bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the Sub-Tour Elimination Methods for the Asymmetric Traveling Salesman Problem Applying the SECA Method
Authors: Bazrafshan Ramin , Hashemkhani Zolfani Sarfaraz Hashemkhani , Al-e-hashem S. Mohammad J. Mirzapour
Published: February 2021

There are many sub-tour elimination constraint (SEC) formulations for the traveling salesman problem (TSP). Among the different methods found in articles, usually three apply more than others. This study examines the Danzig–Fulkerson–Johnson (DFJ), Miller–Tucker–Zemlin (MTZ), and Gavish–Graves (GG) formulations to select the best asymmetric traveling salesman problem (ATSP) formulation. The study introduces five criteria as the number of constraints, number of variables, type of variables, time of solving, and differences between the optimum and the relaxed value for comparing these constraints. The reason for selecting these criteria is that they have the most significant impact on the mathematical problem-solving complexity. A new and well-known multiple-criteria decision making (MCDM) method, the simultaneous evaluation of the criteria and alternatives (SECA) method was applied to analyze these criteria. To use the SECA method for ranking the alternatives and extracting information about the criteria from constraints needs computational computing. In this research, we use CPLEX 12.8 software to compute the criteria value and LINGO 11 software to solve the SECA method. Finally, we conclude that the Gavish–Graves (GG) formulation is the best. The new web-based software was used for testing the results.
From Clonal Hematopoiesis to Therapy-Related Myeloid Neoplasms: The Silent Way of Cancer Progression
Authors: Gurnari Carmelo , Fabiani Emiliano , Falconi Giulia , Travaglini Serena , Ottone Tiziana , Cristiano Antonio , Voso Maria Teresa
Published: February 2021

Clonal hematopoiesis (CH) has been recognized as a predisposing factor for the development of myeloid malignancies. Its detection has been reported at different frequencies across studies, based on the type of genome scanning approach used and the population studied, but the latest insights recognize its virtual ubiquitous presence in older individuals. The discovery of CH in recent years paved the way for a shift in the paradigm of our understanding of the biology of therapy-related myeloid malignancies (t-MNs). Indeed, we moved from the concept of a treatment-induced lesion to a model where CH precedes the commencement of any cancer-related treatment in patients who subsequently develop a t-MN. Invariant patterns of genes seem to contribute to the arising of t-MN cases, with differences regarding the type of treatment received. Here, we review the principal studies concerning CH, the relationship with myeloid progression and the mechanisms of secondary t-MN development.
Study of Probiotic Effects of Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus plantarum 299v Strains on Biochemical and Morphometric Parameters of Rabbits after Obesity Induction
Authors: Bouaziz Assia , Dib Amira Leila , Lakhdara Nedjoua , Kadja Louiza , Espigares Elena , Moreno Elena , Bouaziz Omar , Gagaoua Mohammed
Published: February 2021

This study aimed first to develop an experimental model of obesity and metabolic syndrome over 14 weeks using a diet called “cafeteria”, which is a high-fat diet, to evaluate its consequences on the biochemical and morphometric parameters in ITELV2006 strain rabbits. Second, the trial aimed to evaluate the effect of two strains of probiotics, these being Bifidobacterium animalis subsp. lactis BB-12® and Lactobacillus plantarum 299v®, on the obesity and MetS induced during the first experiment. Overall, the results of the “cafeteria” diet demonstrated significant changes in numerous biochemical and morphometric parameters, reproducing obesity and the main clinical manifestations of the metabolic syndrome in humans. The administration of the two probiotic strains demonstrated an impact on certain parameters of obesity and induced MetS. This study makes it possible to conclude that probiotics could be useful in the treatment of obesity and metabolic syndrome of rabbits, but in a dependent manner. Furthermore, this study evidenced the importance of selecting specific probiotic strains and dosages to achieve desirable results on rabbits or other species.
Assessment of Donkey (Equus asinus africanus) Whole Blood Stored in CPDA-1 and CPD/SAG-M Blood Bags
Authors: Barros Isabella Oliveira , Sousa Rejane Santos , Tavares Marcondes Dias , Rêgo Renato Otaviano , Firmino Paulo Ricardo , Souza Francisco Jocelho Alexandre , Abrantes Maria Rociene , Minervino Antonio Humberto Hamad , Araújo Carolina Akiko Sato Cabral , Ortolani Enrico Lippi , Barrêto Júnior Raimundo Alves
Published: February 2021

Hemotherapy using whole blood and its components is being increasingly used in veterinary therapy. Since it is important to store animal blood while maintaining acceptable hematological, blood gas, and biochemical characteristics, increasing our knowledge of available technologies for strategic blood storage is imperative. Thus, we aimed to assess the hematological, blood gas, and biochemical changes in donkey whole blood using blood bags with two different types of storage agents. Eight adult healthy male donkeys were used; 900 mL of blood was collected from each, with 450 mL stored in citrate-phosphate-dextrose and adenine bags (CPDA-1) and 450 mL stored in bags containing citrate-phosphate-dextrose, adenine, mannitol, and sodium chloride (CPD/SAG-M). Both bags were kept refrigerated between 1 and 6 °C for 42 days. Blood samples were removed from the bags eight times (T): T0 (immediately after blood collection), T1, T3, T7, T14, T21, T35, and T42 (1, 3, 7, 14, 21, 35 and 42 days after storage). Hematological, blood gas, biochemical, and microbiological parameters were assessed. The CPDA-1 bags had a higher packed cell volume when compared to CPD/ SAG-M. The red blood cell count reduced by around 19% in both the bags due to hemolysis, which was confirmed by an increase in plasma hemoglobin. The white blood cell count; pH; concentrations of glucose, sodium, bicarbonate, and 2,3 diphosphoglycerate were reduced in both bags. Meanwhile, pO2, pCO2, lactate dehydrogenase, and levels of potassium increased in the CPDA-1 and CPD/SAG-M bags. Blood bags were efficient for the storage of donkey blood for up to 42 days.
Anemonia sulcata and Its Symbiont Symbiodinium as a Source of Anti-Tumor and Anti-Oxidant Compounds for Colon Cancer Therapy: A Preliminary In Vitro Study
Authors: Cabeza Laura , Peña Mercedes , Martínez Rosario , Mesas Cristina , Galisteo Milagros , Perazzoli Gloria , Prados Jose , Porres Jesús M. , Melguizo Consolación
Published: February 2021

Recently, invertebrate marine species have been investigated for the presence of natural products with antitumor activity. We analyzed the invertebrate Anemonia sulcata with (W) and without (W/O) the presence of its microalgal symbiont Symbiodinium as a source of bioactive compounds that may be applied in the therapy and/or prevention of colorectal cancer (CRC). Animals were mechanically homogenized and subjected to ethanolic extraction. The proximate composition and fatty acid profile were determined. In addition, an in vitro digestion was performed to study the potentially dialyzable fraction. The antioxidant and antitumor activity of the samples and the digestion products were analyzed in CRC cells in vitro. Our results show a high concentration of polyunsaturated fatty acid in the anemone and a great antioxidant capacity, which demonstrated the ability to prevent cell death and a high antitumor activity of the crude homogenates against CRC cells and multicellular tumor spheroids, especially W/O symbiont. These preliminary results support that Anemonia sulcata could be a source of bioactive compounds with antioxidant and antitumor potential against CRC and that the absence of its symbiont may enhance these properties. Further studies will be necessary to define the bioactive compounds of Anemonia sulcata and their mechanisms of action.
Bone Health in Aging Men: Does Zinc and Cuprum Level Matter?
Authors: Rył Aleksandra , Miazgowski Tomasz , Szylińska Aleksandra , Turoń-Skrzypińska Agnieszka , Jurewicz Alina , Bohatyrewicz Andrzej , Rotter Iwona
Published: February 2021

The aim of this study was to assess the associations of serum and bone zinc (Zn) and cuprum (Cu) with bone mineral density (BMD) and content (BMC), markers of bone turnover, and sex hormones. The study group comprised 144 men treated with total hip replacement due to hip osteoarthritis. We measured total, free, and bioavailable testosterone, estradiol, and sex-hormone-binding globulin (sex hormones), as well as parathyroid hormone, osteocalcin, carboxy terminal collagen crosslinks, and N-terminal propeptide of type I procollagen (markers of bone turnover). Total body BMD, BMC, total and visceral fat, and appendicular skeletal mass (ASM) were measured using dual-energy X-ray absorptiometry. ASM index, and total and visceral fat were positively correlated with BMD. Bone Zn correlated neither with sex hormones nor with bone turnover markers; however, it was positively associated both with BMD and with BMC, while bone Cu (as opposed to serum Cu) was not. In multiple regression, the ASM index, Zn/Cu ratio (in both the serum and the bone), and serum Cu concentration were significantly associated with BMD and BMC after adjustment for age and body mass index (BMI). Our results suggest that the Zn/Cu ratio in both the serum and the bone may exert a significant positive effect on total BMD and BMC.
Aroused and Impulsive Effects of Colour Stimuli on Lateral and Logical Abilities
Authors: Xia Guobin , Li Muzi , Henry Philip , Westland Stephen , Queiroz Francisco , Peng Qiwei , Yu Luwen
Published: February 2021

The purpose of this study was to explore the influence of environmental colour on people’s lateral and logical abilities. This was done by evaluating study participants’ response time and error rate when completing six types of psychometric tests that were performed in various hue backgrounds on a computer. To maximise the colour stimulation provided by the monitor, the experiment was carried out in a dark laboratory. Analysis of participants’ response time and error rate showed that different colours could significantly influence arousal and impulsiveness, which suggests that colour has indirect impacts on cognitive abilities. Further analysis revealed that different colours had various effects depending on the type of psychometric test given. These findings suggest that future research on environmental design should consider how to effectively use colour to impact people’s performance and behaviour.
Office Distractions and the Productivity of Building Users: The Effect of Workgroup Sizes and Demographic Characteristics
Authors: Khoshbakht Maryam , Rasheed Eziaku O. , Baird George
Published: February 2021

Knowledge workers are experiencing ever-increasing distractions or unwanted interruptions at workplaces. We explored the effect of unwanted interruptions on an individual’s perceived productivity in various building types, user groups and workgroups. A case study of 68 buildings and their 5149 occupants using the Building Use Studies methodology was employed in this study. The database contains information on the occupants’ perceptions of physical and environmental parameters, including unmined data on the frequency of unwanted interruptions. Pearson’s correlation was used to test the correlation between the variables. In order to determine whether there are any statistically significant differences between the means of two or more independent (unrelated) groups, one-way ANOVA was employed to examine the significance of differences in mean scores between various user groups and workgroups. The evidence of clear correlations between the frequency of unwanted interruptions and perceived productivity is detailed in various user groups and in multiple building types. The Pearson correlation coefficients were −0.361 and −0.348 for sustainable and conventional buildings, respectively, demonstrating a lower sensitivity to unwanted interruptions in sustainable buildings. Females and older participants were more sensitive to unwanted interruptions and their productivity levels were reduced much more by unwanted interruptions. Comparing different sized workgroups, the highest sensitivity to unwanted interruptions for occupants in offices shared with more than 8 people was found. The findings of this study contribute to the understanding of different user needs and preferences in the design of workplaces.
Molybdenum-Containing Metalloenzymes and Synthetic Catalysts for Conversion of Small Molecules
Authors: Kim Donghyeon , Lee Jaeheon , Seo Junhyeok
Published: February 2021

The energy deficiency and environmental problems have motivated researchers to develop energy conversion systems into a sustainable pathway, and the development of catalysts holds the center of the research endeavors. Natural catalysts such as metalloenzymes have maintained energy cycles on Earth, thus proving themselves the optimal catalysts. In the previous research results, the structural and functional analogs of enzymes and nano-sized electrocatalysts have shown promising activities in energy conversion reactions. Mo ion plays essential roles in natural and artificial catalysts, and the unique electrochemical properties render its versatile utilization as an electrocatalyst. In this review paper, we show the current understandings of the Mo-enzyme active sites and the recent advances in the synthesis of Mo-catalysts aiming for high-performing catalysts.
Direct Dimethyl Carbonates Synthesis over CeO2 and Evaluation of Catalyst Morphology Role in Catalytic Performance
Authors: Tamboli Ashif H. , Suzuki Norihiro , Terashima Chiaki , Gosavi Suresh , Kim Hern , Fujishima Akira
Published: February 2021

In recent years, direct synthesis of dimethyl carbonate (DMC) from carbon dioxide (CO2) has received considerable attention due to green and sustainable technology. Here, we report a production of DMC from major greenhouse gases and CO2 using various morphologies of cerium oxide (CeO2). Time-dependent synthesis of CeO2, with controlled morphology having various shapes including sphere, nanorods and spindle shape, along with its formation mechanism is proposed. The experimental results indicate the morphology of CeO2 was mostly dependent on the reaction time where crystal growth occurred through Ostwald ripening. The morphology, size and shape of CeO2 were observed using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM).The crystallographic analysis using X-ray diffraction (XRD) shows cubic fluorite phase of CeO2 with crystallite size ~72.0 nm using the Debye–Scherrer equation. The nitrogen adsorption desorption technique suggested the formation of the highly mesoporous framework of CeO2 and the excellent surface area around 104.5 m2/g obtained for CeO2 spindles by Brunauer–Emmett–Teller (BET) method. The DMC synthesis reactions were studied over CeO2 catalyst with different morphologies. The results of catalytic reactions specify that the morphology of catalyst plays an important role in their catalytic performances, where spindle shape CeO2 was the most active catalyst producing of up to13.04 mmol of DMC. Furthermore, various dehydrating agents were used to improve the DMC production at optimized reaction parameters. The overall results reveal that the higher surface area and spindle shape of CeO2 makes it a useful, reusable catalyst for one-pot DMC synthesis.
Native Aortic Valve Endocarditis Complicated by Splenic Infarction and Giant Mitral-Aortic Intervalvular Fibrosa Pseudoaneurysm—A Case Report and Brief Review of the Literature
Authors: Varga Andreea , Tilea Ioan , Tatar Cristina Maria , Iancu Dragos Gabriel , Jiga Maria Andrada , Dumbrava Robert Adrian , Pop Marian , Suciu Horatiu
Published: February 2021

Background: Pseudoaneurysm of the mitral-aortic intervalvular fibrosa (P-MAIVF) is an unusual complication related to various injuries or conditions which involve the mitro-aortic region; it communicates with the left ventricular outflow tract and is associated with a high-risk of redoubtable complications or sudden death. The cerebral and splenic localizations are frequently seen as manifestations of systemic embolism in infective endocarditis. Currently, there are no specific recommendations related to the diagnosis, management, treatment, or further evolution of patients with P-MAIVF and concomitant splenic infarction. This paper presents the case of a 43-year-old Caucasian woman with a late diagnosis of mixed bicuspid aortic valve disease, affected by an under-detected and undertreated episode of infective endocarditis leading to asymptomatic P-MAIVF. Prime clinical and imagistic diagnosis of splenic infarction indicated further extended investigations were required to clarify the source of embolism. Methods: Integrated multimodality imaging techniques confirmed the unexpected diagnosis of P-MAIVF. Results: The case had a fatal outcome following an uncomplicated yet laborious cardiac surgery. Patient death was attributed to a malignant ventricular arrhythmia. Conclusion: The present case raises awareness by highlighting an unexplained and unexpected splenic infarction association with P-MAIVF as a result of infective endocarditis related to mixed bicuspid aortic valve disease.
Tumour-Agnostic Therapy for Pancreatic Cancer and Biliary Tract Cancer
Authors: Kato Shunsuke
Published: February 2021

The prognosis of patients with solid tumours has remarkably improved with the development of molecular-targeted drugs and immune checkpoint inhibitors. However, the improvements in the prognosis of pancreatic cancer and biliary tract cancer is delayed compared to other carcinomas, and the 5-year survival rates of distal-stage disease are approximately 10 and 20%, respectively. However, a comprehensive analysis of tumour cells using The Cancer Genome Atlas (TCGA) project has led to the identification of various driver mutations. Evidently, few mutations exist across organs, and basket trials targeting driver mutations regardless of the primary organ are being actively conducted. Such basket trials not only focus on the gate keeper-type oncogene mutations, such as HER2 and BRAF, but also focus on the caretaker-type tumour suppressor genes, such as BRCA1/2, mismatch repair-related genes, which cause hereditary cancer syndrome. As oncogene panel testing is a vital approach in routine practice, clinicians should devise a strategy for improved understanding of the cancer genome. Here, the gene mutation profiles of pancreatic cancer and biliary tract cancer have been outlined and the current status of tumour-agnostic therapy in these cancers has been reported.
Medulloblastoma Associated with Down Syndrome: From a Rare Event Leading to a Pathogenic Hypothesis
Authors: Boni Alessandra , Ranalli Marco , Del Baldo Giada , Carta Roberto , Lodi Mariachiara , Agolini Emanuele , Rinelli Martina , Valentini Diletta , Rossi Sabrina , Alesi Viola , Cacchione Antonella , Miele Evelina , Alessi Iside , Caroleo Anna Maria , Colafati Giovanna Stefania , De Ioris Maria Antonietta , Boccuto Luigi , Balducci Mario , Carai Andrea , Mastronuzzi Angela
Published: February 2021

Down syndrome (DS) is the most common chromosome abnormality with a unique cancer predisposition syndrome pattern: a higher risk to develop acute leukemia and a lower incidence of solid tumors. In particular, brain tumors are rarely reported in the DS population, and biological behavior and natural history are not well described and identified. We report a case of a 10-year-old child with DS who presented with a medulloblastoma (MB). Histological examination revealed a classic MB with focal anaplasia and the molecular profile showed the presence of a CTNNB1 variant associated with the wingless (WNT) molecular subgroup with a good prognosis in contrast to our case report that has shown an early metastatic relapse. The nearly seven-fold decreased risk of MB in children with DS suggests the presence of protective biological mechanisms. The cerebellum hypoplasia and the reduced volume of cerebellar granule neuron progenitor cells seem to be a possible favorable condition to prevent MB development via inhibition of neuroectodermal differentiation. Moreover, the NOTCH/WNT dysregulation in DS, which is probably associated with an increased risk of leukemia, suggests a pivotal role of this pathway alteration in the pathogenesis of MB; therefore, this condition should be further investigated in future studies by molecular characterizations.
Passive Microwave Radiometry for the Diagnosis of Coronavirus Disease 2019 Lung Complications in Kyrgyzstan
Authors: Osmonov Batyr , Ovchinnikov Lev , Galazis Christopher , Emilov Berik , Karaibragimov Mustafa , Seitov Meder , Vesnin Sergey , Losev Alexander , Levshinskii Vladislav , Popov Illarion , Mustafin Chingiz , Kasymbekov Turat , Goryanin Igor
Published: February 2021

The global spread of severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), could be due to limited access to diagnostic tests and equipment. Currently, most diagnoses use the reverse transcription polymerase chain reaction (RT-PCR) and chest computed tomography (CT). However, challenges exist with CT use due to infection control, lack of CT availability in low- and middle-income countries, and low RT-PCR sensitivity. Passive microwave radiometry (MWR), a cheap, non-radioactive, and portable technology, has been used for cancer and other diseases’ diagnoses. Here, we tested MWR use first time for the early diagnosis of pulmonary COVID-19 complications in a cross-sectional controlled trial in order to evaluate MWR use in hospitalized patients with COVID-19 pneumonia and healthy individuals. We measured the skin and internal temperature using 30 points identified on the body, for both lungs. Pneumonia and lung damage were diagnosed by both CT scan and doctors’ diagnoses (pneumonia+/pneumonia−). COVID-19 was determined by RT-PCR (covid+/covid−). The best MWR results were obtained for the pneumonia−/covid− and pneumonia+/covid+ groups. The study suggests that MWR could be used for diagnosing pneumonia in COVID-19 patients. Since MWR is inexpensive, its use will ease the financial burden for both patients and countries. Clinical Trial Number: NCT04568525.
Autofluorescence Imaging of the Skin Is an Objective Non-Invasive Technique for Diagnosing Pseudoxanthoma Elasticum
Authors: Farkas Klára , Bozsányi Szabolcs , Plázár Dóra , Bánvölgyi András , Fésűs Luca , Anker Pálma , Zakariás Sára , Lihacova Ilze , Lihachev Alexey , Lange Marta , Arányi Tamás , Wikonkál Norbert M. , Medvecz Márta , Kiss Norbert
Published: February 2021

Pseudoxanthoma elasticum (PXE) is a rare multisystemic autosomal recessive connective tissue disease. In most cases, skin manifestations of PXE are the first to develop, followed later by severe ocular and cardiovascular complications. In our present study, in addition to dermoscopy, we introduced novel techniques, autofluorescence (AF) and diffuse reflectance (DR) imaging for the assessment of affected skin sites of five PXE patients. PXE-affected skin areas in most skin sites showed a previously observed pattern upon dermoscopic examination. With the novel imaging, PXE-affected skin lesions displayed high AF intensity. During our measurements, significantly higher mean, minimum and maximum AF intensity values were found in areas of PXE-affected skin when compared to uninvolved skin. Conversely, images acquired with the use of 660 and 940 nm illumination showed no mentionable difference. Our results demonstrate that AF imaging may be used in the in vivo diagnostics and quantification of the severity of the skin lesions of PXE patients. In addition, it is a safe, fast and cost-effective diagnostic method. AF imaging may be also used to objectively monitor the efficacy of the possible novel therapeutic approaches of PXE in the future.
Differences in Clinical Characteristics and Chest Images between Coronavirus Disease 2019 and Influenza-Associated Pneumonia
Authors: Kim Si-Ho , Wi Yu Mi , Lim Sujin , Han Kil-Tae , Bae In-Gyu
Published: February 2021

Background: Concerns are arising about the simultaneous occurrence of the coronavirus disease 2019 (COVID-19) pandemic and the influenza epidemic, the so-called “twindemic”. In this study, we compared clinical characteristics and chest images from patients with COVID-19 and influenza. Methods: We conducted a case-control study of COVID-19 and age- and sex-matched influenza patients. Clinical characteristics and chest imaging findings between patients with COVID-19 and matched influenza patient controls were compared. Results: A total of 47 patients were enrolled in each group. Anosmia (14.9%) and ageusia (21.3%) were only observed in COVID-19 patients. There were 31 (66%) and 23 (48.9%) patients with COVID-19 and influenza who had pulmonary lesions confirmed by chest computed tomography (CT), respectively. The interval between symptom onset and pneumonia was significantly longer in patients with COVID-19. Round opacities were more common in images from COVID-19 patients (41.9% vs. 8.7%, p = 0.007), whereas pure consolidation (0% vs. 34.9%, p < 0.001) and pleural effusion (0% vs. 17.4%, p = 0.028) were more common in images from influenza patients. Notably, the difference in the number of involved pulmonary lobes observed on CT and pulmonary fields observed on radiographic images was significantly higher in COVID-19-associated pneumonia than that in influenza-associated pneumonia (2.32 ± 1.14 vs. 1.48 ± 0.99, p = 0.010). Conclusions: Chest images and thorough review of clinical findings could provide value for proper differential diagnoses of COVID-19 patients, but they are not sufficiently sensitive for initial diagnoses. In addition, chest radiography could underestimate COVID-19 lung involvement because of the lesion characteristics of COVID-19-associated pneumonia.
Understanding of Developing and Setting Tasks in Geography Lessons by German and Dutch Student Teachers
Authors: Krause Uwe , Budke Alexandra , Maier Veit
Published: February 2021

Setting tasks plays a key role in geography lessons, as they enable students to engage with the subject content, guide lessons towards predefined learning outcomes, and are therefore important for assessment. At the same time, the use of tasks is complex as numerous aspects regarding the content and the students have to be taken into account. Based on theoretical and empirical literature, we identify seven quality criteria for tasks in geography education: motivating and engaging students; addressing the heterogeneity of students; structuring learning processes; comprehensible formulation; considering individual and social learning processes; making meaningful use of materials; and fostering the development of subject specific competences. These criteria were applied in observation of lessons, which were given during an exchange between student geography teachers from a Dutch and German university. Overall, it was found that student teachers recognize the defined quality criteria, but half of them focus on only one or two aspects. The difficulties student teachers face in task setting during their traineeship can partly be explained by their phase of apprenticeship and the context. The developed observation form was considered to be valuable for preparation and observation of and reflection on tasks in geography lessons, and the exchange enabled student teachers to gain an insight into their own teaching practice.
Analysis of Problem Posing Using Different Fractions Meanings
Authors: Martinez Silvia , Blanco Vanessa
Published: February 2021

The aim of this work is to study the knowledge that 11 to 12-year-old pupils have about the different meanings of fractions. For this purpose, an investigation about the ability that 11 to 12-year-old pupils have with fraction problems through problem posing is performed. In particular, we analyze if they pose different types of problems depending on the provided help and if they are able to solve the problems they pose. To do so, after making a classification about types of fractions problems, an instrument is designed to see if students are able to invent and solve problems with different conditions (no reference at all, reference to an image, reference to a graphic representation, and reference to an operation). The analysis of results shows that most of the students properly solve what they invent, and points out that they tend to pose part-whole and part-set problems, even when the given reference suggests another type of problem.
A Lower Bound for the Coherence Block Length in Mobile Radio Channels
Authors: Torres Rafael P. , Pérez Jesús R.
Published: February 2021

A lower bound for the coherence block (ChB) length in mobile radio channels is derived in this paper. The ChB length, associated with a certain mobile radio channel, is of great practical importance in future wireless systems, mainly those based on massive multiple input and multiple output (M-MIMO) technology. In fact, it is one of the factors that determines the achievable spectral efficiency. Firstly, theoretical aspects regarding the mobile radio channels are summarized, focusing on the rigorous definition of coherence bandwidth (BC) and coherence time (TC) parameters. Secondly, the uncertainty relations developed by B. H. Fleury, involving both BC and TC, are presented. Afterwards, a lower bound for the product BCTC is derived, i.e., the ChB length. The obtained bound is an explicit function of easily measurable parameters, such as the delay spread, mobile speed and carrier frequency. Furthermore, and especially important, this bound is also a function of the degree of coherence with which we define both BC and TC. Finally, an application example that illustrates the practical possibilities of the bound obtained is presented. As a further conclusion, the need to determine what degree of correlation is required to consider mobile channels as effectively flat-fading and stationary is highlighted.
Fuzzy-Based Distributed Cooperative Secondary Control with Stability Analysis for Microgrids
Authors: Begum Mahmuda , Eskandari Mohsen , Abuhilaleh Mohammad , Li Li , Zhu Jianguo
Published: February 2021

This research suggests a novel distributed cooperative control methodology for a secondary controller in islanded microgrids (MGs). The proposed control technique not only brings back the frequency/voltage to its reference values, but also maintains precise active and reactive power-sharing among distributed generation (DG) units by means of a sparse communication system. Due to the dynamic behaviour of distributed secondary control (DSC), stability issues are a great concern for a networked MG. To address this issue, the stability analysis is undertaken systematically, utilizing the small-signal state-space linearized model of considering DSC loops and parameters. As the dynamic behaviour of DSC creates new oscillatory modes, an intelligent fuzzy logic-based parameter-tuner is proposed for enhancing the system stability. Accurate tuning of the DSC parameters can develop the functioning of the control system, which increases MG stability to a greater extent. Moreover, the performance of the offered control method is proved by conducting a widespread simulation considering several case scenarios in MATLAB/Simscape platform. The proposed control method addresses the dynamic nature of the MG by supporting the plug-and-play functionality, and working even in fault conditions. Finally, the convergence and comparison study of the offered control system is shown.
Multi-Objective Energy Management of a Micro-Grid Considering Stochastic Nature of Load and Renewable Energy Resources
Authors: Ahmed Deyaa , Ebeed Mohamed , Ali Abdelfatah , Alghamdi Ali S. , Kamel Salah
Published: February 2021

Optimal inclusion of a photovoltaic system and wind energy resources in electrical grids is a strenuous task due to the continuous variation of their output powers and stochastic nature. Thus, it is mandatory to consider the variations of the Renewable energy resources (RERs) for efficient energy management in the electric system. The aim of the paper is to solve the energy management of a micro-grid (MG) connected to the main power system considering the variations of load demand, photovoltaic (PV), and wind turbine (WT) under deterministic and probabilistic conditions. The energy management problem is solved using an efficient algorithm, namely equilibrium optimizer (EO), for a multi-objective function which includes cost minimization, voltage profile improvement, and voltage stability improvement. The simulation results reveal that the optimal installation of a grid-connected PV unit and WT can considerably reduce the total cost and enhance system performance. In addition to that, EO is superior to both whale optimization algorithm (WOA) and sine cosine algorithm (SCA) in terms of the reported objective function.
Efficient Key Agreement Algorithm for Wireless Body Area Networks Using Reusable ECG-Based Features
Authors: Al-Saeed Yasmeen , Eldaydamony Eman , Atwan Ahmed , Elmogy Mohammed , Ouda Osama
Published: February 2021

Wireless Body Area Networks (WBANs) are increasingly employed in different medical applications, such as remote health monitoring, early detection of medical conditions, and computer-assisted rehabilitation. A WBAN connects a number of sensor nodes implanted in and/or fixed on the human body for monitoring his/her physiological characteristics. Although medical healthcare systems could significantly benefit from the advancement of WBAN technology, collecting and transmitting private physiological data in such an open environment raises serious security and privacy concerns. In this paper, we propose a novel key-agreement protocol to secure communications among sensor nodes of WBANs. The proposed protocol is based on measuring and verifying common physiological features at both sender and recipient sensors prior to communicating. Unlike existing protocols, the proposed protocol enables communicating sensors to use their previous session pre-knowledge for secure communication within a specific period of time. This will reduce the time required for establishing the shared key as well as avoid retransmitting extracted features in the medium and hence thwarting eavesdropping attacks while maintaining randomness of the key. Experimental results illustrate the superiority of the proposed key agreement protocol in terms of both feature extraction and key agreement phases with an accuracy of 99.50% and an error rate of 0.005%. The efficacy of the proposed protocol with respect to energy and memory utilization is demonstrated compared with existing key agreement protocols.
A 28 GHz Broadband Helical Inspired End-Fire Antenna and Its MIMO Configuration for 5G Pattern Diversity Applications
Authors: Zahra Hijab , Awan Wahaj Abbas , Ali Wael Abd Ellatif , Hussain Niamat , Abbas Syed Muzahir , Mukhopadhyay Subhas
Published: February 2021

In this paper, an end-fire antenna for 28 GHz broadband communications is proposed with its multiple-input-multiple-output (MIMO) configuration for pattern diversity applications in 5G communication systems and the Internet of Things (IoT). The antenna comprises a simple geometrical structure inspired by a conventional planar helical antenna without utilizing any vias. The presented antenna is printed on both sides of a very thin high-frequency substrate (Rogers RO4003, εr = 3.38) with a thickness of 0.203 mm. Moreover, its MIMO configuration is characterized by reasonable gain, high isolation, good envelope correlation coefficient, broad bandwidth, and high diversity gain. To verify the performance of the proposed antenna, it was fabricated and verified by experimental measurements. Notably, the antenna offers a wide −10 dB measured impedance ranging from 26.25 GHz to 30.14 GHz, covering the frequency band allocated for 5G communication systems with a measured peak gain of 5.83 dB. Furthermore, a performance comparison with the state-of-the-art mm-wave end-fire antennas in terms of operational bandwidth, electrical size, and various MIMO performance parameters shows the worth of the proposed work.
RETRACTED: Kang et al. Achievement of Gradual Conductance Characteristics Based on Interfacial Phase-Change Memory for Artificial Synapse Applications. Electronics 2020, 9, 1268
Authors: Kang Shinyoung , Lee Juyoung , Kang Myounggon , Song Yunheub
Published: February 2021

The authors and journal retract the article, “Achievement of Gradual Conductance Characteristics Based on Interfacial Phase-Change Memory for Artificial Synapse Applications” [...]
Deadlock-Free Planner for Occluded Intersections Using Estimated Visibility of Hidden Vehicles
Authors: Narksri Patiphon , Takeuchi Eijiro , Ninomiya Yoshiki , Takeda Kazuya
Published: February 2021

A common approach used for planning blind intersection crossings is to assume that hypothetical vehicles are approaching the intersection at a constant speed from the occluded areas. Such an assumption can result in a deadlock problem, causing the ego vehicle to remain stopped at an intersection indefinitely due to insufficient visibility. To solve this problem and facilitate safe, deadlock-free intersection crossing, we propose a blind intersection planner that utilizes both the ego vehicle and the approaching vehicle’s visibility. The planner uses a particle filter and our proposed visibility-dependent behavior model of approaching vehicles for predicting hidden vehicles. The behavior model is designed based on an analysis of actual driving data from multiple drivers crossing blind intersections. The proposed planner was tested in a simulation and found to be effective for allowing deadlock-free crossings at intersections where a baseline planner became stuck in a deadlock. The effects of perception accuracy and sensor position on output motion were also investigated. It was found that the proposed planner delayed crossing motion when the perception was imperfect. Furthermore, our results showed that the planner decelerated less while crossing the intersection with the front-mounted sensor configuration compared to the roof-mounted configuration due to the improved visibility. The minimum speed difference between the two sensor configurations was 1.82 m/s at an intersection with relatively poor visibility and 1.50 m/s at an intersection with good visibility.
JPEG Images Encryption Scheme Using Elliptic Curves and A New S-Box Generated by Chaos
Authors: Hernández-Díaz Erick , Pérez-Meana Héctor , Silva-García Víctor , Flores-Carapia Rolando
Published: February 2021

This paper proposes a new symmetric encryption system based on an elliptical curve and chaos, where the encryption is done in a single block and runs for 14 rounds. Here, the 15 encryption keys have the same size as the image and are generated using a solution point of a strong elliptic curve. Using a string of random numbers obtained with a logistic map, a permutation and its inverse are generated, which improve the encryption level and add diffusion to the cryptosystem. Another important contribution to this research is the generation of a substitution box with a non-linearity of 100, which strengthens the cryptosystem against differential and linear attacks that add confusion to the scheme. Moreover, the cryptographic properties of the proposed S-Box are compared with those of the S-Box of the Advanced Encryption Standard (AES) to ascertain that it is a suitable alternative that it is resistant to differential power analysis (DPA) attacks. To verify the robustness of proposed cryptosystem against cryptanalysis and the quality of the cipher text obtained, this system is subjected to different tests, such as entropy, correlation coefficient, χ2, Changing Pixel Rate (NPCR), and Unified Averaged Changing Intensity (UACI). The results are shown and compared with recently proposed systems.
Use of DNA Barcoding Combined with PCR-SFLP to Authenticate Species in Bison Meat Products
Authors: Scales Zerika M. , Narbay Elif , Hellberg Rosalee S.
Published: February 2021

American bison (Bison bison) meat is susceptible to species mislabeling due to its high value and similar appearance to meat from domestic cattle (Bos taurus). DNA barcoding is commonly used to identify animal species. However, as a result of the historical hybridization of American bison and domestic cattle, additional genetic testing is required for species confirmation. The objective of this study was to perform a market survey of bison meat products and verify the species using DNA barcoding combined with polymerase chain reaction-satellite fragment length polymorphism (PCR-SFLP). Bison products (n = 45) were purchased from a variety of retailers. Samples that were positive for domestic cattle with DNA barcoding were further analyzed with PCR-SFLP. DNA barcoding identified bison in 41 products, red deer (Cervus elaphus) in one product, and domestic cattle in three products. PCR-SFLP confirmed the identification of domestic cattle in two samples, while the third sample was identified as bison with ancestral cattle DNA. Overall, mislabeling was detected in 3 of the 45 samples (6.7%). This study revealed that additional DNA testing of species that have undergone historical hybridization provides improved identification results compared to DNA barcoding alone.
Functional Components and Anti-Nutritional Factors in Gluten-Free Grains: A Focus on Quinoa Seeds
Authors: Melini Valentina , Melini Francesca
Published: February 2021

Quinoa (Chenopodium quinoa Willd.) has recently received increasing interest from both scientists and consumers due to its suitability in gluten-free diets, its sustainability, and its claimed superfood qualities. The aim of this paper is to systematically review up-to-date studies on quinoa functional components and anti-nutritional factors, in order to define a baseline for food scientists approaching the investigation of quinoa phytochemicals and providing evidence for the identification of healthier sustainable foods. State of the art evaluations of phytochemical contents in quinoa seeds were obtained. It emerged that phenolic compounds are the most investigated functional components, and spectrophotometric methods have been mostly applied, despite the fact that they do not provide information about single components. Saponins are the most studied among anti-nutritional factors. Betalains, tannins, and phytoecdysteroids have been poorly explored. Information on factors affecting the phytochemical content at harvesting, such as quinoa ecotypes, crop geographical location and growing conditions, are not always available. A comprehensive characterization, encompassing several classes of functional components and anti-nutritional factors, is mainly available for quinoa varieties from South America. However, defining a standard of quality for quinoa seeds is still challenging and requires a harmonization of the analytical approaches, among others.
Rice Bran Oil Attenuates Chronic Inflammation by Inducing M2 Macrophage Switching in High-Fat Diet-Fed Obese Mice
Authors: Park Hyejeong , Yu Seungmin , Kim Wooki
Published: February 2021

Macrophages are involved in all inflammatory processes from killing pathogens to repairing damaged tissue. In the obese state, macrophages infiltrate into enlarged adipose tissue and polarize into pro-inflammatory M1 macrophages, resulting in chronic low-grade inflammation due to the secretion of inflammatory mediators. Rice bran oil (RBO) is an edible oil containing tocopherols, tocotrienols, and γ-oryzanol. Previous research in normal diet-fed mice suggested that RBO mitigates inflammatory responses by modulating mitochondrial respiration of macrophages. Therefore, we investigated if RBO had an anti-inflammatory effect in diet-induced obese mice by assessing the expression of inflammatory markers in epididymal white adipose tissue (eWAT) and polarization of bone marrow-derived macrophages (BMDMs). Rice bran oil exerted a local anti-inflammatory effect in white adipose tissue by suppressing the production of inflammatory mediators and upregulating transcription of anti-inflammatory genes. Rice bran oil also promoted anti-inflammatory M2 macrophage polarization in BMDMs thereby affecting systemic inflammation. Overall, our in vivo and ex vivo results highlight the potential of RBO as a dietary mediator that can ameliorate obesity-induced chronic low-grade inflammation by mediating the expression of inflammation-related factors and macrophage polarization.
Laboratory Studies Using Electrical Resistivity Tomography and Fiber Optic Techniques to Detect Seepage Zones in River Embankments
Authors: Hojat Azadeh , Ferrario Maddalena , Arosio Diego , Brunero Marco , Ivanov Vladislav Ivov , Longoni Laura , Madaschi Andrea , Papini Monica , Tresoldi Greta , Zanzi Luigi
Published: February 2021

We present the results of laboratory experiments on a down-scaled river levee constructed with clayey material collected from a river embankment where a permanent resistivity instrument has operated since 2015. To create potential seepages through the levee, two zones (5 × 4 cm and 10 × 2 cm) were filled with sand during the levee construction. Electrical resistivity tomography (ERT) technique and Fiber Bragg Grating (FBG) technology were used to study time-lapse variations due to seepage. The ERT profile was spread on the levee crest and the Wenner array with unit electrode spacing a = 3 cm was used. Six organic modified ceramics (ORMOCER) coated 250 μm-diameter fibers were deployed in different parts of the levee. Time-lapse measurements were performed for both techniques from the beginning of each experiment when water was added to the river side until the water was continuously exiting from the seepage zones. The results showed that ERT images could detect seepages from the early stages. Although with a short delay compared to ERT, fiber optic sensors also showed their ability to detect water infiltrations by measuring temperature changes. Both technologies being successful, a discussion about respective peculiarities and pros and cons is proposed to suggest some criteria in choosing the proper technique according to the specific needs.
Immersive 3D Educational Contents: A Technical Note for Dental Educators
Authors: Barour Sabira , Richert Raphaël , Virard François , Wulfman Claudine , Iozzino Régis , Elbashti Mahmoud , Naveau Adrien , Ducret Maxime
Published: February 2021

Three-dimensional files featuring patients’ geometry can be obtained through common tools in dental practice, such as an intraoral scanner (IOS) or Cone Beam Computed Tomography (CBCT). The use of 3D files in medical education is promoted, but only few methodologies were reported due to the lack of ease to use and accessible protocols for educators. The aim of this work was to present innovative and accessible methodologies to create 3D files in dental education. The first step requires the definition of the educational outcomes and the situations of interest. The second step relies on the use of IOS and CBCT to digitize the content. The last “post-treatment” steps involve free software for analysis of quality, re-meshing and simplifying the file in accordance with the desired educational activity. Several examples of educational activities using 3D files are illustrated in dental education and discussed. Three-dimensional files open up many accessible applications for a dental educator, but further investigations are required to develop collaborative tools and prevent educational inequalities between establishments.