bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidemiological Trends of Five Common Diarrhea-Associated Enteric Viruses Pre- and Post-Rotavirus Vaccine Introduction in Coastal Kenya
Authors: Lambisia Arnold W. , Onchaga Sylvia , Murunga Nickson , Lewa Clement S. , Nyanjom Steven Ger , Agoti Charles N.
Published: August 2020

Using real-time RT-PCR, we screened stool samples from children aged <5 years presenting with diarrhea and admitted to Kilifi County Hospital, coastal Kenya, pre- (2003 and 2013) and post-rotavirus vaccine introduction (2016 and 2019) for five viruses, namely rotavirus group A (RVA), norovirus GII, adenovirus, astrovirus and sapovirus. Of the 984 samples analyzed, at least one virus was detected in 401 (40.8%) patients. Post rotavirus vaccine introduction, the prevalence of RVA decreased (23.3% vs. 13.8%, p < 0.001) while that of norovirus GII increased (6.6% vs. 10.9%, p = 0.023). The prevalence of adenovirus, astrovirus and sapovirus remained statistically unchanged between the two periods: 9.9% vs. 14.2%, 2.4% vs. 3.2 %, 4.6% vs. 2.6%, (p = 0.053, 0.585 and 0.133), respectively. The median age of diarrhea cases was higher post vaccine introduction (12.5 months, interquartile range (IQR): 7.9–21 vs. 11.2 months pre-introduction, IQR: 6.8–16.5, p < 0.001). In this setting, RVA and adenovirus cases peaked in the dry months while norovirus GII and sapovirus peaked in the rainy season. Astrovirus did not display clear seasonality. In conclusion, following rotavirus vaccine introduction, we found a significant reduction in the prevalence of RVA in coastal Kenya but an increase in norovirus GII prevalence in hospitalized children.
Comparative Pathology of Domestic Pigs and Wild Boar Infected with the Moderately Virulent African Swine Fever Virus Strain “Estonia 2014”
Authors: Sehl Julia , Pikalo Jutta , Schäfer Alexander , Franzke Kati , Pannhorst Katrin , Elnagar Ahmed , Blohm Ulrike , Blome Sandra , Breithaupt Angele
Published: August 2020

Endemically infected European wild boar are considered a major reservoir of African swine fever virus in Europe. While high lethality was observed in the majority of field cases, strains of moderate virulence occurred in the Baltic States. One of these, “Estonia 2014”, led to a higher number of clinically healthy, antibody-positive animals in the hunting bag of North-Eastern Estonia. Experimental characterization showed high virulence in wild boar but moderate virulence in domestic pigs. Putative pathogenic differences between wild boar and domestic pigs are unresolved and comparative pathological studies are limited. We here report on a kinetic experiment in both subspecies. Three animals each were euthanized at 4, 7, and 10 days post infection (dpi). Clinical data confirmed higher virulence in wild boar although macroscopy and viral genome load in blood and tissues were comparable in both subspecies. The percentage of viral antigen positive myeloid cells tested by flow cytometry did not differ significantly in most tissues. Only immunohistochemistry revealed consistently higher viral antigen loads in wild boar tissues in particular 7 dpi, whereas domestic pigs already eliminated the virus. The moderate virulence in domestic pigs could be explained by a more effective viral clearance.
Avermectin Derivatives, Pharmacokinetics, Therapeutic and Toxic Dosages, Mechanism of Action, and Their Biological Effects
Authors: El-Saber Batiha Gaber , Alqahtani Ali , Ilesanmi Omotayo B. , Saati Abdullah A. , El-Mleeh Amany , Hetta Helal F. , Magdy Beshbishy Amany
Published: August 2020

Avermectins are a group of drugs that occurs naturally as a product of fermenting Streptomyces avermitilis, an actinomycetes, isolated from the soil. Eight different structures, including ivermectin, abamectin, doramectin, eprinomectin, moxidectin, and selamectin, were isolated and divided into four major components (A1a, A2a, B1a and B2a) and four minor components (A1b, A2b, B1b, and B2b). Avermectins are generally used as a pesticide for the treatment of pests and parasitic worms as a result of their anthelmintic and insecticidal properties. Additionally, they possess anticancer, anti-diabetic, antiviral, antifungal, and are used for treatment of several metabolic disorders. Avermectin generally works by preventing the transmission of electrical impulse in the muscle and nerves of invertebrates, by amplifying the glutamate effects on the invertebrates-specific gated chloride channel. Avermectin has unwanted effects or reactions, especially when administered indiscriminately, which include respiratory failure, hypotension, and coma. The current review examines the mechanism of actions, biosynthesis, safety, pharmacokinetics, biological toxicity and activities of avermectins.
New Insights into the Stereochemical Requirements of the Bombesin BB1 Receptor Antagonists Binding
Authors: Rasaeifar Bahareh , Gomez-Gutierrez Patricia , Perez Juan J.
Published: August 2020

Members of the family of bombesinlike peptides exert a wide range of biological activities both at the central nervous system and in peripheral tissues through at least three G-Protein Coupled Receptors: BB1, BB2 and BB3. Despite the number of peptide ligands already described, only a few small molecule binders have been disclosed so far, hampering a deeper understanding of their pharmacology. In order to have a deeper understanding of the stereochemical features characterizing binding to the BB1 receptor, we performed the molecular modeling study consisting of the construction of a 3D model of the receptor by homology modeling followed by a docking study of the peptoids PD168368 and PD176252 onto it. Analysis of the complexes permitted us to propose prospective bound conformations of the compounds, consistent with the experimental information available. Subsequently, we defined a pharmacophore describing minimal stereochemical requirements for binding to the BB1 receptor that was used in silico screening. This exercise yielded a set of small molecules that were purchased and tested, showing affinity to the BB1 but not to the BB2 receptor. These molecules exhibit scaffolds of diverse chemical families that can be used as a starting point for the development of novel BB1 antagonists.
Compatible Stability and Aerosol Characteristics of Atrovent® (Ipratropium Bromide) Mixed with Salbutamol Sulfate, Terbutaline Sulfate, Budesonide, and Acetylcysteine
Authors: Chen Yiting , Du Shilin , Zhang Zhirui , He Wenxiu , Lu Enhao , Wang Rui , Sha Xianyi , Ma Yan
Published: August 2020

(1) Background: It is common practice in the treatment of respiratory diseases to mix different inhalation solutions for simultaneous inhalation. At present, a small number of studies have been published that evaluate the physicochemical compatibility and aerosol characteristics of different inhalation medications. However, none of them studied Atrovent®. Our work aims to address the lack of studies on Atrovent®. (2) Methods: Portions of admixtures were withdrawn at certain time intervals after mixing and were tested by pH determination, osmolarity measurement, and high-performance liquid chromatography (HPLC) assay of each active ingredient as measures of physicochemical compatibility. The geometrical and aerosol particle size distribution, active drug delivery rate, and total active drug delivered were measured to characterize aerosol behaviors. (3) Results: During the testing time, no significant variation was found in the pH value, the osmotic pressure, or the active components of admixtures. With the increase in nebulization volume after mixing, fine particle dose (FPD) and total active drug delivered showed statistically significant improvements, while the active drug delivery rate decreased compared to the single-drug preparations. (4) Conclusions: These results endorse the physicochemical compatibility of Atrovent® over 1 h when mixed with other inhalation medications. Considering aerosol characteristics, simultaneous inhalation is more efficient.
Combination Delivery of Alpha-Tocopheryl Succinate and Curcumin Using a GSH-Sensitive Micelle (PAH-SS-PLGA) to Treat Pancreatic Cancer
Authors: Debele Tilahun Ayane , Wu Hung-Chang , Wu Shang-Rung , Shan Yan-Shen , Su Wen-Pin
Published: August 2020

Pancreatic cancer is one of the highest causes of mortality throughout the world; thus, it requires an effective treatment strategy. Some chemotherapeutic agents used in the clinics or under clinical trials are hydrophobic and have poor aqueous solubility; consequently, they also have minimal systemic bioavailability. Nanoparticle-based drug delivery tactics have the potential for overcoming these limitations and enhancing their therapeutic efficacy. Herein, a glutathione (GSH)-sensitive micelle (PAH-SS-PLGA) was synthesized for the combined delivery of alpha-tocopheryl succinate (TOS) and curcumin to improve its therapeutic efficacy. The chemical structures of PAH-SS-PLGA were analyzed using Proton Nuclear Magnetic Resonance (1H-NMR) and Fourier Transform Infrared (FTIR) spectroscopy, whereas the particle size, zeta potential, and surface morphology were observed using dynamic light scattering (DLS) and transmission electron microscopy (TEM). In vitro drug release results revealed that more TOS and curcumin were released in the presence of GSH (5 mM) than the physiological pH value. Fluorescence microscopy images revealed that nanoformulated curcumin/rhodamine was uptaken by PAN02 pancreatic cancer cells. In vitro cytotoxicity assays showed higher cytotoxicity for nanoformulated TOS and/or curcumin than free TOS and/or curcumin. In addition, higher cytotoxicity was observed for combination drugs than free drugs alone. Most interestingly, at all tested concentrations of nanoformulated drugs (PAH-SS-PLGA, TOS, and curcumin), the calculated combination index (CI) value was less than one, which shows that TOS and curcumin have a synergistic effect on cellular proliferation inhibition. Overall, synthesized co-polymers are the best carriers for combination drugs, TOS, and curcumin, because they enhance the therapeutic efficacy and improve pancreatic cancer treatments.
Hot-Melt Extrusion as an Advantageous Technology to Obtain Effervescent Drug Products
Authors: Lima Ana Luiza , Pinho Ludmila A. G. , Chaker Juliano A. , Sa-Barreto Livia L. , Marreto Ricardo Neves , Gratieri Tais , Gelfuso Guilherme M. , Cunha-Filho Marcilio
Published: August 2020

Here, we assessed the feasibility of hot-melt extrusion (HME) to obtain effervescent drug products for the first time. For this, a combined mixture design was employed using paracetamol as a model drug. Extrudates were obtained under reduced torque (up to 0.3 Nm) at 100 °C to preserve the stability of the effervescent salts. Formulations showed vigorous and rapid effervescent disintegration (<3 min), adequate flow characteristics, and complete solubilization of paracetamol instantly after the effervescent reaction. Formulations containing PVPVA in the concentration range of 15–20% m/m were demonstrated to be sensitive to accelerated aging conditions, undergoing marked microstructural changes, since the capture of water led to the agglomeration and loss of their functional characteristics. HPMC matrices, in contrast, proved to be resistant to storage conditions in high relative humidity, showing superior performance to controls, including the commercial product. Moreover, the combined mixture design allowed us to identify significant interactions between the polymeric materials and the disintegrating agents, showing the formulation regions in which the responses are kept within the required levels. In conclusion, this study demonstrates that HME can bring important benefits to the elaboration of effervescent drug products, simplifying the production process and obtaining formulations with improved characteristics, such as faster disintegration, higher drug solubilization, and better stability.
Uniting Drug and Delivery: Metal Oxide Hybrid Nanotherapeutics for Skin Wound Care
Authors: Matter Martin , Probst Sebastian , Läuchli Severin , Herrmann Inge
Published: August 2020

Wound care and soft tissue repair have been a major human concern for millennia. Despite considerable advancements in standards of living and medical abilities, difficult-to-heal wounds remain a major burden for patients, clinicians and the healthcare system alike. Due to an aging population, the rise in chronic diseases such as vascular disease and diabetes, and the increased incidence of antibiotic resistance, the problem is set to worsen. The global wound care market is constantly evolving and expanding, and has yielded a plethora of potential solutions to treat poorly healing wounds. In ancient times, before such a market existed, metals and their ions were frequently used in wound care. In combination with plant extracts, they were used to accelerate the healing of burns, cuts and combat wounds. With the rise of organic chemistry and small molecule drugs and ointments, researchers lost their interest in inorganic materials. Only recently, the advent of nano-engineering has given us a toolbox to develop inorganic materials on a length-scale that is relevant to wound healing processes. The robustness of synthesis, as well as the stability and versatility of inorganic nanotherapeutics gives them potential advantages over small molecule drugs. Both bottom-up and top-down approaches have yielded functional inorganic nanomaterials, some of which unite the wound healing properties of two or more materials. Furthermore, these nanomaterials do not only serve as the active agent, but also as the delivery vehicle, and sometimes as a scaffold. This review article provides an overview of inorganic hybrid nanotherapeutics with promising properties for the wound care field. These therapeutics include combinations of different metals, metal oxides and metal ions. Their production, mechanism of action and applicability will be discussed in comparison to conventional wound healing products.
Off-Axis Vortex Beam Propagation through Classical Optical System in Terms of Kummer Confluent Hypergeometric Function
Authors: Augustyniak Ireneusz , Lamperska Weronika , Masajada Jan , Płociniczak Łukasz , Popiołek-Masajada Agnieszka
Published: August 2020

The analytical solution for the propagation of the laser beam with optical vortex through the system of lenses is presented. The optical vortex is introduced into the laser beam (described as Gaussian beam) by spiral phase plate. The solution is general as it holds for the optical vortex of any integer topological charge, the off-axis position of the spiral phase plate and any number of lenses. Some intriguing conclusions are discussed. The higher order vortices are unstable and split under small phase or amplitude disturbance. Nevertheless, we have shown that off-axis higher order vortices are stable during the propagation through the set of lenses described in paraxial approximation, which is untypical behavior. The vortex trajectory registered at image plane due to spiral phase plate shift behaves like a rigid body. We have introduced a new factor which in our beam plays the same role as Gouy phase in pure Gaussian beam.
The Role of Grafting in the Resistance of Tomato to Viruses
Authors: Spanò Roberta , Ferrara Massimo , Gallitelli Donato , Mascia Tiziana
Published: August 2020

Grafting is routinely implemented in modern agriculture to manage soilborne pathogens such as fungi, oomycetes, bacteria, and viruses of solanaceous crops in a sustainable and environmentally friendly approach. Some rootstock/scion combinations use specific genetic resistance mechanisms to impact also some foliar and airborne pathogens, including arthropod or contact-transmitted viruses. These approaches resulted in poor efficiency in the management of plant viruses with superior virulence such as the strains of tomato spotted wilt virus breaking the Sw5 resistance, strains of cucumber mosaic virus carrying necrogenic satellite RNAs, and necrogenic strains of potato virus Y. Three different studies from our lab documented that suitable levels of resistance/tolerance can be obtained by grafting commercial tomato varieties onto the tomato ecotype Manduria (Ma) rescued in the framework of an Apulian (southern Italy) regional program on biodiversity. Here we review the main approaches, methods, and results of the three case studies and propose some mechanisms leading to the tolerance/resistance observed in susceptible tomato varieties grafted onto Ma as well as in self-grafted plants. The proposed mechanisms include virus movement in plants, RNA interference, genes involved in graft wound response, resilience, and tolerance to virus infection.
In-Situ Deposition of Metal Oxides Nanoparticles in Cellulose Derivative and Its Utilization for Wastewater Disinfection
Authors: Gouda Mohamed , Al-Bokheet Wedad , Al-Omair Mohamed
Published: August 2020

The target of this work is to investigate and assess the utilization of the synthesized in-situ deposition of metal oxide nanoparticles such as nano-nickel oxide (nNiO), nanocopper oxides (nCuO) and nanoiron oxides (nFe3O4) in aminated cellulose (Acell), as a protected and compelling antibacterial channel of contamination from domestic wastewater. The prepared Acell and nNiO/Acell, nCuO/Acell and nFe3O4/Acell nanocomposites were characterized by field emission-scanning electron microscopy (FE-SEM), Fourier transform-infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), selected area diffraction pattern (SAED) and X-ray diffraction techniques (XRD). TEM declared the synthesis of nNiO, nCuO and nFe3O4 with regular size of 10, 23 and 43 nm, correspondingly. The antibacterial impact of both nNiO/Acell, nCuO/Acell and nFe3O4/Acell nanocomposites was inspected against Gram-positive microorganisms (Enterococcus faecalis, Staphylococcus aureus) and Gram-negative microbes (Escherichia coli, Salmonella typhi) utilizing agar disk diffusion routes. Furthermore, the ability of the synthesized nanocomposites as sterilizers for optional domestic wastewater was studied. The data for the disk diffusion obtained revealed that nFe3O4/Acell had a greater antibacterial impact than nCuO/Acell and nNiO/Acell. In addition, the purification of domestic wastewater utilizing 1.0 mg of nFe3O4, nCuO and nNiO in 1 gm of Acell was accomplished by killing 99.6%, 94.5% and 92.0% of total and fecal coliforms inside 10 mins, respectively.
Composites and Copolymers Containing Redox-Active Molecules and Intrinsically Conducting Polymers as Active Masses for Supercapacitor Electrodes—An Introduction
Authors: Holze Rudolf
Published: August 2020

In this introductory report, composites and copolymers combining intrinsically conducting polymers and redox-active organic molecules, suggested as active masses without additional binder and conducting agents for supercapacitor electrodes, possibly using the advantageous properties of both constituents, are presented. A brief overview of the few reported examples of the use of such copolymers, composites, and comparable combinations of organic molecules and carbon supports is given. For comparison a few related reports on similar materials without intrinsically conducting polymers are included.
The Effect of Wettability and Flow Rate on Oil Displacement Using Polymer-Coated Silica Nanoparticles: A Microfluidic Study
Authors: Omran Mohamed , Akarri Salem , Torsaeter Ole
Published: August 2020

Polymer-coated silica nanoparticles (PSiNPs) have been experimentally investigated in core- and micro-scale studies for enhanced oil recovery (EOR). Wettability and flow rate have a considerable effect on oil displacement in porous media. This work investigates the efficiency of PSiNPs for oil recovery on micro-scale at three wettability states (water-wet, intermediate-wet, and oil-wet). In addition, a cluster mobilization regime is considered in all experiments. A microfluidic approach was utilized to perform flooding experiments with constant experimental settings such as flowrate, pore-structure, initial oil topology, porosity, and permeability. In this study, the wettability of the microfluidic chips was altered to have three states of wettability. Firstly, a micro-scale study (brine-oil-glass system) of each wettability condition effect on flow behavior was conducted via monitoring dynamic changes in the oleic phase. Secondly, the obtained results were used as a basis to understand the changes induced by the PSiNPs while flooding at the same conditions. The experimental data were extracted by means of image processing and analysis at a high spatial and temporal resolution. Low injection rate experiments (corresponding to ~1.26 m/day in reservoir) in a brine-oil-glass system showed that the waterflood invaded with a more stable front with a slower displacement velocity in the water-wet state compared to the other states, which had water channeling through the big pores. As a result, a faster stop of the dynamic changes for the intermediate- and oil-wet state was observed, leading to lower oil recoveries compared to the water-wet state. In a cluster mobilization regime, dynamic changes were noticeable only for the oil-wet condition. For the aforementioned different conditions, PSiNPs improved oil displacement efficiency. The usage of PSiNPs showed a better clusterization efficiency, leading to a higher mobilization, smaller remaining oil clusters, and lower connectivity of the residual oil. The knowledge from this experimental work adds to the understanding of the behavior of polymer-coated silica nanoparticles as a recovery agent at different wettability states and a cluster mobilization regime.
Experimental and Numerical Investigation on Improved Design for Profiled Freezing-tube of FSPR
Authors: Duan Yin , Rong Chuanxin , Cheng Hua , Cai Haibing , Wang Zongjin , Yao Zhishu
Published: August 2020

The freeze-sealing pipe roof (FSPR) method, which combines the pipe roof method (PRM) with the artificial ground freezing (AGF) method, has been successfully utilized for the first time in the Gongbei Tunnel Project in China. During the construction process, there have been practical problems such as difficulty in welding of the profiled freezing-tube, easy leakage of refrigerant, and working environment pollution, which bring difficulties to the tunnel construction and may affect the further promotion of this new method in the future. To address these problems, a method of placing double circular freezing-tubes on the inner wall of the hollow pipe and wrapped with cement mortar was put forward to replace the welding profiled freezing-tube in the actual project. By designing a scaled model test, the feasibility and freezing effect of this improved design were verified. The corresponding numerical calculation model was established to study the distribution characteristics and differences of temperature field under two different configurations. The research results show that the Configuration 2, with the improved design, presents a lower temperature and a higher cooling rate; the limiting-tube could limit the excessive development of the frozen soil wall within a certain range, to avoid the adverse impact of frost heave on the ground building structure. Under the premise of meeting the design requirements for freezing, the freezing time of Configuration 2 at the centerline between the pipes and the vertical line of the hollow pipe is 33% and 46% shorter than that of Configuration 1, respectively. Finally, the average thickness of the frozen soil wall at the right side of the hollow pipe, the vertical direction of the hollow pipe, and between the pipes increased 33%, 17%, and 13% in Configuration 2, respectively. The improved design proposed in this paper is not only more convenient in production and installation but is also demonstrated to provide improved freezing effects, providing a strong guarantee for the further popularization and application of the freeze-sealing pipe roof method.
Evaluation of the Turbulence Model Influence on the Numerical Simulation of Cavitating Flow with Emphasis on Temperature Effect
Authors: Deng Yilin , Feng Jian , Wan Fulai , Shen Xi , Xu Bin
Published: August 2020

The aim of this paper is to investigate the influence of different turbulence models (k−ε, RNG k−ε, and SST k−ω) on the numerical simulation of cavitating flow in thermosensitive fluid. The filter-based model and density correction method were employed to correct the turbulent viscosity of the three turbulence models. Numerical results obtained were compared to experimental ones which were conducted on the NACA0015 hydrofoil at different temperatures. The applicability of the numerical solutions of different turbulence model was studied in detail. The modified RNG k−ε model has higher accuracy in the calculation of cavitating flow at different temperatures.
Determination of a Bubble Drag Coefficient during the Formation of Single Gas Bubble in Upward Coflowing Liquid
Authors: Luty Przemysław , Prończuk Mateusz
Published: August 2020

Bubble flow is present in many processes that are the subject of chemical engineering research. Many correlations for determination of the equivalent bubble diameter can be found in the scientific literature. However, there are only few describing the formation of gas bubbles in flowing liquid. Such a phenomenon occurs for instance in airlift apparatuses. Liquid flowing around the gas bubble creates a hydraulic drag force that leads to reduction of the formed bubble diameter. Usually the value of the hydraulic drag coefficient, cD, for bubble formation in the flowing liquid is assumed to be equal to the drag coefficient for bubbles rising in the stagnant liquid, which is far from the reality. Therefore, in this study, to determine the value of the drag coefficient of bubbles forming in flowing liquid, the diameter of the bubbles formed at different liquid velocity was measured using the shadowgraphy method. Using the balance of forces affecting the bubble formed in the coflowing liquid, the hydraulic drag coefficient was determined. The obtained values of the drag coefficient differed significantly from those calculated using the correlation for gas bubble rising in stagnant liquid. The proposed correlation allowed the determination of the diameter of the gas bubble with satisfactory accuracy.
Earth Observation for Settlement Mapping of Amazonian Indigenous Populations to Support SDG7
Authors: Muro Javier , Zurita-Arthos Leo , Jara José , Calderón Esteban , Resl Richard , Rienow Andreas , Graw Valerie
Published: August 2020

Indigenous communities in the Amazon suffer from lack of access to basic services, such as electricity. Due to their isolation and difficult access it is challenging to acquire data on their location, numbers and needs, which would enable adequate development plans. Earth observation (EO), in combination with participatory mapping can support the creation of settlement maps as a basis for creating spatially explicit models of needs of basic services. Combining Landsat time series with SkySat and PlanetScope imagery, we have mapped the location and size of these settlements and modelled the number and densities of their houses. Additionally, we have projected settlement growth by 2030 in order to assess a demand of services that will be valid in the near future. We conducted surveys in 49 communities in the Ecuadorian Amazon to acquire information on the peoples’ living conditions and needs, and validated our model based on the findings. The number of buildings per cleared land had a strong linear relationship with the communities surveyed (adjusted R2 0.8). We used this linear relationship to model the number of buildings for the complete study area as well as for the 2030 settlement projection. Combining this information with data on the living conditions of indigenous communities, we can efficiently estimate the needs of basic services for larger territories and prompt development plans according to indigenous peoples’ needs and wishes.
SAR Image Despeckling by Deep Neural Networks: from a Pre-Trained Model to an End-to-End Training Strategy
Authors: Dalsasso Emanuele , Yang Xiangli , Denis Loïc , Tupin Florence , Yang Wen
Published: August 2020

Speckle reduction is a longstanding topic in synthetic aperture radar (SAR) images. Many different schemes have been proposed for the restoration of intensity SAR images. Among the different possible approaches, methods based on convolutional neural networks (CNNs) have recently shown to reach state-of-the-art performance for SAR image restoration. CNN training requires good training data: many pairs of speckle-free/speckle-corrupted images. This is an issue in SAR applications, given the inherent scarcity of speckle-free images. To handle this problem, this paper analyzes different strategies one can adopt, depending on the speckle removal task one wishes to perform and the availability of multitemporal stacks of SAR data. The first strategy applies a CNN model, trained to remove additive white Gaussian noise from natural images, to a recently proposed SAR speckle removal framework: MuLoG (MUlti-channel LOgarithm with Gaussian denoising). No training on SAR images is performed, the network is readily applied to speckle reduction tasks. The second strategy considers a novel approach to construct a reliable dataset of speckle-free SAR images necessary to train a CNN model. Finally, a hybrid approach is also analyzed: the CNN used to remove additive white Gaussian noise is trained on speckle-free SAR images. The proposed methods are compared to other state-of-the-art speckle removal filters, to evaluate the quality of denoising and to discuss the pros and cons of the different strategies. Along with the paper, we make available the weights of the trained network to allow its usage by other researchers.
Detection of Thermal Changes Related to the 2011 Shinmoedake Volcano Activity, Japan: Spatiotemporal Variation of Singularity of MODIS Data after Discriminating False Changes Due to Cloud
Authors: Tsutsumi Rika , Hattori Katsumi , Yoshino Chie , Genzano Nicola
Published: August 2020

We proposed a cloud discrimination method applicable in Japan using MODIS nighttime data, monitored the singularity of the spatiotemporal correlation of surface temperature anomalies and investigated the possibility of detecting and monitoring lava activity in Shinmoedake. With the aim to detect lava eruption activity in 2011, nine years of data from 2003 to 2011 were analyzed. As a result, the first anomalous singularity in brightness temperature was detected on 26 January 2011. Moreover, the maximum value was detected on 30 January 2011. The values showed larger ones until early February 2011. When an anomalous singularity appeared, it was the only period with the magma-related volcanic activity for Shinmoedake over the analyzed period of nine years. The above facts indicate the effectiveness of the proposed singularity method to monitor the lava activity for Shinmoedake. Therefore, it is concluded that if cloud discrimination is realized with high accuracy, no spurious changes will come to arise, and no false detection of hotspots will be given.
Population Characteristics of Loess Gully System in the Loess Plateau of China
Authors: Na Jiaming , Yang Xin , Tang Guoan , Dang Weiqin , Strobl Josef
Published: August 2020

Gullies in the Loess Plateau of China vary in developmental stages and morphologic sizes. In this case study, in Linjialian watershed in the loess hilly region, we introduced some perspectives from population ecology to explore the population characteristics of the loess gully system. Different types of gullies were extracted based on the digital elevation model and imagery data. Population analysis was then carried out from three aspects, namely, quantity, structure, and distribution. Results showed that in terms of the quantity, hillslope ephemeral gullies (187 numbers/km2 in number density) and bank gullies (8.3 km/km2 in length density) are the most active gullies in this area with an exponential growth trend, and the hillslope ephemeral gully is the dominant type. Along with age structure analysis, the pyramid-shaped age structure indicated that the gully system is at its early or middle stages of development. The spatial distribution of hillslope ephemeral gullies has a clear aspect asymmetry pattern, and the bank gully distribution is symmetrical. A hierarchical structure (hillslope ephemeral gully–bank gully–valley gully in upslope–shoulder line–bottom area) in an elevation distribution is presented. These preliminary results are helpful for further understanding the organized, systematic development, and evolution of the gully system.
The ESA Permanent Facility for Altimetry Calibration: Monitoring Performance of Radar Altimeters for Sentinel-3A, Sentinel-3B and Jason-3 Using Transponder and Sea-Surface Calibrations with FRM Standards
Authors: Mertikas Stelios , Tripolitsiotis Achilleas , Donlon Craig , Mavrocordatos Constantin , Féménias Pierre , Borde Franck , Frantzis Xenophon , Kokolakis Costas , Guinle Thierry , Vergos George , Tziavos Ilias , Cullen Robert
Published: August 2020

This work presents the latest calibration results for the Copernicus Sentinel-3A and -3B and the Jason-3 radar altimeters as determined by the Permanent Facility for Altimetry Calibration (PFAC) in west Crete, Greece. Radar altimeters are used to provide operational measurements for sea surface height, significant wave height and wind speed over oceans. To maintain Fiducial Reference Measurement (FRM) status, the stability and quality of altimetry products need to be continuously monitored throughout the operational phase of each altimeter. External and independent calibration and validation facilities provide an objective assessment of the altimeter’s performance by comparing satellite observations with ground-truth and in-situ measurements and infrastructures. Three independent methods are employed in the PFAC: Range calibration using a transponder, sea-surface calibration relying upon sea-surface Cal/Val sites, and crossover analysis. Procedures to determine FRM uncertainties for Cal/Val results have been demonstrated for each calibration. Biases for Sentinel-3A Passes No. 14, 278 and 335, Sentinel-3B Passes No. 14, 71 and 335, as well as for Jason-3 Passes No. 18 and No. 109 are given. Diverse calibration results by various techniques, infrastructure and settings are presented. Finally, upgrades to the PFAC in support of the Copernicus Sentinel-6 ‘Michael Freilich’, due to launch in November 2020, are summarized.
Evaluation of BDS-3 Orbit Determination Strategies Using Ground-Tracking and Inter-Satellite Link Observation
Authors: Lv Yifei , Geng Tao , Zhao Qile , Xie Xin , Zhang Feng , Wang Xing
Published: August 2020

Dual one-way inter-satellite link (ISL) pseudoranges of BDS-3 satellites can be introduced as an additional measurement along with L-band pseudoranges and phases to improve the accuracy of precise orbit determination (POD). In the existing research, although the clock-free or geometry-free ISL observables are derived from the raw two one-way pseudoranges, only the clock-free observables are adopted for the ISL joint POD (Joint 1 POD) without considering the geometric-free observables. An improved joint (Joint 2 POD) strategy making full use of the clock-free and geometry-free observables is applied in this contribution. The orbits of ground-only POD, ISL-only POD, Joint 1 POD, and Joint 2 POD are comprehensively compared by the orbit overlapping differences, the Satellite Laser Ranging (SLR) residuals, and the characteristics of the satellite clock offsets estimated simultaneously. The comparisons prove that the performance of the Joint 2 POD strategy is better than that of the other three POD strategies regardless of the types of satellites. Moreover, this paper discusses ISL’s contribution to the station selection strategy in terms of the number and distribution. The experimental results show that, when there are more than 20 stations, each additional 10 stations contributes to a maximum of 7.5%, 3.9%, and 2.8% improvement on MEO, IGSO, and GEO satellites 3D accuracy, respectively. When the number of stations reaches 50, the precise orbits achieve similar accuracy to the results using 80 stations. In addition, after adding ISL data, the orbits estimated using 10 regional stations and 10 global stations are greatly improved, and the accuracy between them is only 0.9 cm in 3D errors.
Framework for the Simulation of Sensor Networks Aimed at Evaluating In Situ Calibration Algorithms
Authors: Delaine Florentin , Lebental Bérengère , Rivano Hervé
Published: August 2020

The drastically increasing availability of low-cost sensors for environmental monitoring has fostered a large interest in the literature. One particular challenge for such devices is the fast degradation over time of the quality of their data. Therefore, the instruments require frequent calibrations. Traditionally, this operation is carried out on each sensor in dedicated laboratories. This is not economically sustainable for dense networks of low-cost sensors. An alternative that has been investigated is in situ calibration: exploiting the properties of the sensor network, the instruments are calibrated while staying in the field and preferably without any physical intervention. The literature indicates there is wide variety of in situ calibration strategies depending on the type of sensor network deployed. However, there is a lack for a systematic benchmark of calibration algorithms. In this paper, we propose the first framework for the simulation of sensor networks enabling a systematic comparison of in situ calibration strategies with reproducibility, and scalability. We showcase it on a primary test case applied to several calibration strategies for blind and static sensor networks. The performances of calibration are shown to be tightly related to the deployment of the network itself, the parameters of the algorithm and the metrics used to evaluate the results. We study the impact of the main modelling choices and adjustments of parameters in our framework and highlight their influence on the results of the calibration algorithms. We also show how our framework can be used as a tool for the design of a network of low-cost sensors.
ECG QT-I nterval Measurement Using Wavelet Transformation
Authors: Ohmuta Takao , Mitsui Kazuyuki , Shibata Nitaro
Published: August 2020

Wavelet transformation, with its markedly high time resolution, is an optimal technique for the analysis of non-stationary waveform signals, such as physiological signals. Therefore, wavelet transformation is widely applied to electrocardiographic (ECG) signal processing. However, an appropriate application method for automated QT-interval measurement has yet to be established. In this study, we developed an ECG recognition technique using wavelet transformation and assessed its efficacy and functionality. The results revealed that the difference between the values obtained using our algorithm and the visually measured QT interval was as low as 4.8 ms. Our technique achieves precise automated QT-interval measurement, as well as Te recognition, that is difficult to accomplish even by visual examination under the electromyography noise environment.
Recovering Depth from Still Images for Underwater Dehazing Using Deep Learning
Authors: Pérez Javier , Bryson Mitch , Williams Stefan B. , Sanz Pedro J.
Published: August 2020

Estimating depth from a single image is a challenging problem, but it is also interesting due to the large amount of applications, such as underwater image dehazing. In this paper, a new perspective is provided; by taking advantage of the underwater haze that may provide a strong cue to the depth of the scene, a neural network can be used to estimate it. Using this approach the depthmap can be used in a dehazing method to enhance the image and recover original colors, offering a better input to image recognition algorithms and, thus, improving the robot performance during vision-based tasks such as object detection and characterization of the seafloor. Experiments are conducted on different datasets that cover a wide variety of textures and conditions, while using a dense stereo depthmap as ground truth for training, validation and testing. The results show that the neural network outperforms other alternatives, such as the dark channel prior methods and it is able to accurately estimate depth from a single image after a training stage with depth information.
A Deep Learning Ensemble for Network Anomaly and Cyber-Attack Detection
Authors: Dutta Vibekananda , Choraś Michał , Pawlicki Marek , Kozik Rafał
Published: August 2020

Currently, expert systems and applied machine learning algorithms are widely used to automate network intrusion detection. In critical infrastructure applications of communication technologies, the interaction among various industrial control systems and the Internet environment intrinsic to the IoT technology makes them susceptible to cyber-attacks. Given the existence of the enormous network traffic in critical Cyber-Physical Systems (CPSs), traditional methods of machine learning implemented in network anomaly detection are inefficient. Therefore, recently developed machine learning techniques, with the emphasis on deep learning, are finding their successful implementations in the detection and classification of anomalies at both the network and host levels. This paper presents an ensemble method that leverages deep models such as the Deep Neural Network (DNN) and Long Short-Term Memory (LSTM) and a meta-classifier (i.e., logistic regression) following the principle of stacked generalization. To enhance the capabilities of the proposed approach, the method utilizes a two-step process for the apprehension of network anomalies. In the first stage, data pre-processing, a Deep Sparse AutoEncoder (DSAE) is employed for the feature engineering problem. In the second phase, a stacking ensemble learning approach is utilized for classification. The efficiency of the method disclosed in this work is tested on heterogeneous datasets, including data gathered in the IoT environment, namely IoT-23, LITNET-2020, and NetML-2020. The results of the evaluation of the proposed approach are discussed. Statistical significance is tested and compared to the state-of-the-art approaches in network anomaly detection.
Real-Time Detection of Orbital Maneuvers Using Epoch-Differenced Carrier Phase Observations and Broadcast Ephemeris Data: A Case Study of the BDS Dataset
Authors: Tu Rui , Zhang Rui , Fan Lihong , Han Junqiang , Zhang Pengfei , Lu Xiaochun
Published: August 2020

The orbital maneuvers of the global navigation satellite system (GNSSs) have a significant influence on the performance of the precise positioning, navigation, and timing (PNT) services. Because the Chinese BeiDou Navigation Satellite System (BDS) has three types of satellites in the geostationary orbit (GEO), inclined geosynchronous orbit (IGSO), and medium earth orbit (MEO) maneuvers occur more frequently. Thus, it is essential to determine an effective approach for the detection of orbital maneuvers. This study proposes a method for the detection of orbital maneuvers using epoch-differenced carrier phase observations and broadcast ephemeris data. When using the epoch-differenced velocity estimation as a basic data solution model, the time discrimination and satellite identification factors are defined and used for the real-time detection of the beginning and the pseudorandom noise code (PRN) of satellites. The datasets from four GNSS stations (WUH1, BJF1, POHN, CUT0) from the year 2016 were collected and analyzed. The validations showed that the beginning, the PRN of the orbital maneuver of the satellite can be precisely detected in real time for all GEO, IGSO, and MEO satellites, and the detected results also showed good consistency, with the beginning time at a difference of 1–2 min across different stations. The proposed approach was observed to be more sensitive, and the detected beginning time was about 30 min earlier than the single point positioning approach when the high-precision carrier phase observation was used. Thus, orbital maneuvering can be accurately detected by the proposed method. It not only improves the utilization of the collected data but also improves the performance of PNT services.
SSD vs. YOLO for Detection of Outdoor Urban Advertising Panels under Multiple Variabilities
Authors: Morera Ángel , Sánchez Ángel , Moreno A. Belén , Sappa Ángel D. , Vélez José F.
Published: August 2020

This work compares Single Shot MultiBox Detector (SSD) and You Only Look Once (YOLO) deep neural networks for the outdoor advertisement panel detection problem by handling multiple and combined variabilities in the scenes. Publicity panel detection in images offers important advantages both in the real world as well as in the virtual one. For example, applications like Google Street View can be used for Internet publicity and when detecting these ads panels in images, it could be possible to replace the publicity appearing inside the panels by another from a funding company. In our experiments, both SSD and YOLO detectors have produced acceptable results under variable sizes of panels, illumination conditions, viewing perspectives, partial occlusion of panels, complex background and multiple panels in scenes. Due to the difficulty of finding annotated images for the considered problem, we created our own dataset for conducting the experiments. The major strength of the SSD model was the almost elimination of False Positive (FP) cases, situation that is preferable when the publicity contained inside the panel is analyzed after detecting them. On the other side, YOLO produced better panel localization results detecting a higher number of True Positive (TP) panels with a higher accuracy. Finally, a comparison of the two analyzed object detection models with different types of semantic segmentation networks and using the same evaluation metrics is also included.
A Biomimetic Model of Adaptive Contrast Vision Enhancement from Mantis Shrimp
Authors: Zhong Binbin , Wang Xin , Gan Xin , Yang Tian , Gao Jun
Published: August 2020

Mantis shrimp have complex visual sensors, and thus, they have both color vision and polarization vision, and are adept at using polarization information for visual tasks, such as finding prey. In addition, mantis shrimp, almost unique among animals, can perform three-axis eye movements, such as pitch, yaw, and roll. With this behavior, polarization contrast in their field of view can be adjusted in real time. Inspired by this, we propose a bionic model that can adaptively enhance contrast vision. In this model, a pixel array is used to simulate a compound eye array, and the angle of polarization (AoP) is used as an adjustment mechanism. The polarization information is pre-processed by adjusting the direction of the photosensitive axis point-to-point. Experiments were performed around scenes where the color of the target and the background were similar, or the visibility of the target was low. The influence of the pre-processing model on traditional feature components of polarized light was analyzed. The results show that the model can effectively improve the contrast between the object and the background in the AoP image, enhance the significance of the object, and have important research significance for applications, such as contrast-based object detection.