bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-Phase Sampling Designs for Data Validation in Settings with Covariate Measurement Error and Continuous Outcome
Authors: Amorim Gustavo , Tao Ran , Lotspeich Sarah , Shaw Pamela A. , Lumley Thomas , Shepherd Bryan E.
Published: April 2021

Measurement errors are present in many data collection procedures and can harm analyses by biasing estimates. To correct for measurement error, researchers often validate a subsample of records and then incorporate the information learned from this validation sample into estimation. In practice, the validation sample is often selected using simple random sampling (SRS). However, SRS leads to inefficient estimates because it ignores information on the error-prone variables, which can be highly correlated to the unknown truth. Applying and extending ideas from the two-phase sampling literature, we propose optimal and nearly optimal designs for selecting the validation sample in the classical measurement-error framework. We target designs to improve the efficiency of model-based and design-based estimators, and show how the resulting designs compare to each other. Our results suggest that sampling schemes that extract more information from the error-prone data are substantially more efficient than SRS, for both design- and model-based estimators. The optimal procedure, however, depends on the analysis method, and can differ substantially. This is supported by theory and simulations. We illustrate the various designs using data from an HIV cohort study.
Reflective Consensus Building on the Nation's Largest Confederate Memorial: A Case Study
Authors: Hoffmann Michael H.G.
Published: April 2021

Objective

This study utilized the Reflect! platform, an educational tool, as an instrument to structure deliberations among small groups of people with conflicting views. Can a technology designed to provide guidance for self‐directed learning in small teams of students also be used in projects with “real” stakeholders involved in actual conflicts?

Method

In an exploratory case study, the investigator invited three representatives of civic organizations in Atlanta, Georgia, to collaborate on the problem of dealing with the Confederate Memorial carved in Stone Mountain. The study included qualitative analysis of observational data, structured participant interviews, and participant‐generated materials.

Results

Participants succeeded in formulating a shared position on what to do with the Confederate Memorial on Stone Mountain. However, the study highlights limitations in the interpretation of findings, as well as certain advantages and disadvantages of the platform.

Conclusion

It seems that the Reflect! approach could do most good somewhere in the middle between large‐scale deliberations such as a town hall meeting and professional conflict management. With its step‐by‐step activities and its focus on stimulating reflection, the Reflect! platform can support mutual understanding on highly controversial issues.
The novel HLA‐C*04:407 allele was identified in a Chinese individual
Authors: Wang Wei , Chen Nanying , Zhang Wei , He Ji , Zhu Faming
Published: April 2021

HLA‐C*04:407 shows a single nucleotide substitution at position 740 A > G when compared to HLA‐C*04:01:01:01.
Implicating extracellular vesicles in Plasmodium falciparum artemisinin resistance development
Authors: Tandoh Kwesi Z. , Wilson Michael D. , Quashie Neils B. , Duah‐Quashie Nancy O.
Published: April 2021

Plasmodium falciparum malaria remains a disease of significant public health impact today. With the risk of emerging artemisinin resistance stalling malaria control efforts, the need to deepen our understanding of the parasite's biology is dire. Extracellular vesicles (EVs) are vital to the biology of P. falciparum and play a role in the pathogenesis of malaria. Recent studies have also shown that EVs may play a role in the development of artemisinin resistance in P. falciparum. Here, we highlight evidence on EVs in P. falciparum biology and malaria pathogenesis and argue that there is sufficient ground to propose a role for EVs in the development of P. falciparum artemisinin resistance. We suggest that EVs are actively secreted functional organelles that contribute to cellular homeostasis in P. falciparum‐infected red blood cells under artemisinin pressure. Further exploration of this hypothesized EVs‐based molecular mechanism of artemisinin resistance will aid the discovery of novel antimalarial therapies.
Analysis of current SARS‐CoV‐2 infection in a large population of blood donors evidenced that RNAemia is rare in plasma
Authors: Chaves Daniel Gonçalves , da Silva Malta Maria Clara Fernandes , de Souza Madeira Ferreira Boy Luciana , Miranda Barbosa Aretuza , Fonseca Cinthia Neves , Ellen de Lima Torres Dayanne , Patterson Nogueira Janaína , Medeiros Moreira Hélinse , Cristine Martineli Loureiro Flávia , Vargas de Freitas Silva Jaciane , Aparecida Ribeiro Maísa , Guimarães Mourão Cioffi Júnia , Lobato Martins Marina
Published: April 2021

Background

Transmission of SARS‐CoV‐2 by asymptomatic individuals and by blood transfusion are important issues to understand to control the viral spread. In this work, we estimated the current SARS‐CoV‐2 infection rate in blood donors from Belo Horizonte, Brazil.

Study design and methods

Saliva and blood samples were collected from 4103 blood donors from June 15 to September 30, 2020. Saliva samples were tested by real‐time RT‐PCR for SARS‐CoV‐2 in mini‐pools of four samples. Individual samples were tested for positive or inconclusive pools, and positive donors had their plasma tested.

Results

Twenty‐seven (0.66%) blood donors were positive for SARS‐CoV‐2 in their saliva, but their plasma was negative, except for one, who presented a high viral load in saliva and nasopharyngeal samples and RNAemia in the plasma close to the limit of detection. Fourteen (56%) positive blood donors reported mild symptoms related to COVID‐19 after donation, but the viral load levels were not statistically different between symptomatic and asymptomatic individuals.

Discussion

Despite the measures taken by Blood Centers to avoid blood donors with SARS‐CoV‐2 infection, asymptomatic or presymptomatic carriers are able to donate. The risk of the virus transmission by transfusion seems to be negligible since plasma RNAemia was seen at a very low level in only one (3.7%) of the positive donors, but other studies must be performed to confirm this finding.
Pre‐Implementation of the Age‐Friendly Health Systems Evidence‐Based 4Ms Framework in a Multi‐State Convenient Care Practice
Authors: Dolansky Mary A. , Pohnert Anne , Ball Sarah , McCormack Mary , Hughes Robin , Pino Lilia
Published: April 2021

Background

Quality issues in the delivery of healthcare services to older adults and changes in societal demographics call for a social movement to improve the care of older adults in a variety of healthcare settings, including ambulatory care and convenient care clinics.

Aims

To describe the pre‐implementation phase to integrate the Age‐Friendly Health Systems (AFHS) 4Ms (i.e., What Matters, Medication, Mentation, and Mobility) Framework in 1,100 MinuteClinics (the retail medical clinic of CVS Health) using the Consolidated Framework for Implementation Research (CFIR) and RE‐AIM (an evaluation implementation framework).

Methods

The CFIR and RE‐AIM models guided data collection. Data were collected from all stakeholders (patients, healthcare providers, managers, educators, informatics staff, communications staff, and implementation consultants) via observations, surveys, interviews, focus groups, organizational readiness assessment, stakeholder assessment, and workflow mapping during a 15‐month period to identify potential barriers, facilitators, and other opportunities for implementation.

Results

The CFIR and RE‐AIM implementation frameworks provided a comprehensive approach to guide the pre‐implementation phase of the AFHS 4Ms Framework at the MinuteClinic. The baseline assessments guided by the CFIR revealed important insights in the choice of implementation strategies that were developed and tested in the pre‐implementation phase, and the RE‐AIM guided meaningful components to the development of the logic model.

Linking Action to Evidence

As more healthcare systems integrate the AFHS 4Ms Framework, the approach reported in this quality improvement project can be used in other settings to facilitate a comprehensive implementation.
Speech intelligibility for various head orientations of a listener in an automobile using the speech transmission index
Authors: Liang Linda , Yu Le , Zhao Tong , Meng Qinglin , Yu Guangzheng
Published: April 2021

As well as background noise and the acoustic conditions of the given space, speech intelligibility (SI) is affected by the binaural effect (BE), which is sensitive to the head orientation (HO) of the listener, especially in a small enclosed space such as an automobile. This study uses the speech transmission index (STI) to systematically investigate and predict SI for various HOs of the listener in an automobile. To explore the combined effects of reflections and BE on the auditory perception of speech, several groups of binaural room impulse responses for different speaker locations and HOs are measured in a listening room and an automobile, with the left-side front window (LFW) closed and open, and these are used to calculate the STI. The SI for various configurations is evaluated indirectly using a Chinese STI–SI model. The results show that reflections in the automobile help to increase the STI of the contralateral ear rather than the ipsilateral ear. The LFW is an important reflective boundary but does not always play a dominant role in the STI (SI). Moreover, the STI (SI) can be improved when the listener in the driver seat turns their head inward, i.e., at a negative HO.
Brass instruments as a cascade of two-port networks: Transfer functions, chain parameters, and power efficiency in theory and practice
Authors: Kausel Wilfried , Mayer Alexander , Beauchamp James W.
Published: April 2021

This paper investigates how two-port network theory as a means for system identification can be applied to the analysis of brass instruments. A special focus is placed on the energy conversion efficiency as this is limited by inner damping, which receives much attention by expert players and makers of brasses. Theory suggests that a reconstruction of the 2 × 2 matrix representing the network requires input impedance and transfer function for two different boundary conditions. Besides the normal case of free sound radiation, instruments are also analyzed with the bell closed by a spherical cap. For this purpose, a customized 3D-printed spherical cap was fabricated and attached to the bell. Four measured spectra and the passivity condition over-determine the set of system equations. It is shown how to take advantage of this freedom when analyzing wind instruments. Measurements and simulations of a trumpet and a trombone are presented and compared.
Type 2 immunity induced by bladder extracellular matrix enhances corneal wound healing
Authors: Wang Xiaokun , Chung Liam , Hooks Joshua , Maestas David R. , Lebid Andriana , Andorko James I. , Huleihel Luai , Chin Alexander F. , Wolf Matthew , Remlinger Nathaniel T. , Stepp Mary Ann , Housseau Franck , Elisseeff Jennifer H.
Published: April 2021

Extracellular matrix particulate stimulates local and peripheral type 2 immune response to enhance corneal wound healing.
Crystal structure of ADAMTS13 CUB domains reveals their role in global latency
Authors: Kim H. J. , Xu Y. , Petri A. , Vanhoorelbeke K. , Crawley J. T. B. , Emsley J.
Published: April 2021

The crystal structure of the ADAMTS13 tandem CUB1 and CUB2 domains reveals how protease global latency is conferred.
Randomized, Double-Blind, Placebo- and Positive-Controlled Crossover Study of the Effects of Tebipenem Pivoxil Hydrobromide on QT/QTc Intervals in Healthy Subjects
Authors: Gupta Vipul K. , Maier Gary , Eckburg Paul , Morelli Lisa , Lei Yang , Jain Akash , Manyak Erika , Melnick David
Published: April 2021

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is an orally available prodrug of tebipenem (TBP), a carbapenem with
in vitro
activity against multidrug-resistant Gram-negative pathogens. This study evaluated the effects of single therapeutic and supratherapeutic doses of TBP-PI-HBr on the heart rate-corrected QT interval (QTc) by assessing the concentration-QT interval relationship using exposure-response modeling.
Eduard Suess on graptolites: His very first scientific paper and illustrations
Authors: Şengör* A.M.C.
Published: April 2021

The very first scientific paper by Eduard Suess (1831–1914) treats the graptolites of Bohemia in the present-day Czech Republic (in the Upper Proterozoic to Middle Devonian “Barrandian” extending between Prague and Plzeň). This paper is accompanied by superb drawings of his observations in which Suess took great care not to insert himself between Nature as he perceived it in the framework of the knowledge of his day and his readers. His only limitation was the one imposed by the size of his study objects. His technological means did not allow him to see what we today consider the “right” picture. Nevertheless, we can see what he saw and interpret it through a modern lens of understanding. In his drawings, Suess exercised what the great German geologist Hans Cloos later called “the art of leaving out.” This meant that in the drawings, the parts not relevant to the discussion are left only in outline, whereas parts he wished to highlight are brought to the fore by careful shading. Even the parts left only in outline are not schematic, however; instead they are careful reconstructions true to Nature as much as the material and his technological aids allowed. This characteristic of Suess’ illustrations is seen also in his later field sketches concerning stratigraphy and structural geology and in his depiction of the large tectonic features of our globe representing a window into his manner of thinking.
Neonatal hyperglycaemia is associated with worse neurodevelopmental outcomes in extremely preterm infants
Authors: Zamir Itay , Stoltz Sjöström Elisabeth , Ahlsson Fredrik , Hansen-Pupp Ingrid , Serenius Fredrik , Domellöf Magnus
Published: April 2021

Objective

To assess the associations between neonatal hyperglycaemia and insulin treatment, versus long-term neurodevelopmental outcomes in children born extremely preterm.

Design and setting

Observational national cohort study (Extremely Preterm Infants in Sweden Study) using prospectively and retrospectively collected data. Neurodevelopmental assessment was performed at 6.5 years of age.

Patients

533 infants born <27 gestational weeks during 2004–2007; 436 survivors were assessed at 6.5 years.

Outcome measures

Neurodevelopmental disability (NDD), survival without moderate to severe NDD, Wechsler Intelligence Scale for Children IV Full scale intelligence quotient (WISC-IV FSIQ) and Movement Assessment Battery for Children 2 (MABC-2) total score.

Results

Duration of neonatal hyperglycaemia >8 mmol/L was associated with WISC-IV scores—for each day with hyperglycaemia there was a decrease of 0.33 points (95% CI 0.03 to 0.62) in FSIQ. Neonatal hyperglycaemia >8 mmol/L occurring on 3 consecutive days was associated with lower MABC-2 scores (adjusted mean difference: −4.90; 95% CI −8.90 to −0.89). For each day with hyperglycaemia >8 mmol/L, there was a decrease of 0.55 points (95% CI 0.17 to 0.93) in MABC-2 total score. Insulin treatment was not associated with any of the outcome measures.

Conclusion

Neonatal hyperglycaemia >8 mmol/L was associated with lower intelligence scores and worse motor outcomes at 6.5 years of age. Insulin treatment was not associated with either worsened or improved neurodevelopmental outcomes. Randomised controlled trials are needed to clarify the role of insulin in treating hyperglycaemia in extremely preterm infants.
Non-immune hydrops fetalis secondary to congenital chylothorax with diffuse interstitial lung disease: a diagnostic conundrum
Authors: Ngeow Alvin Jia Hao , Chan Mei Yoke , Teoh Oon Hoe , Sanamandra Sarat Kumar , Chan Daisy Kwai Lin
Published: April 2021

A Chinese male infant was born at 35 weeks weighing 2935 g to a mother with polyhydramnios and prenatal hydrops fetalis. He developed marked respiratory distress secondary to bilateral congenital chylothorax and required pleural drainage, high frequency oscillation and inhaled nitric oxide therapy. He was extubated to non-invasive ventilation by day 14. There was no bacterial or intrauterine infection, haematologic, chromosomal or cardiac disorder. He was exclusively fed medium-chain triglyceride formula. High-resolution CT showed diffuse interstitial lung disease. He received a dexamethasone course for chronic lung disease to facilitate supplemental oxygen weaning. A multidisciplinary team comprising neonatology, pulmonology, haematology, interventional radiology and thoracic surgery considered congenital pulmonary lymphangiectasia as the most likely diagnosis and advised open lung biopsy, lymphangiography or scintigraphy for diagnostic confirmation should symptoms of chylothorax recur. Fortunately, he was weaned off oxygen at 5 months of life, and tolerated human milk challenge at 6 months of life and grew well.
Therapy adjustments in people with type 1 diabetes with impaired hypoglycemia awareness on multiple daily injections using real-time continuous glucose monitoring: a mechanistic analysis of the HypoDE study
Authors: Waldenmaier Delia , Freckmann Guido , Pleus Stefan , Hermanns Norbert , Ehrmann Dominic , Heinemann Lutz , Haug Cornelia
Published: April 2021

Introduction

Studies have shown beneficial effects of real-time continuous glucose monitoring (rtCGM) usage on clinical outcomes. The objective of this analysis was to identify which therapy adjustments were made by people with type 1 diabetes with impaired hypoglycemia awareness during rtCGM usage enabling reductions in the number of low glucose events observed in the HypoDE (Hypoglycemia in Deutschland) study.

Research design and methods

In the multicenter randomized controlled trial in people with type 1 diabetes on multiple daily injections with impaired hypoglycemia awareness, participants recorded their diabetes therapy in 7-day logbooks at baseline and at 6-month follow-up. They used rtCGM or self-monitoring of blood glucose for therapy adjustments. This mechanistic analysis looked at changes in various aspects of therapy.

Results

Logbooks were completed by 70 participants in the rtCGM group and 65 participants in the control group. Participants in the rtCGM group kept their total carbohydrate consumption, daily insulin doses and distribution constant during the study. However, they reported an increased intake of rescue carbohydrates (0.8±0.6 (mean±SD) vs 1.0±0.8 intake/day; baseline-adjusted between-group difference 0.3 intake (0.1–0.5), p=0.031). The glucose threshold at which rescue carbohydrate intake was initiated was elevated from 71±13 mg/dL (3.9±0.7 mmol/L) to 79±14 mg/dL (4.4±0.8 mmol/L) (adjusted between-group difference +7.6 mg/dL (2.4–12.8) (+0.4 mmol/L (0.1–0.7)); p=0.005) in the rtCGM group. Regression analysis showed that follow-up low glucose events were associated with group allocation (p<0.001), low glucose events at baseline (p=0.016) and rescue threshold (p=0.001).

Conclusions

No major adjustments in insulin therapy were made by study participants with impaired hypoglycemia awareness; however, they were more active in preventing hypoglycemia by taking rescue carbohydrates earlier and more often.

Trial registration number

NCT02671968.
Critical role of pathology and laboratory medicine in the conversation surrounding access to healthcare
Authors: Lilley Cullen M , Mirza Kamran M
Published: April 2021

Pathology and laboratory medicine are a key component of a patient’s healthcare. From academic care centres, community hospitals, to clinics across the country, pathology data are a crucial component of patient care. But for much of the modern era, pathology and laboratory medicine have been absent from health policy conversations. Though select members in the field have advocated for an enhanced presence of these specialists in policy conversations, little work has been done to thoroughly evaluate the moral and ethical obligations of the pathologist and the role they play in healthcare justice and access to care. In order to make any substantive improvements in access to care, pathology and laboratory medicine must have a seat at the table. Specifically, pathologists and laboratorians can assist in bringing about change through improving clinician test choice, continuing laboratory improvement programmes, promoting just advanced diagnostic distribution, triage testing and be good stewards of healthcare dollars, and recruiting a more robust laboratory workforce. In order to get to that point, much work has to be done in pathology education and the laboratory personnel training pipeline but there also needs to be adjustments at the system level to better involve this invaluable group of specialists in these policy conversations.
Human rights and COVID-19 triage: a comment on the Bath protocol
Authors: Bhatt Vivek , Michalowski Sabine , Wyllie Aaron , Kuylen Margot , Martin Wayne
Published: April 2021

In their discussion paper of November 2020, Cooket alpresent a draft protocol for navigating circumstances in which emergency services are overwhelmed. Their paper suggests that COVID-related triage decisions should be based on clinical assessment, patient and family consultation, and a range of ethical considerations. In this response, we note that the protocol exhibits an ambiguity that is likely to result in irresolvable dilemmas when put into practice. This ambiguity is exemplified in the paper’s prime ethical imperative (to ‘save more lives and more years of life’), which takes the form of an undefined conjunction whose practical implications are left unspecified. We see this ambiguity in the prime imperative as one manifestation of a broader set of tensions in the protocol. We show that the discipline of human rights provides an essential supplement to the ethical framework on which Cook and colleagues rely, providing a framework for understanding and working through triage dilemmas involving age, discrimination and equality.
The arthritis connection to inflammatory bowel disease (IBD): why has it taken so long to understand it?
Authors: Ashrafi Maedeh , Kuhn Kristine A , Weisman Michael H
Published: April 2021

Inflammatory bowel disease (IBD) associated arthritis is a subgroup of spondyloarthritis (SpA) that has suffered from lack of recognition in rheumatology clinical and research circles for over 100 years. Although clinically distinguishable from rheumatoid arthritis and ankylosing spondylitis, it took advances in detection systems in the middle of the last century (rheumatoid factor, HLA-B27) to convincingly make the final separations. We now know that significant numbers of patients with SpA have associated clinical IBD and almost half of them show subclinical gut inflammation, yet the connection between the gut and the musculoskeletal system has remained a vexing problem. Two publications from Nathan Zvaifler (one in 1960, the other in 1975) presciently described the relationship between the gut and the spine/peripheral joints heralding much of the work present today in laboratories around the world trying to examine basic mechanisms for the connections (there are likely to be many) between the gut, the environment (presumably our intestinal flora) and the downstream effect on the musculoskeletal system. The role of dysregulated microbiome along with microbiome-driven T helper 17 cell expansion and immune cell migration to the joints has been recognised, all of which occur in the appropriate context of genetic background inside and outside of the human leucocyte antigen system. Moreover, different adhesion molecules that mediate immune cells homing to the gut and joints have been noted. In this review, we studied the origins and evolution of IBD-arthritis, proposed pathogenic mechanisms and the current gaps that need to be filled for a complete understanding of IBD-arthritis.
‘It brings light to what you really put into your body’: a focus group study of reactions to messages about nicotine reduction in cigarettes
Authors: Duong Hue Trong , Loud Emily E , Thrasher James F , Henderson Katherine C , Ashley David L , Popova Lucy
Published: April 2021

Objective

In 2017, the US Food and Drug Administration (FDA) announced a proposed regulation to lower nicotine in cigarettes to minimally addictive levels to help smokers quit. We sought to explore effective message strategies communicating about nicotine reduction in cigarettes across the different key audiences that the regulation is most likely to influence.

Methods

We designed four types of messages: efficacy messages, risk messages, a message about alternative sources of nicotine and a compensation message. Sixteen virtual focus groups were conducted in Atlanta and San Francisco in April–May 2020. Data were analysed in NVivo 12.0 using a thematic analysis approach.

Findings

Exclusive smokers were receptive to both efficacy messages and risk messages. Dual users were the only group that was open to resorting to alternative sources of nicotine. Former smokers were critical of these messages as promoting the new kinds of cigarettes and potentially encouraging initiation and relapse of smoking. Non-smokers felt that efficacy messages downplayed the risks of smoking and did not scare people away from smoking. Presenting information that very low nicotine cigarettes (VLNCs) still contain harmful chemicals made smokers question continued smoking in the absence of nicotine and view VLNCs as harmful.

Conclusions

Messages communicating about nicotine reduction in cigarettes might help to motivate smokers to quit and can correct the misperceptions that VLNCs are less harmful. The FDA should consider specific target audiences and use different messages that complement each other in communicating about this regulation.
Scalar fully-heavy tetraquark states $$QQ^\prime {\bar{Q}} \bar{Q^\prime }$$ in QCD sum rules
Authors: Yang Bo-Cheng , Tang Liang , Qiao Cong-Feng
Published: April 2021

Very recently, the LHCb Collaboration observed distinct structures with the $$cc{\bar{c}}{\bar{c}}$$

c
c

c

¯

c

¯

in the $$J/\Psi $$

J
/
Ψ

-pair mass spectrum. In this work, we construct four scalar ($$J^{PC} = 0^{++}$$

J

PC

=

0

+
+

) $$[8_c]_{Q\bar{Q^\prime }}\otimes [8_c]_{Q^\prime {\bar{Q}}}$$

[

8
c

]

Q

Q
′

¯

⊗

[

8
c

]

Q
′

Q

¯

type currents to investigate the fully-heavy tetraquark state $$Q Q^\prime {\bar{Q}} \bar{Q^\prime }$$

Q

Q
′

Q

¯

Q
′

¯

in the framework of QCD sum rules, where $$Q=c, b$$

Q
=
c
,
b

and $$Q^\prime = c, b$$

Q
′

=
c
,
b

. Our results suggest that the broad structure around 6.2-6.8 GeV can be interpreted as the $$0^{++}$$

0

+
+

octet–octet tetraquark states with masses $$6.44\pm 0.11$$

6.44
±
0.11

GeV and $$6.52\pm 0.10$$

6.52
±
0.10

GeV, and the narrow structure around 6.9 GeV can be interpreted as the $$0^{++}$$

0

+
+

octet–octet tetraquark states with masses $$6.87\pm 0.11$$

6.87
±
0.11

GeV and $$6.96\pm 0.11$$

6.96
±
0.11

GeV, respectively. Extending to the b-quark sector,the masses of their fully-bottom partners are found to be around 18.38-18.59 GeV. Additionally, we also analyze the spectra of the $$[8_c]_{c{\bar{c}}}\otimes [8_c]_{b {\bar{b}}}$$

[

8
c

]

c

c

¯

⊗

[

8
c

]

b

b

¯

and $$[8_c]_{c{\bar{b}}}\otimes [8_c]_{b {\bar{c}}}$$

[

8
c

]

c

b

¯

⊗

[

8
c

]

b

c

¯

tetraquark states, which lie in the range of 12.51–12.74 GeV and 12.49–12.81 GeV, respectively.
Erratum to: $$U(1)_{B_3-L_2}$$ explanation of the neutral current $$B-$$anomalies
Authors: Allanach B. C.
Published: April 2021

A Correction to this paper has been published https://doi.org/10.1140/epjc/s10052-021-08855-w
Mossbauer studies of Zn-substituted BiFeO3 multiferroic
Authors: Liu Guoqing , Liu Min , Liu Jin , Deng Shuang , Peng Anguo
Published: April 2021

This work presents an elaborate study of the effect in the structural and magnetic of [Formula: see text] ([Formula: see text], 0.05, 0.10, 0.15, 0.20, 0.25) multiferroic materials, synthesized via a sol-gel auto-combustion method. The synthesized materials are found to have structural distortion in the rhombohedral R3c structure as observed by X-ray diffraction (XRD). Other diffraction peaks were attributed to the second phase [Formula: see text]. The Mossbauer spectra (MS) of [Formula: see text] ([Formula: see text], 0.05, 0.10, 0.15) are fitted with a sextet and a doublet, and the presence of doublet also indicates the [Formula: see text] phase. The results from XRD and MS both show that Zn-substituted BiFeO3 suffers adverse effects on the formation of pure BiFeO3. [Formula: see text] ([Formula: see text], 0.25) are fitted with only one paramagnetic doublet. The absence of sextet means that there is a magnetic destruction of samples on account of a thorough phase transition from a magnetic phase to a non-magnetic phase and/or successful ion substitution (iron ions were replaced with zinc ions).
Cumulative Quality Modeling for HTTP Adaptive Streaming
Authors: Tran Huyen T. T. , Ngoc Nam Pham , Hoßfeld Tobias , Seufert Michael , Thang Truong Cong
Published: April 2021

HTTP Adaptive Streaming has become the de facto choice for multimedia delivery. However, the quality of adaptive video streaming may fluctuate strongly during a session due to throughput fluctuations. So, it is important to evaluate the quality of a streaming session over time. In this article, we propose a model to estimate the cumulative quality for HTTP Adaptive Streaming. In the model, a sliding window of video segments is employed as the basic building block. Through statistical analysis using a subjective dataset, we identify four important components of the cumulative quality model, namely the minimum window quality, the last window quality, the maximum window quality, and the average window quality. Experiment results show that the proposed model achieves high prediction performance and outperforms related quality models. In addition, another advantage of the proposed model is its simplicity and effectiveness for deployment in real-time estimation. Our subjective dataset as well as the source code of the proposed model have been made publicly available at
https://sites.google.com/site/huyenthithanhtran1191/cqmdatabase
.
Toward a Better Understanding of “Cybersecurity”
Authors: Ham Jeroen Van Der
Published: April 2021

The term “cybersecurity” has gained widespread popularity but has not been defined properly. The term is used by many different people to mean different things in different contexts. A better understanding of “cybersecurity” will allow us a better understanding of what it means to be “cybersecure.” This in turn will allow us to take more appropriate measures to ensure actual cybersecurity.
Can Greener Cyrene Replace NMP for Electrode Preparation of NMC 811 Cathodes?
Authors: Zhou Hui , Pei Ben , Fan Qinglu , Xin Fengxia , Whittingham M. Stanley
Published: April 2021

N-methyl-2-pyrrolidone (NMP) is the normally used solvent for cathode processing in lithium battery field. However, its high toxicity attracted more and more environmental scrutiny and was restricted by many chemical legislations in industry applications. So, it is necessary to find a greener and safer alternative to replace it. Dihydrolevoglucosenone (Cyrene), a newly reported green dipolar aprotic solvent, has very similar solvent properties as NMP, making it a very attractive candidate. The possibility to use Cyrene to replace NMP for NMC 811 cathode fabrication was studied. Although PVDF binder has very poor solubility in Cyrene at room temperature, increasing temperature can significantly change this. High temperature (above 80 °C) electrode processing with Cyrene gives promising performance, which is comparable to the conventional NMP fabricated electrode. A proof of principle was provided: Cyrene can be a good green alternative to replace NMP. The positive results reported here may also lead to a search for more Cyrene-like green solvents that have a higher solubility for PVDF, or of PVDF-like binders that are more soluble in Cyrene, to help making the electrode processing much greener.
Short-Term Strong Cathodic Polarization of Ni/YSZ and Pt/YSZ
Authors: Hansen Karin Vels , Kreka Kosova , Balasubramanian Vignesh , Jacobsen Torben
Published: April 2021

The initial stages of YSZ reduction and formation of intermetallic phases at Ni∣YSZ interfaces on strongly cathodically polarized electrodes were studied by a number of potential sweep and impedance techniques. The measurements were carried out in the potential range −1.0 V to −3.0 V vs E°(O2) in H2/H2O at 650 and 750 °C. Below −1.7 V the cathodic current increases almost exponentially, mainly due to electronic conductivity in the YSZ. Reduction and oxidation peaks develop below and above −1.9 V, respectively. The peaks reveal a simultaneous reduction of YSZ at the Ni∣YSZ interface and reoxidation of a Ni-Zr phase. Charges calculated from the reoxidation peaks indicate a thickness of 200 nm for the layer formed by conditioning the electrode for 300 s at −2.6 V vs E°(O2). Impedance measurements show a suppressed arc decreasing with increasing polarization. Below −2.3 V vs E°(O2) a capacitive high frequency arc segment and an inductive low frequency loop develop. Both are ascribed to electronic conductivity. SEM/EDS microscopy on cross sections of samples cooled with and without polarization showed the formation of uniform and homogeneous intermetallic reaction layers which after reoxidation resulted in a two-phased nanostructures.
Towards the Stability of Low-Temperature Aluminum Electrolysis
Authors: Suzdaltsev Andrey V. , Nikolaev Andrey Yu. , Zaikov Yuriy P.
Published: April 2021

The results of several different tests related to the low-temperature aluminum electrolysis were considered in this work. The role of mass transfer processes in the anode-cathode space was recommended to be significant during electrolysis in the low-temperature KF-AlF3 and NaF-AlF3-based melts. The stationary polarization and voltammetry methods were applied in order to study the kinetics of the electrode processes on the carbon and metal electrodes in the KF-AlF3-Al2O3 melts and to select the electrolysis parameters. The schemes of electrode processes were suggested on the basis of electrochemical tests, the flows of substances in the anode-cathode distance were analyzed and the main reasons of the cathode current efficiency decrease during the low-temperature electrolysis in the KF-AlF3-Al2O3 and KF-NaF-AlF3-Al2O3 melts were discussed. It was revealed that the cathode current density should not exceed 0.4–0.55 A cm−2 during the electrolysis at 750 °C–800 °C.
Operando XAS to Illustrate the Importance of Electronic Conductivity in Vanadyl Phosphate Systems
Authors: Zuba Mateusz , Rana Jatinkumar , Siu Carrie , Buyuker IsikSu , Sulicz Ewa , Zhou Hui , Chernova Natasha , Zhang Hanlei , Zhou Guangwen , Whittingham M. Stanley , Piper Louis F. J.
Published: April 2021

Multi-electron cathodes are an exciting class of energy storage materials that can intercalate more than one alkali-ion per transition metal. One such case, nano-sized ε-VOPO4 can intercalate two Li-ions to obtain the theoretical capacity of 305 mAh g−1, despite its inherently poor ionic and electronic conductivity. While carbon additives can compensate for cathode material’s poor conductivity, the type of carbon additive can play a key role in achieving full theoretical capacity of ε-VOPO4. Here, we explore the electrochemical behavior of two sourced carbons while systematically tracking V valence through operando X-ray absorption spectroscopy. The degree of V redox largely depends on the carbon additive’s electrical conductivity and surface coverage, with graphene enabling full 2 li-ion (de)intercalation whereas the use of acetylene black leads to trapped Li-ion. In both cases however, side reactions are promoted when the limits of facile Li (de)intercalation are reached resulting in excess capacities inconsistent with V valence. This excess capacity is more strongly correlated to carbon loading and surface area of the carbon additive rather than any exotic redox mechanism of ε-VOPO4 such as oxygen redox.
A sustainable Non-Enzymatic Approach for Determination of Cholesterol Using Piper nigrum Derived Porous Carbon/α-Fe2O3 Composite Electrode
Authors: Benny Libina , Krishnan Gokul , Agnihotri Ananya S. , Akshaya K. B. , Varghese Anitha , Nidhin M.
Published: April 2021

Activated porous carbon (APC) obtained from Piper nigrum along with α-Fe2O3 have been used to modify carbon paste electrode (CPE) for the highly sensitive and selective electrochemical determination of cholesterol. The enhanced synergistic properties observed between the biomass-derived APC and α-Fe2O3 uplifts the electrocatalytic activity of the modified electrode (APC-Fe2O3/CPE). The prepared α-Fe2O3 nanoparticles were characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Dynamic light scattering (DLS), zeta potential measurements and Thermogravimetric analysis (TGA). High resolution transmission electron microscopy (HRTEM), Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and electrochemical techniques were used to study the physico-chemical properties of the modified electrodes. Experimental conditions such as effect of pH, scan rate and concentration of cholesterol were optimized. Wide linear dynamic range between 25 nM and 300 nM, low limit of detection (LOD) and limit of quantification (LOQ) of 8 nM and 26 nM respectively make the method very effective and sensitive. Cholesterol in human blood serum samples was non-enzymatically determined using the developed method.
Review—Trends on the Development of Non-Enzymatic Electrochemical Sensors Modified with Metal-Oxide Nanostructures for the Quantification of Uric Acid
Authors: Hernández-Ramírez D. , Mendoza-Huizar L. H. , Galán-Vidal C. A. , Aguilar-Lira G.Y. , Álvarez-Romero G.A.
Published: April 2021

Uric acid is one of the most important metabolites as its blood levels can help to diagnose important diseases. Tradicionally, uric acid is determined by enzymatic-spectrophotometric techniques, but in recent years new promising alternatives have arisen. This review is devoted to the development over the past decade of non-enzymatic electrochemical studies based on nano-structures of non-noble metal oxides (Fe2O3, CuO, Cu2O, ZnO, NiO, MnO2, CeO2, MgO, SnO2 and Co3O4) for uric acid detection. The proposals showed the application of electrochemical sensors for the determination of uric acid in blood, urine, pharmaceuticals, water, and commercial shellfish. The developed electrodes are based on vitreous carbon electrodes, carbon paste, or screen-printed, mainly modified with nano-structures of metal oxides to electrochemically oxidize uric acid, where the anodic current peak is used as the analytical signal and the results reported are very promising.
Highly Sensitive and Wide Range Non-Enzymatic Electrochemical Detection of Cholesterol using Pencil Lead Electrodes
Authors: Punnakkal Navaneeth , Raveendran Jeethu , Punathil Vasu Suneesh , G. Nair Bipin , Satheesh Babu T. G.
Published: April 2021

Electrochemical detection of cholesterol has been carried out on pencil lead electrode (PLE) in acetonitrile and acetone (1:1 v/v %) containing 0.3 M lithium perchlorate. The PLEs were explored for the first time for the detection of cholesterol in an organic medium. The electrodes were thoroughly characterized by microscopy and diffraction studies. The PLE exhibited a wide linear range of detection from 0.625 to 9.375 mM and high sensitivity of 1455.22 μA mM−1 cm−2. These characteristics point to the superior performance of the sensor when compared with that reported in the organic medium. The unmodified PLE was highly specific to cholesterol in the presence of commonly interfering biomolecules such as uric acid, dopamine, glucose, ascorbic acid, creatinine and proteins. Calibration plots for real samples were constructed by spiking 0.625–9.375 mM of cholesterol to serum and skin cholesterol samples. In both samples, the PLE show a highly linear response.
Unrestricted Face Recognition Algorithm Based on Transfer Learning on Self-Pickup Cabinet
Authors: Liang Zhixue
Published: April 2021

In the contactless delivery scenario, the self-pickup cabinet is an important terminal delivery device, and face recognition is one of the efficient ways to achieve contactless access express delivery. In order to effectively recognize face images under unrestricted environments, an unrestricted face recognition algorithm based on transfer learning is proposed in this study. First, the region extraction network of the faster RCNN algorithm is improved to improve the recognition speed of the algorithm. Then, the first transfer learning is applied between the large ImageNet dataset and the face image dataset under restricted conditions. The second transfer learning is applied between face image under restricted conditions and unrestricted face image datasets. Finally, the unrestricted face image is processed by the image enhancement algorithm to increase its similarity with the restricted face image, so that the second transfer learning can be carried out effectively. Experimental results show that the proposed algorithm has better recognition rate and recognition speed on the CASIA-WebFace dataset, FLW dataset, and MegaFace dataset.
Lung Infection Segmentation for COVID‐19 Pneumonia Based on a Cascade Convolutional Network from CT Images
Authors: Ranjbarzadeh Ramin , Jafarzadeh Ghoushchi Saeid , Bendechache Malika , Amirabadi Amir , Ab Rahman Mohd Nizam , Baseri Saadi Soroush , Aghamohammadi Amirhossein , Kooshki Forooshani Mersedeh
Published: April 2021

The COVID‐19 pandemic is a global, national, and local public health concern which has caused a significant outbreak in all countries and regions for both males and females around the world. Automated detection of lung infections and their boundaries from medical images offers a great potential to augment the patient treatment healthcare strategies for tackling COVID‐19 and its impacts. Detecting this disease from lung CT scan images is perhaps one of the fastest ways to diagnose patients. However, finding the presence of infected tissues and segment them from CT slices faces numerous challenges, including similar adjacent tissues, vague boundary, and erratic infections. To eliminate these obstacles, we propose a two‐route convolutional neural network (CNN) by extracting global and local features for detecting and classifying COVID‐19 infection from CT images. Each pixel from the image is classified into the normal and infected tissues. For improving the classification accuracy, we used two different strategies including fuzzy c‐means clustering and local directional pattern (LDN) encoding methods to represent the input image differently. This allows us to find more complex pattern from the image. To overcome the overfitting problems due to small samples, an augmentation approach is utilized. The results demonstrated that the proposed framework achieved precision 96%, recall 97%, F score, average surface distance (ASD) of 2.8 ± 0.3 mm, and volume overlap error (VOE) of 5.6 ± 1.2%.
Performance Analysis in the Decode-and-Forward Full-Duplex Relaying Network with SWIPT
Authors: Tran Tin Phu , Van-Duc Phan , Nguyen Tan N. , Vu Le Anh
Published: April 2021

This paper investigates the decode-and-forward (DF) full-duplex (FD) cooperative relaying system with SWIPT. Specifically, the relay node can harvest energy from the source’s RF signal, and then the harvested energy is used for transferring information to the destination. Besides, we consider both direct and two-hop relaying links to transmit data from the source to the destination. In the performance analysis, we derive the exact expressions for outage probability (OP) by applying the receiver’s selection combining (SC) technique. Then, the Monte Carlo simulation is performed to verify the correctness of the mathematical analysis. Finally, the simulations show that the mathematic expressions match simulation results, which authenticates the mathematical analysis.
Removal of Methylene Blue from Aqueous Solutions by Using Nance (Byrsonima crassifolia) Seeds and Peels as Natural Biosorbents
Authors: Robles-Melchor Lorena , Cornejo-Mazón Maribel , Hernández-Martínez Diana Maylet , Gutiérrez-López Gustavo F. , García-Pinilla Santiago , López-Villegas Edgar Oliver , Téllez-Medina Darío Iker
Published: April 2021

Contamination of effluents with chemicals is a serious problem that impacts human health. Methylene blue is a cationic dye found frequently in industrial and urban sewages. In this work, dried grinded seeds and peels of nance were used as biosorbents in aqueous solutions at pH 7 and 10 (simulating urban and textile effluents) finding that Langmuir and Freundlich isotherms adequately described the sorption. Adsorption efficiencies were larger than 98% in all cases and slightly lower at pH 7 due to the closeness with the point of zero charge (pzc) of seeds and peels of nance (5.96 and 3.42, respectively). In all cases, Langmuir adsorption was favorable (RLa < 1), and Gibbs free energy of adsorption was negative indicating spontaneity, and since these values were larger than −80 but lower than 0 kJ/mol, the MB removal process was mainly due to physical interactions, a characteristic of physical adsorption. No significant differences were found amongst bulk mass transfer coefficients for the adsorption of both sorbents, indicating that both bioadsorbents had the same hydrodynamic and driving forces as well as depicted similar MB-adsorbent affinities. Interaction of MB with adsorbents was corroborated by FTIR spectroscopy, and the sorption was evidenced by scanning electron microscopy and image analysis which indicated that both adsorbents had fractal structures.
Design and Implementation of Novel LMI‐Based Iterative Learning Robust Nonlinear Controller
Authors: Riaz Saleem , Lin Hui , Afzal Farkhanda , Maqbool Ayesha
Published: April 2021

An iterative learning robust fault‐tolerant control algorithm is proposed for a class of uncertain discrete systems with repeated action with nonlinear and actuator faults. First, by defining an actuator fault coefficient matrix, we convert the iterative learning control system into an equivalent unknown nonlinear repetitive process model. Then, based on the mixed Lyapunov function approach, we describe the stability of the nonlinear repetitive mechanism on time and trial indices and have appropriate conditions for the repeated control system’s stability in terms of linear matrix inequality theory. Through LMI techniques, we have obtained satisfactory results and controller stability, and robustness against fault tolerance is also discussed in detail. Finally, the simulation results of the output tracking control of the two exemplary models verify the effectiveness of the proposed algorithm.