Purpose To assess the diagnostic performance and interreader agreement of a standardized diagnostic algorithm in determining the histologic type of small (≤4 cm) renal masses (SRMs) with ...multiparametric magnetic resonance (MR) imaging. Materials and Methods This single-center retrospective HIPAA-compliant institutional review board-approved study included 103 patients with 109 SRMs resected between December 2011 and July 2015. The requirement for informed consent was waived. Presurgical renal MR images were reviewed by seven radiologists with diverse experience. Eleven MR imaging features were assessed, and a standardized diagnostic algorithm was used to determine the most likely histologic diagnosis, which was compared with histopathology results after surgery. Interreader variability was tested with the Cohen κ statistic. Regression models using MR imaging features were used to predict the histopathologic diagnosis with 5% significance level. Results Clear cell renal cell carcinoma (RCC) and papillary RCC were diagnosed, with sensitivities of 85% (47 of 55) and 80% (20 of 25), respectively, and specificities of 76% (41 of 54) and 94% (79 of 84), respectively. Interreader agreement was moderate to substantial (clear cell RCC, κ = 0.58; papillary RCC, κ = 0.73). Signal intensity (SI) of the lesion on T2-weighted MR images and degree of contrast enhancement (CE) during the corticomedullary phase were independent predictors of clear cell RCC (SI odds ratio OR: 3.19; 95% confidence interval CI: 1.4, 7.1; P = .003; CE OR, 4.45; 95% CI: 1.8, 10.8; P < .001) and papillary RCC (CE OR, 0.053; 95% CI: 0.02, 0.2; P < .001), and both had substantial interreader agreement (SI, κ = 0.69; CE, κ = 0.71). Poorer performance was observed for chromophobe histology, oncocytomas, and minimal fat angiomyolipomas, (sensitivity range, 14%-67%; specificity range, 97%-99%), with fair to moderate interreader agreement (κ range = 0.23-0.43). Segmental enhancement inversion was an independent predictor of oncocytomas (OR, 16.21; 95% CI: 1.0, 275.4; P = .049), with moderate interreader agreement (κ = 0.49). Conclusion The proposed standardized MR imaging-based diagnostic algorithm had diagnostic accuracy of 81% (88 of 109) and 91% (99 of 109) in the diagnosis of clear cell RCC and papillary RCC, respectively, while achieving moderate to substantial interreader agreement among seven radiologists.
RSNA, 2018 Online supplemental material is available for this article.
The incorporation of highly luminescent core–shell quantum dots (QDs) within a metal–organic framework (MOF) is achieved through a one‐pot method. Through appropriate surface functionalization, the ...QDs are solubilized within MOF‐5 growth media. This permits the incorporation of the QDs within the evolving framework during the reaction. The resulting QD@MOF‐5 composites are characterized using X‐ray fluorescence, cross‐sectional confocal microscopy, energy‐dispersive X‐ray spectroscopy, scanning electron microscopy, and small‐angle X‐ray scattering. The synergistic combination of luminescent QDs and the controlled porosity of MOF‐5 in the QD@MOF‐5 composites is harnessed within a prototype molecular sensor that can discriminate on the basis of molecular size.
Highly luminescent quantum dots (QDs) are successfully incorporated within metal–organic framework (MOF)‐5 crystals. QD@MOF‐5 composites retain the QDs' optical quality and the MOF‐5 cage nanoporosity, despite the dots' size being bigger than the MOF‐5 cavities. X‐ray diffraction studies confirm that no large‐scale distortion of the MOF‐5 lattice exists. Emission quenching tests expose the sieving nature of the composites, opening opportunities for the application of MOFs as optical devices.
An experimental Very Low Frequency (VLF) World-Wide Lightning Location Network (WWLLN) has been developed through collaborations with research institutions across the world, providing global ...real-time locations of lightning discharges. As of April 2006, the network included 25 stations providing coverage for much of the Earth. In this paper we examine the detection efficiency of the WWLLN by comparing the locations from this network with lightning location data purchased from a commercial lightning location network operating in New Zealand. Our analysis confirms that WWLLN favours high peak current return stroke lightning discharges, and that discharges with larger currents are observed by more stations across the global network. We then construct a first principles detection efficiency model to describe the WWLLN, combining calibration information for each station with theoretical modelling to describe the expected amplitudes of the VLF sferics observed by the network. This detection efficiency model allows the prediction of the global variation in WWLLN lightning detection, and an estimate of the minimum CG return stroke peak current required to trigger the network. There are strong spatial variations across the globe, primarily due to station density and sensitivity. The WWLLN is currently best suited to study the occurrence and impacts of high peak-current lightning. For example, in 2005 about 12% of the global elve-producing lightning will have been located by the network. Since the lightning-EMP which produce elves has a high mean rate (210 per minute) it has the potential to significantly influence the ionosphere on regional scales.
Lightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by ...extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.
Thunderstorms have been observed to introduce infrasonic oscillations in the ionosphere, but it is not clear what processes or which parts of the thunderstorm generate the oscillations. In this ...paper, we present a new technique that uses an array of ground‐based GPS total electron content (TEC) measurements to locate the source of the infrasonic oscillations and compare the source locations with thunderstorm features to understand the possible source mechanisms. The location technique utilizes instantaneous phase differences between pairs of GPS‐TEC measurements and an algorithm to best fit the measured and the expected phase differences for assumed source positions and other related parameters. In this preliminary study, the infrasound waves are assumed to propagate along simple geometric raypaths from the source to the measurement locations to avoid extensive computations. The located sources are compared in time and space with thunderstorm development and lightning activity. Sources are often found near the main storm cells, but they are more likely related to the downdraft process than to the updraft process. The sources are also commonly found in the convectively quiet stratiform regions behind active cells and are in good coincidence with extensive lightning discharges and inferred high‐altitude sprites discharges.
Key Points
New technique to locate source of infrasonic wave by using phase difference of GPS‐TEC measurements
Sources located near thunderstorm core but more likely related to downdraft than to updraft
Sources also located in stratiform region, related to lightning and sprites in and above the region
The natural aging behavior of pure ternary Al‐Mg‐Si alloys is investigated by measuring hardness, electrical resistivity and positron lifetime, as well as carrying out thermal analysis and atom probe ...microscopy. It is found that several distinct temporal stages of natural aging can be distinguished in which one of these quantities shows a characteristic behavior and that these times coincide for many of these measurements. The rate of change in the measured data is correlated with proposed solute dynamics during natural aging for both aging that takes place prior to artificial aging (natural pre‐aging) and after artificial underaging (natural secondary aging) heat treatments. Controlling factors for solute dynamics are discussed.
Pure Al‐Mg‐Si alloys are naturally aged after solutionizing and quenching. Measurements of hardness, electrical resistivity, positron lifetime, thermoanalysis, and atom probe tomography suggest at least four different stages of solute and vacancy clustering and early precipitation. The observed correlations between natural pre‐aging, artificial aging, and secondary aging allow for the discussion of solute dynamics in these alloys.
Anaerobic sewage sludge acclimated with sucrose in a completely stirred tank reactor operating at 35°C was used as a seed in a batch experiment to exploit nutrient formulation for biological hydrogen ...production by anaerobic microflora (dominated by
Clostridium pasteurianum) of sewage sludge. The information about the supplement of various nutrients was collected from the existing literature. Taguchi orthogonal arrays were used in the experimental design and a confirmation experiment was conducted. Experimental results indicated that the sewage sludge enriched with proposed nutrients formulation had a hydrogen productivity of
3.43
mol
-H
2
(
mol
sucrose
)
−1
, which was about 30% higher than those of control and using an acidogenic nutrient formulation. This nutrient formulation also increased the hydrogen production rate and hydrogen content by 66% (comparing with the acidogenic nutrient formulation) and 18% (comparing with the control), respectively. Magnesium, sodium, zinc and iron were important trace metals affecting hydrogen production with magnesium the most significant one. Their concentration influences on hydrogen production were different and were discussed. Strategies based on monitoring indicator choice and nutrient concentration control for optimal hydrogen production were proposed.
We use lightning sferics from the World Wide Lightning Location Network to identify storms near 362 Terrestrial Gamma‐ray Flashes (TGFs). The combined spectrum of TGFs with storms within 300 km of ...the sub‐satellite point is much harder than the spectrum of TGFs with more distant storms. When these data are compared with simulations of vertically oriented relativistic runaway breakdown, it is found that the most likely model has a source altitude of 15 km and a wide‐beam geometry. We find four associations of TGFs with individual sferics geolocated to positions more than 300 km from the sub‐satellite point and show that a narrow‐beam source at ≥21 km altitude is unlikely to produce the number of high energy photons in these TGFs.
Anaerobic sewage sludge acclimated with sucrose was used as the seed in a batch experiment to investigate the carbon/nitrogen (C/N)-ratio effects on biological hydrogen production from sucrose. ...Experimental results indicated that the hydrogen production ability of the anaerobic microflora (dominated by
Clostridium pasteurianum) in the sewage sludge was dependent on the influent C/N-ratio. At a C/N-ratio of 47, the hydrogen productivity and hydrogen production rate reached
4.8
mol-H
2/
mol-sucrose
and
270
mmol-H
2/
L-day
, respectively. This increased by 500% and 80%, respectively, compared with the blank. Proper C/N-ratio on hydrogen production enhancement was accomplished by shifting the metabolic pathway. Strategies for optimal hydrogen production are also proposed.
This study uses multi‐station time‐domain very‐low and low‐frequency (VLF/LF) lightning waveforms detected from a range of several hundred kilometers to probe fluctuations in D‐layer ionospheric ...height and peak reflection ratio in three regions near a large thunderstorm on the night of 17 June 2005. These measurements show propagation of the fluctuations away from the thunderstorm in addition to a background eastward‐propagating fluctuation over the entire region. Measured speeds of propagation range from ∼45 m/s to ∼85 m/s, consistent with horizontal propagation speeds of atmospheric gravity waves. The fluctuation propagation is seen in both the ionospheric height measurement and the peak reflection ratio measurement with similar periods and speeds. Ionospheric height perturbations in the measured regions can be as large as 6 km from average, and perturbations in peak reflection ratio can be as large at 100%.
Key Points
D‐layer disturbances are detected propagating outward from thunderstorm region
A new VLF probing technique is used with high temporal and spatial‐resolution
Background atmospheric gravity waves cause large scale disturbances in D‐layer
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