bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of efficient testing and contact tracing in mitigating the COVID-19 pandemic: a network modelling study
Authors: Hu Yiying , Guo Jianying , Li Guanqiao , Lu Xi , Li Xiang , Zhang Yuan , Cong Lin , Kang Yanni , Jia Xiaoyu , Shi Xuanling , Xie Guotong , Zhang Linqi
Published: July 2021

Objectives

This study quantified how the efficiency of testing and contact tracing impacts the spread of COVID-19. The average time interval between infection and quarantine, whether asymptomatic cases are tested or not, and initial delays to beginning a testing and tracing programme were investigated.

Setting

We developed a novel individual-level network model, called CoTECT (Testing Efficiency and Contact Tracing model for COVID-19), using key parameters from recent studies to quantify the impacts of testing and tracing efficiency. The model distinguishes infection from confirmation by integrating a ‘T’ compartment, which represents infections confirmed by testing and quarantine. The compartments of presymptomatic (E), asymptomatic (I), symptomatic (Is), and death with (F) or without (f) test confirmation were also included in the model. Three scenarios were evaluated in a closed population of 3000 individuals to mimic community-level dynamics. Real-world data from four Nordic countries were also analysed.

Primary and secondary outcome measures

Simulation result: total/peak daily infections and confirmed cases, total deaths (confirmed/unconfirmed by testing), fatalities and the case fatality rate. Real-world analysis: confirmed cases and deaths per million people.

Results

(1) Shortening the duration between Is and T from 12 to 4 days reduces infections by 85.2% and deaths by 88.8%. (2) Testing and tracing regardless of symptoms reduce infections by 35.7% and deaths by 46.2% compared with testing only symptomatic cases. (3) Reducing the delay to implementing a testing and tracing programme from 50 to 10 days reduces infections by 35.2% and deaths by 44.6%. These results were robust to sensitivity analysis. An analysis of real-world data showed that tests per case early in the pandemic are critical for reducing confirmed cases and the fatality rate.

Conclusions

Reducing testing delays will help to contain outbreaks. These results provide policymakers with quantitative evidence of efficiency as a critical value in developing testing and contact tracing strategies.
Development and internal validation of a simple prognostic score for early sepsis risk stratification in the emergency department
Authors: Liu Bofu , Li Dongze , Cheng Yisong , Yu Jing , Jia Yu , Zhang Qin , Liu Yanmei , Cao Yu
Published: July 2021

Objectives

No validated, simple, powerful and continuously monitorable risk prediction tools are available for patients with sepsis during the early phases in the emergency department (ED). We sought to derive a novel Simple Sepsis Early Prognostic Score (SSEPS) composed of physiological indicators that do not depend on laboratory tests and that can be used by emergency clinicians in predicting outcomes in patients with sepsis.

Design

Retrospective cohort analysis of a collected data source.

Participants

Patients with sepsis admitted to the ED of the West China Hospital of Sichuan University between July 2015 and June 2016 were included. We excluded patients who were pregnant, those with cardiac or respiratory arrest, and those using vasoactive drugs before admission to the ED.

Primary outcome measures

28-day all-cause mortality.

Results

The SSEPS consisted of age, heart rate, respiratory rate and altered consciousness. Patients in the development cohort with higher SSEPS had a significantly higher mortality (first tertile vs second tertile vs third tertile: 12.5% vs 28.6% vs 53.5%, p<0.001). The area under the receiver operating characteristic curve for SSEPS was 0.762 (95% CI 0.686 to 0.838), which was similar to Sequential Organ Failure Assessment (SOFA) (area under the curve: 0.745, 95% CI 0.692 to 0.798) and Acute Physiology and Chronic Health Evaluation (APACHE II) (area under the curve: 0.750, 95% CI 0.681 to 0.819). Moreover, the decision curve analysis showed that the net benefit of SSEPS was higher than SOFA and APACHE II at any probability threshold.

Conclusion

The SSEPS is simple and useful for clinicians in stratifying high-risk patients with sepsis at the early phase of ED admission.
Repetitive transcranial magnetic stimulation (rTMS) in autism spectrum disorder: protocol for a multicentre randomised controlled clinical trial
Authors: Enticott Peter G , Barlow Karen , Guastella Adam J , Licari Melissa K , Rogasch Nigel C , Middeldorp Christel M , Clark Scott R , Vallence Ann-Maree , Boulton Kelsie A , Hickie Ian B , Whitehouse Andrew J O , Galletly Cherrie , Alvares Gail A , Fujiyama Hakuei , Heussler Helen , Craig Jeffrey M , Kirkovski Melissa , Mills Natalie T , Rinehart Nicole J , Donaldson Peter H , Ford Talitha C , Caeyenberghs Karen , Albein-Urios Natalia , Bekkali Soukayna , Fitzgerald Paul B
Published: July 2021

Introduction

There are no well-established biomedical treatments for the core symptoms of autism spectrum disorder (ASD). A small number of studies suggest that repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, may improve clinical and cognitive outcomes in ASD. We describe here the protocol for a funded multicentre randomised controlled clinical trial to investigate whether a course of rTMS to the right temporoparietal junction (rTPJ), which has demonstrated abnormal brain activation in ASD, can improve social communication in adolescents and young adults with ASD.

Methods and analysis

This study will evaluate the safety and efficacy of a 4-week course of intermittent theta burst stimulation (iTBS, a variant of rTMS) in ASD. Participants meeting criteria for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition ASD (n=150, aged 14–40 years) will receive 20 sessions of either active iTBS (600 pulses) or sham iTBS (in which a sham coil mimics the sensation of iTBS, but no active stimulation is delivered) to the rTPJ. Participants will undergo a range of clinical, cognitive, epi/genetic, and neurophysiological assessments before and at multiple time points up to 6 months after iTBS. Safety will be assessed via a structured questionnaire and adverse event reporting. The study will be conducted from November 2020 to October 2024.

Ethics and dissemination

The study was approved by the Human Research Ethics Committee of Monash Health (Melbourne, Australia) under Australia’s National Mutual Acceptance scheme. The trial will be conducted according to Good Clinical Practice, and findings will be written up for scholarly publication.

Trial registration number

Australian New Zealand Clinical Trials Registry (ACTRN12620000890932).
Is there a correlation between children’s outdoor active mobility behaviour and neighbourhood safety? A systematic review of the evidence
Authors: Zougheibe Roula , Jepson Beverly , Norman Richard , Gudes Ori , Dewan Ashraf
Published: July 2021

Objective

To identify, summarise and evaluate evidence on the correlation between perceived and actual neighbourhood safety (personal and road danger) and diverse forms of outdoor active mobility behaviour (ie, active play, exercise, and travel) among primary-school-aged children.

Design

A systematic review of evidence from observational studies exploring children’s active mobility behaviour and safety.

Data sources

Six electronic databases were searched: Google Scholar, PubMed, Scopus, Science Direct, ProQuest and Web of Science from study inception until July 2020.

Data extraction and synthesis

Study selection and quality assessment were conducted independently by two reviewers. We expanded on a quality assessment tool and adopted a vote-counting technique to determine strength of evidence. The outcomes were categorised by individual, family and neighbourhood levels.

Results

A total of 29 studies were included, with a majority of cross-sectional design. Higher parental perceived personal safety correlated with increased children’s active mobility behaviour, but most commonly in active travel (eg, independent walking or cycling to a local destination). Increased concerns regarding road danger correlated with a decrease in each type of children’s active behaviour; active travel, play and exercise. However, these correlations were influenced by child’s sex/gender, age, car ownership, neighbourhood types, across time, and proximity to destination. Limited or inconclusive evidence was found on correlate of children’s outdoor active mobility behaviour to ‘stranger danger’, children’s perceived personal safety, race/ethnicity, socioeconomic status or measured safety.

Conclusion

Children are restricted by perception of safety. Encouraging children’s active travel may require future strategies to address characteristics relevant to types of the neighbourhood that promote a high sense of personal safety. Children and parents may embrace other types of active mobility behaviour if road danger is mitigated. Sex/gender and age-specific interventions and redesign of public places could lead to child-friendly cities. Future studies may benefit from adopting validated measurement methods and fill existing research gaps.
Evaluating the impact of a common elements-based intervention to improve maternal psychological well-being and mother–infant interaction in rural Pakistan: study protocol for a randomised controlled trial
Authors: Huma Zill-e- , Gillani Ayella , Shafique Fakhira , Rashid Alina , Mahjabeen Bushra , Javed Hashim , Wang Duolao , Rahman Atif , Hamdani Syed Usman
Published: July 2021

Introduction

Millions of children in low resource settings are at high risk of poor development due to factors such as under nutrition, inadequate stimulation and maternal depression. Evidence-based interventions to address these risk factors exist, but often as a separate and overlapping package. The current study aims to evaluate the effectiveness of a common elements-based intervention to improve mother–infant interaction at 12 months post-partum.

Method and analysis

A two-arm, single-blinded, individual randomised controlled trial is being carried out in the community settings of the rural subdistrict of Gujar Khan in Rawalpindi, Pakistan. 250 pregnant women in third trimester with distress (Self-Reporting Questionnaire, cut-off score >9) have been randomised on 1:1 allocation ratio into intervention (n=125) and treatment-as-usual arms (n=125). The participants in the intervention arm will receive 15 individual sessions of intervention on a monthly basis by non-specialist facilitators. The intervention involves components of early stimulation, learning through play, responsive feeding, guided discovery using pictures, behavioural activation and problem solving. The primary outcome is caregiver–infant interaction at 12 months postpartum. The secondary outcomes include maternal psychological well-being, quality of life, social support and empowerment. Infant secondary outcomes include growth, nutrition and development. The data will be collected at baseline, 6 and 12 months postpartum. A qualitative process evaluation will be conducted to inform the feasibility of intervention delivery.

Ethics

Ethics approval for the present study was obtained from the Human Development Research Foundation Institutional Review Board, Islamabad Pakistan.

Dissemination

If proven effective, the study will contribute to scale-up care for maternal and child mental health in low resource settings, globally. The findings of the present study will be published in peer-reviewed journals and presented at conferences and community forums.

Trial registration number

NCT04252807.
Educational resource for antimicrobial resistance and stewardship for dentistry programmes: a research protocol
Authors: Ang Chuan Yok , Dhaliwal Jagjit Singh , Muharram Siti Hanna , Akkawi Muhammad Eid , Hussain Zahid , Rahman Hanif , Kok Yuh Yen , Dhaliwal Sachinjeet Kaur Sodhi , Ming Long Chiau
Published: July 2021

Introduction

Antimicrobial resistance (AMR) is a global public and patient safety issue. With the high AMR risk, ensuring that the next generation of dentists that have optimal knowledge and confidence in the area of AMR is crucial. A systematic approach is vital to design an AMR content that is comprehensive and clinically relevant. The primary objective of this research study will be to implement a consensus-based approach to elucidate AMR content and curriculum priorities for professional dentistry programmes. This research aims to establish consensus along with eliciting opinion on appropriate AMR topics to be covered in the Bachelor of Dental Surgery syllabus.

Methods and analysis

A three-phase approach to validate content for curriculum guidelines on AMR will be adopted. First, literature review and content analysis were conducted to find out the available pertinent literature in dentistry programmes. A total of 23 potential literature have been chosen for inclusion within this study following literature review and analysis in phase 1. The materials found will be used to draft curriculum on antimicrobials for dentistry programmes. The next phase involves the validation of the drafted curriculum content by recruiting local and foreign experts via a survey questionnaire. Finally, Delphi technique will be conducted to obtain consensus on the important or controversial modifications to the revised curriculum.

Ethics and dissemination

An ethics application is currently under review with the Institute of Health Science Research Ethics Committee, Universiti Brunei Darussalam. All participants are required to provide a written consent form. Findings will be used to identify significant knowledge gaps on AMR aspect in a way that results in lasting change in clinical practice. Moreover, AMR content priorities related to dentistry clinical practice will be determined in order to develop need-based educational resource on microbes, hygiene and prudent antimicrobial use for dentistry programmes.
Examining the possible causal relationship between lung function, COPD and Alzheimer’s disease: a Mendelian randomisation study
Authors: Higbee Daniel , Granell Raquel , Walton Esther , Korologou-Linden Roxanna , Davey Smith George , Dodd James
Published: July 2021

Rationale

Large retrospective case-control studies have reported an association between chronic obstructive pulmonary disease (COPD), reduced lung function and an increased risk of Alzheimer’s disease. However, it remains unclear if these diseases are causally linked, or due to shared risk factors. Conventional observational epidemiology suffers from unmeasured confounding and reverse causation. Additional analyses addressing causality are required.

Objectives

To examine a causal relationship between COPD, lung function and Alzheimer’s disease.

Methods

Using two-sample Mendelian randomisation, we used single nucleotide polymorphisms (SNPs) identified in a genome wide association study (GWAS) for lung function as instrumental variables (exposure). Additionally, we used SNPs discovered in a GWAS for COPD in those with moderate to very severe obstruction. The effect of these SNPs on Alzheimer’s disease (outcome) was taken from a GWAS based on a sample of 24 807 patients and 55 058 controls.

Results

We found minimal evidence for an effect of either lung function (OR: 1.02 per SD; 95% CI 0.91 to 1.13; p value 0.68) or liability for COPD on Alzheimer’s disease (OR: 0.97 per SD; 95% CI 0.92 to 1.03; p value 0.40).

Conclusion

Neither reduced lung function nor liability COPD are likely to be causally associated with an increased risk of Alzheimer’s, any observed association is likely due to unmeasured confounding. Scientific attention and health prevention policy may be better focused on overlapping risk factors, rather than attempts to reduce risk of Alzheimer’s disease by targeting impaired lung function or COPD directly.
Effect of oral and transdermal oestrogen therapy on bone mineral density in functional hypothalamic amenorrhoea: a systematic review and meta-analysis
Authors: Aalberg Karoline , Stavem Knut , Norheim Frode , Russell Michael Bjørn , Chaibi Aleksander
Published: July 2021

Background

Female athletes might develop reduced bone mineral density (BMD) and amenorrhoea due to low energy intake.

Objective

To systematically review the literature of randomised controlled trials (RCTs) assessing the effect of oestrogen oral contraceptives (OCP), conjugated oestrogens (CE) and transdermal estradiol (TE) on BMD in premenopausal women with functional hypothalamic amenorrhoea (FHA) due to weight loss, vigorous exercise and/or stress.

Methods

A comprehensive literature search in PubMed, MEDLINE, Cochrane Library, Ovid and CINAHL from inception to 1 October 2020.

Data extraction and synthesis

Two authors independently extracted data. When possible, the data were pooled in a random-effects meta-analysis.

Main outcomes

Difference in BMD (g/cm2) at the lumbar spine.

Results

Nine RCTs comprising 770 participants met the inclusion criteria; five studies applied OCP, two CE and two TE. Four RCTs (two OCP, two TE) found an increased BMD in premenopausal women with FHA, and five (three OCP, two CE) found a decreased BMD compared with controls. A meta-analysis showed no difference in BMD between the treatment and control groups, (standardised mean difference (SMD) 0.30, 95% CI −0.12 to 0.73). A secondary analysis for change scores from baseline to first assessment point, showed a similar overall result (SMD 0.17, 95% CI −0.16 to 0.51). No serious adverse events were reported.

Conclusion

The literature suggests that TE might increase lumbar BMD in premenopausal women with FHA, but pooled results revealed no effect of the intervention. The findings do not support oestrogen therapy to improve BMD in these patient groups.
What do we know about patients’ perspectives and expectations relating to palliative and end-of-life care in advanced liver disease? A systematic review of qualitative literature using ENTREQ guidelines
Authors: Das Debasish , Ali Mafas , Hussain Ithsham Ali , Ingram Josh Thomas Nigel , Johnstone Rachel Sarah , Lopes Jade Jessica , Wadee Tasneem , Chakraborty Nandini
Published: July 2021

Background

Liver disease, a major cause of death worldwide, affects younger people compared with other major causes of death. Palliative and end-of-life care for these patients are often overlooked. Guidelines are emerging on what good end-of-life care in liver disease should look like, but there is a dearth of research into patients’ perspectives even though they are most affected by these guidelines.

Aim

To explore current knowledge and understanding of patients’ lived experiences, perspectives and expectations in relation to palliative and end-of-life care in advanced liver disease.

Design

Systematic review with thematic synthesis complying to the enhancing transparency in reporting the synthesis of qualitative research (ENTREQ) statement.

Setting and participants

Database searches (Ovid Medline, 1946–2021 and Web of Science, 1970–2021) to identify qualitative studies exploring patients’ perspectives of palliative and end-of-life care in advanced liver disease.

Findings

Only eight articles met all criteria. Themes demonstrated repeated hospital admissions towards the end of life, lack of coordinated care in community and barriers in discussion about palliative care in end-stage liver disease due to lack of confidence among professionals and a negative view about palliative care among patients and carers. Emotional, financial and disability-related needs of patients and their carers are often neglected.

Conclusion

There is a dearth of studies exploring patients’ perspectives about care in advanced liver disease relating to palliative and end-of-life care. Lack of coordinated community support and honest conversations around palliative care leads to reduced quality of life. More primary research from diverse population is needed to improve palliative care and end-of-life care in end-stage liver disease.
Early invasive versus non-invasive assessment in patients with suspected non-ST-elevation acute coronary syndrome
Authors: Kite Thomas A , Ladwiniec Andrew , Arnold J Ranjit , McCann Gerry P , Moss Alastair J
Published: July 2021

Non-ST-elevation acute coronary syndrome (NSTE-ACS) comprises a broad spectrum of disease ranging from unstable angina to myocardial infarction. International guidelines recommend a routine invasive strategy for managing patients with NSTE-ACS at high to very high-risk, supported by evidence of improved composite ischaemic outcomes as compared with a selective invasive strategy. However, accurate diagnosis of NSTE-ACS in the acute setting is challenging due to the spectrum of non-coronary disease that can manifest with similar symptoms. Heterogeneous clinical presentations and limited uptake of risk prediction tools can confound physician decision-making regarding the use and timing of invasive coronary angiography (ICA). Large proportions of patients with suspected NSTE-ACS do not require revascularisation but may unnecessarily undergo ICA with its attendant risks and associated costs. Advances in coronary CT angiography and cardiac MRI have prompted evaluation of whether non-invasive strategies may improve patient selection, or whether tailored approaches are better suited to specific subgroups. Future directions include (1) better understanding of risk stratification as a guide to investigation and therapy in suspected NSTE-ACS, (2) randomised clinical trials of non-invasive imaging versus standard of care approaches prior to ICA and (3) defining the optimal timing of very early ICA in high-risk NSTE-ACS.
What’s yours is ours: waiving intellectual property protections for COVID-19 vaccines
Authors: Jecker Nancy S , Atuire Caesar A
Published: July 2021

This paper gives an ethical argument for temporarily waiving intellectual property (IP) protections for COVID-19 vaccines. It examines two proposals under discussion at the World Trade Organization (WTO): the India/South Africa proposal and the WTO Director General proposal. Section I explains the background leading up to the WTO debate. Section II rebuts ethical arguments for retaining current IP protections, which appeal to benefiting society by spurring innovation and protecting rightful ownership. It sets forth positive ethical arguments for a temporary waiver that appeal to standing in solidarity and holding companies accountable. After examining built-in exceptions to existing agreements and finding them inadequate, the paper replies to objections to a temporary waiver and concludes, in section III, that the ethical argument for temporarily waiving IP protection for COVID-19 vaccines is strong.
SPECTRAL EIGENVALUE PROBLEMS OF SELF-SIMILAR MEASURES WITH CONSECUTIVE DIGITS
Authors: LI HAI-XIONG , LI QIAN
Published: July 2021

Let [Formula: see text] be two positive integers. For [Formula: see text], it is well known that the self-similar measure [Formula: see text] defined by [Formula: see text] is a spectral measure with a spectrum [Formula: see text] In this paper, by applying the properties of congruences and the order of elements in the finite group, we obtain some conditions on the integer [Formula: see text] such that the set [Formula: see text] is also a spectrum for [Formula: see text]. Moreover, an example is given to explain our theory.
A STUDY ON HEAT AND MASS TRANSFER OF POWER-LAW NANOFLUIDS IN A FRACTAL POROUS MEDIUM WITH COMPLEX EVAPORATING SURFACE
Authors: LIU SHUAI , ZHU QINGYONG
Published: July 2021

In this paper, a convection and heat transfer problem of power-law fluid in a three-dimensional porous media with complex evaporating surface is studied. The Buoyancy-Marangoni convection for non-Newtonian power-law fluids in porous media is solved using a compact high-order finite volume method. For this model, the left wall is kept at high temperature and high concentration, the right wall is affected by lower temperature and lower concentration, the upper wall is a complex evaporating surface. The Weierstrass–Mandelbrot function is used to approximate the shape of the evaporation interface, the analytical solution of its fractal dimension can be obtained by the pore area fractal dimension, and the volume percentage of liquid. The fluid in the porous cavity is a power-law fluid containing copper oxide nanoparticles. The solid material of the porous medium is aluminum foam. Numerical simulations can be used to determine Marangoni number, Rayleigh number and the pore area fractal dimension on the flow, heat transfer, and mass transfer rate.
THREE KEY PROPERTIES OF A SPECIAL CLASS OF EVOLVING NETWORKS BASED ON TOY-MODEL
Authors: PENG L. , XUE Y. , ZHANG Q. , HE H.
Published: July 2021

In real world, many networks have self-similar structures at different length scales. In this paper, we propose a family of growing symmetrical networks based on toy-model from a deterministic initial graph. We aim to analyze its topological properties, such as the average path length, clustering coefficient and degree distribution, which uses iterative calculations and recursive methods.
Characterization of stochastic equilibrium controls by the Malliavin calculus
Authors: Nguwi Jiang Yu , Privault Nicolas
Published: July 2021

We derive a characterization of equilibrium controls in continuous-time, time-inconsistent control (TIC) problems using the Malliavin calculus. For this, the classical duality analysis of adjoint BSDEs is replaced with the Malliavin integration by parts. This results into a necessary and sufficient maximum principle which is applied to a linear-quadratic TIC problem, recovering previous results obtained by duality analysis in the mean-variance case, and extending them to the linear-quadratic setting. We also show that our results apply beyond the linear-quadratic case by treating the generalized Merton problem.
Sensitivity of steady states in a degenerately damped stochastic Lorenz system
Authors: Földes Juraj , Glatt-Holtz Nathan E. , Herzog David P.
Published: July 2021

We study stability of solutions for a randomly driven and degenerately damped version of the Lorenz ’63 model. Specifically, we prove that when damping is absent in one of the temperature components, the system possesses a unique invariant probability measure if and only if noise acts on the convection variable. On the other hand, if there is a positive growth term on the vertical temperature profile, we prove that there is no normalizable invariant state. Our approach relies on the derivation and analysis of nontrivial Lyapunov functions which ensure positive recurrence or null-recurrence/transience of the dynamics.
Control of the non-geometrically integral reductions
Authors: Liu Chunhui
Published: July 2021

In this paper, for a geometrically integral projective scheme, we will give an upper bound of the product of the norms of its non-geometrically integral reductions over an arbitrary number field. For this aim, we take the adelic viewpoint on this subject.

Résumé (Contrôle des réductions non-géométriquement intègres) Dans cet article, pour un schéma projectif géométriquement intègre, on donnera une majoration du produit des norms de ses réductions non-géométriquement intègre sur un corps de nombres arbitraire. Pour le but, on prend le point de vue adélique autour de ce sujet.
The Ru–Vojta result for subvarieties
Authors: Ru Min , Wang Julie Tzu-Yueh
Published: July 2021

In M. Ru and P. Vojta, A birational Nevanlinna constant and its consequences, Amer. J. Math. 142(3) (2020) 957–991, among other things, proved the so-called general theorem (arithmetic part) which can be viewed as an extension of Schmidt’s subspace theorem. In this paper, we extend their result by replacing the divisors by closed subschemes.
Weighted partition rank and crank moments. III. A list of Andrews–Beck type congruences modulo 5, 7, 11 and 13
Authors: Chern Shane
Published: July 2021

Let [Formula: see text] count the total number of parts among partitions of [Formula: see text] with rank congruent to [Formula: see text] modulo [Formula: see text] and let [Formula: see text] count the total appearances of ones among partitions of [Formula: see text] with crank congruent to [Formula: see text] modulo [Formula: see text]. We provide a list of over 70 congruences modulo [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] involving [Formula: see text] and [Formula: see text], which are known as congruences of Andrews–Beck type. Some recent conjectures of Chan, Mao and Osburn are also included in this list.
Audio Captioning with Composition of Acoustic and Semantic Information
Authors: Özkaya Eren Ayşegül , Sert Mustafa
Published: July 2021

Generating audio captions is a new research area that combines audio and natural language processing to create meaningful textual descriptions for audio clips. To address this problem, previous studies mostly use the encoder–decoder-based models without considering semantic information. To fill this gap, we present a novel encoder–decoder architecture using bi-directional Gated Recurrent Units (BiGRU) with audio and semantic embeddings. We extract semantic embedding by obtaining subjects and verbs from the audio clip captions and combine these embedding with audio embedding to feed the BiGRU-based encoder–decoder model. To enable semantic embeddings for the test audios, we introduce a Multilayer Perceptron classifier to predict the semantic embeddings of those clips. We also present exhaustive experiments to show the efficiency of different features and datasets for our proposed model the audio captioning task. To extract audio features, we use the log Mel energy features, VGGish embeddings, and a pretrained audio neural network (PANN) embeddings. Extensive experiments on two audio captioning datasets Clotho and AudioCaps show that our proposed model outperforms state-of-the-art audio captioning models across different evaluation metrics and using the semantic information improves the captioning performance.
On the double total dominator chromatic number of graphs
Authors: Beggas Fairouz , Kheddouci Hamamache , Marweni Walid
Published: July 2021

In this paper, we introduce and study a new coloring problem of graphs called the double total dominator coloring. A double total dominator coloring of a graph [Formula: see text] with minimum degree at least 2 is a proper vertex coloring of [Formula: see text] such that each vertex has to dominate at least two color classes. The minimum number of colors among all double total dominator coloring of [Formula: see text] is called the double total dominator chromatic number, denoted by [Formula: see text]. Therefore, we establish the close relationship between the double total dominator chromatic number [Formula: see text] and the double total domination number [Formula: see text]. We prove the NP-completeness of the problem. We also examine the effects on [Formula: see text] when [Formula: see text] is modified by some operations. Finally, we discuss the [Formula: see text] number of square of trees by giving some bounds.
Landslide-tsunamis along the flanks of Mount Epomeo, Ischia: propagation patterns and coastal hazard for the Campania Coasts, Italy
Authors: Zaniboni Filippo , Pagnoni Gianluca , Gallotti Glauco , Tinti Stefano , Armigliato Alberto
Published: July 2021

Ischia Island has been repeatedly affected by mass collapses, which are mainly caused by the steepness of the main peak (Mt Epomeo) and by phenomena related to its volcanic activity. The most relevant cases of mass failure studied in the literature and postulated to be tsunamigenic cover a wide spectrum of sizes, from sector collapse to small-volume mass transports. Tsunamis generated by landslides in Ischia may affect the coast of the Campania mainland, including the Gulf of Naples. The focus of this work is an evaluation of the pattern of the maximum tsunami energy. To this purpose, we perform a series of numerical simulations by moving the same landslide source in different hypothetical positions around the island. The landslide dynamics are computed through the code UBO-BLOCK, and the tsunami propagation by employing the code UBO-TSUFD, both developed in-house. The final goal is to characterize the coastal areas of the Campania mainland most exposed to tsunami attack from Ischia sources. It is found that the position of the landslide deeply influences the distribution of the tsunami elevation in the coastal stretch north of the Procida Mt, while, remarkably, it is irrelevant inside the Gulf of Naples where the bathymetric effect prevails.
Hydro-acoustic signals from the Panarea shallow hydrothermal field: new inferences of a direct link with Stromboli
Authors: Longo M. , Lazzaro G. , Caruso C. G. , Corbo A. , Sciré Scappuzzo S. , Italiano F. , Gattuso A. , Romano D.
Published: July 2021

We present the results from a mid-term monitoring activity carried out at the submarine hydrothermal system located off Panarea Island (Aeolian Islands, Italy). The collected data concern multiparametric information from a self-operating seafloor station (acoustics and chemical–physical parameters) acquiring data at regular intervals and transmitting it twice a day in near real-time. The acoustic records were analysed with the principal aim of investigating bubbling variations related to gas flow rate. Several anomalies have been documented, in the bubbling activity detected at high frequencies (100–2000 Hz), as well as in very low acoustic frequencies, related to fluids dynamic along cracks. An astonishing correlation between soil CO
2
flux emissions recorded at Stromboli craters and the acoustic signals in the 1–30 Hz range has been identified, suggesting how this tectonic link could act as an escape route for fluids characterized by a shared source.
(Plenary) Update on the SOFC Program at the DOE’s National Energy Technology Laboratory
Authors: Vora Shailesh , Williams Mark , Jesionowski Gary
Published: July 2021

The Solid Oxide Fuel Cell (SOFC) Program, managed by the U.S. Department of Energy (DOE) Office of Fossil Energy (FE) and administered by the FE’s National Energy Technology Laboratory (NETL), is currently developing low-cost SOFC power generation systems. SOFC power systems have the potential to achieve greater than 60 percent efficiency. The SOFC’s operating temperature is lower than combustion-based processes and precludes NOx formation; there are near-zero emissions of CO2, criteria pollutants, and particulates. Furthermore, SOFC power systems require approximately one-third the amount of water relative to conventional combustion-based power systems. The Program includes the testing of SOFC with natural gas in distributed applications, including data centers. In addition to SOFC, there are several new projects on various aspects of high temperature solid oxide electrolysis cell (SOEC) for electrolysis of water. The development of efficient systems for hydrogen production is very interesting, especially when supplementary heat is provided from solar or other waste heat sources such as nuclear or coal power plants.
Basic Study of Anode Off-Gas Recycling Solid Oxide Fuel Cell Module with Fuel Regenerator
Authors: Nakamura Kazuo , Ide Takahiro , Kawabata Yasuharu , Nakajima Tatsuya , Dohkoh Tatsuki , Tsuji Marie , Akabane Shunnosuke , Hatae Toru
Published: July 2021

A model of an anode off-gas recycling solid oxide fuel cell (SOFC) module with a fuel regenerator was studied. The net alternating current (AC) efficiency was estimated by calculating the fuel concentration of the anode gas and the oxygen concentration of the cathode gas using a process simulation software. The results showed that a maximum net AC efficiency of 76.4% (lower heating value (LHV)) was achieved with recycling and fuel utilization rates of 99.0% and 100.0% CO2 and 43.4% H2O removal by the fuel regenerator. CO2 capture of 98.5% was also attained under the condition. These results showed that an anode off-gas recycling SOFC module can realize high performance in terms of both electrical efficiency and CO2 capture when a fuel regenerator is coupled with CO2 removal.
Principle Demonstration of Fuel Cell System with CO2 Capture
Authors: Akabane Shunnosuke , Dohkoh Tatsuki , Tsuji Marie , Nakajima Tatsuya , Kawabata Yasuharu , Ide Takahiro , Nakamura Kazuo , Hatae Toru
Published: July 2021

Tokyo Gas Co., Ltd. has developed a highly efficient solid oxide fuel cell system by increasing the fuel utilization rate using two-stage stacks and fuel regeneration. To reduce more CO2 emission, we focused on the fuel recycle system and the separation membrane, which removes both steam and carbon dioxide. In this study, we assembled and evaluated the hot module with the separation membrane. The power generation results show DC efficiency of 77.3%LHV at a gross power output of 5.65 kW. The CO2 separation membrane performed 85.2% of CO2 recovery rate from calculation. In addition, CO2 emission factor reached as small as 294 g-CO2/kWh from DC power generation.
Electrochemical Characterization of Intermediate-Temperature Solid Oxide Fuel Cells with PVD-Coated Electrolyte
Authors: Solovyev Andrey , Burmistrov Ilya Nikolaevich , Rabotkin Sergey , Shipilova Anna , Yalovenko Dimitriy Vladimirovich , Semenov Vyacheslav , Bredikhin Sergey Ivanovich
Published: July 2021

Anode-supported solid oxide fuel cells with thin electrolytes show good electrochemical performance. In this work, 4-μm-thick YSZ electrolyte with 2-μm-thick GDC barrier layer is deposited onto the substrates by reactive magnetron sputtering. It is shown that high power density can be obtained for 5 × 5 cm2 cells under planar stacks conditions with stainless steel current collectors. Electrochemical investigations are performed in the temperature range of 600-800°C. High power density of 0.29, 0.83, 1.4 W cm-2 is achieved at a voltage 0.7 V and 600, 700, and 800°C, respectively.
Exploring the Stability of Direct Ethanol Solid Oxide Fuel Cells at Intermediate Temperature
Authors: Fonseca Fabio Coral , Tabuti Francisco , Moraes Tamara , Abe Ricardo , Guimarães Rafael Mariz , Miura Yohei , Fukuyama Yosuke
Published: July 2021

Anode supported fuel cells were tested in direct (no water added) bioethanol at intermediate temperature (600°C and 700°C). The standard fuel cell has reasonable short-term stability under dry ethanol if current is continuously drawn at a minimum fuel utilization factor at 700ºC. However, the YSZ/Ni anode develops carbon deposits as inferred from post fuel cell test analyses and fixed bed steam reforming catalytic tests at 600°C. Thus, an active catalytic layer with tailored properties for ethanol internal reforming was studied. Initial tests investigated the Ir/gadolinium-doped ceria catalysts previously proven stable at 850°C. The main results have shown that the catalytic layer has no significant effect on the performance of the fuel cell running under hydrogen. The use of a ceria-based catalytic layer has enhanced the stability of the fuel cell under dry ethanol at 700°C, but stable operation at 600°C requires the development of more active catalyst.
Estimating the Impacts of Integrating a Solid Oxide Electrolyser into a Coal Power Plant
Authors: Angyus Michael , Williams Mark , Jesionowski Gary , Gemmen Randall , Gerdes Kirk , Ramezan Massood
Published: July 2021

Coal plants are under tremendous stress due to the introduction of renewables, particularly solar, forcing coal plants to rapidly change operations in response to intermittent periods of power demand. These new operating conditions risk hardware damage and lower overall demand for coal-based power, forcing low capacity factors on a coal plant and higher electricity costs. For coal plants to operate efficiently and consistently, it has been proposed that solid oxide electrolyser cells (SOECs) be incorporated into coal plants to produce storable hydrogen from waste/excess heat and excess electricity. An integrated SOEC would enable the boiler to operate at maximum efficiency while borrowing a fraction of the clean high temperature steam for electrolysis. It is likely that the increase in efficiency, consistent operating hours, and revenue from hydrogen sales will outweigh the price of integration, but it is yet unknown whether this solution is profitable. To assess the profitability of SOEC integration into a given coal plant, an Excel sheet was developed that uses inputted coal plant specifications to calculate coal, water and air consumption, electricity, hydrogen and oxygen production, and expected costs and revenue from each to come up with a initial gross estimate of viability. The sheet also automatically calculates the net present value (NPV) and displays the discounted cumulative cash flow.
Development Progress at Hexis SOC Activities
Authors: Grolig Jan Gustav , Bausinger Holger , Sarda Venkatesh , Meier Christoph , Mai Andreas
Published: July 2021

HEXIS is developing and manufacturing SOFC-based micro-CHP systems for houses and/or small companies. This paper will present the long-term experiences on long-term and cyclic testing of fuel cell modules in lab tests as well as results on robustness and performance in the field. It was observed that degradation rates as low as approx. 0.3 %/kh, i.e. 13 mΩ cm²/kh on the short-stack level for over 50,000 h can be reached. These stacks have been analyzed with electrochemical impedance spectroscopy (EIS) at regular intervals, which can provide valuable insights in understanding fundamental degradation mechanisms for long term operation of SOFC stacks. Moreover, the paper will include highlights of new developments such as improvements on cell and stack level as well as new applications for the Hexis technology in general. Finally, the paper will outline some of the future challenges in Hexis’ development activities.
Progress in SOC Development at Fraunhofer IKTS
Authors: Kusnezoff Mihails , Jahn Matthias , Megel Stefan , Reichelt Erik , Trofimenko Nikolai , Herz Gregor , Beckert Weiland , Schilm Jochen , Rost Axel , Schoene Jakob , Wagner Doerte , Ganzer Gregor , Sauchuk Viktar , Nousch Laura , Hielscher Sebastian , Hartmann Mathias , Rothe Stefan , Michaelis Alexander
Published: July 2021

After long and successful development history of Solid Oxide Cells (SOC) continuous improvement in performance, longevity, manufacturing, and system integration it is necessary to bring this highly efficient technology to the market. The activities on material development and optimization at IKTS are focused mainly on enhancement of durability for SOFC, SOEC, and rSOC operation and on boosting the power density. During recent years considerable efforts on simplification and automation of cell and stack manufacturing processes have been addressed. The processes for electrode manufacturing have been adjusted for high yield automated printing on thin electrolytes with integrated quality control measures. Efficient ways for reduction of time and energy consumption for sealing process of SOC stacks have been found and demonstrated in pilot production as well as automated assembling of components to stacks was shown. The increasing interest in “green hydrogen” created multiple opportunities for SOEC technology to be considered as inherent part of industrial and chemical processes. IKTS pioneering work on coupled operation of SOEC module with Fischer-Tropsch reactor provided first demonstration of feasibility of this approach for wax production. However, high power electrolysis applications (>10 MW) will need new approaches for stack design and put higher requirements on durability.
Recent Highlights of Solid Oxide Fuel Cell and Electrolysis Research at DTU Energy
Authors: Hagen Anke , Frandsen Henrik Lund
Published: July 2021

Research on solid oxide concepts has a long tradition at the Department of Energy Conversion and Storage (DTU Energy) of the Technical University of Denmark. It spans from fundamental topics such as materials & electrode development over methodology development for example in micro structural & electrochemical characterization, up to the applied level, where integration of SOC with up- and down-stream processes becomes important. Significant funding from National and European programs supported this research. The presentation will introduce highlights of recent achievements in the areas of (i) materials & electrode development to reach higher activity and better durability, (ii) cell & stack development for lowering costs and increasing robustness, (iii) power to X concepts with special emphasis on X= fuels, (iv) lifetime & diagnostics approaches for accelerating durability studies, and (v) modelling from materials to stack levels aiding lifetime evaluation and designing of stacks & systems.
Stack Optimization and Testing for its Integration in a rSOC-Based Renewable Energy Storage System
Authors: Cubizolles Geraud , Mouginn Julie , Di Iorio Stéphane , Hanoux Pierre , Pylypko Sergii
Published: July 2021

Stacks dedicated to rSOC operation require improvements as compared to stacks dedicated to purely SOEC or SOFC mode. Starting from an electrolysis stack, improvements have been performed in the European project REFLEX, mainly to enhance reactants distribution, reduce pressure drops, integrate new cells specifically developed as part of REFLEX project, and finally integrate larger cells to reduce stack and system cost and footprint. For easier handling, mechanical connection to the system was optimized. Long-term degradation tests were performed both for reference and optimized cells within two 5-cell stacks. A full size 25-cell stack was assembled integrating optimized connections to gases lines, specific stack clamping system and internal electrical insulation required for stack integration into REFLEX modules. For prospective reason enlarged cells were produced and integrated within first a 5-cell stack, and then a 25-cell stack. Finally, stability of performance along pre-serial manufacturing process was checked for 20 stacks before their delivery for integration into REFLEX modules.
High Pressure Water Electrolyser Development for Space Exploration Surface Missions
Authors: Balomenou Stella , Tsiplakides Dimitrios , Papazisi Kalliopi-Maria , Farmaki Maria-Eleftheria , Bimpiri Naouma , Waernhus Ivar , Thambiraj Nelson , Vik Arild , Buergler Brandon , Lamaze Brigitte
Published: July 2021

This paper describes the developments under a European Space Agency (ESA) activity for the development of a high-pressure steam electrolyser system for exploration surface missions. The base case scenario considered is a hydrogen and oxygen production unit for lunar missions, where water for the electrolyser is generated from ice-bearing consolidated regolith.
Load Cycling Tests of Reversible Solid Oxide Cells – Effects of Current Density, Steam Content, and Utilization
Authors: Hauch Anne , Pylypko Sergii , Cubizolles Geraud , Mouginn Julie
Published: July 2021

Four single cell rSOC tests were conducted to investigate the effect of current density, steam content and degree of utilization both upon galvanostatic SOFC and SOEC testing, and load cycling operation. Long-term degradation tests were performed at 700°C during constant galvanostatic SOFC (250 h) and SOEC (250 h) conditions followed by load cycling operation (up to 1000 h) in cycles of 16 h SOFC and 8 h SOEC. Applied current densities were 0.6 A/cm2 and -1.2 A/cm2; and 0.4 A/cm2 and -0.6 A/cm2; inlet gas composition i.e. p(H2O)/p(H2) of 90/10 and dry H2, as well as a test applying p(H2O)/p(H2) of 50/50 for both modes. Furthermore, two different utilization degrees (80% and 40%) were applied. From these tests it is evident that the high current density is detrimental for the fuel electrode durability while high p(H2O) does not seem problematic and cells sustained mechanical integrity upon load cycling.