bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the Potential of High-Resolution Satellite Imagery for the Detection of Soybean Sudden Death Syndrome
Authors: Raza Muhammad M. , Harding Chris , Liebman Matt , Leandro Leonor F.
Published: April 2020

Sudden death syndrome (SDS) is one of the major yield-limiting soybean diseases in the Midwestern United States. Effective management for SDS requires accurate detection in soybean fields. Since traditional scouting methods are time-consuming, labor-intensive, and often destructive, alternative methods to monitor SDS in large soybean fields are needed. This study explores the potential of using high-resolution (3 m) PlanetScope satellite imagery for detection of SDS using the random forest classification algorithm. Image data from blue, green, red, and near-infrared (NIR) spectral bands, the calculated normalized difference vegetation index (NDVI), and crop rotation information were used to detect healthy and SDS-infected quadrats in a soybean field experiment with different rotation treatments, located in Boone County, Iowa. Datasets collected during the 2016, 2017, and 2018 soybean growing seasons were analyzed. The results indicate that spectral features, when combined with ground-based information, can detect areas in soybean plots that are at risk for disease, even before foliar symptoms develop. The classification of healthy and diseased soybean quadrats was >75% accurate and the area under the receiver operating characteristic curve (AUROC) was >70%. Our results indicate that high-resolution satellite imagery and random forest analyses have the potential to detect SDS in soybean fields, and that this approach may facilitate large-scale monitoring of SDS (and possibly other economically important soybean diseases). It may also be useful for guiding recommendations for site-specific management in current and future seasons.
Vehicle and Vessel Detection on Satellite Imagery: A Comparative Study on Single-Shot Detectors
Authors: Ophoff Tanguy , Puttemans Steven , Kalogirou Vasileios , Robin Jean-Philippe , Goedemé Toon
Published: April 2020

In this paper, we investigate the feasibility of automatic small object detection, such as vehicles and vessels, in satellite imagery with a spatial resolution between 0.3 and 0.5 m. The main challenges of this task are the small objects, as well as the spread in object sizes, with objects ranging from 5 to a few hundred pixels in length. We first annotated 1500 km2, making sure to have equal amounts of land and water data. On top of this dataset we trained and evaluated four different single-shot object detection networks: YOLOV2, YOLOV3, D-YOLO and YOLT, adjusting the many hyperparameters to achieve maximal accuracy. We performed various experiments to better understand the performance and differences between the models. The best performing model, D-YOLO, reached an average precision of 60% for vehicles and 66% for vessels and can process an image of around 1 Gpx in 14 s. We conclude that these models, if properly tuned, can thus indeed be used to help speed up the workflows of satellite data analysts and to create even bigger datasets, making it possible to train even better models in the future.
The Effect of a LED Lighting Crosswalk on Pedestrian Safety: Some Experimental Results
Authors: Patella Sergio Maria , Sportiello Simone , Carrese Stefano , Bella Francesco , Asdrubali Francesco
Published: April 2020

The research presented in this paper is focused on the definition of a new methodology for evaluating how illuminated crosswalks influence drivers’ behavior when approaching the zebra in nighttime conditions. The proposed methodology is based on in situ speed measurements, and cars’ speed was detected in an urban road segment of the city of Rome with a Telelaser instrument. Vehicles speed profiles are measured in the same road segment both in LED-illuminated conditions and in non-illuminated conditions. Results have shown a promising impact of the LED lighting system on pedestrian safety. In fact, cars’ mean speed decreases by 19.3% at the crosswalk section in illuminated conditions. Moreover, a positive effect on safety, in terms of mean speed reduction (−16.4%), was found even in the absence of pedestrians.
Challenging the Hero Narrative: Moving towards Reparational Citizenship Education
Authors: Walsh Gary M.
Published: April 2020

In his book, No More Heroes: Grassroots Challenges to the Savior Mentality, Jordan Flaherty claims the saviour mentality exists when “you want to help others but are not open to guidance from those you want to help”. According to Flaherty, the adoption of this mentality results in charitable activities at individual and community levels without broader systemic change, leaving unjust power relations unaddressed. He argues that this mentality is underpinned by racism, colonialism and capitalism, as well as an unethical and historically problematic understanding of charity. With reference to the ongoing partnership work between Scotland and Malawi, this article summarises a conceptual investigation into the possibility that Global Citizenship Education perpetuates the hero narrative. Historical, political and educational research is connected to Bhabha’s theory of cultural hybridity to conceptualise a theory of Reparational Citizenship Education, in contrast to the “reciprocal” approach favoured by policy makers and charitable organisations in Scotland. It is argued that this conceptual shift involves taking the hero narrative to task and that this approach has theoretical and practical implications for the future of Global Citizenship Education.
Can Social Networks Make Us More Sensitive to Social Discrimination? E-Contact, Identity Processes and Perception of Online Sexual Discrimination in a Sample of Facebook Users
Authors: Mancini Tiziana , Imperato Chiara
Published: April 2020

In recent years psychosocial studies have given a growing attention to online intergroup contact in reducing prejudice. Nevertheless, there is still a lack of evidence on processes that could mediate this relation. The present study aimed to fill this gap. Focused on intergroup relationships between people with different sexual orientations, it examined whether and to what extent identity processes—i.e., sexual identity commitment and exploration—mediated the relationship between online intergroup contact and perception of mediated and vicarious sexual online discrimination on Facebook. Data was collected with a sample of 357 Facebook users (Mage = 26.07, SD = 8.37; females: 64.9%, males: 35.1%) who completed an online questionnaire. A full Structural Equation Modeling was tested. Results showed that: (a) Online contact was positively associated with perceived online sexual discrimination; (b) online contact was positively associated with identity exploration but not commitment; (c) exploration—but not commitment—was positively associated with perceived online sexual discrimination; (d) sexual identity exploration—but not commitment—mediated the relationship between online contact and perception of sexual discrimination, increasing the positive effect of contact on perceived discrimination. Limitations and directions for future research were discussed.
Corporate Social Responsibility in Hotels: A Proposal of a Measurement of its Performance through Marketing Variables
Authors: Mariño-Romero José Manuel , Hernández-Mogollón José Manuel , Campón-Cerro Ana María , Folgado-Fernández José Antonio
Published: April 2020

The research into Corporate Social Responsibility (CSR) has been prolific in the last years, although few studies have focused their attention on studying its relationship with economic performance within the hotel industry, even less incorporating marketing variables as a result. This work aims to determine the relationship between the implementation of CSR policies and their influence on the Revenue Per Available Room (RevPAR) in Spanish hotels, through marketing variables. A quantitative methodology was conducted using an online survey, gathering a sample of 230 hotel managers from Spain. The results of the structural model analyzed reveal that CSR has a discreet but significant role for understanding how marketing variables and RevPAR operate. CSR has a direct impact on RevPAR, but it also influences it indirectly through marketing variables. Therefore, CSR arises as a fundamental strategy to improve the results of the hotel sector in the long term.
Still Green at Fifteen? Investigating Environmental Awareness of the PISA 2015 Population: Cross-National Differences and Correlates
Authors: List Marit Kristine , Schmidt Fabian T. C. , Mundt Daria , Föste-Eggers Dennis
Published: April 2020

The PISA studies provide unique opportunities to investigate the competencies and attitudes of 15-year-olds across the world. Past research investigating environmental awareness (EA) in PISA 2006 found associations between EA and science-related competencies and attitudes. Investigating EA in the PISA studies may have important implications for education for sustainable development (ESD): results may show which factors should be considered in educational interventions to enhance students’ EA. Cross-national analyses of EA may provide insights into the predictors of EA on a local, national or international level. This study investigates the individual, school, and country level predictors of EA in PISA 2015 (365,194 students, 12,594 schools, 53 countries). The multi-level regression analysis on EA reveals that most of the variance is located at the student level. On the individual level, variables related to science learning in school are associated with EA across all countries. This study also compares the degrees of EA in the 2006 and 2015 populations. The results show similar degrees of EA in 2006 and 2015. Altogether, the study provides cross-country evidence on important aspects that should be addressed in successful ESD programs.
Influence of Treatments and Covers on NH3 Emissions from Dairy Cow and Buffalo Manure Storage
Authors: Scotto di Perta Ester , Mautone Antonio , Oliva Marco , Cervelli Elena , Pindozzi Stefania
Published: April 2020

The storage of livestock manure is responsible for ammonia emissions into the atmosphere. Different natural covers could be used during animal manure storage, but the mitigation effect is influenced by the manure characteristics due to the housing or treatment systems. Starting from cattle and buffalo manure, the objectives of this study were (i) to assess the effect of anaerobic digestion (AD) and solid–liquid separation (SLS) on ammonia emissions during storage as well as natural crust development and (ii) to investigate the reduction in ammonia emissions by using a layer of straw to cover the stored animal manure. Storage conditions were simulated in a small-scale application in a climate-controlled room. Results showed that the higher organic matter content of cow raw slurry facilitated the surface crust formation starting from the first days of storage. AD with SLS increased ammonia emissions (48.5%) due to the increase of the ammoniacal nitrogen content. On the other hand, animal manure covered with a layer of straw showed a 7.3% reduction of ammonia emissions. This study suggests that treatments and covering strategies must be calibrated to different manure types to enhance the mitigation effect.
Analysis and Prediction of Land Use in Beijing-Tianjin-Hebei Region: A Study Based on the Improved Convolutional Neural Network Model
Authors: Liu Haojie , Liu Jinyue , Yang Weixin , Chen Jianing , Zhu Mingyang
Published: April 2020

During the rapid economic development of China, there are certain blind decisions made in the use of land resources, which poses a significant threat to sustainable development. With the help of the improved convolutional neural network model, this paper analyzes the land use of the Beijing-Tianjin-Hebei region of China from 1995 to 2018, and provides a prediction for 2023. The research results show that: (1) There is still much room for improvement in the land use of the Beijing-Tianjin-Hebei region, with dry land taking up the largest proportion of land in these three locations; (2) Beijing’s development has been well protected in terms of land use. It is predicted that by 2023, the proportions of its woodland, grassland, and rivers, lakes, reservoirs and ponds would increase by 0.26%, 0.30%, and 0.61%, respectively, compared with their proportion in 2018; (3) the land use type in Tianjin during the research period was generally stable. In 2018, the proportion of its woodland and grassland had increased by 1.04% and 0.61%, respectively, compared with that of 1995; and (4) many ecological and environmental problems were exposed during the construction of highways in Hebei province. The area of sand land, saline-alkali land, marshland, bare land, and bare rock areas have all increased, and their total proportion is predicted to reach 1.48% by 2023.
Analysis of the Habitat Fragmentation of Ecosystems in Belize Using Landscape Metrics
Authors: Flowers Bryon , Huang Kuo-Tsang , Aldana Gerardo O.
Published: April 2020

Landscape metrics have been of game changing importance in the analysis of ecosystems’ composition and landscape cohesion. With the increasing urban and agricultural expansion, the natural flora and fauna of many highly diverse areas have been degraded. Fragmentation of ecosystems and habitats have stressed the biodiversity of Belize. To understand the dynamics of this change, a study was conducted using three moderately separate years of ecosystem landscape data. The metrics used for the analysis were area-weighted mean shape index (AWMSI), mean shape index (MSI), edge density (ED), mean patch size (MPS), number of patches (NUMP), and class area (CA). These metrics were produced for the years 2001, 2011, and 2017. The classes of agricultural use, lowland savannas, mangroves and littoral forests, urban, and wetlands were the subjects for analysis. Using the GIS extension Patch Analyst, parametric runs were performed. From these results, a one-way ANOVA test of the NUMP, Tukey HSD test, and Scheffé Multiple Comparison test were performed. The results indicate that there has been significant habitat fragmentation, especially from the years 2001 to 2011. Agricultural areas increased by 19.37% in just 10 years, with the NUMP of some habitats increasing by 284%. The results also show fluctuation in ED and a decrease in overall MPS, all indicating high fragmentation. These changes have been mostly induced due to the expansion of agricultural activities and urbanization, especially in the northern parts of Belize. It is imperative that additional policies be implemented to deter the effects of habitat fragmentation upon the existing ecosystems of Belize and elsewhere.
Does Water Context Matter in Water Conservation Decision Behaviour?
Authors: Rodriguez-Sanchez Carla , Sarabia-Sanchez Francisco J.
Published: April 2020

This study examines whether water scarcity context affects water conservation decision behaviour. We do this analysing a decision model that includes perceived message credibility, water consumption risk, and personal involvement variables. The sample consists of residents of more than 20 Spanish cities, and contexts of water scarcity (n = 420) and non-scarcity (n = 217) are compared. Spain was chosen because it is one of the most water-stressed (difference between consumption and reserves) countries in Europe, and water scarcity is a key factor affecting water conservation efforts. We employ regression analysis with partial least squares (PLS) and multi-group techniques. Two relevant findings can be highlighted. First, the most relevant variable in the model is personal involvement in water conservation practices. Second, although in general our model is not sensitive to the water scarcity context, we observe that individuals living in areas with water scarcity report greater levels of personal involvement and water conservation decision behaviour. We conclude by providing the implications for water managers and policymakers and suggesting avenues for future research.
Quantum-Gravity Screening Effect of the Cosmological Constant in the DeSitter Space–Time
Authors: Cremaschini Claudio , Tessarotto Massimo
Published: April 2020

Small-amplitude quantum-gravity periodic perturbations of the metric tensor, occurring in sequences of phase-shifted oscillations, are investigated for vacuum conditions and in the context of the manifestly-covariant theory of quantum gravity. The theoretical background is provided by the Hamiltonian representation of the quantum hydrodynamic equations yielding, in turn, quantum modifications of the Einstein field equations. It is shown that in the case of the DeSitter space–time sequences of small-size periodic perturbations with prescribed frequency are actually permitted, each one with its characteristic initial phase. The same perturbations give rise to non-linear modifications of the Einstein field equations in terms of a suitable stochastic-averaged and divergence-free quantum stress-energy tensor. As a result, a quantum-driven screening effect arises which is shown to affect the magnitude of the cosmological constant. Observable features on the DeSitter space–time solution and on the graviton mass estimate are pointed out.
Analyzing the Energy Efficiency of Fan Systems by Using the Dimensional Analysis (DA) Method
Authors: Popov Gencho , Klimentov Kliment , Kostov Boris , Dimitrova Reneta
Published: April 2020

This work represents a method for investigating the energy efficiency of fan systems used to transport fluids. Applying the methods of dimensional analysis (DA) enables establishing five dimensionless complexes ( π criteria), including some basic parameters having impacts on the consumed energy used for the transportation of a unit quantity of air. The proposed criterion π 1 includes the specific energy consumption e v (specific fan power SFP), and is used for the quantitative evaluation of the energy effectiveness of the fluid transportation. This criterion also includes the main geometric size of the pipe system (network) and the gas properties. The criterion π 3 indicates the impact of the applied method of flow rate regulation on the effective energy use of fan systems. This criterion includes parameters characterizing the selected method of flow rate regulation: speed ( n ) for using the frequency method and the referred length ( L T P ) of the pipe system for using the throttle method. The established (proposed) dimensionless parameters are used to study a concrete fan system. The obtained results concerning the evaluation of the impact of the two most used methods of flow rate regulation (frequency and throttle), as well as the density variation as a result of the temperature change, on the effective energy use are graphically presented: π 1 = f ( π 3 ) .
Selecting FFT Word Length for an OFDM Receiver That Supports Undersampling
Authors: Petrellis Nikos
Published: April 2020

In this paper, we focus on Orthogonal Frequency Division Multiplexing (OFDM) transceivers where undersampling is employed by the receiver Analog/Digital Converter (ADC) when sparse information is exchanged. Several Fast Fourier Transform (FFT) symmetry properties are exploited to allow the substitution of specific input values by others that have already been sampled by the ADC. Several architectures have been proposed in the literature for efficient FFT implementations in terms of power, speed and hardware resources. The FFT input/output values, twiddle factors, etc., are complex numbers with their real and imaginary parts being represented using fixed point format. A tradeoff has to be made between rounding error and complexity. The optimal minimum FFT word length is investigated by combining the undersampling and the rounding error. A configurable new FFT architecture has been developed in hardware description language to test the error model with various FFT sizes, word lengths and Quadrature Amplitude Modulations (QAM). A system designer can take into account the sparseness of the input data and define the desired rounding and undersampling error relation. Τhe developed error model would then predict the required word length and ADC resolution with average Root Mean Square Error (RMSE) less than 1.
Multi-Symplectic Method for the Logarithmic-KdV Equation
Authors: Zhang Yu , Li Shaohua
Published: April 2020

The multi-symplectic integrator, as a numerical integration approach with symmetry, is known to have the characteristic of preserving the qualitative features and geometric properties of certain systems. Using the multi-symplectic integrator, the numerical simulation of the Gaussian solitary wave propagation of the logarithmic Korteweg–de Vries (logarithmic-KdV) equation was investigated. The multi-symplectic formulation of the logarithmic-KdV equation was explored by introducing some intermediate variables. A fully implicit version of the centered box scheme was used to discretize the multi-symplectic equations. In addition, numerical experiments were carried out to show the conservative properties of the proposed scheme.
A Multistable Chaotic Jerk System with Coexisting and Hidden Attractors: Dynamical and Complexity Analysis, FPGA-Based Realization, and Chaos Stabilization Using a Robust Controller
Authors: Chen Heng , He Shaobo , Pano Azucena Ana Dalia , Yousefpour Amin , Jahanshahi Hadi , López Miguel A. , Alcaraz Raúl
Published: April 2020

In the present work, a new nonequilibrium four-dimensional chaotic jerk system is presented. The proposed system includes only one constant term and has coexisting and hidden attractors. Firstly, the dynamical behavior of the system is investigated using bifurcation diagrams and Lyapunov exponents. It is illustrated that this system either possesses symmetric equilibrium points or does not possess an equilibrium. Rich dynamics are found by varying system parameters. It is shown that the system enters chaos through experiencing a cascade of period doublings, and the existence of chaos is verified. Then, coexisting and hidden chaotic attractors are observed, and basin attraction is plotted. Moreover, using the multiscale C0 algorithm, the complexity of the system is investigated, and a broad area of high complexity is displayed in the parameter planes. In addition, the chaotic behavior of the system is studied by field-programmable gate array implementation. A novel methodology to discretize, simulate, and implement the proposed system is presented, and the successful implementation of the proposed system on FPGA is verified through the simulation outcome. Finally, a robust sliding mode controller is designed to suppress the chaotic behavior of the system. To deal with unexpected disturbances and uncertainties, a disturbance observer is developed along with the designed controller. To show the successful performance of the designed control scheme, numerical simulations are also presented.
A Novel Method for Performance Improvement of Chaos-Based Substitution Boxes
Authors: Artuğer Fırat , Özkaynak Fatih
Published: April 2020

Symmetry plays an important role in nonlinear system theory. In particular, it offers several methods by which to understand and model the chaotic behavior of mathematical, physical and biological systems. This study examines chaotic behavior in the field of information security. A novel method is proposed to improve the performance of chaos-based substitution box structures. Substitution box structures have a special role in block cipher algorithms, since they are the only nonlinear components in substitution permutation network architectures. However, the substitution box structures used in modern block encryption algorithms contain various vulnerabilities to side-channel attacks. Recent studies have shown that chaos-based designs can offer a variety of opportunities to prevent side-channel attacks. However, the problem of chaos-based designs is that substitution box performance criteria are worse than designs based on mathematical transformation. In this study, a postprocessing algorithm is proposed to improve the performance of chaos-based designs. The analysis results show that the proposed method can improve the performance criteria. The importance of these results is that chaos-based designs may offer opportunities for other practical applications in addition to the prevention of side-channel attacks.
Symmetry Evolution in Chaotic System
Authors: Li Chunbiao , Sun Jiayu , Lu Tianai , Lei Tengfei
Published: April 2020

A comprehensive exploration of symmetry and conditional symmetry is made from the evolution of symmetry. Unlike other chaotic systems of conditional symmetry, in this work it is derived from the symmetric diffusionless Lorenz system. Transformation from symmetry and asymmetry to conditional symmetry is examined by constant planting and dimension growth, which proves that the offset boosting of some necessary variables is the key factor for reestablishing polarity balance in a dynamical system.
Prediction of Metabolic Syndrome in a Mexican Population Applying Machine Learning Algorithms
Authors: Gutiérrez-Esparza Guadalupe Obdulia , Infante Vázquez Oscar , Vallejo Maite , Hernández-Torruco José
Published: April 2020

Metabolic syndrome is a health condition that increases the risk of heart diseases, diabetes, and stroke. The prognostic variables that identify this syndrome have already been defined by the World Health Organization (WHO), the National Cholesterol Education Program Third Adult Treatment Panel (ATP III) as well as by the International Diabetes Federation. According to these guides, there is some symmetry among anthropometric prognostic variables to classify abdominal obesity in people with metabolic syndrome. However, some appear to be more sensitive than others, nevertheless, these proposed definitions have failed to appropriately classify a specific population or ethnic group. In this work, we used the ATP III criteria as the framework with the purpose to rank the health parameters (clinical and anthropometric measurements, lifestyle data, and blood tests) from a data set of 2942 participants of Mexico City Tlalpan 2020 cohort, applying machine learning algorithms. We aimed to find the most appropriate prognostic variables to classify Mexicans with metabolic syndrome. The criteria of sensitivity, specificity, and balanced accuracy were used for validation. The ATP III using Waist-to-Height-Ratio (WHtR) as an anthropometric index for the diagnosis of abdominal obesity achieved better performance in classification than waist or body mass index. Further work is needed to assess its precision as a classification tool for Metabolic Syndrome in a Mexican population.
Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration
Authors: Dyakin Victor V. , Wisniewski Thomas M. , Lajtha Abel
Published: April 2020

Biochirality is the subject of distinct branches of science, including biophysics, biochemistry, the stereochemistry of protein folding, neuroscience, brain functional laterality and bioinformatics. At the protein level, biochirality is closely associated with various post-translational modifications (PTMs) accompanied by the non-equilibrium phase transitions (PhTs NE). PTMs NE support the dynamic balance of the prevalent chirality of enzymes and their substrates. The stereoselective nature of most biochemical reactions is evident in the enzymatic (Enz) and spontaneous (Sp) PTMs (PTMs Enz and PTMs Sp) of proteins. Protein chirality, which embraces biophysics and biochemistry, is a subject of this review. In this broad field, we focus attention to the amyloid-beta (Aβ) peptide, known for its essential cellular functions and associations with neuropathology. The widely discussed amyloid cascade hypothesis (ACH) of Alzheimer’s disease (AD) states that disease pathogenesis is initiated by the oligomerization and subsequent aggregation of the Aβ peptide into plaques. The racemization-induced aggregation of protein and RNA have been extensively studied in the search for the contribution of spontaneous stochastic stereo-specific mechanisms that are common for both kinds of biomolecules. The failure of numerous Aβ drug-targeting therapies requires the reconsolidation of the ACH with the concept of PTMs Sp. The progress in methods of chiral discrimination can help overcome previous limitations in the understanding of AD pathogenesis. The primary target of attention becomes the network of stereospecific PTMs that affect the aggregation of many pathogenic agents, including Aβ. Extensive recent experimental results describe the truncated, isomerized and racemized forms of Aβ and the interplay between enzymatic and PTMs Sp. Currently, accumulated data suggest that non-enzymatic PTMs Sp occur in parallel to an existing metabolic network of enzymatic pathways, meaning that the presence and activity of enzymes does not prevent non-enzymatic reactions from occurring. PTMs Sp impact the functions of many proteins and peptides, including Aβ. This is in logical agreement with the silently accepted racemization hypothesis of protein aggregation (RHPA). Therefore, the ACH of AD should be complemented by the concept of PTMs Sp and RHPA.
Thermogravitational Convection of Hybrid Nanofluid in a Porous Chamber with a Central Heat-Conducting Body
Authors: A. Sheremet Mikhail , Cimpean Dalia Sabina , Pop Ioan
Published: April 2020

A problem with the thermogravitational energy transference of a hybrid nanofluid (Al2O3-SiO2/H2O) in a porous space with a central heat-conducting body has been presented and numerical analysis has been performed. Governing equations, transformed in terms of non-dimensional parameters, have been solved by a developed numerical algorithm based on the finite difference technique. The behavior of streamlines and isotherms was investigated, and the impact of various important characteristics is discussed. The variation in the average and local Nusselt numbers was studied; by selecting various appropriate nano-sized particle combinations in hybrid nanosuspension, the desired energy transport strength could be obtained. The results were compared and successfully validated with previous reported numerical and experimental data from the literature.
Uremia-Associated Ageing of the Thymus and Adaptive Immune Responses
Authors: Betjes Michiel GH
Published: April 2020

Progressive loss of renal function is associated with a series of changes of the adaptive immune system which collectively constitute premature immunological ageing. This phenomenon contributes significantly to the mortality and morbidity of end-stage renal disease (ESRD) patients. In this review, the effect of ESRD on the T cell part of the adaptive immune system is highlighted. Naïve T cell lymphopenia, in combination with the expansion of highly differentiated memory T cells, are the hallmarks of immunological ageing. The decreased production of newly formed T cells by the thymus is critically involved. This affects both the CD4 and CD8 T cell compartment and may contribute to the expansion of memory T cells. The expanding populations of memory T cells have a pro-inflammatory phenotype, add to low-grade inflammation already present in ESRD patients and destabilize atherosclerotic plaques. The effect of loss of renal function on the thymus is not reversed after restoring renal function by kidney transplantation and constitutes a long-term mortality risk factor. Promising results from animal experiments have shown that rejuvenation of the thymus is a possibility, although not yet applicable in humans.
Protein-Lipid Interaction of Cytolytic Toxin Cyt2Aa2 on Model Lipid Bilayers of Erythrocyte Cell Membrane
Authors: Tharad Sudarat , Promdonkoy Boonhiang , Toca-Herrera José L.
Published: April 2020

Cytolytic toxin (Cyt) is a toxin among Bacillus thuringiensis insecticidal proteins. Cyt toxin directly interacts with membrane lipids for cytolytic action. However, low hemolytic activity is desired to avoid non-specific effects in mammals. In this work, the interaction between Cyt2Aa2 toxin and model lipid bilayers mimicking the erythrocyte membrane was investigated for Cyt2Aa2 wild type (WT) and the T144A mutant, a variant with lower hemolytic activity. Quartz crystal microbalance with dissipation (QCM-D) results revealed a smaller lipid binding capacity for the T144A mutant than for the WT. In particular, the T144A mutant was unable to bind to the phosphatidylcholine lipid (POPC) bilayer. However, the addition of cholesterol (Chol) or sphingomyelin (SM) to the POPC bilayer promoted binding of the T144 mutant. Moreover, atomic force microscopy (AFM) images unveiled small aggregates of the T144A mutant on the 1:1 sphingomyelin/POPC bilayers. In contrast, the lipid binding trend for WT and T144A mutant was comparable for the 1:0.4 POPC/cholesterol and the 1:1:1 sphingomyelin/POPC/cholesterol bilayers. Furthermore, the binding of WT and T144A mutant onto erythrocyte cells was investigated. The experiments showed that the T144A mutant and the WT bind onto different areas of the erythrocyte membrane. Overall the results suggest that the T144 residue plays an important role for lipid binding.
Assessment of Fungal Contamination in Fish Feed from the Lake Victoria Basin, Uganda
Authors: Namulawa Victoria Tibenda , Mutiga Samuel , Musimbi Fred , Akello Sundy , Ngángá Fredrick , Kago Leah , Kyallo Martina , Harvey Jagger , Ghimire Sita
Published: April 2020

The emergence of commercial fish farming has stimulated the establishment of fish feed factories in Uganda. However, no information is available on the safety of the feed, mainly due to lack of mycotoxin testing facilities and weak regulatory systems. A study was carried out to examine fungal colonization and mycotoxin contamination in fish feed samples (n = 147) of different types collected from nine fish farms (n = 81) and seven fish feed factories (n = 66) in the Lake Victoria Basin (LVB). Fungi were isolated in potato dextrose agar, grouped into morphotypes and representative isolates from each morphotype were identified based on the internal transcribed spacer (ITS) region of ribosomal DNA sequences. Aflatoxin B1 (AFB1) and total fumonisin (combinations of B1, B2 and B3; hereinafter named fumonisin) levels in feed samples were determined by enzyme-linked immunosorbent assay (ELISA). A wide range of fungi, including toxigenic Aspergillus flavus and Fusarium verticillioides, were isolated from the fish feed samples. AFB1 was detected in 48% of the factory samples and in 63% of the farm samples, with toxin levels <40 and >400 µg/kg, respectively. Similarly, 31% of the factory samples and 29% of the farm samples had fumonisin contamination ranging between 0.1 and 4.06 mg/kg. Pellets and powder had higher mycotoxin contamination compared to other commercially available fish feed types. This study shows AFB1 as a potential fish feed safety issue in the LVB and suggests a need for more research on mycotoxin residues in fish fillets.
Oral Charcoal Adsorbents Attenuate Neointima Formation of Arteriovenous Fistulas
Authors: Shih Yu-Chung , Wu Chih-Cheng , Wang Shen-Chih , Liou Jun-Yang , Huang Po-Hsun , Tarng Der-Cherng
Published: April 2020

Chronic kidney disease (CKD) accelerates the development of neointima formation at the anastomosis site of arteriovenous (AV) fistulas. Accumulation of certain uremic toxins has a deleterious effect on the cardiovascular system. The oral charcoal adsorbent, AST-120, reduces circulating and tissue uremic toxins, but its effect on neointima formation at an AV fistula is unknown. To understand the effect of CKD and AST-120 on neointima formation, we created AV fistulas (common carotid artery to the external jugular vein in an end-to-side anastomosis) in mice with and without CKD. AST-120 was administered in chow before and after AV fistula creation. Administration of AST-120 significantly decreased serum indoxyl sulfate levels in CKD mice. CKD mice had a larger neointima area than non-CKD mice, and administration of AST-120 in CKD mice attenuated neointima formation. Both smooth muscle cell and fibrin components were increased in CKD mice, and AST-120 decreased both. RNA expression of MMP-2, MMP-9, TNFα, and TGFβ was increased in neointima tissue of CKD mice, and AST-120 administration neutralized the expression. Our results provided in vivo evidence to support the role of uremic toxin-binding therapy on the prevention of neointima formation. Peri-operative AST-120 administration deserves further investigation as a potential therapy to improve AV fistula patency.
Do Antibiotics Potentiate Proteases in Hemotoxic Snake Venoms?
Authors: Sørensen Christoffer V. , Knudsen Cecilie , auf dem Keller Ulrich , Kalogeropoulos Konstantinos , Gutiérrez-Jiménez Cristina , Pucca Manuela B. , Arantes Eliane C. , Bordon Karla , Laustsen Andreas H.
Published: April 2020

Antibiotics are often administered with antivenom following snakebite envenomings in order to avoid secondary bacterial infections. However, to this date, no studies have evaluated whether antibiotics may have undesirable potentiating effects on snake venom. Herein, we demonstrate that four commonly used antibiotics affect the enzymatic activities of proteolytic snake venom toxins in two different in vitro assays. Similar findings in vivo could have clinical implications for snakebite management and require further examination.
Tat-Based Therapies as an Adjuvant for an HIV-1 Functional Cure
Authors: Jin Hongping , Li Dongsheng , Lin Min-Hsuan , Li Li , Harrich David
Published: April 2020

The human immunodeficiency virus type 1 (HIV) establishes a chronic infection that can be well controlled, but not cured, by combined antiretroviral therapy (cART). Interventions have been explored to accomplish a functional cure, meaning that a patient remains infected but HIV is undetectable in the blood, with the aim of allowing patients to live without cART. Tat, the viral transactivator of transcription protein, plays a critical role in controlling HIV transcription, latency, and viral rebound following the interruption of cART treatment. Therefore, a logical approach for controlling HIV would be to block Tat. Tackling Tat with inhibitors has been a difficult task, but some recent discoveries hold promise. Two anti-HIV proteins, Nullbasic (a mutant of Tat) and HT1 (a fusion of HEXIM1 and Tat functional domains) inhibit viral transcription by interfering with the interaction of Tat and cellular factors. Two small molecules, didehydro-cortistatin A (dCA) and triptolide, inhibit Tat by different mechanisms: dCA through direct binding and triptolide through enhanced proteasomal degradation. Finally, two Tat-based vaccines under development elicit Tat-neutralizing antibodies. These vaccines have increased the levels of CD4+ cells and reduced viral loads in HIV-infected people, suggesting that the new vaccines are therapeutic. This review summarizes recent developments of anti-Tat agents and how they could contribute to a functional cure for HIV.
2′, 5′-Oligoadenylate Synthetase 2 (OAS2) Inhibits Zika Virus Replication through Activation of Type Ι IFN Signaling Pathway
Authors: Liao Xinzhong , Xie He , Li Shilin , Ye Haiyan , Li Shuang , Ren Kai , Li Yujia , Xu Min , Lin Wenyu , Duan Xiaoqiong , Yang Chunhui , Chen Limin
Published: April 2020

Background: 2′, 5′-oligoadenylate synthetase 2 (OAS2) has been known as an antiviral interferon-stimulated gene (ISG). However, the role of OAS2 on Zika virus (ZIKV) replication is still unknown. In this study, we sought to explore the effect of OAS2 on ZIKV replication and its underlying mechanism. Methods: We performed RNA-Seq in A549 cells with or without ZIKV infection. OAS2 or RIG-I was overexpressed by plasmid transfection or knocked down by siRNA in A549 cells. Expression levels of mRNA and protein of selected genes were detected by RT-qPCR and Western Blot, respectively. Interferon stimulated response element (ISRE) activity was examined by dual luciferase assay. Results: We found that ZIKV infection induced OAS2 expression through a RIG-I-dependent pathway. OAS2 overexpression inhibited ZIKV replication, while OAS2 knockdown increased ZIKV replication. We observed that OAS2 inhibited ZIKV replication through enhanced IFNβ expression, leading to the activation of the Jak/STAT signaling pathway. Conclusion: ZIKV infection induced OAS2 expression, which in turn exerted its anti-ZIKV activities through the IFN-activated Jak/STAT signaling pathway.
Bacteriophage ZCSE2 is a Potent Antimicrobial against Salmonella enterica Serovars: Ultrastructure, Genomics and Efficacy
Authors: Mohamed Ahmed , Taha Omar , El-Sherif Hesham M. , Connerton Phillippa L. , Hooton Steven P.T. , Bassim Nabil D. , Connerton Ian F. , El-Shibiny Ayman
Published: April 2020

Developing novel antimicrobials capable of controlling multidrug-resistant bacterial pathogens is essential to restrict the use of antibiotics. Bacteriophages (phages) constitute a major resource that can be harnessed as an alternative to traditional antimicrobial therapies. Phage ZCSE2 was isolated among several others from raw sewage but was distinguished by broad-spectrum activity against Salmonella serovars considered pathogenic to humans and animals. Lytic profiles of ZCSE2 against a panel of Salmonella were determined together with low temperature activity and pH stability. The morphological features of the phage and host infection processes were characterized using a combination of transmission electron and atomic force microscopies. Whole genome sequencing of ZCSE2 produced a complete DNA sequence of 53,965 bp. No known virulence genes were identified in the sequence data, making ZCSE2 a good candidate for phage-mediated biological control purposes. ZCSE2 was further tested against S. Enteritidis in liquid culture and was observed to reduce the target bacterium to below the limits of detection from initial concentrations of 107–108 Colony Forming Units (CFU)/mL. With a broad host-range against pathogenic Salmonella serovars, phage ZCSE2 constitutes a potential tool against a major cause of human and animal disease.
In Silico Analysis of Genetic Diversity of Human Hepatitis B Virus in Southeast Asia, Australia and New Zealand
Authors: Phan Ngoc , Faddy Helen , Flower Robert , Spann Kirsten , Roulis Eileen
Published: April 2020

The extent of whole genome diversity amongst hepatitis B virus (HBV) genotypes is not well described. This study aimed to update the current distribution of HBV types and to investigate mutation rates and nucleotide diversity between genotypes in Southeast Asia, Australia and New Zealand. We retrieved 930 human HBV complete genomes from these regions from the NCBI nucleotide database for genotyping, detection of potential recombination, serotype prediction, mutation identification and comparative genome analyses. Overall, HBV genotypes B (44.1%) and C (46.2%) together with predicted serotypes adr (36%), adw2 (29%) and ayw1 (19.9%) were the most commonly circulating HBV types in the studied region. The three HBV variants identified most frequently were p.V5L, c.1896G>A and double mutation c.1762A>T/c.1764G>A, while genotypes B and C had the widest range of mutation types. The study also highlighted the distinct nucleotide diversity of HBV genotypes for whole genome and along the genome length. Therefore, this study provided a robust update to HBV currently circulating in Southeast Asia, Australia and New Zealand as well as an insight into the association of HBV genetic hypervariability and prevalence of well reported mutations.
Predicting River Embankment Failure Caused by Toe Scour Considering 1D and 2D Hydraulic Models: A Case Study of Da-An River, Taiwan
Authors: Chang Chih-Hsin , Chen Hongey , Guo Wen-Dar , Yeh Sen-Hai , Chen Wei-Bo , Liu Che-Hsin , Lee Shih-Chiang
Published: April 2020

Physically based numerical models can predict scour depth at embankments located in bend reaches. However, methodologies for utilizing these numerical models to assess the risk of reinforced concrete embankment failure are rarely investigated. Therefore, a new assessment methodology is proposed to predict the riverbank failure caused by bend scour. The methodology is primarily based on a bend scour simulation model that integrates a one-dimensional (1D) hydraulic model, a two-dimensional (2D) hydrodynamic finite-volume model, and an empirical equation of bend scour prediction. The model was first applied to the Shuiwei Embankment located in a river bend reach of Da-An River in Taiwan and verified against results from the 1D hydraulic model and field data. The model was then used to simulate 2D flow field and the temporal evolution of bend scour depth under different return period flood events to examine the relationships between river discharge, water level, shear stress, and bend scour depth. The influence of shear stress on the stability of toe protections was also investigated. The field data (from two events) and numerical solutions (four scenarios) were assessed to conceive two empirical equations for predicting shear stress and bend scour depth. A new assessment methodology was proposed using these two equations to predict the risk of river embankment failure during flood periods. The proposed methodology can be easily applied in other disaster-prone regions to mitigate the effects of disasters caused by bend scouring.
Long-Term Spatiotemporal Variation and Environmental Driving Forces Analyses of Algal Blooms in Taihu Lake Based on Multi-Source Satellite and Land Observations
Authors: Zhang Tiantian , Hu Hong , Ma Xiaoshuang , Zhang Yaobo
Published: April 2020

The algal blooms caused by the eutrophication of lakes is a major environmental problem. In this study, we took China’s Taihu Lake as the research area, using multi-source satellite imagery data to monitor the information of algal blooms from 2008 to 2017. Following the analyses of the temporal and spatial variation trends of the blooms, water quality and meteorological data from land observation stations were employed to investigate the main environmental driving forces of the algal bloom outbreaks. The results show that, over the decade, the blooms with medium and higher hazard degrees mainly occurred in summer and autumn, and especially in autumn. From 2008 to 2016, the algal blooms outbreak degree was relatively stable, but, in 2017, it was severe, and the Northwest Lake area and the northern bays had heavier blooms than the other lake areas. From the analyses of the environmental driving forces, the variation trend of total nitrogen (TN) and total phosphorus (TP) concentrations in Taihu Lake from 2008 to 2017 was moderate, and the minimum concentrations of TN and TP both exceeded the threshold for algal bloom outbreaks. It was also found that the algal bloom area had notable correlations with the sunshine duration, wind speed and direction, precipitation, and air pressure. The research results of this paper will provide a theoretical basis for the scientific prediction of the occurrence of algal blooms in Taihu Lake.