NASA’s Double Asteroid Redirection Test (DART) mission will impact its target asteroid, Dimorphos, at an oblique angle that will not be known prior to the impact. We computed iSALE-3D simulations of ...DART-like impacts on asteroid surfaces at different impact angles and found that the vertical momentum transfer efficiency, β, is similar for different impact angles, however, the imparted momentum is reduced as the impact angle decreases. It is expected that the momentum imparted from a 45∘ impact is reduced by up to 50% compared to a vertical impact. The direction of the ejected momentum is not normal to the surface, however it is observed to ‘straighten up’ with crater growth. iSALE-2D simulations of vertical impacts provide context for the iSALE-3D simulation results and show that the ejection angle varies with both target properties and with crater growth. While the ejection angle is relatively insensitive to the target porosity, it varies by up to 30∘ with target coefficient of internal friction. The simulation results presented in this paper can help constrain target properties from the DART crater ejecta cone, which will be imaged by the LICIACube. The results presented here represent the basis for an empirical scaling relationship for oblique impacts and can be used as a framework to determine an analytical approximation of the vertical component of the ejecta momentum, β−1, given known target properties.
•Ejection angle is sensitive to target properties and impact angle.•In vertical impacts the ejection angle can vary by up to 30∘ depending on target.•Different impact angles do not influence the vertical momentum transfer efficiency.•The imparted momentum is reduced with decreasing impact angle.•The direction of the total momentum vector ‘straightens up’ with crater growth.
Display omitted
•DART-MS, GC–MS, and LC-MS were used to analyze black pepper samples and their results were compared;•Chemometrics was applied to classify the black pepper samples based on their ...origins;•DART-MS has been demonstrated as a simple and high-throughput method for discrimination studies of food materials.
The current study applied gas chromatography-mass spectrometry (GC–MS), liquid chromatography-mass spectrometry (LC-MS), and thermal desorption direct analysis in real-time mass spectrometry (TD-DART-MS) methods to the analysis of black pepper (Piper nigrum L.) samples from different countries. The black pepper powder samples were analyzed directly by TD-DART-MS without any extraction, but for GC–MS and LC-MS methods, a methanol extraction procedure was employed before the analysis. Various compounds, such as piperamides and terpenes, were detected. Partial least squares-discriminant analysis (PLS-DA) was used to classify black pepper samples based on their origins. Total ion mass spectrum (TMS) data profiles from GC–MS, LC-MS, and TD-DART-MS methods were constructed and evaluated for the performance of classification. A cubic-root data transformation was tested in the data preprocessing and found to be effective for improving the classification rates. The average classification rates of PLS-DA models with GC–MS-cubic-root-TMS, LC-MS-cubic-root-TMS, and DART-MS-cubic-root-TMS data representations were 94.1 ± 0.6%, 87.7 ± 0.6%, and 97.0 ± 0.3% respectively, for 100-time bootstrapped-Latin-partition cross-validation. This study presents for the first time the analysis of plant-based food materials by using TD-DART-MS, and it has been demonstrated as a simple and high-throughput method for classification studies.
Deep-Ocean Measurements of Tsunami Waves Rabinovich, Alexander B.; Eblé, Marie C.
Pure and applied geophysics,
12/2015, Letnik:
172, Številka:
12
Journal Article
Recenzirano
Deep-ocean tsunami measurements play a major role in understanding the physics of tsunami wave generation and propagation, and in improving the effectiveness of tsunami warning systems. This paper ...provides an overview of the history of tsunami recording in the open ocean from the earliest days, approximately 50 years ago, to the present day. Modern tsunami monitoring systems such as the self-contained Deep-ocean Assessment and Reporting of Tsunamis and innovative cabled sensing networks, including, but not limited to, the Japanese bottom cable projects and the NEPTUNE-Canada geophysical bottom observatory, are highlighted. The specific peculiarities of seafloor longwave observations in the deep ocean are discussed and compared with observations recorded in coastal regions. Tsunami detection in bottom pressure observations is exemplified through analysis of distant (22,000 km from the source) records of the 2004 Sumatra tsunami in the northeastern Pacific.
Despite native whey (hereafter termed WHEY) being a watery by-product rich in high-value nutritional components, it poses environmental concerns. Recently, the techniques of thermal-mechanical ...microparticulation to produce microparticulated whey (MPW) and a further process to ferment MPW (FMPW) were suggested, in order to recycle whey into a protein concentrated soft dairy cream that acquires also fat mimicking functionality. Aiming at monitoring the effects of this recycling process on the products’ metabolic profiles, samples (n = 8) of WHEY, MPW and two sub-types of FMPW were analysed by combining direct analysis in real time coupled with high resolution mass spectrometry (DART-HRMS). The most informative ions were used to build a partial least squared discriminant analysis (PLS-DA) model to assess the biochemical compounds that characterize and differentiate WHEY from MPW and FMPW. The DART-HRMS fingerprints acquired in negative mode accurately differentiated samples throughout the steps of microparticulation and fermentation. Post-fermentation, greater relative abundances of lactic acid, glucosamine and histidyl-aspartic acid were detected in both subtypes of FMPW, which were moderately differentiated by DART-HRMS. Moreover, while WHEY and MPW contained high relative abundances of hydroxyglutaric and malic acids, the fermented derivates (FMPW) were characterised by elevated levels of volatile compounds (tetradecanal, hexadecene and tetradecene) and fermentative end-products (diethyltartrate and histidyl-aspartic acid). DART-HRMS successfully captured a pool of informative biomarkers useful to understand the chemical and metabolomic changes occurring in microparticulation and fermentation processes used to recycle whey. This analytical technique is an operative supporting step needed for comprehensive assessment of the nutritional and organoleptic properties of the proposed whey-based soft cream dairy food.
•Epigenetic changes play an important role in the adaptation response of forest trees.•Eucalyptus is a robust system to track epigenetic changes in response to environment.•Site-specific DNA ...methylation changes were identified for each of five eucalypt clones.•No consistently shared epigenetic marks were found for all clones across environments.•Results showed that the observed epigenetic variation is mainly genotype dependent.
Phenotypic plasticity refers to the ability of a single genotype to express distinct phenotypes in response to the environment, a crucial feature for sessile organisms like forest trees, especially in a scenario of global climate change. Several studies show that epigenetic regulation plays an important role in this plastic adaptation response, driving the search for associations between natural epigenetic variation with environmental cues and phenotypic traits based on patterns of cytosine methylation. Clonally propagated trees across variable sites offer a robust system to control for the confounding effect of the background genetic variation among genotypes, allowing the analysis of epigenetic modifications in response to variable environments. In this study we investigated the overall patterns of epigenetic changes by the analysis of the genome-wide DNA methylation status based on high throughput MS-DArT-seq (Methyl Sensitive DArT-seq sequencing) of reduced genome complexity representations. We compared patterns of DNA methylation of biological replicates of leaf and xylem tissue samples of four commercially planted elite Eucalyptus grandis × Eucalyptus urophylla clones and one Eucalyptus urophylla in two contrasting sites in Brazil, and the association of these methylation patterns with the environments and growth traits. DNA sequence reads were mapped against the Eucalyptus grandis reference genome, counting and annotating differentially methylated sites. A total of 90,378 MS-DArT-seq sites were identified, the majority (~70%) located in genes and 10% in transposable elements. The distribution of methylation sites showed extensive variation between the five genotypes and the environments. Sets of methylation sites exclusive to each location were identified for each clone but no consistently shared epigenetic marks for all five clones were found across environments. Multiple correspondence analysis suggests a significant contribution of the genetic background on the distribution of methylation changes. We used a gene-environment association analysis to search for association of methylation patterns with growth traits. A total of 445 methylation sites across all 11 Eucalyptus chromosomes were found significantly associated with one or more of the three measured traits (total height, estimated volume and breast high diameter). The absence of clustered differentially methylated sites is consistent with the fact that complex growth traits are governed by a large number of loci of small effect across the entire genome suggesting that this same pattern will likely hold for what regards epigenetic marks.
Fast Antenna Lightning Mapping Array (FALMA), a low‐frequency lightning mapping system comprising an array of fast antennas, was developed and established in Gifu, Japan, during the summer of 2017. ...Location results of two hybrid flashes and a cloud‐to‐ground flash comprising 11 return strokes (RSs) are described in detail in this paper. Results show that concurrent branches of stepped leaders can be readily resolved, and K changes and dart leaders with speeds up to 2.4 × 107 m/s are also well imaged. These results demonstrate that FALMA can reconstruct three‐dimensional structures of lightning flashes with great details. Location accuracy of FALMA is estimated by comparing the located striking points of successive RSs in cloud‐to‐ground flashes. Results show that distances between successive RSs are mainly below 25 m, indicating exceptionally high location accuracy of FALMA.
Plain Language Summary
We have developed a lightning mapping system called Fast Antenna Lightning Mapping Array (FALMA). FALMA detects low‐frequency radio waves produced by lightning discharges at multiple sites and can reconstruct 3‐D structures of lightning flashes. Three lightning flashes are analyzed in detail in this paper, and animations of seven cases are provided in the supporting information. These results demonstrate that FALMA can show development of lightning discharges in great details and accuracy. Types and polarities of lightning discharges can also be determined by the recorded electric field change waveforms. FALMA is expected to become a unique tool for lightning and thunderstorm researches. Research studies of several topics are already underway based on the observation data in the summer of 2017.
Key Points
Lightning 3‐D mapping with high accuracy and great details has been realized by the Fast Antenna Lightning Mapping Array (FALMA)
Stepped leaders with multiple branches, K changes, and dart leaders with speeds up to 2.4 × 107 m/s are well imaged
Horizontal location accuracy is estimated to be around 20 m by comparing locations of successive return strokes in CG flashes
Unmanned aerial vehicle (UAV) swarms have become a promising solution to enhance modern wireless communication in complicated environments. However, due to the existence of real-world malicious ...attacks, the performance of prediction and optimisation methods used for UAV swarms are easily degraded. In this paper, we propose a novel deep learning-based user mobility prediction, user assignment and drone position optimisation scheme for a UAV swarm-enabled wireless communication system in the presence of malicious Global Navigation Satellite System (GNSS) spoofing attackers. Specifically, a robust deep learning-based user mobility prediction model, namely denoising autoencoder recurrent transformer (DART), is designed. Additionally, two efficient user assignment and drone position optimisation methods are proposed. The proposed deep learning model forecasts user locations, on which we construct and solve assignment and position optimisation problems. Simulation results show that the proposed deep learning-based prediction-optimisation scheme can provide up to 30% higher overall sum rate compared with the adversarially trained long short-term memory (LSTM) baseline and almost double the overall sum rate compared with the vanilla LSTM baseline.
After the first and second return strokes (RSs) of a multi-branch triggered lightning flash, the M component of two different initiation mechanisms burned: (1) Upward leader (UL)-M component, (2) ...Downward leader (DL)-M component. The UL-M component burned immediately after the RS (about 0.5 ms after the RS). At this time, an UL developing to the cloud generated outside the main channel of the continuous current (CC). With the development of the UL, the M component is formed in the CC channel. The obvious DL process can be observed during DL-M component. The speed of DL is about 2 × 107 m/s, when DL was intercepted by CC channel, M component will generate. The current peak and electric field peak of the UL-M component were larger than those of the DL-M component. It was worth noting that the M component formed by the UL slightly developing to the ground at the head of it did not produce an electric field change at the observation point 2 (1550 m horizontally from the rocket triggered lightning point), which was a result of the combined effect of the positive charge in the branch head and the negative charge in the main channel at the same height. The reflection phenomenon of the M component was also observed in a DL-M component process. The CC in the channel after the RS plays a key role in the formation of the M component. It forms the M component by intercepting the current wave transmitted to the ground from the cloud or the lightning branch.
•High-speed camera data shows the M component of two different mechanisms: (1) Upward leader -M component, (2) Downward leader -M component.•Continuous current channel intercepts the charge to form M component.•The current peak and electric field peak of the UL-M component were larger than those of the DL-M component.
Economically motivated adulteration (EMA) of herbs and spices is very frequent and a major cause of concern to consumers, manufacturers and legislators. Rapid, non-targeted methods capable of ...distinguishing authentic herbs from those mixed with low cost materials are desirable. To this aim, ambient mass spectrometry (AMS) was applied to authenticate dried oregano leaves. Authentic and adulterated oregano samples were submitted to two extraction procedures and analysed in positive and negative ion modes by direct analysis in real time-high resolution mass spectrometry (DART-HRMS). Mid-level data fusion of the four blocks of DART-HRMS data was performed, and the resultant unique dataset was submitted to supervised statistical analysis to ascertain the signals that discriminate authentic from adulterated oregano. The fourteen most informative signals of authenticity were tentatively assigned and validated by support vector machine (SVM). In the final model, accuracy, sensitivity and specificity of >90% were obtained. Independent authentic and adulterated oregano samples were used to validate the discriminative m/z values and evaluate the classification capability of the model. To the best of our knowledge this is the first application of AMS coupled to mid-level data fusion for oregano authentication.
Display omitted
•DART-HRMS can quickly and reliably screen for adulterated oregano.•A mid-level data fusion of DART-HRMS data was performed.•A classification model was built based on merged DART-HRMS data.•Validation of the classification model was successful.•High accuracy, sensitivity and specificity of the method were achieved.
PDF
