Porous materials are of great importance in various industrial applications. Microscopic modifications in the pore structures of these materials can change their functional behavior. We treat Indiana ...limestone by lasers to modify its pore structures microscopically. Microcomputed tomography (micro-CT) of the treated samples reveal that pulsed Nd:YAG laser with energy 330 mJ increases open porosity of limestone by 15% and almost doubles the total porosity. This laser increases the limestone pore connectivity by 460%. High power CO2 laser increases the open porosity by 20% but it reduces the pore connectivity of limestone. Our findings show that pulsed laser beams induce high increase in porosity and connectivity. 3D pore scale modeling using Cascaded lattice Boltzmann method (CLBM) on a D3Q27 model shows that regions treated by pulsed Nd:YAG lasers exhibit enhanced fluid transport efficiency compared to untreated regions. The obtained results successfully demonstrate that lasers can be used to induce a well controlled heat transfer in porous materials directly enhancing their morphometric characteristics and microscopic fluid transport behavior.
Display omitted
•Microscopic changes are induced in the morphometric properties of Indiana limestone rock by using lasers.•Pulsed lasers induce a great increase in micro-porosity with greater pore-connectivity.•Nd:YAG Laser treatment enhances open porosity and pore-connectivity by 15% and 460%.•Pulsed lasers widen the separation range and reduce the separation thickness while CO2 laser reduces the pore connectivity.•Results show that laser treatments enhance the microscopic fluid transport efficiency in porous materials.
Purpose:
A novel method for flat-detector computed tomography was developed to enable volume-of-interest (VOI) imaging at high resolution, low noise, and reduced dose. For this, a full low-dose ...overview (OV) scan and a local high-dose scan of a VOI are combined.
Methods:
The first scan yields an overview of the whole object and enables the selection of an arbitrary VOI. The second scan of that VOI assures high image quality within the interesting volume. The combination of the two consecutive scans is based on a forward projection of the reconstructed OV volume that was registered to the VOI. The artificial projection data of the OV scan are combined with the measured VOI data in the raw data domain. Different projection values are matched by an appropriate transformation and weighting. The reconstruction is performed with a standard Feldkamp-type algorithm. In simulations, the combination of OV scan and VOI scan was investigated on a mathematically described phantom. In measurements, spatial resolution and noise were evaluated with image quality phantoms. Modulation transfer functions and noise values were calculated. Measurements of an anthropomorphic head phantom were used to validate the proposed method for realistic applications, e.g., imaging stents. In Monte Carlo simulations, 3D dose distributions were calculated and dose values were assessed quantitatively.
Results:
By the proposed combination method, an image is generated which covers the whole object and provides the VOI at high image quality. In the OV image, a resolution of 0.7 lp/mm (line pairs per millimeter) and noise of 63.5 HU were determined. Inside the VOI, resolution was increased to 2.4 lp/mm and noise was decreased to 18.7 HU. For the performed measurements, the cumulative dose was significantly reduced in comparison to conventional scans by up to 93%. The dose of a high-quality scan, for example, was reduced from 97 to less than 7 mGy, while keeping image quality constant within the VOI.
Conclusions:
The proposed VOI application with two scans is an effective way to ensure high image quality within the VOI while simultaneously reducing the cumulative patient dose.
Human and ecological health have been threatened by the increase of cyanobacteria harmful algal blooms (cyanoHABs) in freshwater systems. Successful mitigation of this risk requires understanding the ...factors driving cyanoHABs at a broad scale. To inform management priorities and decisions, we employed random forest modeling to identify major cyanoHAB drivers in 369 freshwater lakes distributed across 15 upper Midwest states during the 2011 bloom season (July–October). We used Cyanobacteria Index (CI_cyano)—A remotely sensed product derived from the MEdium Resolution Imaging Spectrometer (MERIS) aboard the European Space Agency's Envisat satellite—as the response variable to obtain variable importance metrics for 75 landscape and lake physiographic predictor variables. Lakes were stratified into high and low elevation categories to further focus CI_cyano variable importance identification by anthropogenic and natural influences. “High elevation” watershed land cover (LC) was primarily forest or natural vegetation, compared with “low elevation” watersheds LC dominated by anthropogenic landscapes (e.g., agriculture and municipalities). We used the top ranked 25 Random Forest variables to create a classification and regression tree (CART) for both low and high elevation lake designations to identify variable thresholds for possible management mitigation. Mean CI_cyano was 3 times larger for “low elevation” lakes than for “high elevation” lakes, with both mean values exceeding the “High” World Health Organization recreational guidance/action level threshold for cyanobacteria (100,000 cells/mL). Agrarian‐related variables were prominent across all 369 lakes and low elevation lakes. High elevation lakes showed more influence of lakeside LC than for the low elevation lakes.
Key Points
Cyanobacteria drivers ranked for 369 freshwater lakes in central United States
Anthropogenic influences notable in top rankings across all watersheds
We used dynamic single-photon emission computed tomography (D-SPECT) to overcome the interference of the planar dynamic imaging due to the overlap of internal organs, thus more accurate physiological ...function can be obtained.
3D printed gastric phantom was used to simulate gastric emptying (GE). First, the planar dynamic liquid GE procedure was used and served as the reference value; second, D-SPECT followed by repeated liquid GE procedures with three gamma cameras were used. The emptying flow rate of the gastric phantom simulated three flow rates of liquid, semisolid and solid. Third, we simulated the intestinal activity that interfered with the residual value obtained by 2D dynamic imaging, which was compared with D-SPECT. Then, we brought the 3D VOI data into the postprocessing program to obtain the residual activity curve and residual percentage.
The residual amount obtained in the phantom at 60th minutes in the first stage is 14.57%; the residual amount of liquid emptying are Siemens: 3.33%, GE: 15.06%, PHILIPS: 1.12%; residual amount for semisolid are Siemens: 47.36%, GE: 54.25%, PHILIPS: 51.57%; residual amount for solids are Siemens: 63.98%, GE: 66.88%, PHILIPS: 63.76%. All values are within the normal range. Then, we simulated the intestinal activity that interfered with the residual value obtained by 2D dynamic imaging: 75-90 min: 10.42, 19.48, 19.51 and 11.02%; however, the residual values obtained with 3D SPECT VOI data: 75-90 min: 1.42, 1.41, 1.35 and 1.02%. These results show that the emptying data errors caused by intestinal overlap can be effectively corrected (P = 0.017).
D-SPECT imaging can overcome the interference in the semiquantitative data of residual GE caused in 2D mode.
The increasing use of sensor-derived information from planned, ad-hoc, and/or opportunistically deployed sensor networks provides enhanced visibility to everyday activities and processes, enabling ...fast-paced data-to-decision in personal, social, civilian, military, and business contexts. The value that information brings to this visibility and ensuing decisions depends on the quality characteristics of the information gathered. In this article, we highlight, refine, and extend upon our past work in the areas of quality and value of information (QoI and VoI) for sensor networks. Specifically, we present and elaborate on our two-layer QoI/VoI definition, where the former relates to context-independent aspects and the latter to context-dependent aspects of an information product. Then, we refine our taxonomy of pertinent QoI and VoI attributes anchored around a simple ontological relationship between the two. Finally, we introduce a framework for scoring and ranking information products based on their VoI attributes using the analytic hierarchy multicriteria decision process, illustrated via a simple example.
In this paper, information theory is applied for probabilistic sensitivity analysis and surrogate modelling with active learning. One of the authors has recently proposed the adoption of the ...informational coefficient of correlation as a measure of dependence between random variables, in place of the largely adopted linear coefficient of correlation. Here, it is shown that the informational coefficient of correlation can be used for probabilistic sensitivity analysis based on the Value of Information (VoI). Effective Informational sensitivity indices based on the mutual information are presented. Moreover, two novel learning functions for adaptive sampling are proposed. The first, called H-function, gives rise to the method AK-H (Adaptive Kriging-Entropy), which describes the epistemic uncertainty through the entropy metric. The second, called MI-function, gives rise to the method AL-MI (Active Learning-Mutual Information), which describes the model error through the Mutual Information. The peculiarity of AL-MI is that it allows the implementation of active learning in any kind of surrogate modelling, even different from Kriging. The two learning functions are applied for two different categories of problems: (i) regression and (ii) evaluation of failure probability within the framework of structural reliability analysis. Numerical examples show its features and its potential for application of the proposed approach.
•A novel framework of Information theory for uncertainty quantification is proposed.•The framework is grounded on the informational coefficient of correlation.•Informational sensitivity indices based on the Value of Information (VoI) are proposed.•Learning functions based on entropy and mutual information are proposed.•Learning functions are applied for both regression and evaluation of failure probability.
COVID-19 is caused by SARS-CoV-2, several virulent variants of which have emerged since 2019. More than 529 million people have been infected, and at least 6 million have died. Our aim was to develop ...a fast, accurate, low-cost method for detecting and identifying newly emerging variants of concern (VOCs) that could pose a global threat. The 341-bp DNA sequence of a specific region of the SARS-CoV-2’s spike protein was amplified by a one-step PCR on RNA samples from 46 patients. The product was sequenced using next-generation sequencing (NGS). DNA sequences from seven genomes, the original Wuhan isolate and six different representative variants obtained from the GISAID website, were used as references. Complete whole-genome sequences from local isolates were also obtained from the GISAID website, and their RNA was used for comparison. We used an amplicon-based NGS method (termed VOC-NGS) for genotyping and successfully identified all 46 samples. Fifteen (32.6%) were like the original isolate. Twenty-seven were VOCs: nine (19.5%) Alpha, eight (19%) Delta, six (14%) Beta, and four (8.7%) Omicron. Two were variants of interest (VOI): one (2%) Kappa and one (2%) Zeta. Two samples were mixtures of two variants, one of Alpha and Beta and one of Alpha and Delta. The Spearman correlation between whole-genome sequencing (WGS) and VOC-NGS was significant (P < 0.001) with perfect agreement (Kappa = 0.916) for 36/38 (94.7%) samples with VOC-NGS detecting all the known VOCs. Genotyping by VOC-NGS enables rapid screening of high-throughput clinical samples that includes the identification of VOCs and mixtures of variants, at lower cost than WGS. IMPORTANCE The manuscript described SARS-Cov-2 genotyping by VOC-NGS, which presents an ideal balance of accuracy, rapidity, and cost for detecting and globally tracking VOCs and some VOI of SARS-CoV-2. A large number of clinical samples can be tested together. Rapid introduction of new mutations at a specific site of the spike protein necessitates efficient strain detection and identification to enable choice of treatment and the application of vaccination, as well as planning public health policy.
The extrusion tectonic model for the southeastern margin of the Himalayan orogeny links the crustal shear activity along the Red River Shear Zone (RRSZ) to the opening of the South China Sea (SCS). ...The Day Nui Con Voi (DNCV) metamorphic massif in northern Vietnam strikes NW-SE, is bounded by the RRSZ to the south and continues along the strike where it meets the SCS. The DNCV is thus a critical area to document thermotectonic history in order to advance our understanding of the tectonic evolution of Indochina extrusion and its relationship to the opening of the SCS. Our new
40
Ar/
39
Ar data combined with microstructural and petrological analyses constrained the timing of the left-lateral shearing of the RRSZ and revealed the thermal evolution of the DNCV metamorphic massif. Three ductile deformation events were observed. D
1
formed NNW-SSE striking upright folds under granulite to upper amphibolite facies conditions. D
2
was a horizontal to sub-horizontal folding event that occurred at amphibolite facies conditions. D
3
was a doming event that formed NW-SE striking up-right folds bounded by left-lateral shearing mylonite belts along the two limbs. The S/C fabrics were defined by muscovite fish, quartz + albite + K-feldspar aggregates, and muscovite folia. The D
3
doming event exhumed the DNCV metamorphic massif from amphibolite facies conditions to the lower greenschist facies conditions. The
40
Ar/
39
Ar ages obtained from amphibole (∼26 Ma), phlogopite (∼25 Ma), muscovites (∼24-23 Ma), biotite (∼25-23 Ma), and K-feldspars (∼25-22 Ma) from different structural domains of the DNCV metamorphic massif indicated a rapid exhumation ∼26–22 Ma. We interpreted this as the time period for the D
3
event, with the onset of left-lateral shearing occurring around 24 Ma based on ages obtained from syn-kinematic muscovites. This age was much younger than the initiation of sea-floor spreading of the SCS (since 32 Ma) but coincided with the age for the ridge jump event in the SCS. Based on these new data, we proposed that extrusion tectonism cannot be the cause for the initial opening of the SCS. Rather, the extrusion of the Indochina block was temporally correlative with the southward ridge jump event of the already opened SCS.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with increased transmissibility, virulence and immune escape abilities have heavily altered the COVID-19 pandemic’s course. ...Deciphering local and global transmission patterns of those variants is thus key in building a profound understanding of the virus’ spread around the globe. In the present study, we investigate SARS-CoV-2 variant epidemiology in Côte d’Ivoire, Western sub-Saharan Africa. We therefore generated 234 full SARS-CoV-2 genomes stemming from Central and Northern Côte d’Ivoire. Covering the first and second pandemic wave the country had been facing, we identified 20 viral lineages and showed that in Côte d’Ivoire the second pandemic wave in 2021 was driven by the spread of the Alpha (B.1.1.7) and Eta (B.1.525) variant. Our analyses are consistent with a limited number of international introductions of Alpha and Eta into Côte d’Ivoire, and those introduction events mostly stemmed from within the West African subregion. This suggests that subregional travel to Côte d’Ivoire had more impact on local pandemic waves than direct intercontinental travel.
PDF
