Brand Personality and Revisit Intention: The Mediating Role of Tourists' Self-Image Congruity

Purpose- Brand personality plays an important role in the development of tourists' self-image congruence and revisit intention. This paper attempts to shed light on the relationship between brand personality and self-image congruence and revisit intention through a quantitative analysis.Design - Data were collected from 496 Vietnamese tourists who visited the top five tourist sites in Vietnam, including Ha Long, Phu Quoc, Sapa, Nha Trang, and Hoi An. Methodology - By using SEM in AMOS version 24 CFA was performed to test the the overall measurement model.Findings - Multivariate data analysis demonstrated that five dimensions of brand personality. (Excitement, Sincerity, Sophistication, Competence, and Ruggedness) have a positive effect on self-image congruence and revisit intention. While excitement appears to be most helpful for developing self-image congruence, sincerity has the highest benefit for increasing revisit intention, sincerity has the highest utility for increasing revisit intention. In addition, revisit intention is most influenced by excitement and least influenced by sophistication through self-image congruence. Originality of the research - The findings highlight the important role of attributes associated with tourist destinations. Managers in the tourism sector should be familiar with these characteristics in order to position or strengthen their destination's brand with the aim of delivering to each tourist group a customized experience that resonate with their shared values. The insights provided by this paper also have important implications for travel companies in the gradual recovery of the country's smoke-free industry under the conditions of the COVID-19 pandemic.

ICAM-1 MEDIATES PLASMACYTOID DENDRITIC CELL SENSING OF SARS-CoV-2-INFECTED CELLS

Background: Plasmacytoid dendritic cells (pDCs) are the major producer of type I IFNs (IFN-I), the critically important antiviral cytokines against SARS-CoV- 2. Although pDCs can sense cell-free SARS-CoV-2 virions, it is unknown whether they can detect infected cells to produce IFN-I. Since cell-to-cell transmission accounts for 90% of SARS-CoV-2 infections (Zeng et al., 2022), we examined the relevance of pDC sensing of infected cells in SARS-CoV-2 infection and whether the virus exploits this pathway to evade IFN-I responses. Method(s): LSPQ1, the first SARS-CoV-2 clinical isolate received from the Public Health Laboratory of Quebec, was used as a prototype virus. SARS-CoV-2 variants of concerns (VOCs) were also used. PBMCs or enriched pDCs were cocultured with mock-infected or SARS-CoV-2-infected HeLa-hACE2 or Calu-3. Either PBMCs, enriched pDCs, or HeLa-hACE2 were pretreated with anti-human ICAM-1 antibody or isotype control. The conjugate formation was determined by flow cytometry. Polarized Caco cells were used to validate critical data. Result(s): Upon sensing infected cells, PBMCs release 6-fold more IFN-I than they do when exposed to cell-free virions. Antibody-mediated depletion of pDCs from PBMCs abolishes IFN-I secretion. Direct contact of pDCs with infected cells is required for sensing since the use of a transwell membrane reduces IFN-I release by 85%. Infected cells form conjugates with pDCs more frequently (3.2-fold higher) than uninfected cells. Blocking ICAM-1 on infected cells or pDCs impacts conjugate formation and significantly suppresses IFN-I production by 55-80%, suggesting bidirectional interaction. Moreover, human lung cells infected with VOCs are sensed to a different extent with the alpha variant being the least efficiently sensed by pDCs compared to the delta or omicron strains. Even though SARS-CoV-2 is primarily released from the apical domain of polarized infected Caco cells, sensing of infected cells does occur upon direct contact of pDCs with the basolateral domain, highlighting how pDCs antiviral responses might be triggered in respiratory tissues. Conclusion(s): pDC sensing of infected cells accounts for the vast majority of IFN-I released during SARS-CoV-2 infection. ICAM-1 promotes physical contact between pDCs and infected cells, thus leading to efficient sensing. Differential pDC sensing of SARS-CoV-2 VOC-infected cells suggests that some VOCs might manipulate the interactions of pDCs with infected cells to limit IFN-I responses.

COVID-19 management using respiratory supports in the ward, Australian hospital

Introduction/Aim: Acute hypoxaemic respiratory failure occurs often in people with COVID-19 pneumonia, with high need for respiratory support therapies (RST). We aimed to examine the clinical management of COVID-19 pneumonia including use of ward-based RST. Method(s): A ambispective electronic medical record review was conducted at an Australian tertiary hospital for COVID-19 patients requiring ward-based RST between 28/02/2020 and 18/03/2022. Result(s): Of 964 patient records identified, 670 were included, with 61% male and mean age 62 years (SD=19). 344 (51.4%) were unvaccinated, with 120 (17.9%) having >=1respiratory comorbidities. Prone positional therapy was achieved in 63 (9.4%) and recommended in 221 (33%) patients. High flow nasal oxygen (HFNO;n = 243, 36.2%), continuous positive airway pressure (CPAP;n = 131, 19.5%) and non-invasive ventilation (NIV;n = 4, 0.6%) were frequently administered to patients. 120 (49.4%) patients received both HFNO and CPAP. Arterial blood gases were infrequently measured prior to initiation of HFNO (n = 23, 9.5%) or CPAP (n = 25,19.1%). Target saturation aims were documented in 547 (81.6%) patients with a medical prescription for RST in 486 (72.5%). Patients using HFNO/CPAP/NIV had a daily respiratory nurse consultant review 236 (97.1%) with documented RST prescriptions and aims. Medical verification occurred at least once per admission from a consultant or advanced trainee for 213 (87.6%) HFNO patients and 117 (89.3%) CPAP patients. Median usage of HFNO was 2 days (IQR 1-4) and for CPAP 1 days (IQR 0.5-3). The median length of stay was 5 days (IQR 3-8). Clinical escalation with transfer to ICU occurred in 90 (13.4%) patients, with 24 (26.6%) intubated. 44 (6.6%) patients died. Most (n = 424, 63.2%) were discharged directly home without requiring domiciliary respiratory supports. Conclusion(s): Multidisciplinary, ward-based RST was successfully provided to most patients with COVID-19 pneumonia with clear documentation of processes of care. Support for and expansion of ward-based RST models of care should be considered longer term. Conflict of Interest: Nil.

Impact of the Mobile Banking Application Ratings on the Vietnamese Bank Service Income

Based on the relationship between fintech and bank performance and the role of mobile ap- plications in bank operations, we investigate the impact of mobile banking application (MBA) ratings on bank service income. The quarterly data from the 15 biggest Vietnamese commer- cial banks in 2019-2020 were extracted from the public financial statements and the Google Play Store. The Generalized Least Squares method is applied to process the proposed regression models. We find a positive impact of MBA ratings on bank service income. We additionally ex- plore the MBA quality of a large bank that does not meet customer expectations and how the in- teraction between MBA ratings and leverage harms bank service income. Finally, users gener- ally appreciate the MBA quality, and COVID-19 does not affect the link between MBA ratings and bank service income. The study provides novel knowledge on customer behavior through MBA ratings and their effect on bank service income in an emerging country.

The 2021 SIIM-FISABIO-RSNA Machine Learning COVID-19 Challenge: Annotation and Standard Exam Classification of COVID-19 Chest Radiographs.

We describe the curation, annotation methodology, and characteristics of the dataset used in an artificial intelligence challenge for detection and localization of COVID-19 on chest radiographs. The chest radiographs were annotated by an international group of radiologists into four mutually exclusive categories, including "typical," "indeterminate," and "atypical appearance" for COVID-19, or "negative for pneumonia," adapted from previously published guidelines, and bounding boxes were placed on airspace opacities. This dataset and respective annotations are available to researchers for academic and noncommercial use.

Financial reporting quality in pandemic era: case analysis of Vietnamese enterprises

This study aimed to evaluate the financial reporting quality (FRQ) of Vietnamese enterprises in the pandemic era. It also examines the effect of the Big 4 audit firms in addition to non-Big 4 audits, and internal control effectiveness (ICE) on FRQ. The case study method was implemented to complete the scale of the FRQ identified by IASB in 2010 (FASB & IASB 2010) and identify the challenges encountered when preparing and representing financial reports (FRs) during the COVID-19 pandemic crisis. The survey was conducted to measure the FRQ and to examine the effect of the three factors detailed above on the FRQ. The research results indicate that all three factors significantly affect the FRQ. The results also imply the predictive value of Vietnam enterprises' FRs in that they have been strongly affected by the COVID-19 pandemic. © 2021 Informa UK Limited, trading as Taylor & Francis Group.

Understanding perceived shopping effectiveness with omnichannel: A MOA theory perspective

Customers' shopping effectiveness is a critical factor in encouraging customers to stay with the firms, the knowledge regarding how to provide shopping effectiveness in an omnichannel retailing environment remains underexplored. Thus, this study draws on Motivation-Opportunity-Ability theory (MOA) and examines MOA factors affecting customers' perceived shopping effectiveness, which in turn influences customers' omnichannel usage continuance intention. The expected findings may suggest that the opportunity factor, channel integration quality encompassing channel-service configuration, content consistency, process consistency, and assurance quality, positively influences customers' percieved shopping effectiveness. Furthermore, the motivation factors such as relative advantage, perceived ease of use, personalized incentives, flow, and enjoyment, have positive effects on customers' perceived shopping effectiveness. In addition, ability factors encompassing technology readiness and self efficacy are expected to influence perceived shopping effectiveness. As a result, perceived shopping effectiveness positively influences omnichannel usage continuance intention. These findings enhance the literature on the shopping values and channel integration quality in an omnichannel retailing environment. These findings also offer insightful implications for omnichannel retailers in terms of creating and managing customers' shopping effectivess in the post-COVID period. © 2022 International Consortium for Electronic Business. All rights reserved.

Correction: Rapid prediction of possible inhibitors for SARS-CoV-2 main protease using docking and FPL simulations.

[This corrects the article DOI: 10.1039/D0RA06212J.].

COVID-19 in Vietnam: Perception of Urban Workers and Compliance with the National Social Distancing Policies

Using an online survey with about 650 persons living in urban areas in Vietnam and working in different job positions, this chapter aimed to explore how they perceived various measures in containing COVID-19 and how they complied with and evaluated different government policies in controlling the pandemic. In particular, we disaggregated data of the urban workers into gender (male vs. female), job positions (wageearners vs. other), social insurance participation (mandatory, voluntary, and non-participating), and self-rated health (good vs. bad). We found that the respondents highly appreciated the government with the provided information of COVID-19 and the implemented policies to contain the pandemic. People showed quite good compliance with the national social distancing policies since they went out of their homes mostly for essential work, while very rarely for other reasons or nonessential work. We could see various differences in perceptions and compliance levels of the respondents in terms of age, gender, residential area, and health status. Based on those findings along with the existing studies, we recommended that appropriate measures stabilising social and economic activities within the country should be continuously implemented so as to maintain or alternate jobs for people working in severely affected economic sectors. Also, providing accessible and affordable healthcare measures to all people, especially for poor and informal workers who are particularly risky to infectious diseases, should also be given great consideration. Sufficient goods and services for people to meet their basic needs during social distancing should be continuously maintained. © 2022 by World Scientific Publishing Co. Pte. Ltd.

Measurements of pulse rate using facial video cameras in reference to ECGs from smart devices and personal computers under low-illumination conditions

Background: Effortless and contactless monitoring technologies enable the collection of vital signs in a remote fashion without the need for physical contact with the patients. Videoplethysmography (VPG) is a technique developed to measure the pulse rate of an individual using facial video recorded by the video cameras embedded into smart devices and personal computers. It is an innovative solution to the challenges associated with the new healthcare delivery system under the SARS-CoV-1/2 pandemic. Despite these advantages, there is a knowledge gap around the performance of such technologies, especially in cardiac patients using the technology in various lighting conditions. In this work, we aim to assess the performance of the VPG technology when acquiring indoor pulse rates in patients with a history of atrial fibrillation (AF). Method(s): We evaluated the VPG technology in measuring the pulse rate in AF patients at low illumination levels. We performed an experiment in which AF patients were asked to stare at the screen of multiple devices while their VPG recordings were acquired for 25 s. We tested the VPG technology when running on 3 types of devices: an S10 smartphone (SP), a Tab3 tablet (TB), and a laptop with a Logitech C920 webcam (PC). We used a single-lead Holter ECG recorder to collect the ECG and measure heart rate (HR) at the time of the facial video. We evaluated the accuracy of measurements across a cohort of AF patients after collecting VPG signals from the three devices in various illumination conditions: 50 (dark surrounding area) to 500 (indoor office) lux, and two types of lights (LED and incandescent). We used the Bland-Altman (BA) method to measure the level of agreement between VPG- and ECG-based measurements of HR under various conditions. Finally, we measured the rates of rejection of recordings associated with each level of illumination and source of lights. Result(s): We present the results for the cohort of AF patients enrolled in this IRB-approved study from June to September 2021. Seventeen subjects were enrolled (12 men, 68+/-11 yrs). The BA plots shown in figure below do not show any bias. Furthermore, the mean difference in heart rate from VPG and ECG was inferior to 0.7 bpm across the 3 devices with confidence intervals ranging from 3 to 12 BPM (PC device showing the largest CI). The rate of rejection of VPG signal for too low quality was 60% at 50 lx, and 23% at 500 lx. The precision of heart rate measurements was higher under LED lights than under incandescent lights: measurement error+/-CI were (0.2+/-3 bpm) vs. (0.3+/-10 bpm), respectively. Conclusion(s): This VPG technology enables accurate measurements of pulse rates in patients with a history of AF when acquired in in-door conditions (low and normal illumination levels). The proposed method ensures a consistent level of accuracy even at low illumination (50 lx). This video-cardiac monitoring method represents a unique solution for physicians to measure their patient's heart rate during telemedicine visits. [Formula presented] Copyright © 2022

Tracking Student Attendance in Virtual Classes Based on MTCNN and FaceNet

All classes are held online in order to ensure safety during the COVID pandemic. Unlike onsite classes, it is difficult for us to determine the full participation of students in the class, as well as to detect strangers entering the classroom. Therefore, We propose a student monitoring system based on facial recognition approaches. Classical models in face recognition are reviewed and tested to select the appropriate model. Specifically, we design the system with models such as MTCNN, FaceNet, and propose measures to identify people in the database. The results show that the system takes an average of 30 s for learning and 2 s for identifying a new face, respectively. Experiments also indicate that the ability to recognize faces achieves high results in normal lighting conditions. Unrecognized cases mostly fall into too dark light conditions. The important point is that the system was less likely to misrecognize objects in most of our tests. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Outcomes associated with secondary Staphylococcus aureus infection in COVID-19 patients

Introduction: Among COVID-19 patients, bacterial infections are associated with significant morbidity and mortality. Staphylococcus aureus is the principal pathogen causing bacterial infections in COVID-19 patients. Typically, clinical outcomes between methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) infections have demonstrated worse outcomes with MRSA. Outcomes of MRSA vs. MSSA remain limited in COVID-19 patients. Research Question or Hypothesis: We sought to evaluate clinical outcomes among COVID-19 patients with MRSA vs. MSSA infections. Study Design: Observational, retrospective cohort Methods: Hospitalized adults with confirmed COVID-19 and secondary S. aureus infections were evaluated from January 2020 to July 2022. Secondary infection was defined as a positive culture 48-hours after COVID-19 diagnosis. Cohorts were stratified by S. aureus susceptibility and pandemic year. Primary outcome was in-hospital allcause mortality. Secondary outcomes included 30-day mortality, allcause intensive care unit (ICU) mortality, and 60-day hospital readmission. Result(s): A total of 108 adults met the study criteria, 33 (30.5%) MRSA and 75 (69.4%) MSSA patients. At baseline, 84 (78%) patients were in the ICU with a mean APACHE-II score of 34.21+/-19.53. Six patients (5.6%) received at least 1 dose of mRNA vaccine. Primary sources of infection included respiratory (68%) and blood (25%), with no differences between cohorts. There was no statistical difference in inhospital all-cause mortality (51.5% vs. 62.7%, p=0.37), 30-day mortality (60.6% vs. 66.7%, p=0.61), all-cause ICU mortality (51.5% vs. 62.7%, p=0.37) and 60-day readmission (6.1% vs. 6.7%, p=0.92) between MRSA and MSSA, respectively. Mortality remained high when stratified by pandemic year 56.2% (2020), 68.2% (2021), and 46.2% (2022);p=0.619. Conclusion(s): Unlike patients without COVID-19, no significant differences in MRSA and MSSA outcomes were found. Mortality remained high in patients with secondary S. aureus infections throughout the study period. Further investigations are warranted to determine if COVID-19 patients respond differently than non-COVID-19 patients regarding the type of S. aureus secondary infection.

Réponse humorale après infection à SARS-CoV-2 des patients atteints de rhumatisme inflammatoire chronique en comparaison à celle de sujets sains : analyse des données des cohortes COVID-RIC2 et COVID-BIOTOUL

Introduction L'immunosuppression sévère est un des facteurs de risque de sévérité de la COVID-19. Les patients atteints de rhumatisme inflammatoire chronique (RIC) exposés au rituximab et aux corticoïdes à forte dose sont à plus haut risque de forme sévère de COVID-19 et ont une moins bonne réponse humorale aux vaccins de la COVID-19. Peu de données sont disponibles sur la réponse humorale après infection chez les patients atteints de RIC et l'impact éventuel des traitements sur cette immunisation. L'objectif de ce travail était de comparer la réponse humorale post infection à COVID-19 chez les patients atteints de RIC par rapport à celle d'une population témoin non immunodéprimée. Patients et méthodes Cas : tous les patients suivis en consultation pour une polyarthrite rhumatoïde (PR) ou une spondyloarthrite (SpA) dans 16 centres français ont été invités à participer à l'étude COVID-RIC et ont bénéficié d'une sérologie systématique SARS-CoV2. Les patients ayant une sérologie positive ont été sélectionnés pour participer à la cohorte COVID-RIC2 et inclus entre mars et octobre 2021. Témoins : les soignants du CHU de Toulouse ont été invités à réaliser une sérologie systématique SARS-CoV2 en juillet 2020. Ceux dont la sérologie était positive étaient inclus la cohorte COVID-BIOTOUL pour un suivi sérologique trimestriel. Les sujets de COVID-BIOTOUL ont été appariés 1 :1 aux patients de COVID-RIC2 sur l'âge, le sexe et le délai entre la date de survenue de l'infection COVID-19 et le prélèvement biologique. Dosages sérologiques : un dosage des immunoglobines totales (Igtot) dirigées contre la protéine S du SARS-CoV2 a été réalisé dans le laboratoire de virologie du CHU de Toulouse. Analyses : les taux médians d'Igtot ont été comparés par un test de Wilcoxon. Résultats 93 patients ont été inclus dans chaque groupe (âge moyen 49 ans, délai médian entre l'infection et le prélèvement : 150 jours). Dans le groupe COVID-RIC2, 46 patients avaient une PR (89 % de femmes, DAS28-CRP moyen : 2,97), et 47 une SpA (61 % de femmes, ASDAS-CRP moyen : 2,36). Le taux d'Igtot était comparable entre les groupes (taux médian chez les RIC : 155BAU [EIQ : 7–376] versus 120BAU [EIQ : 35–320], p = 0,6). Il n'y avait pas de différence de taux d'Igtot après stratification sur l'âge, le sexe, le type de RIC ou le délai après infection. Les 14 patients RIC ayant eu une forme sévère de COVID-19 (nécessité d'une oxygénothérapie) avaient des taux d'Igtot plus élevés (taux médian chez les 14 RIC avec COVID sévère : 374,7 BAU [EIQ : 155,3–916,8) versus 122,1 [EIQ : 6,6–304,7], p < 0,01). Parmi les patients RIC, seuls 2 avaient reçu du rituximab et 3 de l'abatacept et leur taux d'Igtot étaient très faibles (taux médians chez les patients sous rituximab : 3,5 BAU [EIQ : 0,0 ;6,9], sous abatacept : 5,7BAU [EIQ :2,6–187,4]). Les autres traitements (csDMARDs, tsDMARDs et autres bDMARDs) n'avaient pas d'effet sur les taux d'Igtot chez les patients RIC en comparaison aux témoins. Conclusion Les patients atteints de RIC ont une réponse humorale comparable aux témoins sains après une infection à COVID-19. La sévérité des symptômes était associée à de plus forts taux d'Igtot chez les patients atteints de RIC. Les traitements de fond en dehors des traitements par rituximab et abatacept ne semblaient pas avoir d'influence sur la réponse humorale.

Blended Learning for Secondary Schools in Nam Dinh Province to Satisfy New Standards: The Current Situation and Proposed Models

We offered blended learning models for high schools in Nam Dinh province to satisfy Vietnam's new criteria. These models were based on general approaches to issues, theoretical research, and field research based on surveys and anket questionnaires conducted throughout the area. The results of a survey demonstrate that high school teachers in Nam Dinh have gained a fundamental grasp of blended learning and have, in practice, embraced both online and face-to-face instruction, particularly during the height of the Covid-19 outbreak. However, there was not a standard model for blended learning, therefore it was only used by a few persons. In other contexts, the concept of "blended learning" referred to what was effectively a face-to-face session that was broadcast over the Internet without the necessary adjustments being made to the content, methodology, or evaluation. As a result, we offer a number of different ways to blended learning for high schools in Nam Dinh in order to improve the quality of education provided throughout the province.

VBlock—Blockchain-Based Traceability in Medical Products Supply Chain Management: A Case Study in VietNam

The COVID-19 is putting tremendous pressure on the medical facilities supply, as the demand for facilities has significantly outweighed the production capability. Several rogue traders have taken advantage of this issue to distribute counterfeit products. Moreover, some sellers advertise genuine products with unreasonably high prices. Our team believes that fake or overpriced facilities will significantly complicate the battle against COVID, thereby posing millions of lives to risk. That is why our team is developing V-Block. V-Block is a supply chain management system that harnesses the power of Blockchain. Its primary goals are to assist the government in tracking the product’s distribution process and help customers avoid questionable deals. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Disruptions of cytological screening procedures due to the COVID-19 pandemic in Slovakia : Juliana Melichová

Background During the COVID-19 pandemic, most settings experienced healthcare service disruptions. The majority of cytological screening procedures were postponed to focus on assisting patients infected with COVID-19. In this study, we aimed to analyse the impact of the impact of the COVID-19 pandemic on the uptake of cervical cancer screening in Slovakia. Methods Data on cytological screening procedures were obtained from two of the three health insurance companies in Slovakia for the years 2019 and 2020, covering the population of women aged 15 and older. All data were calculated stratified for age groups. Rates of cytological screenings were calculated as the number of procedures per women registered in the insurance company in the same age group and rate ratios were calculated as ratios of the rates for the years 2020 and 2019 for the same age group. Incidence rates were calculated as the number of newly diagnosed cervical cancer cases per women registered in the insurance company in the respective year. Results Rate ratios of cytological screening procedures revealed that in both examined health insurance companies, the rate of cytological exams was lower in 2020 compared to 2019 (0.95 and 0.89). This was observed across all age groups. The results showed a clear and statistically significant age gradient, indicating that the level of disruption increased with age. The age group 60-69 years had the highest incidence rate of cervical cancer in 2019, at 54.3 per 100 000. In 2020, the highest rate was 48.3 in the age group 50-59 years. The lowest rates were in children and young adults (<20 years). Conclusions This study confirms the significant impact of the pandemic on cervical cancer screening uptake in Slovakia, which may have delayed the diagnosis of cervical cancer into later stages of the disease with a worse prognosis. This may lead to increased mortality and years lived with disability due to this disease in Slovakia. Key messages • Disruptions in cervical cancer screenings were observed in Slovakia during the COVID-19 pandemic which may result in an increase in cervical cancer incidence and mortality. • Strategies should be implemented to maintain cancer screening programs during health emergencies to avoid excessive mortality and morbidity.

Unsupervised Deep learning-based Feature Fusion Approach for Detection and Analysis of COVID-19 using X-ray and CT Images

Aims: This study investigates an unsupervised deep learning-based feature fusion approach for the detection and analysis of COVID-19 using chest X-ray (CXR) and Computed tomography (CT) images. Background: The outbreak of COVID-19 has affected millions of people all around the world and the disease is diagnosed by the reverse transcription-polymerase chain reaction (RT-PCR) test which suffers from a lower viral load, and sampling error, etc. Computed tomography (CT) and chest X-ray (CXR) scans can be examined as most infected people suffer from lungs infection. Both CT and CXR imaging techniques are useful for the COVID-19 diagnosis at an early stage and it is an alternative to the RT-PCR test. Objective: The manual diagnosis of CT scans and CXR images are labour-intensive and consumes a lot of time. To handle this situation, many AI-based solutions are researched including deep learning-based detection models, which can be used to help the radiologist to make a better diagnosis. However, the availability of annotated data for COVID-19 detection is limited due to the need for domain expertise and expensive annotation cost. Also, most existing state-of-the-art deep learning-based detection models follow a supervised learning approach. Therefore, in this work, we have explored various unsupervised learning models for COVID-19 detection which does not need a labelled dataset. Methods: In this work, we propose an unsupervised deep learning-based COVID-19 detection approach that incorporates the feature fusion method for performance enhancement. Four different sets of experiments are run on both CT and CXR scan datasets where convolutional autoencoders, pre-trained CNNs, hybrid, and PCA-based models are used for feature extraction and K-means and GMM techniques are used for clustering. Results: The maximum accuracy of 84% is achieved by the model Autoencoder3-ResNet50 (GMM) on the CT dataset and for the CXR dataset, both Autoencoder1-VGG16 (KMeans and GMM) models achieved 70% accuracy. Conclusion: Our proposed deep unsupervised learning, feature fusion-based COVID-19 detection approach achieved promising results on both datasets. It also outperforms four well-known existing unsupervised approaches. © 2022 Ravi and Pham.

Market volatility and spillover across 24 sectors in Vietnam

While market volatility and volatility connectedness across different financial markets have been examined, the spillover effects across sectors have been under-examined. As such, this study aims to examine market volatility and the volatility patterns for 24 Vietnamese sectors. Our study uses the ARMA-GARCH estimation technique over the 2012-2021 period. The spillover effects between these sectors are then investigated using the vector autoregression (VAR) technique. Three key findings are as follows. First, the market volatility of Development Investment, Education, and Securities is most affected by the market volatility from the previous periods, whereas Construction is least affected. Second, the Vietnamese stock market exhibits a substantial intersector connectedness above 60 per cent from 2012 to 2021. However, the sectoral spillover effects increase to around 90 per cent during the Covid-19 pandemic. We found that Aquaculture, Building Materials, Food, and Plastic are the four primary risk transmitters at the sectoral level. Third, market volatility for Energy, Plastic, and Steel is unaffected by the pandemic. Meanwhile, Securities, Fertilizer, and Transportation exhibited a significant increase in market volatility during Covid-19. Based on these empirical results, policy implications have emerged for the Vietnamese government to support affected industries to recover and develop.