Depressive symptoms similar to those in other dementias are commonly detected in FTD. However, the diagnostic methods are heterogeneous, and symptoms of depression often overlap with manifestations of FTD. Having a standardized diagnostic approach to depression in FTD will greatly facilitate future research in this area.

[Clinical picture, diagnostics and prophylaxis of a syndrome in conditions of the Far North].

PubMed

Ukhocskiĭ, D M; Tegza, V Iu; Rezvantsev, M V; Vasil'chenko, V V; Belikova, T M

2014-10-01

The analysis of a clinical picture barometeosensitivity in a seaside zone of the Far North is carried out in the article. A diagnostic test included the following laboratory assessments: complete blood count, complete urinary analysis, biomedical measurement assessment, immunology blood research and functional renal test; analysis of the level of an electrolyte in the blood and hormone receptor status; and the following instrumental diagnostics: The auscultatory Korotkov's method of determining blood pressure, electrocardiography, variational pulsometry, chest X-ray, mechanocardiography, echocardiography and abdominal ultrasound; and also consultation of ophthalmologist and neuropathologist. Every patient should keep a diary "weather - health" before and after the treatment. Peculiarities of cardiovascular system, vegetative systems and neuroendocrine system of servicemen, coming to the Far North and mechanisms of development of barometeosensivity were revealed. It has been established that atmospheric pressure variation affects systolic and diastolic blood pressure, heart rate, systolic discharge, Kerdo index, effectiveness of myocardial function, end-diastolic and end-systolic volume, level of cholesterol, triglycerides, kalium, adrenalin, triiodothyronine, blood plasma and plasma renin activity in barometeosensetiv servicemen. The criteria of diagnostics of barometeosensivity in conditions of the Far North are suggested. The influence of baromemteosensivity on the combat capability of serviceman is researched.

Diagnostic Accuracy and Cost-Effectiveness of Alternative Methods for Detection of Soil-Transmitted Helminths in a Post-Treatment Setting in Western Kenya

PubMed Central

Kepha, Stella; Kihara, Jimmy H.; Njenga, Sammy M.; Pullan, Rachel L.; Brooker, Simon J.

2014-01-01

Objectives This study evaluates the diagnostic accuracy and cost-effectiveness of the Kato-Katz and Mini-FLOTAC methods for detection of soil-transmitted helminths (STH) in a post-treatment setting in western Kenya. A cost analysis also explores the cost implications of collecting samples during school surveys when compared to household surveys. Methods Stool samples were collected from children (n = 652) attending 18 schools in Bungoma County and diagnosed by the Kato-Katz and Mini-FLOTAC coprological methods. Sensitivity and additional diagnostic performance measures were analyzed using Bayesian latent class modeling. Financial and economic costs were calculated for all survey and diagnostic activities, and cost per child tested, cost per case detected and cost per STH infection correctly classified were estimated. A sensitivity analysis was conducted to assess the impact of various survey parameters on cost estimates. Results Both diagnostic methods exhibited comparable sensitivity for detection of any STH species over single and consecutive day sampling: 52.0% for single day Kato-Katz; 49.1% for single-day Mini-FLOTAC; 76.9% for consecutive day Kato-Katz; and 74.1% for consecutive day Mini-FLOTAC. Diagnostic performance did not differ significantly between methods for the different STH species. Use of Kato-Katz with school-based sampling was the lowest cost scenario for cost per child tested ($10.14) and cost per case correctly classified ($12.84). Cost per case detected was lowest for Kato-Katz used in community-based sampling ($128.24). Sensitivity analysis revealed the cost of case detection for any STH decreased non-linearly as prevalence rates increased and was influenced by the number of samples collected. Conclusions The Kato-Katz method was comparable in diagnostic sensitivity to the Mini-FLOTAC method, but afforded greater cost-effectiveness. Future work is required to evaluate the cost-effectiveness of STH surveillance in different settings. PMID:24810593

Diagnostic accuracy and cost-effectiveness of alternative methods for detection of soil-transmitted helminths in a post-treatment setting in western Kenya.

PubMed

Assefa, Liya M; Crellen, Thomas; Kepha, Stella; Kihara, Jimmy H; Njenga, Sammy M; Pullan, Rachel L; Brooker, Simon J

2014-05-01

This study evaluates the diagnostic accuracy and cost-effectiveness of the Kato-Katz and Mini-FLOTAC methods for detection of soil-transmitted helminths (STH) in a post-treatment setting in western Kenya. A cost analysis also explores the cost implications of collecting samples during school surveys when compared to household surveys. Stool samples were collected from children (n = 652) attending 18 schools in Bungoma County and diagnosed by the Kato-Katz and Mini-FLOTAC coprological methods. Sensitivity and additional diagnostic performance measures were analyzed using Bayesian latent class modeling. Financial and economic costs were calculated for all survey and diagnostic activities, and cost per child tested, cost per case detected and cost per STH infection correctly classified were estimated. A sensitivity analysis was conducted to assess the impact of various survey parameters on cost estimates. Both diagnostic methods exhibited comparable sensitivity for detection of any STH species over single and consecutive day sampling: 52.0% for single day Kato-Katz; 49.1% for single-day Mini-FLOTAC; 76.9% for consecutive day Kato-Katz; and 74.1% for consecutive day Mini-FLOTAC. Diagnostic performance did not differ significantly between methods for the different STH species. Use of Kato-Katz with school-based sampling was the lowest cost scenario for cost per child tested ($10.14) and cost per case correctly classified ($12.84). Cost per case detected was lowest for Kato-Katz used in community-based sampling ($128.24). Sensitivity analysis revealed the cost of case detection for any STH decreased non-linearly as prevalence rates increased and was influenced by the number of samples collected. The Kato-Katz method was comparable in diagnostic sensitivity to the Mini-FLOTAC method, but afforded greater cost-effectiveness. Future work is required to evaluate the cost-effectiveness of STH surveillance in different settings.

High diagnostic accuracy of histone H4-IgG autoantibodies in systemic lupus erythematosus.

PubMed

Vordenbäumen, Stefan; Böhmer, Paloma; Brinks, Ralph; Fischer-Betz, Rebecca; Richter, Jutta; Bleck, Ellen; Rengers, Petra; Göhler, Heike; Zucht, Hans-Dieter; Budde, Petra; Schulz-Knappe, Peter; Schneider, Matthias

2018-03-01

Diagnosis of SLE relies on the detection of autoantibodies. We aimed to assess the diagnostic potential of histone H4 and H2A variant antibodies in SLE. IgG-autoantibodies to histones H4 (HIST1H4A), H2A type 2-A (HIST2H2AA3) and H2A type 2-C (HIST2H2AC) were measured along with a standard antibody (SA) set including SSA, SSB, Sm, U1-RNP and RPLP2 in a multiplex magnetic microsphere-based assay in 153 SLE patients [85% female, 41 (13.5) years] and 81 healthy controls [77% female, 43.3 (12.4) years]. Receiver operating characteristic analysis was performed to assess diagnostic performance of individual markers. Logistic regression analysis was performed on a random split of samples to determine the additional value of histone antibodies in comparison with SA by likelihood ratio test and determination of diagnostic accuracy in the remaining validation samples. Microsphere-based assay showed good interclass correlation (mean 0.85, range 0.73-0.99) and diagnostic performance in receiver operating characteristic analysis (area under the curve (AUC) range 84.8-93.2) compared with routine assay for SA parameters. HIST1H4A-IgG was the marker with the best individual diagnostic performance for SLE vs healthy (AUC 0.97, sensitivity 95% at 90% specificity). HIST1H4A-IgG was an independent significant predictor for the diagnosis of SLE in multivariate modelling (P < 0.0001), and significantly improved prediction of SLE over SA parameters alone (residual deviance 45.9 vs 97.1, P = 4.3 × 10-11). Diagnostic accuracy in the training and validation samples was 89 and 86% for SA, and 95 and 89% with the addition of HIST1H4A-IgG. HIST1H4A-IgG antibodies improve diagnostic accuracy for SLE vs healthy. © The Author(s) 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. [br]For Permissions, please email: journals.permissions@oup.com

Instantaneous wave-free ratio as an alternative to fractional flow reserve in assessment of moderate coronary stenoses: A meta-analysis of diagnostic accuracy studies.

PubMed

Maini, Rohit; Moscona, John; Katigbak, Paul; Fernandez, Camilo; Sidhu, Gursukhmandeep; Saleh, Qusai; Irimpen, Anand; Samson, Rohan; LeJemtel, Thierry

2017-12-27

Fractional flow reserve (FFR) remains underutilized due to practical concerns related to the need for hyperemic agents. These concerns have prompted the study of instantaneous wave-free ratio (iFR), a vasodilator-free index of coronary stenosis. Non-inferior cardiovascular outcomes have been demonstrated in two recent randomized clinic trials. We performed this meta-analysis to provide a necessary update of the diagnostic accuracy of iFR referenced to FFR based on the addition of eight more recent studies and 3727 more lesions. We searched the PubMed, EMBASE, Central, ProQuest, and Web of Science databases for full text articles published through May 31, 2017 to identify studies addressing the diagnostic accuracy of iFR referenced to FFR≤0.80. The following keywords were used: "instantaneous wave-free ratio" OR "iFR" AND "fractional flow reserve" OR "FFR." In total, 16 studies comprising 5756 lesions were identified. Pooled diagnostic accuracy estimates of iFR versus FFR≤0.80 were: sensitivity, 0.78 (95% CI, 0.76-0.79); specificity, 0.83 (0.81-0.84); positive likelihood ratio, 4.54 (3.85-5.35); negative likelihood ratio, 0.28 (0.24-0.32); diagnostic odds ratio, 17.38 (14.16-21.34); area under the summary receiver-operating characteristic curve, 0.87; and an overall diagnostic accuracy of 0.81 (0.78-0.84). In conclusion, iFR showed excellent agreement with FFR as a resting index of coronary stenosis severity without the undesired effects and cost of hyperemic agents. When considering along with its clinical outcome data and ease of application, the diagnostic accuracy of iFR supports its use as a suitable alternative to FFR for physiology-guided revascularization of moderate coronary stenoses. We performed a meta-analysis of the diagnostic accuracy of iFR referenced to FFR. iFR showed excellent agreement with FFR as a resting index of coronary stenosis severity without the undesired effects and cost of hyperemic agents. This supports its use as a suitable alternative to FFR for physiology-guided revascularization of moderate coronary stenoses. Copyright © 2017. Published by Elsevier Inc.

Impact of arrhythmia on diagnostic performance of adenosine stress CMR in patients with suspected or known coronary artery disease.

PubMed

Greulich, Simon; Steubing, Hannah; Birkmeier, Stefan; Grün, Stefan; Bentz, Kerstin; Sechtem, Udo; Mahrholdt, Heiko

2015-11-05

The diagnostic performance of adenosine stress cardiovascular magnetic resonance (CMR) in patients with arrhythmias presenting for work-up of suspected or known CAD is largely unknown, since most CMR studies currently available exclude arrhythmic patients from analysis fearing gating problems, or other artifacts will impair image quality. The primary aim of our study was to evaluate the diagnostic performance of adenosine stress CMR for detection of significant coronary stenosis in patients with arrhythmia presenting for 1) work-up of suspected coronary artery disease (CAD), or 2) work-up of ischemia in known CAD. Patients with arrhythmia referred for work-up of suspected CAD or work-up of ischemia in known CAD undergoing adenosine stress CMR were included if they had coronary angiography within four weeks of CMR. One hundred fifty-nine patients were included (n = 64 atrial fibrillation, n = 87 frequent ventricular extrasystoles, n = 8 frequent supraventricular extrasystoles). Of these, n = 72 had suspected CAD, and n = 87 had known CAD. Diagnostic accuracy of the adenosine stress CMR for detection of significant CAD was 73 % for the entire population (sensitivity 72 %, specificity 76 %). Diagnostic accuracy was 75 % (sensitivity 80 %, specificity 74 %) in patients with suspected CAD, and 74 % (sensitivity 71 %, specificity 79 %) in the group with known CAD. For different types of arrhythmia, diagnostic accuracy of CMR was 70 % in the atrial fibrillation group, and 79 % in patients with ventricular extrasystoles. On a per coronary territory analysis, diagnostic accuracy of CMR was 77 % for stenosis of the left and 82 % for stenosis of the right coronary artery. The present data demonstrates good diagnostic performance of adenosine stress CMR for detection of significant coronary stenosis in patients with arrhythmia presenting for work-up of suspected CAD, or work-up of ischemia in known CAD. This holds true for a per patient, as well as for a per coronary territory analysis.

Diagnostic performance of random urine samples using albumin concentration vs ratio of albumin to creatinine for microalbuminuria screening in patients with diabetes mellitus: a systematic review and meta-analysis.

PubMed

Wu, Hon-Yen; Peng, Yu-Sen; Chiang, Chih-Kang; Huang, Jenq-Wen; Hung, Kuan-Yu; Wu, Kwan-Dun; Tu, Yu-Kang; Chien, Kuo-Liong

2014-07-01

A random urine sample measuring the albumin concentration (UAC) without simultaneously measuring the urinary creatinine is less expensive than measuring the ratio of albumin to creatinine (ACR), but comparisons of their diagnostic performance for microalbuminuria screening among patients with diabetes mellitus (DM) have not been undertaken in previous meta-analyses. To compare the diagnostic performance of the UAC vs the ACR in random urine samples for microalbuminuria screening among patients with DM. Electronic literature searches of PubMed, MEDLINE, and Scopus for English-language publications from the earliest available date of indexing through July 31, 2012. Clinical studies assessing the UAC or the ACR of random urine samples in detecting the presence of microalbuminuria among patients with DM using a urinary albumin excretion rate of 30 to 300 mg/d in 24-hour timed urine collections as the criterion standard. Bivariate random-effects models for analysis and pooling of the diagnostic performance measures across studies, as well as comparisons between different screening tests. The primary end point was the diagnostic performance measures of the UAC or the ACR in random urine samples, as well as comparisons between them. We identified 14 studies, with a total of 2078 patients; 9 studies reported on the UAC, and 12 studies reported on the ACR. Meta-analysis showed pooled sensitivities of 0.85 and 0.87 for the UAC and the ACR, respectively, and pooled specificities of 0.88 and 0.88, respectively. No differences in sensitivity (P = .70), specificity (P = .63), or diagnostic odds ratios (P = .59) between the UAC and the ACR were found. The time point of urine collection did not affect the diagnostic performance of either test. The UAC and the ACR yielded high sensitivity and specificity for the detection of microalbuminuria. Because the diagnostic performance of the UAC is comparable to that of the ACR, our findings indicate that the UAC of random urine samples may become the screening tool of choice for the population with DM, considering the rising incidence of DM and the constrained health care resources in many countries.

[Cost-benefit analysis of the active screening of pulmonary tuberculosis in a recluse population entering prison].

PubMed

Martín, V; Domínguez, A; Alcaide, J

1997-01-01

In spanish prisons, tuberculosis is a serious problem of public health and health authorities don't take it seriously. To prove the efficiency of pulmonary tuberculosis case-finding on arrival at prison in order to get location resources in this activity. Cost-benefit analysis of a case-finding program compared with to wait for diagnostic to illness. The sensitivity of test was fixed in 80% and the specificity in 99.99%. The cost was based on market prices. Sensitivity analysis was done in every variables as well as tridimensional analysis in those one of more influence. The case-finding was efficient on prevalences of tuberculosis over 5 per mil. Its efficiency was hardly affected by discount social rates or the sensitivity of diagnostic tests. The prevalence of illness, the cost of diagnostic activities as well as the success of treatment and the specificity of diagnostic tests used had as influence on the efficiency model. The tridimensional analysis proved that the case-finding of pulmonary tuberculosis has efficiency on low prevalences (1 per thousand), provided the number of people cured is a 5% higher than the alternative one and the costs of case-finding less than 1,000 pesetas per subject. The case-finding pulmonary tuberculosis on arrival at prisons is of high efficiency. In a cost-opportunity situation (location of available resources, penitentiary and extrapenitentiary) the program is very efficacious taking into account the fact of higher prevalence of pulmonary tuberculosis in this people.

Diagnostic accuracy of 18F-FDG-PET and PET/CT in the differential diagnosis between malignant and benign pleural lesions: a systematic review and meta-analysis.

PubMed

Treglia, Giorgio; Sadeghi, Ramin; Annunziata, Salvatore; Lococo, Filippo; Cafarotti, Stefano; Bertagna, Francesco; Prior, John O; Ceriani, Luca; Giovanella, Luca

2014-01-01

To systematically review and meta-analyze published data about the diagnostic accuracy of fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) and PET/computed tomography (CT) in the differential diagnosis between malignant and benign pleural lesions. A comprehensive literature search of studies published through June 2013 regarding the diagnostic performance of (18)F-FDG-PET and PET/CT in the differential diagnosis of pleural lesions was carried out. All retrieved studies were reviewed and qualitatively analyzed. Pooled sensitivity, specificity, positive and negative likelihood ratio (LR+ and LR-) and diagnostic odds ratio (DOR) of (18)F-FDG-PET or PET/CT in the differential diagnosis of pleural lesions on a per-patient-based analysis were calculated. The area under the summary receiver operating characteristic curve (AUC) was calculated to measure the accuracy of these methods. Subanalyses considering device used (PET or PET/CT) were performed. Sixteen studies including 745 patients were included in the systematic review. The meta-analysis of 11 selected studies provided the following results: sensitivity 95% (95% confidence interval [95%CI]: 92-97%), specificity 82% (95%CI: 76-88%), LR+ 5.3 (95%CI: 2.4-11.8), LR- 0.09 (95%CI: 0.05-0.14), DOR 74 (95%CI: 34-161). The AUC was 0.95. No significant improvement of the diagnostic accuracy considering PET/CT studies only was found. (18)F-FDG-PET and PET/CT demonstrated to be accurate diagnostic imaging methods in the differential diagnosis between malignant and benign pleural lesions; nevertheless, possible sources of false-negative and false-positive results should be kept in mind. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

Application of a Novel Diagnostic Rule in the Differential Diagnosis between Acute Gouty Arthritis and Septic Arthritis.

PubMed

Lee, Kwang-Hoon; Choi, Sang-Tae; Lee, Soo-Kyung; Lee, Joo-Hyun; Yoon, Bo-Young

2015-06-01

Septic arthritis and gout are major diseases that should be suspected in patients with acute monoarthritis. These two diseases are clinically similar and often indistinguishable without the help of synovial fluid analysis. Recently, a novel diagnostic rule for gout without synovial fluid analysis was developed and showed relevant performances. This study aimed to determine whether this diagnostic rule could perform well in distinguishing gout from septic arthritis. The diagnostic rule comprises 7 clinical and laboratory variables, each of which is given a specified score. The probability of gout is classified into 3 groups according to the sum of the scores: high (≥ 8), intermediate (> 4 to < 8) and low probability (≤ 4). In this retrospective study, we applied this diagnostic rule to 136 patients who presented as acute monoarthritis and were subsequently diagnosed as acute gout (n = 82) and septic arthritis (n = 54) based on synovial fluid analysis. The mean sum of scores of acute gout patients was significantly higher than that of those with septic arthritis (8.6 ± 0.2 vs. 3.6 ± 0.32, P < 0.001). Patients with acute gout had significantly more 'high', and less 'low' probabilities compared to those with septic arthritis (Eta[η]: 0.776). The prevalence of acute gouty arthritis, as confirmed by the presence of monosodium crystal, was 95.5% (61/64), 57.5% (19/33), and 5.1% (2/39) in high, intermediate and low probability group, respectively. The recently introduced diagnostic rule properly discriminates acute gout from septic arthritis. It may help physicians diagnose gout in cases difficult to be differentiated from septic arthritis.

Xpert MTB/RIF Assay for Pulmonary Tuberculosis and Rifampicin Resistance in Children: a Meta-Analysis.

PubMed

Wang, X W; Pappoe, F; Huang, Y; Cheng, X W; Xu, D F; Wang, H; Xu, Y H

2015-01-01

The Xpert MTB/RIF assay has been recommended by WHO to replace conventional microscopy, culture, and drug resistance tests. It simultaneously detects both Mycobacterium tuberculosis infection (TB) and resistance to rifampicin (RIF) within two hours. The objective was to review the available research studies on the accuracy of the Xpert MTB/RIF assay for diagnosing pulmonary TB and RIF-resistance in children. A comprehensive search of Pubmed and Embase was performed up to October 28, 2014. We identified published articles estimating the diagnostic accuracy of the Xpert MTB/RIF assay in children with or without HIV using culture or culture plus clinical TB as standard reference. QUADAS-2 tool was used to evaluate the quality of the studies. A summary estimation for sensitivity, specificity, diagnostic odds ratios (DOR), and the area under the summary ROC curve (AUC) was performed. Meta-analysis was used to establish the overall accuracy. 11 diagnostic studies with 3801 patients were included in the systematic review. The overall analysis revealed a moderate sensitivity and high specificity of 65% (95% CI: 61 - 69%) and 99% (95% CI: 98 - 99%), respectively, and a pooled diagnostic odds ratio of 164.09 (95% CI: 111.89 - 240.64). The AUC value was found to be 0.94. The pooled sensitivity and specificity for paediatric rifampicin resistance were 94.0% (95% CI: 80.0 - 93.0%) and 99.0% (95% CI: 95.0 - 98.0%), respectively. Hence, the Xpert MTB/RIF assay has good diagnostic and rifampicin performance for paediatric pulmonary tuberculosis. The Xpert MTB/RIF is sensitive and specific for diagnosing paediatric pulmonary TB. It is also effective in detecting rifamnicin resistance. It can, therefore, be used as an initial diagnostic tool.

Serum Mesothelin for Diagnosing Malignant Pleural Mesothelioma: An Individual Patient Data Meta-Analysis

PubMed Central

Hollevoet, Kevin; Reitsma, Johannes B.; Creaney, Jenette; Grigoriu, Bogdan D.; Robinson, Bruce W.; Scherpereel, Arnaud; Cristaudo, Alfonso; Pass, Harvey I.; Nackaerts, Kristiaan; Rodríguez Portal, José A.; Schneider, Joachim; Muley, Thomas; Di Serio, Francesca; Baas, Paul; Tomasetti, Marco; Rai, Alex J.; van Meerbeeck, Jan P.

2012-01-01

Purpose Mesothelin is currently considered the best available serum biomarker of malignant pleural mesothelioma. To examine the diagnostic accuracy and use of serum mesothelin in early diagnosis, we performed an individual patient data (IPD) meta-analysis. Methods The literature search identified 16 diagnostic studies of serum mesothelin, measured with the Mesomark enzyme-linked immunosorbent assay. IPD of 4,491 individuals were collected, including several control groups and 1,026 patients with malignant pleural mesothelioma. Mesothelin levels were standardized for between-study differences and age, after which the diagnostic accuracy and the factors affecting it were examined with receiver operating characteristic (ROC) regression analysis. Results At a common diagnostic threshold of 2.00 nmol/L, the sensitivities and specificities of mesothelin in the different studies ranged widely from 19% to 68% and 88% to 100%, respectively. This heterogeneity can be explained by differences in study population, because type of control group, mesothelioma stage, and histologic subtype significantly affected the diagnostic accuracy. The use of mesothelin in early diagnosis was evaluated by differentiating 217 patients with stage I or II epithelioid and biphasic mesothelioma from 1,612 symptomatic or high-risk controls. The resulting area under the ROC curve was 0.77 (95% CI, 0.73 to 0.81). At 95% specificity, mesothelin displayed a sensitivity of 32% (95% CI, 26% to 40%). Conclusion In patients suspected of having mesothelioma, a positive blood test for mesothelin at a high-specificity threshold is a strong incentive to urge further diagnostic steps. However, the poor sensitivity of mesothelin clearly limits its added value to early diagnosis and emphasizes the need for further biomarker research. PMID:22412141

Peers without fears? Barriers to effective communication among primary care physicians and oncologists about diagnostic delays in cancer.

PubMed

Lipitz-Snyderman, Allison; Kale, Minal; Robbins, Laura; Pfister, David; Fortier, Elizabeth; Pocus, Valerie; Chimonas, Susan; Weingart, Saul N

2017-11-01

Relatively little attention has been devoted to the role of communication between physicians as a mechanism for individual and organisational learning about diagnostic delays. This study's objective was to elicit physicians' perceptions about and experiences with communication among physicians regarding diagnostic delays in cancer. Qualitative analysis based on seven focus groups. Fifty-one physicians affiliated with three New York-based academic medical centres participated, with six to nine subjects per group. We used content analysis to identify commonalities among primary care physicians and specialists (ie, medical and surgical oncologists). Perceptions and experiences with physician-to-physician communication about delays in cancer diagnosis. Our analysis identified five major themes: openness to communication, benefits of communication, fears about giving and receiving feedback, infrastructure barriers to communication and overcoming barriers to communication. Subjects valued communication about cancer diagnostic delays, but they had many concerns and fears about providing and receiving feedback in practice. Subjects expressed reluctance to communicate if there was insufficient information to attribute responsibility, if it would have no direct benefit or if it would jeopardise their existing relationships. They supported sensitive approaches to conveying information, as they feared eliciting or being subject to feelings of incompetence or shame. Subjects also cited organisational barriers. They offered suggestions that might facilitate communication about delays. Addressing the barriers to communication among physicians about diagnostic delays is needed to promote a culture of learning across specialties and institutions. Supporting open and honest discussions about diagnostic delays may help build safer health systems. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Diagnostic efficacy of microscopy, rapid diagnostic test and polymerase chain reaction for malaria using bayesian latent class analysis.

PubMed

Saha, Sreemanti; Narang, Rahul; Deshmukh, Pradeep; Pote, Kiran; Anvikar, Anup; Narang, Pratibha

2017-01-01

The diagnostic techniques for malaria are undergoing a change depending on the availability of newer diagnostics and annual parasite index of infection in a particular area. At the country level, guidelines are available for selection of diagnostic tests; however, at the local level, this decision is made based on malaria situation in the area. The tests are evaluated against the gold standard, and if that standard has limitations, it becomes difficult to compare other available tests. Bayesian latent class analysis computes its internal standard rather than using the conventional gold standard and helps comparison of various tests including the conventional gold standard. In a cross-sectional study conducted in a tertiary care hospital setting, we have evaluated smear microscopy, rapid diagnostic test (RDT), and polymerase chain reaction (PCR) for diagnosis of malaria using Bayesian latent class analysis. We found the magnitude of malaria to be 17.7% (95% confidence interval: 12.5%-23.9%) among the study subjects. In the present study, the sensitivity of microscopy was 63%, but it had very high specificity (99.4%). Sensitivity and specificity of RDT and PCR were high with RDT having a marginally higher sensitivity (94% vs. 90%) and specificity (99% vs. 95%). On comparison of likelihood ratios (LRs), RDT had the highest LR for positive test result (175) and the lowest LR for negative test result (0.058) among the three tests. In settings like ours conventional smear microscopy may be replaced with RDT and as we move toward elimination and facilities become available PCR may be roped into detect cases with lower parasitaemia.

Low-dose aspirin use and survival in breast cancer patients: A nationwide cohort study.

PubMed

Mc Menamin, Úna C; Cardwell, Chris R; Hughes, Carmel M; Murray, Liam J

2017-04-01

Preclinical evidence from breast cancer cell lines and animal models suggest that aspirin could have anti-cancer properties. In a large breast cancer patient cohort, we investigated whether post-diagnostic low-dose aspirin use was associated with a reduction in the risk of breast cancer-specific mortality. We identified 15,140 newly diagnosed breast cancer patients within the Scottish Cancer Registry. Linkages to the Scottish Prescribing Information System provided data on dispensed medications and breast cancer-specific deaths were identified from National Records of Scotland Death Records. Time-dependent Cox regression models were used to calculate hazard ratios (HR) and 95% CIs for breast cancer-specific and all-cause mortality by post-diagnostic low-dose aspirin use. HRs were adjusted for a range of potential confounders including age at diagnosis, year of diagnosis, cancer stage, grade, cancer treatments received, comorbidities, socioeconomic status and use of statins. Secondary analysis investigated the association between pre-diagnostic low-dose aspirin use and breast cancer-specific and all-cause mortality. Post-diagnostic users of low-dose aspirin appeared to have increased breast cancer-specific mortality compared with non-users (HR 1.44, 95% CI 1.26, 1.65) but this association was entirely attenuated after adjustment for potential confounders (adjusted HR 0.92, 95% CI 0.75, 1.14). Findings were similar in analysis by increasing duration of use and in analysis of pre-diagnostic low-dose aspirin use. In this large nationwide study of breast cancer patients, we found little evidence of an association between post-diagnostic low-dose aspirin use and cancer-specific mortality. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of companion diagnostics on efficacy and safety of targeted anti-cancer drugs: systematic review and meta-analyses

PubMed Central

Ocana, Alberto; Ethier, Josee-Lyne; Díez-González, Laura; Corrales-Sánchez, Verónica; Srikanthan, Amirrtha; Gascón-Escribano, María J.; Templeton, Arnoud J.; Vera-Badillo, Francisco; Seruga, Bostjan; Niraula, Saroj; Pandiella, Atanasio; Amir, Eitan

2015-01-01

Background Companion diagnostics aim to identify patients that will respond to targeted therapies, therefore increasing the clinical efficacy of such drugs. Less is known about their influence on safety and tolerability of targeted anti-cancer agents. Methods and findings Randomized trials evaluating targeted agents for solid tumors approved by the US Food and Drug Administration since year 2000 were assessed. Odds ratios (OR) and and 95% confidence intervals (CI) were computed for treatment-related death, treatment-discontinuation related to toxicity and occurrence of any grade 3/4 adverse events (AEs). The 12 most commonly reported individual AEs were also explored. ORs were pooled in a meta-analysis. Analysis comprised 41 trials evaluating 28 targeted agents. Seventeen trials (41%) utilized companion diagnostics. Compared to control groups, targeted drugs in experimental arms were associated with increased odds of treatment discontinuation, grade 3/4 AEs, and toxic death irrespective of whether they utilized companion diagnostics or not. Compared to drugs without available companion diagnostics, agents with companion diagnostics had a lower magnitude of increased odds of treatment discontinuation (OR = 1.12 versus 1.65, p < 0.001) and grade 3/4 AEs (OR = 1.09 versus 2.10, p < 0.001), but no difference in risk of toxic death (OR = 1.40 versus 1.27, p = 0.69). Differences between agents with and without companion diagnostics were greatest for diarrhea (OR = 1.29 vs. 2.43, p < 0.001), vomiting (OR = 0.86 vs. 1.44, p = 0.005), cutaneous toxicity (OR = 1.82 vs. 3.88, p < 0.001) and neuropathy (OR = 0.64 vs. 1.60, p < 0.001). Conclusions Targeted drugs with companion diagnostics are associated with improved safety, and tolerability. Differences were most marked for gastrointestinal, cutaneous and neurological toxicity. PMID:26446908

Influence of companion diagnostics on efficacy and safety of targeted anti-cancer drugs: systematic review and meta-analyses.

PubMed

Ocana, Alberto; Ethier, Josee-Lyne; Díez-González, Laura; Corrales-Sánchez, Verónica; Srikanthan, Amirrtha; Gascón-Escribano, María J; Templeton, Arnoud J; Vera-Badillo, Francisco; Seruga, Bostjan; Niraula, Saroj; Pandiella, Atanasio; Amir, Eitan

2015-11-24

Companion diagnostics aim to identify patients that will respond to targeted therapies, therefore increasing the clinical efficacy of such drugs. Less is known about their influence on safety and tolerability of targeted anti-cancer agents. Randomized trials evaluating targeted agents for solid tumors approved by the US Food and Drug Administration since year 2000 were assessed. Odds ratios (OR) and and 95% confidence intervals (CI) were computed for treatment-related death, treatment-discontinuation related to toxicity and occurrence of any grade 3/4 adverse events (AEs). The 12 most commonly reported individual AEs were also explored. ORs were pooled in a meta-analysis. Analysis comprised 41 trials evaluating 28 targeted agents. Seventeen trials (41%) utilized companion diagnostics. Compared to control groups, targeted drugs in experimental arms were associated with increased odds of treatment discontinuation, grade 3/4 AEs, and toxic death irrespective of whether they utilized companion diagnostics or not. Compared to drugs without available companion diagnostics, agents with companion diagnostics had a lower magnitude of increased odds of treatment discontinuation (OR = 1.12 vs. 1.65, p < 0.001) and grade 3/4 AEs (OR = 1.09 vs. 2.10, p < 0.001), but no difference in risk of toxic death (OR = 1.40 vs. 1.27, p = 0.69). Differences between agents with and without companion diagnostics were greatest for diarrhea (OR = 1.29 vs. 2.43, p < 0.001), vomiting (OR = 0.86 vs. 1.44, p = 0.005), cutaneous toxicity (OR = 1.82 vs. 3.88, p < 0.001) and neuropathy (OR = 0.64 vs. 1.60, p < 0.001). Targeted drugs with companion diagnostics are associated with improved safety, and tolerability. Differences were most marked for gastrointestinal, cutaneous and neurological toxicity.

The Effect of Study Design Biases on the Diagnostic Accuracy of Magnetic Resonance Imaging to Detect Silicone Breast Implant Ruptures: A Meta-Analysis

PubMed Central

Song, Jae W.; Kim, Hyungjin Myra; Bellfi, Lillian T.; Chung, Kevin C.

2010-01-01

Background All silicone breast implant recipients are recommended by the US Food and Drug Administration to undergo serial screening to detect implant rupture with magnetic resonance imaging (MRI). We performed a systematic review of the literature to assess the quality of diagnostic accuracy studies utilizing MRI or ultrasound to detect silicone breast implant rupture and conducted a meta-analysis to examine the effect of study design biases on the estimation of MRI diagnostic accuracy measures. Method Studies investigating the diagnostic accuracy of MRI and ultrasound in evaluating ruptured silicone breast implants were identified using MEDLINE, EMBASE, ISI Web of Science, and Cochrane library databases. Two reviewers independently screened potential studies for inclusion and extracted data. Study design biases were assessed using the QUADAS tool and the STARDS checklist. Meta-analyses estimated the influence of biases on diagnostic odds ratios. Results Among 1175 identified articles, 21 met the inclusion criteria. Most studies using MRI (n= 10 of 16) and ultrasound (n=10 of 13) examined symptomatic subjects. Meta-analyses revealed that MRI studies evaluating symptomatic subjects had 14-fold higher diagnostic accuracy estimates compared to studies using an asymptomatic sample (RDOR 13.8; 95% CI 1.83–104.6) and 2-fold higher diagnostic accuracy estimates compared to studies using a screening sample (RDOR 1.89; 95% CI 0.05–75.7). Conclusion Many of the published studies utilizing MRI or ultrasound to detect silicone breast implant rupture are flawed with methodological biases. These methodological shortcomings may result in overestimated MRI diagnostic accuracy measures and should be interpreted with caution when applying the data to a screening population. PMID:21364405

Deletion Diagnostics for Alternating Logistic Regressions

PubMed Central

Preisser, John S.; By, Kunthel; Perin, Jamie; Qaqish, Bahjat F.

2013-01-01

Deletion diagnostics are introduced for the regression analysis of clustered binary outcomes estimated with alternating logistic regressions, an implementation of generalized estimating equations (GEE) that estimates regression coefficients in a marginal mean model and in a model for the intracluster association given by the log odds ratio. The diagnostics are developed within an estimating equations framework that recasts the estimating functions for association parameters based upon conditional residuals into equivalent functions based upon marginal residuals. Extensions of earlier work on GEE diagnostics follow directly, including computational formulae for one-step deletion diagnostics that measure the influence of a cluster of observations on the estimated regression parameters and on the overall marginal mean or association model fit. The diagnostic formulae are evaluated with simulations studies and with an application concerning an assessment of factors associated with health maintenance visits in primary care medical practices. The application and the simulations demonstrate that the proposed cluster-deletion diagnostics for alternating logistic regressions are good approximations of their exact fully iterated counterparts. PMID:22777960

Diagnostic value underlies asymmetric updating of impressions in the morality and ability domains.

PubMed

Mende-Siedlecki, Peter; Baron, Sean G; Todorov, Alexander

2013-12-11

While positive behavioral information is diagnostic when evaluating a person's abilities, negative information is diagnostic when evaluating morality. Although social psychology has considered these two domains as orthogonal and distinct from one another, we demonstrate that this asymmetry in diagnosticity can be explained by a single parsimonious principle--the perceived frequency of behaviors in these domains. Less frequent behaviors (e.g., high ability and low morality) are weighed more heavily in evaluations. We show that this statistical principle of frequency-derived diagnosticity is evident in human participants at both behavioral and neural levels of analysis. Specifically, activity in right ventrolateral prefrontal cortex increased preferentially when participants updated impressions based on diagnostic behaviors, and further, activity in this region covaried parametrically with the perceived frequency of behaviors. Activity in left ventrolateral PFC, left inferior frontal gyrus, and left superior temporal sulcus showed similar patterns of diagnosticity and sensitivity, though additional analyses confirmed that these regions responded primarily to updates based on immoral behaviors.

Stray light analysis for the Thomson scattering diagnostic of the ETE Tokamak.

PubMed

Berni, L A; Albuquerque, B F C

2010-12-01

Thomson scattering is a well-established diagnostic for measuring local electron temperature and density in fusion plasma, but this technique is particularly difficult to implement due to stray light that can easily mask the scattered signal from plasma. To mitigate this problem in the multipoint Thomson scattering system implemented at the ETE (Experimento Tokamak Esférico) a detailed stray light analysis was performed. The diagnostic system was simulated in ZEMAX software and scattering profiles of the mechanical parts were measured in the laboratory in order to have near realistic results. From simulation, it was possible to identify the main points that contribute to the stray signals and changes in the dump were implemented reducing the stray light signals up to 60 times.

Global analyses of water vapor, cloud and precipitation derived from a diagnostic assimilation of SSM/I geophysical retrievals

NASA Technical Reports Server (NTRS)

Robertson, Franklin R.; Cohen, Charles

1990-01-01

An analytical approach is described for diagnostically assimilating moisture data from Special Sensor Microwave Imager (SSM/I) into a global analysis of water vapor, cloud content, and precipitation. In this method, 3D fields of wind and temperature values taken from ECMWF gridded analysis are used to drive moisture conservation equations with parameterized microphysical treatment of vapor, liquid, and ice; the evolving field of water vapor is periodically updated or constrained by SSM/I retrievals of precipitable water. Initial results indicate that this diagnostic model can produce realistic large-scale fields of cloud and precipitation. The resulting water vapor analyses agree well with SSM/I and have an additional advantage of being synoptic.

Diagnosing collisions of magnetized, high energy density plasma flows using a combination of collective Thomson scattering, Faraday rotation, and interferometry (invited).

PubMed

Swadling, G F; Lebedev, S V; Hall, G N; Patankar, S; Stewart, N H; Smith, R A; Harvey-Thompson, A J; Burdiak, G C; de Grouchy, P; Skidmore, J; Suttle, L; Suzuki-Vidal, F; Bland, S N; Kwek, K H; Pickworth, L; Bennett, M; Hare, J D; Rozmus, W; Yuan, J

2014-11-01

A suite of laser based diagnostics is used to study interactions of magnetised, supersonic, radiatively cooled plasma flows produced using the Magpie pulse power generator (1.4 MA, 240 ns rise time). Collective optical Thomson scattering measures the time-resolved local flow velocity and temperature across 7-14 spatial positions. The scattering spectrum is recorded from multiple directions, allowing more accurate reconstruction of the flow velocity vectors. The areal electron density is measured using 2D interferometry; optimisation and analysis are discussed. The Faraday rotation diagnostic, operating at 1053 nm, measures the magnetic field distribution in the plasma. Measurements obtained simultaneously by these diagnostics are used to constrain analysis, increasing the accuracy of interpretation.

MULTI-KEV X-RAY YIELDS FROM HIGH-Z GAS TARGETS FIELDED AT OMEGA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kane, J O; Fournier, K B; May, M J

2010-11-04

The authors report on modeling of x-ray yield from gas-filled targets shot at the OMEGA laser facility. The OMEGA targets were 1.8 mm long, 1.95 mm in diameter Be cans filled with either a 50:50 Ar:Xe mixture, pure Ar, pure Kr or pure Xe at {approx} 1 atm. The OMEGA experiments heated the gas with 20 kJ of 3{omega} ({approx} 350 nm) laser energy delivered in a 1 ns square pulse. the emitted x-ray flux was monitored with the x-ray diode based DANTE instruments in the sub-keV range. Two-dimensional x-ray images (for energies 3-5 keV) of the targets were recordedmore » with gated x-ray detectors. The x-ray spectra were recorded with the HENWAY crystal spectrometer at OMEGA. Predictions are 2D r-z cylindrical with DCA NLTE atomic physics. Models generally: (1) underpredict the Xe L-shell yields; (2) overpredict the Ar K-shell yields; (3) correctly predict the Xe thermal yields; and (4) greatly underpredict the Ar thermal yields. However, there are spreads within the data, e.g. the DMX Ar K-shell yields are correctly predicted. The predicted thermal yields show strong angular dependence.« less

Spectroscopics database for warm Xenon and Iron in Astrophysics and Laboratory Astrophysics conditions

NASA Astrophysics Data System (ADS)

Busquet, Michel; Klapisch, Marcel; Bar-Shalom, Avi; Oreg, Josse

2010-11-01

The main contribution to spectral properties of astrophysics mixtures come often from Iron. On the other hand, in the so-called domain of ``Laboratory Astrophysics,'' where astrophysics phenomena are scaled down to the laboratory, Xenon (and Argon) are commonly used gases. At so called ``warm'' temperatures (T=5-50eV), L-shell Iron and M-shell Xenon present a very large number of spectral lines, originating from billions of levels. More often than not, Local Thermodynamical Equilibrium is assumed, leading to noticeable simplification of the computation. Nevertheless, complex and powerful atomic structure codes are required. We take benefit of powerful statistics and numerics, included in our atomic structure codes, STA[1] and HULLAC[2], to generate the required spectra. Recent improvements in both fields (statistics, numerics and convergence control) allow obtaining large databases (ro x T grid of > 200x200 points, and > 10000 frequencies) for temperature down to a few eV. We plan to port these improvements in the NLTE code SCROLL[3]. [1] A.Bar-Shalom, et al, Phys. Rev. A 40, 3183 (1989) [2] M.Busquet,et al, J.Phys. IV France 133, 973-975 (2006); A.Bar-Shalom, M.Klapisch, J.Oreg, J.Oreg, JQSRT 71, 169, (2001) [3] A.Bar-Shalom, et al, Phys. Rev. E 56, R70 (1997)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Latour, M.; Fontaine, G.; Brassard, P.

Taking advantage of a recent FORS2/VLT spectroscopic sample of extreme horizontal branch (EHB) stars in ω Cen, we isolate 38 spectra well suited for detailed atmospheric studies and determine their fundamental parameters (T {sub eff}, log g, and log N(He)/N(H)) using NLTE, metal line-blanketed models. We find that our targets can be divided into three groups: 6 stars are hot (T {sub eff} ≳ 45,000 K) H-rich subdwarf O stars, 7 stars are typical H-rich sdB stars (T {sub eff} ≲ 35,000 K), and the remaining 25 targets at intermediate effective temperatures are He-rich (log N(He)/N(H) ≳ –1.0) subdwarfs. Surprisingly,more » and quite interestingly, these He-rich hot subdwarfs in ω Cen cluster in a narrow temperature range (∼35,000 K to ∼40,000 K). We additionally measure the atmospheric carbon abundance and find a most interesting positive correlation between the carbon and helium atmospheric abundances. This correlation certainly bears the signature of diffusion processes—most likely gravitational settling impeded by stellar winds or internal turbulence—but also constrains possible formation scenarios proposed for EHB stars in ω Cen. For the He-rich objects in particular, the clear link between helium and carbon enhancement points toward a late hot flasher evolutionary history.« less

Sub-percent Photometry: Faint DA White Dwarf Spectrophotometric Standards for Astrophysical Observatories

NASA Astrophysics Data System (ADS)

Narayan, Gautham; Axelrod, Tim; Calamida, Annalisa; Saha, Abhijit; Matheson, Thomas; Olszewski, Edward; Holberg, Jay; Holberg, Jay; Bohlin, Ralph; Stubbs, Christopher W.; Rest, Armin; Deustua, Susana; Sabbi, Elena; MacKenty, John W.; Points, Sean D.; Hubeny, Ivan

2018-01-01

We have established a network of faint (16.5 < V < 19) hot DA white dwarfs as spectrophotometric standards for present and future wide-field observatories. Our standards are accessible from both hemispheres and suitable for ground and space-based covering the UV to the near IR. The network is tied directly to the most precise astrophysical reference presently available - the CALSPEC standards - through a multi-cycle program imaging using the Wide-Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We have developed two independent analyses to forward model all the observed photometry and ground-based spectroscopy and infer a spectral energy distribution for each source using a non-local-thermodynamic-equilibrium (NLTE) DA white dwarf atmosphere extincted by interstellar dust. The models are in excellent agreement with each other, and agree with the observations to better than 0.01 mag in all passbands, and better than 0.005 mag in the optical. The high-precision of these faint sources, tied directly to the most accurate flux standards presently available, make our network of standards ideally suited for any experiments that have very stringent requirements on absolute flux calibration, such as studies of dark energy using the Large Synoptic Survey Telescope (LSST) and the Wide-Field Infrared Survey Telescope (WFIRST).

DISCOVERY OF SUPER-Li-RICH RED GIANTS IN DWARF SPHEROIDAL GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirby, Evan N.; Fu, Xiaoting; Deng, Licai

2012-06-10

Stars destroy lithium (Li) in their normal evolution. The convective envelopes of evolved red giants reach temperatures of millions of kelvin, hot enough for the {sup 7}Li(p, {alpha}){sup 4}He reaction to burn Li efficiently. Only about 1% of first-ascent red giants more luminous than the luminosity function bump in the red giant branch exhibit A(Li) > 1.5. Nonetheless, Li-rich red giants do exist. We present 15 Li-rich red giants-14 of which are new discoveries-among a sample of 2054 red giants in Milky Way dwarf satellite galaxies. Our sample more than doubles the number of low-mass, metal-poor ([Fe/H] {approx}< -0.7) Li-richmore » red giants, and it includes the most-metal-poor Li-enhanced star known ([Fe/H] = -2.82, A(Li){sub NLTE} = 3.15). Because most of the stars have Li abundances larger than the universe's primordial value, the Li in these stars must have been created rather than saved from destruction. These Li-rich stars appear like other stars in the same galaxies in every measurable regard other than Li abundance. We consider the possibility that Li enrichment is a universal phase of evolution that affects all stars, and it seems rare only because it is brief.« less

Correction of the near threshold behavior of electron collisional excitation cross-sections in the plane-wave Born approximation

DOE PAGES

Kilcrease, D. P.; Brookes, S.

2013-08-19

The modeling of NLTE plasmas requires the solution of population rate equations to determine the populations of the various atomic levels relevant to a particular problem. The equations require many cross sections for excitation, de-excitation, ionization and recombination. Additionally, a simple and computational fast way to calculate electron collisional excitation cross-sections for ions is by using the plane-wave Born approximation. This is essentially a high-energy approximation and the cross section suffers from the unphysical problem of going to zero near threshold. Various remedies for this problem have been employed with varying degrees of success. We present a correction procedure formore » the Born cross-sections that employs the Elwert–Sommerfeld factor to correct for the use of plane waves instead of Coulomb waves in an attempt to produce a cross-section similar to that from using the more time consuming Coulomb Born approximation. We compare this new approximation with other, often employed correction procedures. Furthermore, we also look at some further modifications to our Born Elwert procedure and its combination with Y.K. Kim's correction of the Coulomb Born approximation for singly charged ions that more accurately approximate convergent close coupling calculations.« less

A macro-ergonomic work system analysis of the diagnostic testing process in an outpatient health care facility for process improvement and patient safety.

PubMed

Hallock, M L; Alper, S J; Karsh, B

The diagnosis of illness is important for quality patient care and patient safety and is greatly aided by diagnostic testing. For diagnostic tests, such as pathology and radiology, to positively impact patient care, the tests must be processed and the physician and patient must be notified of the results in a timely fashion. There are many steps in the diagnostic testing process, from ordering to result dissemination, where the process can break down and therefore delay patient care and reduce patient safety. This study was carried out to examine the diagnostic testing process (i.e. from ordering to result notification) and used a macro-ergonomic work system analysis to uncover system design flaws that contributed to delayed physician and patient notification of results. The study was carried out in a large urban outpatient health-care facility made up of 30 outpatient clinics. Results indicated a number of variances that contributed to delays, the majority of which occurred across the boundaries of different systems and were related to poor or absent feedback structures. Recommendations for improvements are discussed.

Microfluidic paper-based analytical devices for potential use in quantitative and direct detection of disease biomarkers in clinical analysis.

PubMed

Lim, Wei Yin; Goh, Boon Tong; Khor, Sook Mei

2017-08-15

Clinicians, working in the health-care diagnostic systems of developing countries, currently face the challenges of rising costs, increased number of patient visits, and limited resources. A significant trend is using low-cost substrates to develop microfluidic devices for diagnostic purposes. Various fabrication techniques, materials, and detection methods have been explored to develop these devices. Microfluidic paper-based analytical devices (μPADs) have gained attention for sensing multiplex analytes, confirming diagnostic test results, rapid sample analysis, and reducing the volume of samples and analytical reagents. μPADs, which can provide accurate and reliable direct measurement without sample pretreatment, can reduce patient medical burden and yield rapid test results, aiding physicians in choosing appropriate treatment. The objectives of this review are to provide an overview of the strategies used for developing paper-based sensors with enhanced analytical performances and to discuss the current challenges, limitations, advantages, disadvantages, and future prospects of paper-based microfluidic platforms in clinical diagnostics. μPADs, with validated and justified analytical performances, can potentially improve the quality of life by providing inexpensive, rapid, portable, biodegradable, and reliable diagnostics. Copyright © 2017 Elsevier B.V. All rights reserved.

Meta-epidemiologic study showed frequent time trends in summary estimates from meta-analyses of diagnostic accuracy studies.

PubMed

Cohen, Jérémie F; Korevaar, Daniël A; Wang, Junfeng; Leeflang, Mariska M; Bossuyt, Patrick M

2016-09-01

To evaluate changes over time in summary estimates from meta-analyses of diagnostic accuracy studies. We included 48 meta-analyses from 35 MEDLINE-indexed systematic reviews published between September 2011 and January 2012 (743 diagnostic accuracy studies; 344,015 participants). Within each meta-analysis, we ranked studies by publication date. We applied random-effects cumulative meta-analysis to follow how summary estimates of sensitivity and specificity evolved over time. Time trends were assessed by fitting a weighted linear regression model of the summary accuracy estimate against rank of publication. The median of the 48 slopes was -0.02 (-0.08 to 0.03) for sensitivity and -0.01 (-0.03 to 0.03) for specificity. Twelve of 96 (12.5%) time trends in sensitivity or specificity were statistically significant. We found a significant time trend in at least one accuracy measure for 11 of the 48 (23%) meta-analyses. Time trends in summary estimates are relatively frequent in meta-analyses of diagnostic accuracy studies. Results from early meta-analyses of diagnostic accuracy studies should be considered with caution. Copyright © 2016 Elsevier Inc. All rights reserved.

Identification of Serum Periostin as a Potential Diagnostic and Prognostic Marker for Colorectal Cancer.

PubMed

Dong, Dong; Zhang, Lufang; Jia, Li; Ji, Wei; Wang, Zhiyong; Ren, Li; Niu, Ruifang; Zhou, Yunli

2018-06-01

Periostin (POSTN) plays an important role in numerous cancers, especially in gastrointestinal malignancy. The objective of this study was to investigate the diagnostic and prognostic role of serum POSTN in colorectal cancer (CRC). Serum periostin, together with CEA, CA19.9, CA72.4, and CA242 levels were measured in samples from 108 patients with CRC and 56 healthy controls, and their correlation with clinical characteristics was further analyzed. Receiver operating curves (ROC), Kaplan-Meier curves, and log-rank analyses were used to evaluate diagnostic and prognostic significance. Serum POSTN levels were significantly higher in patients with CRC compared with healthy controls (p < 0.0001) and associated with clinical stages (p < 0.001). ROC analysis revealed that POSTN was a biomarker comparable to CEA, CA19.9, and CA72.4 to distinguish all CRC from healthy controls (AUC = 0.75). Moreover, POSTN retained its diagnostic ability for CEA-negative (AUC = 0.69) and CA19.9-negative CRC patients (AUC = 0.71). Survival analysis revealed that patients with lower serum POSTN had longer overall survival than those with high serum POSTN (p = 0.0146). Serum POSTN might be a novel diagnostic and prognostic biomarker for patients with CRC.

Unproven diagnostic procedures in IgE-mediated allergic diseases.

PubMed

Niggemann, B; Grüber, C

2004-08-01

A considerable body of literature on therapeutic aspects of complementary and alternative medicine has been published in recent years, but little is known on diagnostic procedures. This short review lists complementary and alternative diagnostic procedures for the diagnosis of allergic diseases and presents an assessment of their usefulness for the daily practice. The review of the literature revealed that neither the determination of specific immunoglobulin G-antibodies in serum, the hair-analysis, the cytotoxic test, kinesiology, iridology, or electrodermal testing represent useful tests for the daily practice. To date, no complementary or alternative diagnostic procedure can be recommended as a meaningful element in the diagnostic work-up of allergic diseases. This is especially true for food allergy: properly performed oral food challenges still represent the gold standard for implementing specific diets in food allergic individuals. Ineffective diagnostic approaches may be costly for the consumer and delay appropriate therapy.

En Route to the Clinic: Diagnostic Sequencing Applications Using the Ion Torrent (7th Annual SFAF Meeting, 2012)

ScienceCinema

Muzny, Donna

2018-01-15

Donna Muzny on "En route to the clinic: Diagnostic sequencing applications using the Ion Torrent" at the 2012 Sequencing, Finishing, Analysis in the Future Meeting held June 5-7, 2012 in Santa Fe, New Mexico.

Cognitive Diagnostic Analysis Using Hierarchically Structured Skills

ERIC Educational Resources Information Center

Su, Yu-Lan

2013-01-01

This dissertation proposes two modified cognitive diagnostic models (CDMs), the deterministic, inputs, noisy, "and" gate with hierarchy (DINA-H) model and the deterministic, inputs, noisy, "or" gate with hierarchy (DINO-H) model. Both models incorporate the hierarchical structures of the cognitive skills in the model estimation…

Diagnostic value of creatine kinase activity in canine cerebrospinal fluid.

PubMed

Ferreira, Alexandra

2016-10-01

This study aimed to determine whether creatine kinase (CK) activity in cerebrospinal fluid (CSF) has diagnostic value for various groups of neurological conditions or for different anatomical areas of the nervous system (NS). The age, breed, results of CSF analysis, and diagnosis of 578 canine patients presenting with various neurological conditions between January 2009 and February 2015 were retrospectively collected. The cases were divided according to anatomical areas of the nervous system, i.e., brain, spinal cord, and peripheral nervous system, and into groups according to the nature of the condition diagnosed: vascular, immune/inflammatory/infectious, traumatic, toxic, anomalous, metabolic, idiopathic, neoplastic, and degenerative. Statistical analysis showed that CSF-CK alone cannot be used as a diagnostic tool and that total proteins in the CSF and red blood cells (RBCs) do not have a significant relationship with the CSF-CK activity. CSF-CK did not have a diagnostic value for different disease groups or anatomical areas of the nervous system.

Combining principles of Cognitive Load Theory and diagnostic error analysis for designing job aids: Effects on motivation and diagnostic performance in a process control task.

PubMed

Kluge, Annette; Grauel, Britta; Burkolter, Dina

2013-03-01

Two studies are presented in which the design of a procedural aid and the impact of an additional decision aid for process control were assessed. In Study 1, a procedural aid was developed that avoids imposing unnecessary extraneous cognitive load on novices when controlling a complex technical system. This newly designed procedural aid positively affected germane load, attention, satisfaction, motivation, knowledge acquisition and diagnostic speed for novel faults. In Study 2, the effect of a decision aid for use before the procedural aid was investigated, which was developed based on an analysis of diagnostic errors committed in Study 1. Results showed that novices were able to diagnose both novel faults and practised faults, and were even faster at diagnosing novel faults. This research contributes to the question of how to optimally support novices in dealing with technical faults in process control. Copyright © 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Analysis of "dry" mesothelioma with ultrasound guided biopsies.

PubMed

Stigt, Jos A; Boers, James E; Groen, Harry J M

2012-12-01

Image-guided sampling of the thickened pleura is a sensitive approach in patients with malignant pleural mesothelioma with pleural effusion. Malignant pleural mesothelioma presenting without effusion however is more of a diagnostic challenge. In this study we report the diagnostic yield and complications of ultrasound-guided cutting needle biopsies in this particular category of patients. A retrospective database analysis from September 2007 until January 2012 was performed in 56 patients with malignant pleural mesothelioma. Clinical characteristics and results of diagnostic evaluations were analysed. Of the 56 patients with malignant pleural mesothelioma, 20 patients presented without pleural effusion of with locular effusion. Ultrasound-guided cutting needle biopsy was performed in 14/20 patients with a diagnostic accuracy of 80%. Only 1 patient had mild haemoptysis immediately following biopsies. Diagnosing patients with pleural thickenings suspect for malignant mesothelioma without pleural effusion or with loculated pleural effusion is effective and safe with ultrasound-guided cutting needle biopsies. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Diagnostic and prognostic value of microRNA-628 for cancers.

PubMed

Li, Jing-Hua; Sun, Shan-Shan; Fu, Chang-Jin; Zhang, An-Qi; Wang, Chen; Xu, Rong; Xie, Shu-Yang; Wang, Ping-Yu

2018-01-01

Background: Many studies manifested miRNA-628 (miR-628) was deregulated in various cancers, indicating that miR-628 might serve as a novel biomarker of cancer diagnosis and prognosis, but it's role was still uncertain. This study aimed to evaluate the value of miR-628 in various cancers for diagnosis and prognosis, as well as its predictive power in combination biomarkers. Materials and Methods: A literature search was performed using Medline (via PubMed), Embase, Web of Science databases, and Ovid platform up to November 2017. Meta-analysis was performed to provide summative outcomes. Quality assessment of each included study was performed. Results: Twelve articles with 20 studies were included in our meta-analysis, including 8 articles with 15 studies for diagnostic meta-analysis and 4 articles with 5 studies for prognostic meta-analysis. For the diagnostic meta-analysis of miR-628 alone, the overall pooled results for sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and the area under the summary receiver operating characteristic (SROC) curve (AUC) were 0.81 (95% CI: 0.62-0.91), 0.72 (95% CI: 0.48-0.88), 2.90 (95% CI: 1.50-5.40), 0.27 (95% CI: 0.14-0.50), 11.0 (95% CI: 4.00-25.00), and 0.84 (95% CI: 0.80-0.87), respectively. For the diagnostic meta-analysis of miR-628-related combination biomarkers, the above six parameters were 0.89 (95% CI: 0.84-0.92), 0.93 (95% CI: 0.82-0.97), 12.30 (95% CI: 4.70-32.50), 0.12 (95% CI: 0.08-0.19), and 100.00 (95% CI: 28.00-354.00), 0.93 (95% CI: 0.90-0.95), respectively. For the prognostic meta-analysis, patients with lower miR-628 had significant shorter overall survival than high expression of miR-628 (HR = 1.553, 95% CI: 1.041-2.318, z = 2.16, P = 0.031). Conclusions: This study confirms that miR-628 may be a promising biomarker for cancer diagnosis and prognosis. Expertly, microRNAs combination biomarkers could be a new alternative for clinical application.

1998 Technology Showcase. JOAP International Condition Monitoring Conference.

DTIC Science & Technology

1998-04-01

Systems using Automated SEM/ EDX and New Diagnostic Routines 276 N. W Farrant & T. Luckhurst ADVANCED DIAGNOSTIC SYSTEMS Model-Based Diagnostics of Gas...Microscopy with Energy Dispersive X-Ray (SEM/ EDX ) micro analysis packages and Energy Dispersive X-Ray Fluorescence (EDXRF) analytical equipment. Therqfore...wear particles separated by ferrogram method. a- I WEAR PARTICLE A SLAS 97 (HOME PAGE) Fig I Home Page NONFE;RROUS MATERIAL A wW~ a48 -1, rV fr , ý b

Diagnostic Health Monitoring System Development for Army Vehicle Reliability

DTIC Science & Technology

2011-07-01

19-24 3.4 Receiver Operator Characteristics for fault detection ……………………….. 24-28 3.5 Extended diagnostic speed bump modal data analysis...extended diagnostic speed bump was akin to the use of modal impact testing for exciting broadband frequency ranges in mechanical systems for use in...for a front axle wheel crossing measured using long cleat for ( ) first 30, ( ) second 11, ( ) third 11, ( ) fourth 11, and ( ) fifth 11 data series

The Technologist Function in Fields Related to Radiology: Tasks in Radiation Therapy and Diagnostic Ultrasound. Research Report No. 9; Relating Technologist Tasks in Diagnostic Radiology, Ultrasound and Radiation Therapy. Research Report No. 10.

ERIC Educational Resources Information Center

Gilpatrick, Eleanor

The two research reports included in this document describe the application of the Health Services Mobility Study (HSMS) task analysis method to two technologist functions and examine the interrelationships of these tasks with those in diagnostic radiology. (The HSMS method includes processes for using the data for designing job ladders, for…

Diagnostic value of serum squamous cell carcinoma antigen for hepatocellular carcinoma: a systematic review and meta-analysis.

PubMed

Yu, Jing; Wang, Zhao-Juan; Chen, Long-Hua; Dong, Wen-Zhu

2017-02-01

The aim of this study was to ascertain the diagnostic value of serum squamous cell carcinoma antigen (SCCA) and SCCA-IgM for hepatocellular carcinoma (HCC). After a comprehensive search of PubMed and Web of Science databases, we identified eligible studies on the diagnostic value serum SCCAs for HCC. The quality of the eligible studies was assessed using the revised Quality Assessment for Studies of Diagnostic Accuracy (QUADAS-2) tool. The overall diagnostic value of SCCAs for HCC was pooled using a bivariate model. Twelve studies were included in this systematic review and meta-analysis. The pooled sensitivities for SCCA and SCCA-IgM were 0.61 (95% confidence interval [CI], 0.37-0.81) and 0.70 (95% CI, 0.55-0.82), respectively. The corresponding specificities were 0.80 (95% CI, 0.52-0.94) and 0.62 (95% CI, 0.51-0.72), respectively. The areas under summary receiver operating characteristic (sROC) curves for SCCA and SCCA-IgM were 0.76 (95% CI, 0.72-0.80) and 0.70 (95% CI, 0.66-0.74), respectively. Major design deficiencies of the included studies were two-gate design and partial verification bias. Therefore, we concluded that both serum SCCA and SCCA-IgM have a fair diagnostic value for HCC.

Admixture analysis of the diagnostic subtypes of social anxiety disorder: implications for the DSM-V.

PubMed

Aderka, Idan M; Nickerson, Angela; Hofmann, Stefan G

2012-06-01

Much controversy exists regarding diagnostic subtypes of social anxiety disorder (SAD). The present study used admixture analysis to examine whether individuals with generalized and nongeneralized SAD belong to the same or different populations of origin. This can inform diagnostic subtyping of SAD in the forthcoming DSM-V. Treatment-seeking individuals with generalized SAD (n = 154) and nongeneralized SAD (n = 48) completed a battery of questionnaires. Based on participants' responses to the Liebowitz Social Anxiety Scale (LSAS), we estimated log likelihood and chi-square goodness-of-fit for models with 1, 2, 3, or 4 populations of origin, and compared models using forward stepwise estimation and maximum likelihood ratio tests. Admixture analyses suggested that the two diagnostic subtypes of SAD belong to the same underlying population of origin. In addition, observable differences in depression, general anxiety, and comorbidity were no longer significant when controlling for social anxiety severity. Our sample was recruited in the U.S. and was a treatment-seeking sample. Future studies should examine whether our results generalize to different cultures, and community samples. Support for qualitative differences between SAD subtypes was not found. Rather, our findings support the notion that the diagnostic subtypes of SAD differ quantitatively, and that SAD exists on a continuum of severity. This finding informs diagnostic subtyping of SAD in the forthcoming DSM-V. Copyright © 2011 Elsevier Ltd. All rights reserved.

LASER BIOLOGY AND MEDICINE: Application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air

NASA Astrophysics Data System (ADS)

Stepanov, E. V.; Milyaev, Varerii A.

2002-11-01

The application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air in biomedical diagnostics is discussed. The principle of operation and the design of a laser analyser for studying the composition of exhaled air are described. The results of detection of gaseous biomarkers in exhaled air, including clinical studies, which demonstrate the diagnostic possibilities of the method, are presented.

Efficiency of the Bethesda System for Thyroid Cytopathology.

PubMed

Mora-Guzmán, Ismael; Muñoz de Nova, José Luis; Marín-Campos, Cristina; Jiménez-Heffernan, José Antonio; Cuesta Pérez, Juan Julián; Lahera Vargas, Marcos; Torres Mínguez, Emma; Martín-Pérez, Elena

2018-03-28

Fine-needle aspiration biopsies are a key tool for preoperative assessment of thyroid nodules, and the Bethesda system is the preferred method to report cytological analysis. The purpose of this study is to assess the efficiency of the Bethesda system to identify the malignancy risk of thyroid nodules. Patients who underwent thyroid surgery between June 2010 and June 2017 were included. Samples were classified into 6categories according to rates of malignancy associated with each diagnostic category. In order to investigate the correlation between categories, a statistical analysis compared the categories with pathology reports. Diagnostic indicators were calculated as a screening test (categories IV, V, VI as true-positive) and as a method to identify malignancy (V, VI as true-positive). In a series of 522 patients, we found 184 (35.2%) malignant tumours, papillary carcinoma being the most prevalent with 155 cases (84.2%). Malignant rates for diagnostic categories were: I, 0%; II, 1.5%; III, 6.4%; IV, 31%; V, 86.5%; VI, 100%. A robust correlation was identified between categories on statistical analysis. For the «screening test» analysis, sensitivity was 98.9%, specificity 84.4%, positive predictive value 69.6%, negative predictive value 99.5%, and diagnostic accuracy 88.2%. Analysing the accuracy to detect malignancy, values were: sensitivity 98.6%, specificity 97.6%, positive predictive value 93.5%, negative predictive value 99.5%, diagnostic accuracy 97.9%. The Bethesda system is a clear and reliable approach to report thyroid cytology and therefore is an effective tool to identify malignancy risk and guide clinical management. Copyright © 2018 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

Accuracy of i-Scan for Optical Diagnosis of Colonic Polyps: A Meta-Analysis

PubMed Central

Guo, Chuan-Guo; Ji, Rui; Li, Yan-Qing

2015-01-01

Background i-Scan is a novel virtual chromoendoscopy system designed to enhance surface and vascular patterns to improve optical diagnostic performance. Numerous prospective studies have been done to evaluate the accuracy of i-Scan in differentiating colonic neoplasms from non-neoplasms. i-Scan could be an effective endoscopic technique for optical diagnosis of colonic polyps. Objective Our aim of this study was to perform a meta-analysis of published data to establish the diagnostic accuracy of i-Scan for optical diagnosis of colonic polyps. Methods We searched PubMed, Medline, Elsevier ScienceDirect and Cochrane Library databases. We used a bivariate meta-analysis following a random effects model to summarize the data and plotted hierarchical summary receiver-operating characteristic (HSROC) curves. The area under the HSROC curve (AUC) serves as an indicator of the diagnostic accuracy. Results The meta-analysis included a total of 925 patients and 2312 polyps. For the overall studies, the area under the HSROC curve was 0.96. The summary sensitivity was 90.4% (95%CI 85%-94.1%) and specificity was 90.9% (95%CI 84.3%-94.9%). In 11 studies predicting polyps histology in real-time, the summary sensitivity and specificity was 91.5% (95%CI 85.7%-95.1%) and 92.1% (95%CI 84.5%-96.1%), respectively, with the AUC of 0.97. For three different diagnostic criteria (Kudo, NICE, others), the sensitivity was 86.3%, 93.0%, 85.0%, respectively and specificity was 84.8%, 94.4%, 91.8%, respectively. Conclusions Endoscopic diagnosis with i-Scan has accurate optical diagnostic performance to differentiate neoplastic from non-neoplastic polyps with an area under the HSROC curve exceeding 0.90. Both the sensitivity and specificity for diagnosing colonic polyps are over 90%. PMID:25978459

Accuracy of computed tomographic features in differentiating intestinal tuberculosis from Crohn's disease: a systematic review with meta-analysis.

PubMed

Kedia, Saurabh; Sharma, Raju; Sreenivas, Vishnubhatla; Madhusudhan, Kumble Seetharama; Sharma, Vishal; Bopanna, Sawan; Pratap Mouli, Venigalla; Dhingra, Rajan; Yadav, Dawesh Prakash; Makharia, Govind; Ahuja, Vineet

2017-04-01

Abdominal computed tomography (CT) can noninvasively image the entire gastrointestinal tract and assess extraintestinal features that are important in differentiating Crohn's disease (CD) and intestinal tuberculosis (ITB). The present meta-analysis pooled the results of all studies on the role of CT abdomen in differentiating between CD and ITB. We searched PubMed and Embase for all publications in English that analyzed the features differentiating between CD and ITB on abdominal CT. The features included comb sign, necrotic lymph nodes, asymmetric bowel wall thickening, skip lesions, fibrofatty proliferation, mural stratification, ileocaecal area, long segment, and left colonic involvements. Sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio (DOR) were calculated for all the features. Symmetric receiver operating characteristic curve was plotted for features present in >3 studies. Heterogeneity and publication bias was assessed and sensitivity analysis was performed by excluding studies that compared features on conventional abdominal CT instead of CT enterography (CTE). We included 6 studies (4 CTE, 1 conventional abdominal CT, and 1 CTE+conventional abdominal CT) involving 417 and 195 patients with CD and ITB, respectively. Necrotic lymph nodes had the highest diagnostic accuracy (sensitivity, 23%; specificity, 100%; DOR, 30.2) for ITB diagnosis, and comb sign (sensitivity, 82%; specificity, 81%; DOR, 21.5) followed by skip lesions (sensitivity, 86%; specificity, 74%; DOR, 16.5) had the highest diagnostic accuracy for CD diagnosis. On sensitivity analysis, the diagnostic accuracy of other features excluding asymmetric bowel wall thickening remained similar. Necrotic lymph nodes and comb sign on abdominal CT had the best diagnostic accuracy in differentiating CD and ITB.

Systematic review and meta-analysis of single-balloon enteroscopy-assisted ERCP in patients with surgically altered GI anatomy.

PubMed

Inamdar, Sumant; Slattery, Eoin; Sejpal, Divyesh V; Miller, Larry S; Pleskow, Douglas K; Berzin, Tyler M; Trindade, Arvind J

2015-07-01

Surgically altered pancreaticobiliary anatomy increases the difficulty of performing ERCP. Single-balloon enteroscopy (SBE) is a relatively new technique that can be used for ERCP in patients with surgically altered anatomy. To evaluate the therapeutic and diagnostic success of SBE-ERCP among patients with surgically altered anatomy. Systematic review and meta-analysis of studies involving SBE-ERCP in patients with Roux-en-Y gastric bypass, hepaticojejunostomy, or Whipple procedure. Enteroscopy success was defined as success in reaching the papilla and/or biliary anastomosis by using SBE. Diagnostic success was defined as obtaining a cholangiogram. Procedural success was defined as the ability to provide successful intervention, if appropriate. A random-effects model was used. A total of 461 patients underwent SBE-ERCP from 15 trials. The pooled enteroscopy, diagnostic, and procedural success rates were 80.9% (95% confidence interval [CI], 75.3%-86.4%), 69.4% (95% CI, 61.0%-77.9%), and 61.7% (95% CI, 52.9%-70.5%), respectively. There was statistical large heterogeneity for enteroscopy, diagnostic, and therapeutic success (P < .001 for all). Adverse events occurred in 6.5% (95% CI, 4.7%-9.1%) of patients. There was no evidence of publication bias in this meta-analysis. Our findings and interpretations are limited by the quantity and heterogeneity of the studies included in the analysis. SBE-ERCP has high diagnostic and procedural success rates in this challenging patient population. It should be considered a first-line intervention when biliary access is required after Roux-en-Y gastric bypass, hepaticojejunostomy, or Whipple procedure. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Diagnostic efficacy of contrast-enhanced sonography by combined qualitative and quantitative analysis in breast lesions: a comparative study with magnetic resonance imaging.

PubMed

Wang, Lin; Du, Jing; Li, Feng-Hua; Fang, Hua; Hua, Jia; Wan, Cai-Feng

2013-10-01

The purpose of this study was to evaluate the diagnostic efficacy of contrast-enhanced sonography for differentiation of breast lesions by combined qualitative and quantitative analyses in comparison to magnetic resonance imaging (MRI). Fifty-six patients with American College of Radiology Breast Imaging Reporting and Data System category 3 to 5 breast lesions on conventional sonography were evaluated by contrast-enhanced sonography and MRI. A comparative analysis of diagnostic results between contrast-enhanced sonography and MRI was conducted in light of the pathologic findings. Pathologic analysis showed 26 benign and 30 malignant lesions. The predominant enhancement patterns of the benign lesions on contrast-enhanced sonography were homogeneous, centrifugal, and isoenhancement or hypoenhancement, whereas the patterns of the malignant lesions were mainly heterogeneous, centripetal, and hyperenhancement. The detection rates for perfusion defects and peripheral radial vessels in the malignant group were much higher than those in the benign group (P < .05). As to quantitative analysis, statistically significant differences were found in peak and time-to-peak values between the groups (P < .05). With pathologic findings as the reference standard, the sensitivity, specificity, and accuracy of contrast-enhanced sonography and MRI were 90.0%, 92.3%, 91.1% and 96.7%, 88.5%, and 92.9%, respectively. The two methods had a concordant rate of 87.5% (49 of 56), and the concordance test gave a value of κ = 0.75, indicating that there was high concordance in breast lesion assessment between the two diagnostic modalities. Contrast-enhanced sonography provided typical enhancement patterns and valuable quantitative parameters, which showed good agreement with MRI in diagnostic efficacy and may potentially improve characterization of breast lesions.

Serum Anti-Glycan Antibody Biomarkers for Inflammatory Bowel Disease Diagnosis and Progression: A Systematic Review and Meta-analysis

PubMed Central

Kaul, Amit; Hutfless, Susan; Liu, Ling; Bayless, Theodore M.; Marohn, Michael R.; Li, Xuhang

2011-01-01

BACKGROUND Anti-glycan antibody serologic markers may serve as useful adjunct in the diagnosis/prognosis of inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC). This meta-analysis/systemic review was aimed to evaluate the diagnostic value, as well as the association of anti-glycan biomarkers with IBD susceptible gene variants, disease complications, and need for surgery in IBD. METHODS The diagnostic odds ratio (DOR), 95% confidence interval (CI), and sensitivity/specificity were used to compare the diagnostic value of individual and combinations of anti-glycan markers and their association with disease course (complication and/or need for surgery). RESULTS Fourteen studies were included in the systemic review and nine in the meta-analysis. Individually, ASCA had the highest DOR for differentiating IBD from healthy (DOR 21.1; 1.8-247.3; 2 studies), and CD from UC (DOR 10.2; CI 7.7-13.7; 7 studies). For combination of ≥2 markers, the DOR was 2.8 (CI 2.2-3.6; 2 studies) for CD-related surgery, higher than any individual marker, while the DOR for differentiating CD from UC was 10.2 (CI 5.6-18.5; 3 studies) and for complication was 2.8 (CI 2.2-3.7; 2 studies), similar to individual markers. CONCLUSIONS ASCA had the highest diagnostic value among individual anti-glycan markers. While ACCA had the highest association with complications, ASCA and ACCA associated equally with need for surgery. Although in most individual studies, combination of ≥2 markers had a better diagnostic value as well as higher association with complications and need for surgery, we found the combination performing slightly better than any individual marker in our meta-analysis. PMID:22294465

MiR-139 in digestive system tumor diagnosis and detection: Bioinformatics and meta-analysis.

PubMed

Wang, Yu-Hui; Ji, Jia; Weng, Hong; Wang, Bi-Cheng; Wang, Fu-Bing

2018-06-05

Accumulating evidence has indicated that microRNAs play important roles in the initiation and progression of digestive system tumors. However, previous studies suggest that the accuracy of miRNA detection in digestive system tumors was inconsistent. The candidate miRNAs were obtained from The Cancer Genome Atlas (TCGA). Meta-analysis was performed to evaluate the diagnostic value of these miRNAs in digestive system tumors. Furthermore, the potential target genes of the miRNAs were predicted and assessed with functional analysis. According to TCGA data, miR-139 was a common biomarker of digestive system tumors. It was markedly reduced in tumor tissues as compared with non-cancerous tissues in digestive system tumors. In the meta-analysis, the pooled diagnostic odds ratio (DOR) and AUC was 57.51 (95% CI: 14.25-232.04) and 0.96 (95% CI: 0.94-0.97), respectively. Furthermore, the overall sensitivity and specificity was 0.89 (95% CI: 0.73-0.96) and 0.91 (95% CI: 0.75-0.97), respectively. The diagnostic value of tissue miR-139 was higher than the diagnostic value of blood miR-139. In particular, miR-139 was a superior marker for distinguishing colorectal cancer. miR-139 could be a potential biomarker for diagnosis of digestive system tumors especially colorectal cancer. Copyright © 2017. Published by Elsevier B.V.

Carrier diagnostics and prevention of hemoglobinopathies in early pregnancy in The Netherlands: a pilot study.

PubMed

Giordano, P C; Plancke, A; Van Meir, C A; Janssen, C A H; Kok, P J M J; Van Rooijen-Nijdam, I H; Tanis, B C; van Huisseling, J C M; Versteegh, F G A

2006-08-01

We have offered, for the first time in The Netherlands, carrier diagnostics for hemoglobinopathies (HbP) to early pregnant women. The aim of this study was to establish whether carrier analysis would be welcome by the public and feasible at the outpatient level. One hundred and thirty-nine randomly selected women were informed and offered basic carrier diagnostics at the first pregnancy control. Carrier diagnostics was accepted by 136 women (97.8%). The population consisted of 31% of recent immigrants and 69% of native Dutch. One carrier of HbS and one of beta-thalassemia were found, both among the group of the recent immigrants. In both cases, partners were tested excluding a couple at risk. In addition, five carriers of alpha(+)-thalassemia were diagnosed at the molecular level, one of them in the native Dutch population. Basic carrier analysis was done both at the Hospital Laboratory and at the Reference Laboratory. No discrepancies were found. This pilot study shows that (1) as predicted the prevalence of risk-related HbP and of alpha(+)-thalassemia is high in the immigrant population. (2) The compliance with carrier analysis in both native Dutch and immigrants is virtually total and (3) carrier diagnosis in early pregnancy and partner analysis in Hospital Laboratories is possible and is an effective tool for primary prevention of HbP in The Netherlands.

Serum Immunoglobulin G4 in Discriminating Autoimmune Pancreatitis From Pancreatic Cancer: A Diagnostic Meta-analysis.

PubMed

Dai, Cong; Cao, Qin; Jiang, Min; Sun, Ming-Jun

2018-03-01

Differentiation between autoimmune pancreatitis (AIP) and pancreatic cancer (PC) is a clinical challenge. Emerging published data on the accuracy of serum immunoglobulin G4 (IgG4) for the differential diagnosis between AIP and PC are inconsistent. The objective of our study was to perform a meta-analysis evaluating the clinical utility of serum IgG4 in the differential diagnosis between AIP and PC. We performed a systematic literature search of multiple electronic databases. The methodological quality of each study was assessed according to the Quality Assessment of Diagnostic Accuracy Studies checklist. Random-effects model was used to summarize the diagnostic odds ratio and other measures of accuracy. Eleven studies comprising 523 AIP patients and 771 PC patients were included in the meta-analysis. The summary estimates for serum IgG4 in distinguishing AIP from PC were as follows: diagnostic odds ratio, 57.30 (95% confidence interval [CI], 23.17-141.67); sensitivity, 0.72 (95% CI, 0.68-0.76); specificity, 0.93 (95% CI, 0.91-0.94). The area under the curve of serum IgG4 in distinguishing AIP from PC was 0.9200. Our meta-analysis found that serum IgG4 has high specificity and relatively low sensitivity in the differential diagnosis between AIP and PC. Therefore, serum IgG4 is useful in distinguishing AIP from PC.

Residual gas analyzer mass spectrometry for human breath analysis: a new tool for the non-invasive diagnosis of Helicobacter pylori infection.

PubMed

Maity, Abhijit; Banik, Gourab D; Ghosh, Chiranjit; Som, Suman; Chaudhuri, Sujit; Daschakraborty, Sunil B; Ghosh, Shibendu; Ghosh, Barnali; Raychaudhuri, Arup K; Pradhan, Manik

2014-03-01

A residual gas analyzer (RGA) coupled with a high vacuum chamber is described for the non-invasive diagnosis of the Helicobacter pylori (H. pylori) infection through ¹³C-urea breath analysis. The present RGA-based mass spectrometry (MS) method is capable of measuring high-precision ¹³CO₂ isotope enrichments in exhaled breath samples from individuals harboring the H. pylori infection. The system exhibited 100% diagnostic sensitivity, and 93% specificity alongside positive and negative predictive values of 95% and 100%, respectively, compared with invasive endoscopy-based biopsy tests. A statistically sound diagnostic cut-off value for the presence of H. pylori was determined to be 3.0‰ using a receiver operating characteristic curve analysis. The diagnostic accuracy and validity of the results are also supported by optical off-axis integrated cavity output spectroscopy measurements. The δ¹³(DOB)C‰ values of both methods correlated well (R² = 0.9973 at 30 min). The RGA-based instrumental setup described here is simple, robust, easy-to-use and more portable and cost-effective compared to all other currently available detection methods, thus making it a new point-of-care medical diagnostic tool for the purpose of large-scale screening of the H. pylori infection in real time. The RGA-MS technique should have broad applicability for ¹³C-breath tests in a wide range of biomedical research and clinical diagnostics for many other diseases and metabolic disorders.

Understanding diagnostic variability in breast pathology: lessons learned from an expert consensus review panel

PubMed Central

Allison, Kimberly H; Reisch, Lisa M; Carney, Patricia A; Weaver, Donald L; Schnitt, Stuart J; O’Malley, Frances P; Geller, Berta M; Elmore, Joann G

2015-01-01

Aims To gain a better understanding of the reasons for diagnostic variability, with the aim of reducing the phenomenon. Methods and results In preparation for a study on the interpretation of breast specimens (B-PATH), a panel of three experienced breast pathologists reviewed 336 cases to develop consensus reference diagnoses. After independent assessment, cases coded as diagnostically discordant were discussed at consensus meetings. By the use of qualitative data analysis techniques, transcripts of 16 h of consensus meetings for a subset of 201 cases were analysed. Diagnostic variability could be attributed to three overall root causes: (i) pathologist-related; (ii) diagnostic coding/study methodology-related; and (iii) specimen-related. Most pathologist-related root causes were attributable to professional differences in pathologists’ opinions about whether the diagnostic criteria for a specific diagnosis were met, most frequently in cases of atypia. Diagnostic coding/study methodology-related root causes were primarily miscategorizations of descriptive text diagnoses, which led to the development of a standardized electronic diagnostic form (BPATH-Dx). Specimen-related root causes included artefacts, limited diagnostic material, and poor slide quality. After re-review and discussion, a consensus diagnosis could be assigned in all cases. Conclusions Diagnostic variability is related to multiple factors, but consensus conferences, standardized electronic reporting formats and comments on suboptimal specimen quality can be used to reduce diagnostic variability. PMID:24511905

Faultfinder: A diagnostic expert system with graceful degradation for onboard aircraft applications

NASA Technical Reports Server (NTRS)

Abbott, Kathy H.; Schutte, Paul C.; Palmer, Michael T.; Ricks, Wendell R.

1988-01-01

A research effort was conducted to explore the application of artificial intelligence technology to automation of fault monitoring and diagnosis as an aid to the flight crew. Human diagnostic reasoning was analyzed and actual accident and incident cases were reconstructed. Based on this analysis and reconstruction, diagnostic concepts were conceived and implemented for an aircraft's engine and hydraulic subsystems. These concepts are embedded within a multistage approach to diagnosis that reasons about time-based, causal, and qualitative information, and enables a certain amount of graceful degradation. The diagnostic concepts are implemented in a computer program called Faultfinder that serves as a research prototype.

[Theoretical grounds of a structural and functional model for quality assurance of radiation diagnostics under conditions of development of the modern health care system in Ukraine].

PubMed

Korop, Oleg A; Lenskykh, Sergiy V

2018-01-01

Introduction: Modern changes in the health care system of Ukraine are focused on financial support in providing medical and diagnostic care to the population and are based on deep and consistent structural and functional transformations. They are aimed at providing adequate quality care, which is the main target function and a principal criterion for operation of health care system. The urgency of this problem is increasing in the context of reforming the health care system and global changes in the governmental financial guarantees for the provision of medical services to the population. The aim of the work is to provide theoretical grounds for a structural and functional model of quality assurance of radiation diagnostics at all levels of medical care given to the population under the current health care reform in Ukraine. Materials and methods: The object of the study is organizing the operation of the radiation diagnostic service; the information is based on the actual data on the characteristics of radiation diagnosis at different levels of medical care provision. Methods of systematic approach, system analysis and structural and functional analysis of the operating system of radiation diagnostics are used. Review: The basis of the quality assurance model is the cyclical process, which includes the stages of the problem identifition, planning of its solution, organization of the system for implementation of decisions, monitoring the quality management process of the radiation diagnostics, and factors influencing the quality of the radiation diagnostics service. These factors include the quality of the structure, process, results, organization of management and control of current processes and the results of radiation diagnostics management. Conclusions: The advantages of the proposed model for ensuring the quality of the radiation diagnostics service are its systemacy and complexity, elimination of identified defects and deficiencies, and achievement of profitability through modern redistribution and use of existing resources of the health care system. The results of adequate service quality management activities in radiation diagnostics are the improvement of organizational and economic principles along with legislative regulation, the implementation of a modern system of radiation diagnostics in the state health care at the national and regional levels, the increase of the accessibility, quality and efficiency of the radiation diagnostics service.

Gene expression-based molecular diagnostic system for malignant gliomas is superior to histological diagnosis.

PubMed

Shirahata, Mitsuaki; Iwao-Koizumi, Kyoko; Saito, Sakae; Ueno, Noriko; Oda, Masashi; Hashimoto, Nobuo; Takahashi, Jun A; Kato, Kikuya

2007-12-15

Current morphology-based glioma classification methods do not adequately reflect the complex biology of gliomas, thus limiting their prognostic ability. In this study, we focused on anaplastic oligodendroglioma and glioblastoma, which typically follow distinct clinical courses. Our goal was to construct a clinically useful molecular diagnostic system based on gene expression profiling. The expression of 3,456 genes in 32 patients, 12 and 20 of whom had prognostically distinct anaplastic oligodendroglioma and glioblastoma, respectively, was measured by PCR array. Next to unsupervised methods, we did supervised analysis using a weighted voting algorithm to construct a diagnostic system discriminating anaplastic oligodendroglioma from glioblastoma. The diagnostic accuracy of this system was evaluated by leave-one-out cross-validation. The clinical utility was tested on a microarray-based data set of 50 malignant gliomas from a previous study. Unsupervised analysis showed divergent global gene expression patterns between the two tumor classes. A supervised binary classification model showed 100% (95% confidence interval, 89.4-100%) diagnostic accuracy by leave-one-out cross-validation using 168 diagnostic genes. Applied to a gene expression data set from a previous study, our model correlated better with outcome than histologic diagnosis, and also displayed 96.6% (28 of 29) consistency with the molecular classification scheme used for these histologically controversial gliomas in the original article. Furthermore, we observed that histologically diagnosed glioblastoma samples that shared anaplastic oligodendroglioma molecular characteristics tended to be associated with longer survival. Our molecular diagnostic system showed reproducible clinical utility and prognostic ability superior to traditional histopathologic diagnosis for malignant glioma.

Evaluation of diagnostic criteria for panic attack using item response theory: findings from the National Comorbidity Survey in USA.

PubMed

Ietsugu, Tetsuji; Sukigara, Masune; Furukawa, Toshiaki A

2007-12-01

The dichotomous diagnostic systems such as the Diagnostic and Statistical Manual of Mental Disorders (DSM) and International Classification of Diseases (ICD) lose much important information concerning what each symptom can offer. This study explored the characteristics and performances of DSM-IV and ICD-10 diagnostic criteria items for panic attack using modern item response theory (IRT). The National Comorbidity Survey used the Composite International Diagnostic Interview to assess 14 DSM-IV and ICD-10 panic attack diagnostic criteria items in the general population in the USA. The dimensionality and measurement properties of these items were evaluated using dichotomous factor analysis and the two-parameter IRT model. A total of 1213 respondents reported at least one subsyndromal or syndromal panic attack in their lifetime. Factor analysis indicated that all items constitute a unidimensional construct. The two-parameter IRT model produced meaningful and interpretable results. Among items with high discrimination parameters, the difficulty parameter for "palpitation" was relatively low, while those for "choking," "fear of dying" and "paresthesia" were relatively high. Several items including "dry mouth" and "fear of losing control" had low discrimination parameters. The item characteristics of diagnostic criteria among help-seeking clinical populations may be different from those that we observed in the general population and deserve further examination. "Paresthesia," "choking" and "fear of dying" can be thought to be good indicators of severe panic attacks, while "palpitation" can discriminate well between cases and non-cases at low level of panic attack severity. Items such as "dry mouth" would contribute less to the discrimination.

Difference of Diagnostic Rates and Analytical Methods in the Test Positions of Vestibular Evoked Myogenic Potentials

PubMed Central

Park, Jeong Mee; Yong, Sang Yeol; Kim, Jong Heon; Kim, Hee; Park, Sang-Yoo

2014-01-01

Objective To compare the differences of diagnostic rates, of the two widely used test positions, in measuring vestibular evoked myogenic potentials (VEMP) and selecting the most appropriate analytical method for diagnostic criteria for the patients with vertigo. Methods Thirty-two patients with vertigo were tested in two comparative testing positions: turning the head to the opposite side of the evaluating side and bowing while in seated position, and bowing while in supine positions. Abnormalities were determined by prolonged latency of p13 or n23, shortening of the interpeak latency, and absence of VEMP formation. Results Using the three criteria above for determining abnormalities, both the seated and supine positions showed no significant differences in diagnostic rates, however, the concordance correlation of the two positions was low. When using only the prolonged latency of p13 or n23 in the two positions, diagnostic rates were not significantly different and their concordance correlation was high. On the other hand, using only the shortened interpeak latency in both positions showed no significant difference of diagnostic rates, and the degree of agreement between two positions was low. Conclusion Bowing while in seated position with the head turned in the opposite direction to the area being evaluated is found to be the best VEMP test position due to the consistent level of sternocleidomastoid muscle tension and the high level of compliance. Also, among other diagnostic analysis methods, using prolonged latency of p13 or n23 as the criterion is found to be the most appropriate method of analysis for the VEMP test. PMID:24855617

Efficacy and safety of cryobiopsy versus forceps biopsy for interstitial lung diseases and lung tumours: A systematic review and meta-analysis.

PubMed

Ganganah, Oormila; Guo, Shu Liang; Chiniah, Manu; Li, Yi Shi

2016-07-01

Forceps biopsy (FB) is the most commonly used diagnostic tool for lung pathologies. FB is associated with a high diagnostic failure rate. Cryobiopsy (CB) is a novel technique providing a larger specimen size, few artefacts, more alveolar parts and superior diagnostic yield. CB, however, has drawbacks such as higher bleeding and pneumothorax rate. We conducted a meta-analysis to investigate the specimen area, diagnostic rate and bleeding severity in CB versus FB in interstitial lung diseases (ILDs) and lung tumours. A systematic literature search of PUBMED, BIOSIS PREVIEW and OVID databases was conducted using specific search terms. Eligible studies including RCTs and non-RCTs comparing cryobiopsy/cryotransbronchial biopsy (CB/CTBB) and forceps biopsy/forceps transbronchial biopsy (FB/FTBB) for specimen area, diagnostic rate and bleeding rate in ILDs and lung tumours were analysed. Two reviewers independently extracted data and evaluated the quality of the studies. Eight studies involving 916 patients were analysed. Specimen area (mm(2) ) was significantly larger in CB/CTBB than FB/FTBB (standard mean difference = 1.21, 95% confidence interval (0.94, 1.48), P < 0.00001). The diagnostic rate was significantly higher in CB/CTBB than FB/FTBB (Risk ratio 1.36, 95% confidence interval (1.16, 1.59), P = 0.0002). Three studies compared the bleeding severity with only one showing significantly more bleeding in CB. Cryobiopsy/cryotransbronchial shows superiority to FB/FTBB for specimen area and diagnostic rate. CB/CTBB has better efficacy over FB/FTBB. © 2016 Asian Pacific Society of Respirology.

The Relationship of Comorbidities and Patient Navigation to Time to Diagnostic Resolution after Abnormal Cancer Screening

PubMed Central

Whitley, Elizabeth M; Raich, Peter C; Dudley, Donald J; Freund, Karen M; Paskett, Electra D; Patierno, Steven R; Simon, Melissa; Warren-Mears, Victoria; Snyder, Frederick R

2016-01-01

Background Whether patient navigation improves outcomes in patients with comorbidities is unknown. Study aims were to determine the effect of comorbidities on time to diagnostic resolution following an abnormal cancer screening test, and to examine for patients with comorbidities, if patient navigation improves timeliness and likelihood of diagnostic resolution compared to patients without navigation. Methods A secondary analysis from the Patient Navigation Research Program sites that collected comorbidity data using the Charlson Comorbidity Index (CCI) was conducted. Participants were 6,349 patients with abnormal breast, cervical, colon or prostate cancer screening tests between 2007 and 2011. The intervention was patient navigation or usual care. CCI data were highly skewed across projects and cancer sites and were categorized as 0, no comorbidities identified, CCI score of 0 (76% of cases); 1, CCI score of 1 (16% of cases); or 2, CCI score of ≥2 (8% of cases). A separate adjusted hazards ratio for each site and cancer type was obtained, and then pooled using meta-analysis random effects methodology. Results Having a CCI score of ≥2 delayed the time to diagnostic resolution following an abnormal cancer screening test compared with those with fewer than one comorbidity. Patient Navigation reduced delays in diagnostic resolution with the greatest benefit seen in those with a CCI score of ≥2. Conclusions Persons with a CCI score of ≥2 experienced significant delays in timely diagnostic care compared to patients without comorbidities. Patient navigation was effective in reducing delays in diagnostic resolution among those with CCI scores > 1. PMID:27648520

Catecholamines profiles at diagnosis: Increased diagnostic sensitivity and correlation with biological and clinical features in neuroblastoma patients.

PubMed

Verly, Iedan R N; van Kuilenburg, André B P; Abeling, Nico G G M; Goorden, Susan M I; Fiocco, Marta; Vaz, Frédéric M; van Noesel, Max M; Zwaan, C Michel; Kaspers, GertJan L; Merks, Johannes H M; Caron, Huib N; Tytgat, Godelieve A M

2017-02-01

Neuroblastoma (NBL) accounts for 10% of the paediatric malignancies and is responsible for 15% of the paediatric cancer-related deaths. Vanillylmandelic acid (VMA) and homovanillic acid (HVA) are most commonly analysed in urine of NBL patients. However, their diagnostic sensitivity is suboptimal (82%). Therefore, we performed in-depth analysis of the diagnostic sensitivity of a panel of urinary catecholamine metabolites. Retrospective study of a panel of 8 urinary catecholamine metabolites (VMA, HVA, 3-methoxytyramine [3MT], dopamine, epinephrine, metanephrine, norepinephrine and normetanephrine [NMN]) from 301 NBL patients at diagnosis. Special attention was given to subgroups, metaiodobenzylguanidine (MIBG) non-avid tumours and VMA/HVA negative patients. Elevated catecholamine metabolites, especially 3MT, correlated with nine out of 12 NBL characteristics such as stage, age, MYCN amplification, loss of heterozygosity for 1p and bone-marrow invasion. The combination of the classical markers VMA and HVA had a diagnostic sensitivity of 84%. NMN was the most sensitive single diagnostic metabolite with overall sensitivity of 89%. When all 8 metabolites were combined, a diagnostic sensitivity of 95% was achieved. Among the VMA and HVA negative patients, were also 29% with stage 4 disease, which usually had elevation of other catecholamine metabolites (93%). Diagnostic sensitivity for patients with MIBG non-avid tumour was improved from 33% (VMA and/or HVA) to 89% by measuring the panel. Our study demonstrates that analysis of a urinary catecholamine metabolite panel, comprising 8 metabolites, ensures the highest sensitivity to diagnose NBL patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

Socioeconomic and Behavioral Factors Associated with Tuberculosis Diagnostic Delay in Lima, Peru.

PubMed

Bonadonna, Lily V; Saunders, Matthew J; Guio, Heinner; Zegarra, Roberto; Evans, Carlton A

2018-06-01

Early detection and diagnosis of tuberculosis (TB) is a global priority. Prolonged symptom duration before TB diagnosis is associated with increased morbidity, mortality, and risk of transmission. We aimed to determine socioeconomic and behavioral factors associated with diagnostic delays among patients with TB. Data were collected from 105 patients with TB using a semi-structured interview guide in Lima, Peru. Factors associated with diagnostic delay were analyzed using negative binomial regression. The median delay from when symptoms commenced and the first positive diagnostic sample in public health facilities was 57 days (interquartile range: 28-126). In multivariable analysis, greater diagnostic delay was independently associated with patient older age, female gender, lower personal income before diagnosis, living with fewer people, and having more visits to professional health facilities before diagnosis (all P < 0.05). Patients who first sought care at a private health facility had more visits overall to professional health facilities before diagnosis than those who first sought care from public or insured employee health facilities and had longer diagnostic delay in analysis adjusted for age and gender. Patients with TB were significantly more likely to first self-medicate than to visit professional health facilities before diagnosis ( P = 0.003). Thus, diagnostic delay was prolonged, greatest among older, low-income women, and varied according to the type of care sought by individuals when their symptoms commenced. These findings suggest that TB case-finding initiatives should target vulnerable groups in informal and private health facilities, where many patients with TB first seek health care.

A Pilot Study on Modeling of Diagnostic Criteria Using OWL and SWRL.

PubMed

Hong, Na; Jiang, Guoqian; Pathak, Jyotishiman; Chute, Christopher G

2015-01-01

The objective of this study is to describe our efforts in a pilot study on modeling diagnostic criteria using a Semantic Web-based approach. We reused the basic framework of the ICD-11 content model and refined it into an operational model in the Web Ontology Language (OWL). The refinement is based on a bottom-up analysis method, in which we analyzed data elements (including value sets) in a collection (n=20) of randomly selected diagnostic criteria. We also performed a case study to formalize rule logic in the diagnostic criteria of metabolic syndrome using the Semantic Web Rule Language (SWRL). The results demonstrated that it is feasible to use OWL and SWRL to formalize the diagnostic criteria knowledge, and to execute the rules through reasoning.

Analysis of the Astronomy Diagnostic Test

ERIC Educational Resources Information Center

Brogt, Erik; Sabers, Darrell; Prather, Edward E.; Deming, Grace L.; Hufnagel, Beth; Slater, Timothy F.

2007-01-01

Seventy undergraduate class sections were examined from the database of Astronomy Diagnostic Test (ADT) results of Deming and Hufnagel to determine if course format correlated with ADT normalized gain scores. Normalized gains were calculated for four different classroom scenarios: lecture, lecture with discussion, lecture with lab, and lecture…

Assessment of Different Strategies to Determine MAP-specific Cellular Immune Responses in Cattle

USDA-ARS?s Scientific Manuscript database

Assessment of cellular immunity in cattle against Mycobacterium avium ssp. paratuberculosis (MAP) by established methods remains unsatisfactory for diagnostic purposes. Recent studies conclude that analysis of T-cell subset responsiveness may improve diagnostic outcome. Aim of this study was to iden...

Diagnostic Testing in Mathematics: An Extension of the PIAT?

ERIC Educational Resources Information Center

Algozzine, Bob; McGraw, Karen

1980-01-01

The article addresses the usefulness of the Peabody Individual Achievement Test (PIAT) in assessing various levels of arithmetic performance. The mathematics subtest of the PIAT is considered in terms of purpose; mathematical abilities subsections (foundations, basic facts, applications); diagnostic testing (the error analysis matrix); and poor…

Knee Arthroscopy Simulation: A Randomized Controlled Trial Evaluating the Effectiveness of the Imperial Knee Arthroscopy Cognitive Task Analysis (IKACTA) Tool.

PubMed

Bhattacharyya, Rahul; Davidson, Donald J; Sugand, Kapil; Bartlett, Matthew J; Bhattacharya, Rajarshi; Gupte, Chinmay M

2017-10-04

Virtual-reality and cadaveric simulations are expensive and not readily accessible. Innovative and accessible training adjuncts are required to help to meet training needs. Cognitive task analysis has been used extensively to train pilots and in other surgical specialties. However, the use of cognitive task analyses within orthopaedics is in its infancy. The purpose of this study was to evaluate the effectiveness of a novel cognitive task analysis tool to train novice surgeons in diagnostic knee arthroscopy in high-fidelity, phantom-limb simulation. Three expert knee surgeons were interviewed independently to generate a list of technical steps, decision points, and errors for diagnostic knee arthroscopy. A modified Delphi technique was used to generate the final cognitive task analysis. A video and a voiceover were recorded for each phase of this procedure. These were combined to produce the Imperial Knee Arthroscopy Cognitive Task Analysis (IKACTA) tool that utilizes written and audiovisual stimuli to describe each phase of a diagnostic knee arthroscopy. In this double-blinded, randomized controlled trial, a power calculation was performed prior to recruitment. Sixteen novice orthopaedic trainees who performed ≤10 diagnostic knee arthroscopies were randomized into 2 equal groups. The intervention group (IKACTA group) was given the IKACTA tool and the control group had no additional learning material. They were assessed objectively (validated Arthroscopic Surgical Skill Evaluation Tool [ASSET] global rating scale) on a high-fidelity, phantom-knee simulator. All participants, using the Likert rating scale, subjectively rated the tool. The mean ASSET score (and standard deviation) was 19.5 ± 3.7 points in the IKACTA group and 10.6 ± 2.3 points in the control group, resulting in an improvement of 8.9 points (95% confidence interval, 7.6 to 10.1 points; p = 0.002); the score was determined as 51.3% (19.5 of 38) for the IKACTA group, 27.9% (10.6 of 38) for the control group, and 23.4% (8.9 of 38) for the improvement. All participants agreed that the cognitive task analysis learning tool was a useful training adjunct to learning in the operating room. To our knowledge, this is the first cognitive task analysis in diagnostic knee arthroscopy that is user-friendly and inexpensive and has demonstrated significant benefits in training. The IKACTA will provide trainees with a demonstrably strong foundation in diagnostic knee arthroscopy that will flatten learning curves in both technical skills and decision-making.

Feasibility and diagnostic performance of dual-tracer-guided sentinel lymph node biopsy in cT1-2N0M0 gastric cancer: a systematic review and meta-analysis of diagnostic studies.

PubMed

Huang, Ling; Wei, Tao; Chen, Junjun; Zhou, Donghui

2017-05-16

Dual-tracer-guided sentinel lymph node (SLN) biopsy may provide a promising diagnostic tool to assess accurately the status of lymph node metastasis in the surgical operation and assure the oncologic safety of the function or stomach preserving surgery. The diagnostic performance of this technology in recent studies varied. Thus, we conducted this meta-analysis. This systematic review and meta-analysis was registered at the PROSPERO. Eligible studies were searched in the PubMed, EMBASE, Web of Knowledge, and Cochrane Library databases. A random-effect model was used to pool the data. Summary receiver operator characteristic curves, analysis for publication bias, meta-regression, and subgroup analysis were also performed. The pooled SLN identification rate and sensitivity were 0.97 and 0.89. 99m Tc-human serum albumin with indocyanine green (ICG), 99m Tc-antimony sulfur colloid with ICG, performing SLN biopsy ≥15 min after dye injection, an SLN ≥5, the basin dissection, laparoscopic surgery, in studies conducted in Japan and studies published after 2012, were associated with higher sensitivity. CT1 stage, performing SLN biopsy ≥15 min after dye injection, in studies conducted in Japan and studies published after 2012, were related with a higher identification rate. Dual tracer is promising in SLN biopsy in gastric cancer, and the clinical application of SLN biopsy should be limited to the patients of cT1N0M0 gastric cancer. The combination of 99m Tc-human serum albumin and ICG as well as the combination of 99m Tc-antimony sulfur colloid and ICG may be the optimal tracer combination. However, it seems not justified to put this technique into routine clinical application recently. Some factors that might enhance diagnostic value are identified.

Fecal immunochemical test for predicting mucosal healing in ulcerative colitis patients: A systematic review and meta-analysis.

PubMed

Dai, Cong; Jiang, Min; Sun, Ming-Jun; Cao, Qin

2018-05-01

Fecal immunochemical test (FIT) is a promising marker for assessment of inflammatory bowel disease activity. However, the utility of FIT for predicting mucosal healing (MH) of ulcerative colitis (UC) patients has yet to be clearly demonstrated. The objective of our study was to perform a diagnostic test accuracy test meta-analysis evaluating the diagnostic accuracy of FIT in predicting MH of UC patients. We systematically searched the databases from inception to November 2017 that evaluated MH in UC. The methodological quality of each study was assessed according to the Quality Assessment of Diagnostic Accuracy Studies checklist. The extracted data were pooled using a summary receiver operating characteristic curve model. Random-effects model was used to summarize the diagnostic odds ratio, sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio. Six studies comprising 625 UC patients were included in the meta-analysis. The pooled sensitivity and specificity values for predicting MH in UC were 0.77 (95% confidence interval [CI], 0.72-0.81) and 0.81 (95% CI, 0.76-0.85), respectively. The FIT level had a high rule-in value (positive likelihood ratio, 3.79; 95% CI, 2.85-5.03) and a moderate rule-out value (negative likelihood ratio, 0.26; 95% CI, 0.16-0.43) for predicting MH in UC. The results of the receiver operating characteristic curve analysis (area under the curve, 0.88; standard error of the mean, 0.02) and diagnostic odds ratio (18.08; 95% CI, 9.57-34.13) also revealed improved discrimination for identifying MH in UC with FIT concentration. Our meta-analysis has found that FIT is a simple, reliable non-invasive marker for predicting MH in UC patients. © 2018 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.