bluuebunny/crossref_metadata_2025 huggingface dataset:
Variable Changes of Circulating ANGPTL3 and ANGPTL4 in Different Obese Phenotypes: Relationship with Vasodilator Dysfunction
Authors: Schinzari Francesca , Vizioli Giuseppina , Campia Umberto , Tesauro Manfredi , Cardillo Carmine
Published: August 2021

Obesity associates with premature atherosclerosis and an increased burden of cardiovascular disease, especially when accompanied by abnormalities of lipid and glucose metabolism. Angiopoietin-like (ANGPTL)3 and ANGPTL4 are metabolic regulators, whose upregulation is associated with dyslipidemia, insulin resistance and atherosclerosis. We analyzed, therefore, changes in circulating ANGPTL3 and ANGPTL4 in obese patients with different metabolic phenotypes and their relation with impaired vasodilator reactivity, an early abnormality in atherosclerosis. Compared to the lean subjects (n = 42), circulating ANGPTL3 was elevated (both p > 0.001) in the patients with metabolically unhealthy obesity (MUO; n = 87) and type 2 diabetes (T2D; n = 31), but not in those with metabolically healthy obesity (MHO; n = 48, p > 0.05). Circulating ANGPTL4, by contrast, was increased in all obese subgroups (all p < 0.001 vs. lean subjects). Vasodilator responses to both acetylcholine and sodium nitroprusside were reduced in the three obese subgroups vs. lean subjects (all p < 0.001), with greater impairment in the patients with T2D than in those with MHO and MUO (all p < 0.05). In the whole population, an inverse relationship (r = 0.27; p = 0.003) was observed between circulating ANGPTL4 and endothelium-dependent vasorelaxation. Circulating ANGPTL3 and ANGPTL4 undergo variable changes in obese patients with different metabolic phenotypes; changes in ANGPTL4 relate to endothelial dysfunction, making this protein a possible target for vascular prevention in these patients.
Structural Dissection of Viral Spike-Protein Binding of SARS-CoV-2 and SARS-CoV-1 to the Human Angiotensin-Converting Enzyme 2 (ACE2) as Cellular Receptor
Authors: Giordano Deborah , De Masi Luigi , Argenio Maria Antonia , Facchiano Angelo
Published: August 2021

An outbreak by a new severe acute respiratory syndrome betacoronavirus (SARS-CoV-2) has spread CoronaVirus Disease 2019 (COVID-19) all over the world. Immediately, following studies have confirmed the human Angiotensin-Converting Enzyme 2 (ACE2) as a cellular receptor of viral Spike-Protein (Sp) that mediates the CoV-2 invasion into the pulmonary host cells. Here, we compared the molecular interactions of the viral Sp from previous SARS-CoV-1 of 2002 and SARS-CoV-2 with the host ACE2 protein by in silico analysis of the available experimental structures of Sp-ACE2 complexes. The K417 amino acid residue, located in the region of Sp Receptor-Binding Domain (RBD) of the new coronavirus SARS-CoV-2, showed to have a key role for the binding to the ACE2 N-terminal region. The R426 residue of SARS-CoV-1 Sp-RBD also plays a key role, although by interacting with the central region of the ACE2 sequence. Therefore, our study evidenced peculiarities in the interactions of the two Sp-ACE2 complexes. Our outcomes were consistent with previously reported mutagenesis studies on SARS-CoV-1 and support the idea that a new and different RBD was acquired by SARS-CoV-2. These results have interesting implications and suggest further investigations.
Characterization of Intracellular Structure Changes of Microcystis under Sonication Treatment by Polarized Light Scattering
Authors: Li Jiajin , Zou Chujun , Liao Ran , Peng Liang , Wang Hongjian , Guo Zhiming , Ma Hui
Published: August 2021

Cyanobacterial bloom is one of the most urgent global environmental issues, which eventually could threaten human health and safety. Sonication treatment (ST) is a potential effective method to control cyanobacteria blooms in the field. Currently, the bottleneck of extensive application of ST is the difficulty to estimate the ST effect on the cyanobacterial cells and then determine suitable ST times in the field. In this study, cyanobacterial Microcystis samples sonicated at different times were first measured by a spectrophotometer to calculate the removal efficiency of Microcystis cells. Additionally, they were observed by TEM to reveal the intracellular structure changes of the cells. Then the samples were measured by an experimental setup based on polarized light scattering to measure the polarization parameters. Experimental results indicated that the polarization parameters can effectively characterize the intracellular structural changes of Microcystis cells with different ST times, which is quite consistent with the results for removal efficiency and TEM images. Further, the optimal ST time can be inferred by the polarization parameters. These results demonstrate that polarized light scattering can be a potentially powerful tool to explore suitable times for sonication treatment of cyanobacteria blooms.
Inflammatory Biomarkers in Febrile Seizure: A Comprehensive Bibliometric, Review and Visualization Analysis
Authors: Maniu Ionela , Costea Raluca , Maniu George , Neamtu Bogdan Mihai
Published: August 2021

Background: Inflammatory markers association with many diseases is the subject of many articles and reviews. This study presents a comprehensive bibliometric review and visualization analysis of inflammatory biomarkers (IB) in the context of febrile seizure (FS) patients. Methods: The study focused on IB in FS using (1) bibliometric analysis specific indicators and maps in order to analyze and present the network of authors, journals, universities, and countries, and (2) automated literature screening and unsupervised clustering approach for filtering and topic cluster identification. Results: We conducted a literature mining search on FS research, specifically IB in the context of FS, using the automated tools VOSviewer and Bibliometrix. Indices of the inflammatory response (in the context of febrile seizures) identified by the literature mining are (pro/anti-inflammatory) cytokines, such as interleukin IL-1β, IL-6, IL-8, I-10, IL-22, tumor necrosis factor (TNF-α), neutrophil-to-lymphocyte ratio (NLR), mean platelet volume (MPV), platelet count (PLT), and red blood cell distribution width (RDW). The resulted bibliometric maps and topic clusters offer a comprehensive overview, the status and leading trends on existing research of inflammatory biomarkers in FS. Conclusion: The analysis using bibliometrics and review with graphical presentations can be useful in investigating and (better) understanding the relationship between FS and IB.
Eco-Sustainable Wood Waste Panels for Building Applications: Influence of Different Species and Assembling Techniques on Thermal, Acoustic, and Environmental Performance
Authors: Merli Francesca , Belloni Elisa , Buratti Cinzia
Published: August 2021

Multiple high quality wood waste from a window manufacturer is identified and collected. Eco-sustainable panels, with promising acoustic and thermal insulating performance, were then fabricated. The available wood is of different tree species (pine, oak, and mahogany) and size (pieces of wood, mixed coarse chips, and mixed fine chips). Moreover, scraps of olive tree pruning from local areas were collected for reuse. The aim of the research is to assembly panels (300 × 300 mm2) both with different techniques (hand-made and hot-pressed) and type of adhesive (vinyl and flour glues) and to evaluate their thermal, acoustic, and environmental performance. All the panels present thermal and acoustic performance comparable with the similar ones available in the literature or with commercial solutions. The thermal conductivity varies in the 0.071 to 0.084 W/mK range at an average temperature of 10 °C, depending on the tree species, the assembly technique, and regardless of the type of adhesive used. Oak wood panels are characterized by both better sound absorption (α peak value of 0.9, similar to pine pressed sample with flour glue) and insulation (transmission loss up to 11 dB at 1700 Hz) properties. However, their added value is the low environmental impact assessed through life cycle analysis in compliance with ISO 14040, especially for panels assembled with natural glue.
Environmental Product Declarations of Structural Wood: A Review of Impacts and Potential Pitfalls for Practice
Authors: Rasmussen Freja , Andersen Camilla , Wittchen Alexandra , Hansen Rasmus , Birgisdóttir Harpa
Published: August 2021

The use of wood and timber products in the construction of buildings is repeatedly pointed towards as a mean for lowering the environmental footprint. With several countries preparing regulation for life cycle assessment of buildings, practitioners from industry will presumably look to the pool of data on wood products found in environmental product declarations (EPDs). However, the EPDs may vary broadly in terms of reporting and results. This study provides a comprehensive review of 81 third-party verified EN 15804 EPDs of cross laminated timber (CLT), glulam, laminated veneer lumber (LVL) and timber. The 81 EPDs represent 86 different products and 152 different product scenarios. The EPDs mainly represent European production, but also North America and Australia/New Zealand productions are represented. Reported global warming potential (GWP) from the EPDs vary within each of the investigated product categories, due to density of the products and the end-of-life scenarios applied. Median results per kg of product, excluding the biogenic CO2, are found at 0.26, 0.24, and 0.17 kg CO2e for CLT, glulam, and timber, respectively. Results further showed that the correlation between GWP and other impact categories is limited. Analysis of the inherent data uncertainty showed to add up to ±41% to reported impacts when assessed with an uncertainty method from the literature. However, in some of the average EPDs, even larger uncertainties of up to 90% for GWP are reported. Life cycle assessment practitioners can use the median values from this study as generic data in their assessments of buildings. To make the EPDs easier to use for practitioners, a more detailed coordination between EPD programs and their product category rules is recommended, as well as digitalization of EPD data.
A Social Network-Based Examination on Bid Riggers’ Relationships in the Construction Industry: A Case Study of China
Authors: Xiao Liang , Ye Kunhui , Zhou Junhong , Ye Xiaoting , Tekka Ramadhani Said
Published: August 2021

Collusive bidding has been an insidious issue in the construction industry. Bidders initiate collusive networks of various sizes to win market shares. The popularity of collusive bidding networks affects market fairness and erodes the interests of market players. Although considerable research efforts were made to diagnose collusive bidding networks, there remains a gap in knowledge regarding the relationships bid riggers use to engage in the networks. Therefore, this study used the social network method, where two hundred sixteen collusion cases were collected from China to test these relationships. The results show that collusive bidding networks were characterized by sparseness, a small scale, a high concentration, and strong randomness. Three types of collusive bidding networks were also detected: contractual, spontaneous, and shadow. Furthermore, these collusive bidding networks had discrepancies regarding participants’ identities, forms of collusive bids, and the determination of bid winners. It was found that the proposed social network model of deliberating bid riggers’ relationships lays a solid foundation for the detection of collusive bidding in the construction sector.
First-Principles Study of Electronic and Optical Properties of Two-Dimensional WSSe/BSe van der Waals Heterostructure with High Solar-to-Hydrogen Efficiency
Authors: Zhu Zhengyang , Ren Kai , Shu Huabing , Cui Zhen , Huang Zhaoming , Yu Jin , Xu Yujing
Published: August 2021

In this paper, the optical and electronic properties of WSSe/BSe heterostructure are investigated by first-principles calculations. The most stable stacking pattern of the WSSe/BSe compounds is formed by van der Waals interaction with a thermal stability proved by ab initio molecular dynamics simulation. The WSSe/BSe heterostructure exhibits a type-I band alignment with direct bandgap of 2.151 eV, which can improve the effective recombination of photoexcited holes and electrons. Furthermore, the band alignment of the WSSe/BSe heterostructure can straddle the water redox potential at pH 0–8, and it has a wide absorption range for visible light. In particular, the solar-to-hydrogen efficiency of the WSSe/BSe heterostructure is obtained at as high as 44.9% at pH 4 and 5. All these investigations show that the WSSe/BSe heterostructure has potential application in photocatalysts to decompose water.
Drosophila, an Integrative Model to Study the Features of Muscle Stem Cells in Development and Regeneration
Authors: Boukhatmi Hadi
Published: August 2021

Muscle stem cells (MuSCs) are essential for muscle growth, maintenance and repair. Over the past decade, experiments in Drosophila have been instrumental in understanding the molecular and cellular mechanisms regulating MuSCs (also known as adult muscle precursors, AMPs) during development. A large number of genetic tools available in fruit flies provides an ideal framework to address new questions which could not be addressed with other model organisms. This review reports the main findings revealed by the study of Drosophila AMPs, with a specific focus on how AMPs are specified and properly positioned, how they acquire their identity and which are the environmental cues controlling their behavior and fate. The review also describes the recent identification of the Drosophila adult MuSCs that have similar characteristics to vertebrates MuSCs. Integration of the different levels of MuSCs analysis in flies is likely to provide new fundamental knowledge in muscle stem cell biology largely applicable to other systems.
Biomarkers of Allostatic Load as Correlates of Impairment in Youth with Chronic Pain: An Initial Investigation
Authors: Nelson Sarah , Bento Samantha , Enlow Michelle Bosquet
Published: August 2021

Pediatric chronic pain is common and responsible for significant healthcare burden. However, the mechanisms underlying the development and/or maintenance of pediatric chronic pain remain poorly understood. Allostatic load (AL), or wear and tear on the nervous system following significant or prolonged stress, has been proposed to play a role in the maintenance of chronic pain, but minimal research has examined this possibility. This gap in research is particularly notable given the high exposure to adverse childhood experiences (ACEs; abuse/neglect, etc.) and psychological stress in this population. Accordingly, the current study aimed to preliminarily examine the measurement of AL in a treatment-seeking pediatric pain population. Biomarkers were collected during an already scheduled new patient pain evaluation and included salivary cortisol, dehydroepiandrosterone (DHEA), and C-reactive protein, in addition to waist–hip ratio, body-mass index, and blood pressure. A total of 61 children and adolescents with chronic pain (Mage = 14.47 years; 88.5% female and white/Caucasian) completed study procedures and were included in analyses. Preliminary results indicated that a multifactorial AL composite is feasible to assess for in a tertiary pain treatment setting and that over 50% of youth with chronic pain were classified as high risk for AL (two or more risk factors). Further, it was found that individual AL risk factors were significantly associated with functional disability and that AL may moderate the association between psychosocial and functional outcomes. Given the pilot nature of this study, results should be used to inform future investigations with larger and more diverse pediatric pain samples.
The Relationship between Sarcopenic Obesity, Weight-Loss and Maintenance Outcomes during Obesity Management: Are Additional Strategies Required?
Authors: El Masri Dana , Itani Leila , Tannir Hana , Kreidieh Dima , El Ghoch Marwan
Published: August 2021

The lack of long-term maintenance of the weight loss achieved during weight-management programs is the major cause of failure in obesity treatments. The identification of factors related to this outcome has clinical implications. Therefore, we aimed to assess the relationship between sarcopenic obesity (SO) and the weight-loss percentage (WL%). The WL% was measured at the six-month follow-up and after more than 12 months, in 46 adult participants with obesity, during an individualized weight-management program where participants were categorized as having or not having SO at the baseline. At the six-month follow-up, participants with SO did not display a significant difference in terms of WL%, when compared to those without SO (−10.49 ± 5.75% vs. −12.73 ± 4.30%; p = 0.148). However, after a longer term (i.e., >12 months), the WL% appeared to be significantly lower in the former (SO vs. non-SO) (−7.34 ± 6.29% vs. −11.43 ± 4.31%; p = 0.024). In fact, partial correlation analysis revealed a relationship between SO at the baseline and a lower WL% after more than 12 months (ρ = −0.425, p = 0.009), after controlling for age, sex, and body mass index (BMI). Participants with SO appeared to face more difficulties in maintaining the achieved WL over a longer term (>12 months follow-up) by comparison with their counterparts (i.e., non-SO). Should this finding be replicated in larger-sample studies, new strategies should be adopted for these patients in order to improve this clinical outcome, especially during the weight-maintenance phase.
CuI/Spiro-OMeTAD Double-Layer Hole Transport Layer to Improve Photovoltaic Performance of Perovskite Solar Cells
Authors: Lu Chaoqun , Zhang Weijia , Jiang Zhaoyi , Zhang Yulong , Ni Cong
Published: August 2021

The hole transport layer (HTL) is one of the main factors affecting the efficiency and stability of perovskite solar cells (PSCs). However, obtaining HTLs with the desired properties through current preparation techniques remains a challenge. In the present study, we propose a new method which can be used to achieve a double-layer HTL, by inserting a CuI layer between the perovskite layer and Spiro-OMeTAD layer via a solution spin coating process. The CuI layer deposited on the surface of the perovskite film directly covers the rough perovskite surface, covering the surface defects of the perovskite, while a layer of CuI film avoids the defects caused by Spiro-OMetad pinholes. The double-layer HTLs improve roughness and reduce charge recombination of the Spiro-OMeTAD layer, thereby resulting in superior hole extraction capabilities and faster hole mobility. The CuI/Spiro-OMeTAD double-layer HTLs-based devices were prepared in N2 gloveboxes and obtained an optimized PCE (photoelectric conversion efficiency) of 17.44%. Furthermore, their stability was improved due to the barrier effect of the inorganic CuI layer on the entry of air and moisture into the perovskite layer. The results demonstrate that another deposited CuI film is a promising method for realizing high-performance and air-stable PSCs.
Complementing Privacy and Utility Trade-Off with Self-Organising Maps
Authors: Mohammed Kabiru , Ayesh Aladdin , Boiten Eerke
Published: August 2021

In recent years, data-enabled technologies have intensified the rate and scale at which organisations collect and analyse data. Data mining techniques are applied to realise the full potential of large-scale data analysis. These techniques are highly efficient in sifting through big data to extract hidden knowledge and assist evidence-based decisions, offering significant benefits to their adopters. However, this capability is constrained by important legal, ethical and reputational concerns. These concerns arise because they can be exploited to allow inferences to be made on sensitive data, thus posing severe threats to individuals’ privacy. Studies have shown Privacy-Preserving Data Mining (PPDM) can adequately address this privacy risk and permit knowledge extraction in mining processes. Several published works in this area have utilised clustering techniques to enforce anonymisation models on private data, which work by grouping the data into clusters using a quality measure and generalising the data in each group separately to achieve an anonymisation threshold. However, existing approaches do not work well with high-dimensional data, since it is difficult to develop good groupings without incurring excessive information loss. Our work aims to complement this balancing act by optimising utility in PPDM processes. To illustrate this, we propose a hybrid approach, that combines self-organising maps with conventional privacy-based clustering algorithms. We demonstrate through experimental evaluation, that results from our approach produce more utility for data mining tasks and outperforms conventional privacy-based clustering algorithms. This approach can significantly enable large-scale analysis of data in a privacy-preserving and trustworthy manner.
The Deposit Formation Mechanism in Coal-Fired Rotary Kiln for Iron Ore Pellet Production: A Review
Authors: Wang Shuai , Guo Yufeng , Liu Kuo , Yang Zhuang , Liu Yajing , Jiang Ying , Chen Feng , Zheng Fuqiang , Yang Lingzhi
Published: August 2021

The deposit-forming problem is one of the main bottlenecks restricting the yield and production benefit of iron ore pellets produced by coal-fired rotary kilns. In order to implement measures to ensure the efficient production of pellets by coal-fired rotary kilns, the mechanism and influencing factors on the deposit formation were reviewed. The pellet powder and coal ash come together to form the material base of the deposit. Meanwhile, the local reducing atmosphere caused by the continued combustion of residual carbon increases the FeO content, resulting in the formation of low-melting-point silicates. Moreover, alkali metal elements in coal ash can also promote liquid phase formation to cause serious deposit aggregation problems. During high-temperature roasting, the liquid phase corrodes the surface of the refractory brick to form the initial deposit, whereafter, it binds the pellet powder and coal ash from the material layer, which causes the deposit to accumulate continuously. The deposit formation of coal-fired rotary kilns is the result of interaction between many factors, which includes the quality of the green pellets, the composition of coal ash, the combustion efficiency of pulverized coal, roasting temperature, FeO content and alkali metal input. Finally, it is recommended that some measures to mitigate deposit formation can be adopted, such as increasing the compression strength of preheated pellets, choosing high-quality raw materials with low alkali metals, improving the combustion of pulverized coal.
Systematic Comparison on Convective Heat Transfer Characteristics of Several Pin Fins for Turbine Cooling
Authors: Xu Jin , Zhang Ke , Duan Jingtian , Lei Jiang , Wu Junmei
Published: August 2021

This paper is focused on the heat transfer augment ability and friction factor of different cross-section pin fins. An experimental study is conducted in a wide rectangular channel. The steady-state thermochromic liquid crystals (TLC) method is applied to measure the tested surface temperature. Nine sets of pin fins are employed in the experiment. The nominal diameter of all pin fins is the same value. Nine sets of pin fins have three roundness shapes (Circle, Ellipse and Oblong), three streamline shapes (Dropform, NACA and Lancet) and three quadrangle shapes (Diamond, Diamond-s and Square), respectively. The arrangement parameters of all nine shapes are kept the same. As they have the same nominal diameter and arrangement, the channel blockage ratio is the same for each pin fin set. Reynolds numbers range from 10,000 to 60,000. The pressure losses of pin fin arrays are measured to obtain friction factor. Meanwhile, the overall thermal performances of all nine sets are also considered and compared. The results show heat transfer enhancement abilities of quadrangle shape pin fins are relatively higher than the roundness and streamline shapes. Diamond-s pin fins present the largest averaged Nusselt number and overall thermal performance on the endwall for all the nine pin fins under different Re. Concerning overall thermal performance, the traditional Circle pin fin is the second best. The pressure loss of streamline shape pin fins is the lowest in these three shape types. Moreover, the characteristic of local heat transfer distribution varies substantially for different pin shapes at low Re.
Mesomorphic Behaviour and DFT Insight of Arylidene Schiff Base Liquid Crystals and Their Pyridine Impact Investigation
Authors: Zakaria Mohamed A. , Alazmi Mohammed , Katariya Kanubhai D. , El Kilany Yeldez , El Ashry El Sayed H. , Jaremko Mariusz , Hagar Mohamed , Mohammady Sayed Z.
Published: August 2021

A new series of Schiff base liquid crystal have been prepared and studied. Schiff bases of p-alkyl aniline derivatives and 4-phenyl pyridine-4′-carbaldehyde were prepared. The terminal alkyl groups substituting aniline are of varied chain length, namely C8, C12 and C14. The structures of the compounds were elucidated by 1H NMR and 13C NMR. The mesomorphic thermal and optical characteristics of the samples were determined via differential thermal analysis (DSC) and polarization optical microscopy (POM). All compounds exhibit enantiotropic dimorphic mesophase behaviour, referred to as smectic X1 (SmX1) and smectic X2 (Sm A). Experimental results obtained for the mesophases were correlated with density functional theory (DFT) theoretical calculations. The results of the new series are further compared to two series of compounds bearing pyridine (two ring Schiff bases) and biphenyl, respectively, in their mesogens. The series of compounds of one pyridine ring are generally not mesomorphic. The results indicate that the alkyl chain length has a strong impact on the mesomorphic characteristics and thermal stabilities of the different mesophases. As a trend, the temperature ranges of both of smectic mesophases of all compounds are higher in new compounds bearing the 4-phenyl pyridine moiety. In addition, the total mesophase range is generally higher in the new compounds when compared to their biphenyl analogues. Finally, theoretical DFT calculations were performed to illustrate the experimental finding of the mesomorphic behaviour in terms of the molecular geometry and aromaticity, π–π stacking and LOL-π.
RF-Characterization of HZO Thin Film Varactors
Authors: Abdulazhanov Sukhrob , Le Quang Huy , Huynh Dang Khoa , Wang Defu , Lederer Maximilian , Olivo Ricardo , Mertens Konstantin , Emara Jennifer , Kämpfe Thomas , Gerlach Gerald
Published: August 2021

A microwave characterization at UHF band of a ferroelectric hafnium zirconium oxide metal-ferroelectric-metal (MFM) capacitors for varactor applications has been performed. By using an impedance reflectivity method, a complex dielectric permittivity was obtained at frequencies up to 500 MHz. Ferroelectric Hf0.5Zr0.5O2 of 10 nm thickness has demonstrated a stable permittivity switching in the whole frequency range. A constant increase of the calculated dielectric loss is observed, which is shown to be an effect of electric field distribution on highly resistive titanium nitride (TiN) thin film electrodes. The C-V characteristics of a “butterfly” shape was also extracted, where the varactors exhibited a reduction of capacitance tunability from 18.6% at 10 MHz to 15.4% at 500 MHz.
Cesarean Hysterectomy in Abnormally Invasive Placenta: The Role of Prenatal Diagnosis
Authors: Cubo Ana Maria , Villalba Yarza Ana , Gastaca Irene , Lapresa-Alcalde María Victoria , Doyague Maria José , Gónzalez Cristina , Sayagués José María
Published: August 2021

An abnormally invasive placenta (AIP) is a placenta that cannot be removed spontaneously or manually without causing severe bleeding. It is a dangerous condition associated with a high rate of maternal and perinatal morbidity and mortality due to the high rate of massive bleeding and visceral injuries. The standardized ultrasound diagnostic criteria have helped improve its early diagnosis, which is essential to plan coordinated actions to reduce associated morbimortality. We present a case report in which ultrasound diagnosis played a decisive role, enabling the coordination of a multidisciplinary team and improving the immediate care of both mother and newborn. Cesarean hysterectomy was performed with minimal blood loss and a good postsurgical recovery.
A Novel Framework for Anomaly Detection for Satellite Momentum Wheel Based on Optimized SVM and Huffman-Multi-Scale Entropy
Authors: Li Yuqing , Lei Mingjia , Liu Pengpeng , Wang Rixin , Xu Minqiang
Published: August 2021

The health status of the momentum wheel is vital for a satellite. Recently, research on anomaly detection for satellites has become more and more extensive. Previous research mostly required simulation models for key components. However, the physical models are difficult to construct, and the simulation data does not match the telemetry data in engineering applications. To overcome the above problem, this paper proposes a new anomaly detection framework based on real telemetry data. First, the time-domain and frequency-domain features of the preprocessed telemetry signal are calculated, and the effective features are selected through evaluation. Second, a new Huffman-multi-scale entropy (HMSE) system is proposed, which can effectively improve the discrimination between different data types. Third, this paper adopts a multi-class SVM model based on the directed acyclic graph (DAG) principle and proposes an improved adaptive particle swarm optimization (APSO) method to train the SVM model. The proposed method is applied to anomaly detection for satellite momentum wheel voltage telemetry data. The recognition accuracy and detection rate of the method proposed in this paper can reach 99.60% and 99.87%. Compared with other methods, the proposed method can effectively improve the recognition accuracy and detection rate, and it can also effectively reduce the false alarm rate and the missed alarm rate.
Occlusion-Based Explanations in Deep Recurrent Models for Biomedical Signals
Authors: Resta Michele , Monreale Anna , Bacciu Davide
Published: August 2021

The biomedical field is characterized by an ever-increasing production of sequential data, which often come in the form of biosignals capturing the time-evolution of physiological processes, such as blood pressure and brain activity. This has motivated a large body of research dealing with the development of machine learning techniques for the predictive analysis of such biosignals. Unfortunately, in high-stakes decision making, such as clinical diagnosis, the opacity of machine learning models becomes a crucial aspect to be addressed in order to increase the trust and adoption of AI technology. In this paper, we propose a model agnostic explanation method, based on occlusion, that enables the learning of the input’s influence on the model predictions. We specifically target problems involving the predictive analysis of time-series data and the models that are typically used to deal with data of such nature, i.e., recurrent neural networks. Our approach is able to provide two different kinds of explanations: one suitable for technical experts, who need to verify the quality and correctness of machine learning models, and one suited to physicians, who need to understand the rationale underlying the prediction to make aware decisions. A wide experimentation on different physiological data demonstrates the effectiveness of our approach both in classification and regression tasks.
Causality in Reversed Time Series: Reversed or Conserved?
Authors: Kořenek Jakub , Hlinka Jaroslav
Published: August 2021

The inference of causal relations between observable phenomena is paramount across scientific disciplines; however, the means for such enterprise without experimental manipulation are limited. A commonly applied principle is that of the cause preceding and predicting the effect, taking into account other circumstances. Intuitively, when the temporal order of events is reverted, one would expect the cause and effect to apparently switch roles. This was previously demonstrated in bivariate linear systems and used in design of improved causal inference scores, while such behaviour in linear systems has been put in contrast with nonlinear chaotic systems where the inferred causal direction appears unchanged under time reversal. The presented work explores the conditions under which the causal reversal happens—either perfectly, approximately, or not at all—using theoretical analysis, low-dimensional examples, and network simulations, focusing on the simplified yet illustrative linear vector autoregressive process of order one. We start with a theoretical analysis that demonstrates that a perfect coupling reversal under time reversal occurs only under very specific conditions, followed up by constructing low-dimensional examples where indeed the dominant causal direction is even conserved rather than reversed. Finally, simulations of random as well as realistically motivated network coupling patterns from brain and climate show that level of coupling reversal and conservation can be well predicted by asymmetry and anormality indices introduced based on the theoretical analysis of the problem. The consequences for causal inference are discussed.
Heat Transfer and Entropy in a Vertical Porous Plate Subjected to Suction Velocity and MHD
Authors: Ahammad N. Ameer , Badruddin Irfan Anjum , Kamangar Sarfaraz , Khaleed H.M.T. , Saleel C. Ahamed , Mahlia Teuku Meurah Indra
Published: August 2021

This article presents an investigation of heat transfer in a porous medium adjacent to a vertical plate. The porous medium is subjected to a magnetohydrodynamic effect and suction velocity. The governing equations are nondepersonalized and converted into ordinary differential equations. The resulting equations are solved with the help of the finite difference method. The impact of various parameters, such as the Prandtl number, Grashof number, permeability parameter, radiation parameter, Eckert number, viscous dissipation parameter, and magnetic parameter, on fluid flow characteristics inside the porous medium is discussed. Entropy generation in the medium is analyzed with respect to various parameters, including the Brinkman number and Reynolds number. It is noted that the velocity profile decreases in magnitude with respect to the Prandtl number, but increases with the radiation parameter. The Eckert number has a marginal effect on the velocity profile. An increased radiation effect leads to a reduced thermal gradient at the hot surface.
Cointegration, Root Functions and Minimal Bases
Authors: Franchi Massimo , Paruolo Paolo
Published: August 2021

This paper discusses the notion of cointegrating space for linear processes integrated of any order. It first shows that the notions of (polynomial) cointegrating vectors and of root functions coincide. Second, it discusses how the cointegrating space can be defined (i) as a vector space of polynomial vectors over complex scalars, (ii) as a free module of polynomial vectors over scalar polynomials, or finally (iii) as a vector space of rational vectors over rational scalars. Third, it shows that a canonical set of root functions can be used as a basis of the various notions of cointegrating space. Fourth, it reviews results on how to reduce polynomial bases to minimal order—i.e., minimal bases. The application of these results to Vector AutoRegressive processes integrated of order 2 is found to imply the separation of polynomial cointegrating vectors from non-polynomial ones.
A Two-Stage DEA Model to Evaluate the Performance of Iberian Banks
Authors: Moutinho Victor , Vale José , Bertuzi Rui , Bandeira Ana Maria , Palhares José
Published: August 2021

This paper’s goal is twofold: it aims to assess the performance of 58 Iberian banks and explore the relationship between such performance and the banks’ Intellectual Capital (IC) efficiency during a post-crisis period. As long as the authors are aware, there is a gap in the literature in exploring the relationship between banks’ global performance and IC efficiency. First, the Data Envelopment Analysis model was adopted to measure the efficiency of Iberian banks and rank them according to their performance. Data were collected digitally, specifically by using the Bankscope database provided by Bureau van Dijk. Results show that by improving their resources management practices, banks can significantly increase their efficiency. Then, fractional regressions were used to infer the relationship between IC’s efficiency and the scores obtained in the first stage. Results suggest that Iberian banks’ global performance is mainly determined by their human capital efficiency. Finally, this study stresses the importance of IC measurement to support more efficient decision-making by bank managers.
Collaborative Video-Based Learning Using Tablet Computers to Teach Job Skills to Students with Intellectual Disabilities
Authors: Roldán-Álvarez David , Martín Estefanía , Haya Pablo A.
Published: August 2021

Information and Communication Technologies (ICT) provide different opportunities to students with intellectual disabilities and to professionals who work with them. However, few studies address the use of collaborative learning platforms and handheld devices to enhance the integration of people with intellectual disabilities in the labour market. We present a learning experience where active methodologies, such as collaborative work, are combined with the use of iPads and a learning management system following a video self-modelling methodology. The goal of this study was to determine whether the combination of traditional methodologies and new could be appropriate for students with intellectual disabilities and how they behave when having to rate their partner’s work. The results show that the combination of active learning methodologies, video self-modelling and the use of learning platforms and tablets is promising for teaching job related skills to students with intellectual disabilities, as participants experienced increased motivation to complete the tasks, improving their skills in the process.
Roles of the School Psychologist–Current versus Preferred Roles in the Greek Schools: A Case Study from the Island of Crete
Authors: Panteri Maria , Calmaestra Juan , Marín-Díaz Verónica
Published: August 2021

In the international literature it is frequently reported that school psychologists would like to reduce their involvement in evaluation and assessment activities in favor of an increase in other services and roles. The present study examines the perceptions of teachers and school psychologists regarding the roles of school psychologists on the island of Crete, Greece. For this purpose, an online questionnaire about the current and preferred roles of the school psychologist was distributed. Two hundred and seventy-nine (279) teachers and fifty-seven (57) school psychologists participated in this research study. The analysis and comparison of the participants’ responses revealed significant differences in their beliefs about the current and preferred roles of the psychologist. Emphasis was placed by psychologists on systematic interventions such as consultation and by teachers on counseling for their personal problems. Overall, respondents in this study recognized the usefulness of the school psychologist in the educational sector. A unified framework of reference for the range of the schools’ psychological services would enhance common understanding and facilitate the professional role of school psychologists and effective student referral to the related professional services.
Learning and Well-Being in Educational Practices with Children and Adolescents Undergoing Cancer Treatment
Authors: dos Santos Paulo Ricardo , Barbosa Débora N. F. , Neto Eduardo G. Azevedo , Barbosa Jorge L. V. , Correia Sérgio D. , Leithardt Valderi R. Q.
Published: August 2021

The use of information communication technologies (ICT) in education brings up new possibilities of promoting learning and health experiences. In this sense, education contexts of the 21st century must consider these two areas of knowledge, especially their integration. This article presents learning practices developed with mobile devices and games in order to improve learning and well-being in children and adolescents undergoing cancer treatment in a non-formal educational setting. The methodology is based on qualitative case studies with content-based data analyses, involving informal interviews and observation methods. The study considers data from five patients who participated in the research between 2015 and 2019. The results demonstrate a positive influence of the practices with mobile technologies and games in terms of learning and in the well-being experience of patients during the treatment.
Mapping K-12 Computer Science Teacher’s Interest, Self-Confidence, and Knowledge about the Use of Educational Robotics to Teach
Authors: Dorotea Nuno , Piedade João , Pedro Ana
Published: August 2021

This paper reports a case study, developed in K-12 Portuguese Education, that aimed to analyze the computer science teachers’ knowledge, interest, and self-confidence to use educational robotics and other programable objects in classroom activities to teach computer science concepts and to promote students’ computational thinking skills. The research design was organized into a descriptive and exploratory quantitative approach. The participants were 174 in-service computer science teachers of Portuguese public education. The data was gathered from the participants, through the online application of the Robotics Interest Questionnaire scale (RIQ). Very positive levels of teacher’s knowledge, interest, and self-efficacy to use educational robotics for teaching purposes were reported in the study outcomes. These constructs were underlined in several studies as relevant factors to promote the use of educational robotics and other similar technologies by the teachers. Despite the study limitations and the small context, a set of relevant results was highlighted on computer science in-service teachers’ interest and preparation to use robotics and to support their students in learning activities with these artifacts.
Spoof Surface Plasmon Polaritons Developed from SIW Using Ring Slots and Vias
Authors: Tan Longfei , Xu Kaida , Liu Yiqun , Guo Yingjiang , Cui Jianlei
Published: August 2021

A new type of spoof surface plasmon polaritons (SSPPs) developed from conventional substrate integrated waveguide (SIW) using ring slots and vias is proposed in this paper. The asymptotic frequency and lower cutoff frequency of the SSPP structure can be easily tuned by changing the width of SIW walls and radius of the ring slot, respectively. A trapezoidal microstrip line and a small ring slot are used for the efficient mode conversion to smoothly transit from microstrip line to the proposed SSPP structure. The presented SSPPs have a flat bandpass filtering response with adjustable center frequency and bandwidth. In order to better verify the transmission and cutoff characteristics, two bandpass filters using the proposed SSPPs with relative bandwidths of 61.7% and 76.4%, respectively, are fabricated and measured. Good agreement between the simulations and measurements verifies the proposed design idea.
Induction Machine On-Line Parameter Identification for Resource-Constrained Microcontrollers Based on Steady-State Voltage Model
Authors: Kostal Tomas , Kobrle Pavel
Published: August 2021

This paper presents a new, computationally modest on-line identification method for the simultaneous estimation of the rotor resistance and magnetizing inductance of an induction machine suitable for electric drives that use an indirect field-oriented control strategy (IFOC), and their control hardware is equipped with a resource-constrained microcontroller. Such drives can be found both in the manufacturing industry and railway traction vehicles in the thousands, having either older control hardware that cannot cope with computationally excessive identification methods or being in cost-sensitive applications, thus being equipped with a low-cost microcontroller. IFOC is a very common control strategy for such drives due to its good dynamic properties and comparatively simple implementation. However, it is sensitive to inaccuracies of rotor resistance and magnetizing inductance. These two parameters change during the operation of the drive, being influenced by the temperature, frequency, and saturation of the magnetic circuit. Improper values of parameters in the controller can degrade the performance of IFOC, resulting in slower acceleration or unnecessary oversaturation of the machine. Respecting these changes can therefore bring significant benefits such as the good dynamic properties of the drive, which can shorten operations in the manufacturing industry or travel times of vehicles. A number of on-line identification methods for monitoring the parameter changes have been published so far, but the majority of them are demanding on microcontroller time or its memory. The proposed method, on the contrary, is comparatively simple and thus easy for implementation with low requirements to the microcontroller. Therefore, it is suitable for both upgrades of existing drives or new low-cost applications. Derivation of the method from the mathematical model and the final algorithm for the microcontroller are presented. The performance of the proposed method is validated with experimental results obtained with a 3.5 kW induction machine drive with an industrial microcontroller during a warming test and under various loads and frequencies.
Evaluating Common-Mode Voltage Based Trade-Offs in Differential-Ended and Single-Supplied Signal Conditioning Amplifiers
Authors: Petkovsek Marko , Zajec Peter
Published: August 2021

This paper focuses on a differential voltage measurement in low-voltage automotive devices whose subunits are separated with a low-side safety switch. In contrast to conventional applications with high-side switches, a common-mode voltage (CMV) with negative polarity exists at the input of the signal conditioning circuitry. To overcome the shortage of dedicated integrated circuits capable of withstanding negative CMV, the paper investigates single- and two-stage differential circuits with single-supplied operational amplifiers to find a cost-optimized counterpart. In addition, the proposed procedure tunes the circuit parameters in such a manner to obtain the largest possible full-scale range at the output. Though, such optimization results in very uncommon values for gain and reference voltages. This issue is additionally evaluated for reference voltages that are either cost-effective or more easily accessible to increase the circuit feasibility. Since the impact of resistances on circuits’ behaviour could be diminished to a great extent using high-precision and matched pair resistors, the sensitivity analysis was investigated only for a reference voltage change. Furthermore, a reversed termination of measured voltages results in a simplified reference voltage selection without hindering circuits’ performance, proven by simulation and experimental results.
Test for Reliability for Mission Critical Applications
Authors: Pipponzi Mauro , Sangiovanni-Vincentelli Alberto
Published: August 2021

Test for Reliability is a test flow where an Integrated Circuit (IC) device is continuously stressed under several corner conditions that can be dynamically adapted based on the real-time observation of the critical signals of the device during the evolution of the test. We present our approach for a successful Test-for-Reliability flow, going beyond the objectives of the traditional reliability approach, and covering the entire process from design to failure analysis.