We investigate interacting scenarios that belong to a wider class, since they include a dynamical dark energy component whose equation of state follows various one-parameter parametrizations. We ...confront them with the latest observational data from the cosmic microwave background, the joint light-curve sample from type Ia supernovae, baryon acoustic oscillations, Hubble parameter measurements from cosmic chronometers (CC), and a Gaussian prior on the Hubble parameter H0. In all examined scenarios we find a nonzero interaction; nevertheless, the noninteracting case is allowed within 2σ. Concerning the current value of the dark energy equation of state for all combinations of data sets, it always lies in the phantom regime at more than 2–3 standard deviations. Finally, for all interacting models, independently of the combination of data sets considered, the estimated values of the present Hubble parameter H0 are greater compared to the ΛCDM-based Planck estimate and close to the local measurements, thus alleviating the H0 tension.
A systematic measurement of radon/thoron concentration by using pin-holes dosimeter and their decay products by deposition based progeny sensors have been carried out in indoor environment of ...district Palwal, Southern Haryana, India. LR-115 type-II of cellulose nitrate with thick polyester base film was used as detectors. A total 150 locations were selected for measurements over a period of 40 days. In this paper, results of winter season are reported and compared with results of summer and rainy season. The measured average indoor thoron gas concentration (34.6 ± 1.5) is about 3.5 times higher than the world average value (10 Bq m.sup.-3). The average values for radon concentration, EERC, and EETC is found below the world average values of 40 Bq m.sup.-3 for radon, 15 Bq m.sup.-3 for EERC, and 0.5 Bq m.sup.-3 for EETC. The average annual effective dose inhaled by humans was estimated and compared with recommended limits of ICRP and WHO.
Spectroscopic methods have proven to be reliable and of high selectivity by utilizing the characteristic spectral absorption signature of trace gases such as NO.sub.2 . However, they typically lack ...the spatiotemporal resolution required for real-time imaging measurements of NO.sub.2 emissions. We propose imaging measurements of NO.sub.2 in the visible spectral range using a novel instrument, an NO.sub.2 camera based on the principle of gas correlation spectroscopy (GCS). For this purpose two gas cells (cuvettes) are placed in front of two camera modules. One gas cell is empty, while the other is filled with a high concentration of the target gas. The filled gas cell operates as a non-dispersive spectral filter to the incoming light, maintaining the two-dimensional imaging capability of the sensor arrays. NO.sub.2 images are generated on the basis of the signal ratio between the two images in the spectral window between 430 and 445 nm, where the NO.sub.2 absorption cross section is strongly structured. The capabilities and limits of the instrument are investigated in a numerical forward model. The predictions of this model are verified in a proof-of-concept measurement, in which the column densities in specially prepared reference cells were measured with the NO.sub.2 camera and a conventional differential optical absorption spectroscopy (DOAS) instrument. Finally, results from measurements at a large power plant, the Großkraftwerk Mannheim (GKM), are presented. NO.sub.2 column densities of the plume emitted from a GKM chimney are quantified at a spatiotemporal resolution of 1/12 frames per second (FPS) and 0.9 mx0.9 m. A detection limit of 2â10.sup.16 molec. cm.sup.-2 was reached. An NO.sub.2 mass flux of Fm=(7.4±4.2) kg h.sup.-1 was estimated on the basis of wind speeds obtained from consecutive images. The instrument prototype is highly portable for building costs of below EUR 2000.
A new electrochemical interface based on polyacrylic acid (PAAcid) immobilized in a Nafion® polymeric matrix on graphite screen-printed electrodes for detecting copper is presented. The copper is ...retained in the surface due to the capacity of the polyacid to chelate metals, and quantified using square wave voltammetry. The response was characterized by spectroscopic techniques (UV-vis-IR), which confirmed the chelation from the Cu.sup.2+ ions by the acid. A calibration curve is presented, showing good linearity and repeatability and its usefulness as a sensor. The range of operation goes from 15 to 50 muM, with a detection limit of 12 muM, making the sensor useful for measurements in environmental samples (after a preconcentration step) and in drinking water.
This article presents a literature review of sensors for the monitoring of benzene in ambient air and other volatile organic compounds. Combined with information provided by stakeholders, ...manufacturers and literature, the review considers commercially available sensors, including PID-based sensors, semiconductor (resistive gas sensors) and portable on-line measuring devices as for example sensor arrays. The bibliographic collection includes the following topics: sensor description, field of application at fixed sites, indoor and ambient air monitoring, range of concentration levels and limit of detection in air, model descriptions of the phenomena involved in the sensor detection process, gaseous interference selectivity of sensors in complex VOC matrix, validation data in lab experiments and under field conditions.
Purpose:
In this paper, the authors propose a novel efficient method to segment ultrasound images of the prostate with weak boundaries. Segmentation of the prostate from ultrasound images with weak ...boundaries widely exists in clinical applications. One of the most typical examples is the diagnosis and treatment of prostate cancer. Accurate segmentation of the prostate boundaries from ultrasound images plays an important role in many prostate-related applications such as the accurate placement of the biopsy needles, the assignment of the appropriate therapy in cancer treatment, and the measurement of the prostate volume.
Methods:
Ultrasound images of the prostate are usually corrupted with intensity inhomogeneities, weak boundaries, and unwanted edges, which make the segmentation of the prostate an inherently difficult task. Regarding to these difficulties, the authors introduce an active band term and an edge descriptor term in the modified level set energy functional. The active band term is to deal with intensity inhomogeneities and the edge descriptor term is to capture the weak boundaries or to rule out unwanted boundaries. The level set function of the proposed model is updated in a band region around the zero level set which the authors call it an active band. The active band restricts the authors’ method to utilize the local image information in a banded region around the prostate contour. Compared to traditional level set methods, the average intensities inside∖outside the zero level set are only computed in this banded region. Thus, only pixels in the active band have influence on the evolution of the level set. For weak boundaries, they are hard to be distinguished by human eyes, but in local patches in the band region around prostate boundaries, they are easier to be detected. The authors incorporate an edge descriptor to calculate the total intensity variation in a local patch paralleled to the normal direction of the zero level set, which can detect weak boundaries and avoid unwanted edges in the ultrasound images.
Results:
The efficiency of the proposed model is demonstrated by experiments on real 3D volume images and 2D ultrasound images and comparisons with other approaches. Validation results on real 3D TRUS prostate images show that the authors’ model can obtain a Dice similarity coefficient (DSC) of 94.03% ± 1.50% and a sensitivity of 93.16% ± 2.30%. Experiments on 100 typical 2D ultrasound images show that the authors’ method can obtain a sensitivity of 94.87% ± 1.85% and a DSC of 95.82% ± 2.23%. A reproducibility experiment is done to evaluate the robustness of the proposed model.
Conclusions:
As far as the authors know, prostate segmentation from ultrasound images with weak boundaries and unwanted edges is a difficult task. A novel method using level sets with active band and the intensity variation across edges is proposed in this paper. Extensive experimental results demonstrate that the proposed method is more efficient and accurate.
In this contribution, we emphasize the need for a sophisticated characterization of measurement devices in particular for optical bidirectional measurements. As an example, the ongoing ...characterization of the UV-microscope at PTB’s linescale comparator is presented. First results of spectroscopic measurements of the employed UV-LED are presented and the impact of deviations in the center wavelength of the LED on the measurements are illustrated by rigorous simulations.
The lattice dynamics of tetragonal Srsub.2VOsub.4 with a Ruddlesden—Popper-layered crystal structure was studied via Raman spectroscopy. We observed three of the four expected Raman-active modes ...under ambient conditions. Mode Grüneisen parameters and the implicit fractions of two Asub.1g Raman-active modes were determined from high-pressure and high-temperature Raman spectroscopy experiments. The low-energy Asub.1g Raman-active mode involving Sr motions along the c direction has a large isothermal Grüneisen parameter about seven times larger than that of the high-energy Asub.1g Raman-active mode involving apical O motions along the c direction and is, therefore, more anharmonic. The thermodynamic Grüneisen parameter is significantly smaller in Srsub.2VOsub.4 than in Srsub.2TiOsub.4 due to the smaller Grüneisen parameter of the high-energy Asub.1g Raman-active mode and other vibrational modes that still need to be identified. The explicit contribution of the low-energy Asub.1g Raman-active mode is negative, and the implicit contribution due to volume change is much larger. Both volume implicit and anharmonic explicit contributions of the high-energy Asub.1g Raman-active mode have similar positive values. The Raman experiment in the air shows that Srsub.2VOsub.4 begins to decompose above 200 °C.
The short-wave infrared (SWIR) module of the Tropospheric Monitoring Instrument (TROPOMI) on board the ESA's Sentinel-5 precursor (S5p) satellite has been very stable during its 5 years in orbit. ...Calibration was performed on the ground, complemented by measurements during in-flight instrument commissioning. The radiometric response and general performance of the SWIR module are monitored by on-board calibration sources. We show that after 5 years in orbit, TROPOMI-SWIR has continued to show excellent performance with degradation of at most 0.1 % in transmission and having lost less than 0.3 % of the detector pixels. Independent validation of the instrument calibration, via vicarious calibration, can be done through comparisons with ground-based reflectance data. In this work, ground measurements at the Railroad Valley Playa, a valley in central Nevada that is often used as a reference for satellite measurements, are used to perform vicarious calibration of the TROPOMI-SWIR measurements. This is done using dedicated measurement campaigns as well as automated reflectance measurements within the RADCALNET programme. As such, TROPOMI-SWIR is an excellent test case to explore the methodology of vicarious calibration applied to infrared spectroscopy. Using methodology developed for the vicarious calibration of the OCO-2 and GOSAT missions, the absolute radiometry of TROPOMI-SWIR performance is independently verified to be stable down to â¼ 6 %-10 % using the Railroad Valley when both the absolute and relative radiometric calibrations are applied. Differences with the on-board calibration originate from the bidirectional reflection distribution function (BRDF) effects of the desert surface, the large variety in viewing angles, and the different sizes of footprints of the TROPOMI pixels. Vicarious calibration is shown to be an additional valuable tool in validating radiance-level performances of infrared instruments such as TROPOMI-SWIR in the field of atmospheric composition. It remains clear that for instruments of similar design and resolution to TROPOMI-SWIR, on-board calibration sources will continue to provide superior results due to the limitations of the vicarious calibration method.
PDF
