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In the early stages of the pandemic, Saudi Arabia and other countries in the Arab Gulf region relied on non-pharmaceutical therapies to limit the effect of the pandemic, much like other nations across the world. In comparison to other nations in the area or globally, these interventions were successful at lowering the healthcare burden. This was accomplished via the deterioration of the economy, education, and a variety of other societal activities. By the end of 2020, the promise of effective vaccinations against SARS-CoV-2 have been realized, and vaccination programs have begun in developed countries, followed by the rest of the world. Despite this, there is still a long way to go in the fight against the disease. In order to explore disease transmission, vaccine rollout and prioritisation, as well as behavioural dynamics, we relied on an age-structured compartmental model. We examine how individual and social behaviour changes in response to the initiation of vaccination campaigns and the relaxation of non-pharmacological treatments. Overall, vaccination remains the most effective method of containing the disease and resuming normal life. Additionally, we evaluate several vaccination prioritisation schemes based on age group, behavioural responses, vaccine effectiveness, and vaccination rollout speed. We applied our model to four Arab Gulf nations (Saudi Arabia, Bahrain, the United Arab Emirates, and Oman), which were chosen for their low mortality rate compared to other countries in the region or worldwide, as well as their demographic and economic settings. We fitted the model using actual pandemic data in these countries. Our results suggest that vaccinations focused on the elderly and rapid vaccine distribution are critical for reducing disease resurgence. Our result also reinforces the cautious note that early relaxation of safety measures may compromise the vaccine's short-term advantages.

In this study, we determine and compare the incubation duration, serial interval, pre-symptomatic transmission, and case fatality rate of MERS-CoV and COVID-19 in Saudi Arabia based on contact tracing data we acquired in Saudi Arabia. The date of infection and infector-infectee pairings are deduced from travel history to Saudi Arabia or exposure to confirmed cases. The incubation times and serial intervals are estimated using parametric models accounting for exposure interval censoring. Our estimations show that MERS-CoV has a mean incubation time of 7.21 (95% CI: 6.59–7.85) days, whereas COVID-19 (for the circulating strain in the study period) has a mean incubation period of 5.43(95% CI: 4.81–6.11) days. MERS-CoV has an estimated serial interval of 14.13(95% CI: 13.9–14.7) days, while COVID-19 has an estimated serial interval of 5.1(95% CI: 5.0–5.5) days. The COVID-19 serial interval is found to be shorter than the incubation time, indicating that pre-symptomatic transmission may occur in a significant fraction of transmission events. We conclude that during the COVID-19 wave studied, at least 75% of transmission happened prior to the onset of symptoms. The CFR for MERS-CoV is estimated to be 38.1% (95% CI: 36.8–39.5), while the CFR for COVID-19 1.67% (95% CI: 1.63–1.71). This work is expected to help design future surveillance and intervention program targeted at specific respiratory virus outbreaks, and have implications for contingency planning for future coronavirus outbreaks.\ud

Structured epidemic models can be formulated as first-order hyperbolic PDEs, where the "spatial" variables represent individual traits, called structures. For models with two structures, we propose a numerical technique to approximate $R_{0}$, which measures the transmissibility of an infectious disease and, rigorously, is defined as the dominant eigenvalue of a next-generation operator. Via bivariate collocation and cubature on tensor grids, the latter is approximated with a finite-dimensional matrix, so that its dominant eigenvalue can easily be computed with standard techniques. We use test examples to investigate experimentally the behavior of the approximation: the convergence order appears to be infinite when the corresponding eigenfunction is smooth, and finite for less regular eigenfunctions. To demonstrate the effectiveness of the technique for more realistic applications, we present a new epidemic model structured by demographic age and immunity, and study the approximation of $R_{0}$ in some particular cases of interest., 24 pages, 5 figures, submitted for publication

We conducted a comparative study of the COVID-19 epidemic in three different settings: mainland China, the Guangdong province of China and South Korea, by formulating two disease transmission dynamics models which incorporate epidemic characteristics and setting-specific interventions, and fitting the models to multi-source data to identify initial and effective reproduction numbers and evaluate effectiveness of interventions. We estimated the initial basic reproduction number for South Korea, the Guangdong province and mainland China as 2.6 (95% confidence interval (CI): (2.5, 2.7)), 3.0 (95%CI: (2.6, 3.3)) and 3.8 (95%CI: (3.5,4.2)), respectively, given a serial interval with mean of 5 days with standard deviation of 3 days. We found that the effective reproduction number for the Guangdong province and mainland China has fallen below the threshold 1 since February 8th and 18th respectively, while the effective reproduction number for South Korea remains high until March 2nd Moreover our model-based analysis shows that the COVID-19 epidemics in South Korean is almost under control with the cumulative confirmed cases tending to be stable as of April 14th. Through sensitivity analysis, we show that a coherent and integrated approach with stringent public health interventions is the key to the success of containing the epidemic in China and especially its provinces outside its epicenter. In comparison, we find that the extremely high detection rate is the key factor determining the success in controlling the COVID-19 epidemics in South Korea. The experience of outbreak control in mainland China and South Korea should be a guiding reference for the rest of the world.

To explore the metabolic mechanism of differential plasma interleukin (IL)-6 expression in patients with rheumatoid arthritis (RA). A total of 240 RA patients were enrolled in the non-target metabolomics study cohort and 69 healthy volunteers were included as healthy controls (HCs). Plasma IL-6 levels were detected by electrochemiluminescence assay. Plasma metabolites were detected by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Patients with active RA (n = 20) and remissive RA (n = 20) and 20 HCs were enrolled in the targeted validation cohort. Metabolites identified by non-target metabolomics were quantitatively analyzed by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry. Effects of 1-oleoyl-sn-glycero-3-phosphocholine (OGPC) associated with IL-6 on MH7A cells were assessed. After 24-h or 48-h induction by TNF-α, the supernatants were collected for IL-6 quantification by enzyme-linked immunosorbent assay. Furthermore, Western blot was performed to investigate the relative JAK2 and p-JAK2 expressions. With an increasing IL-6 level, OGPC shown to be related to the glycerophospholipid metabolism pathway by Kyoto Encyclopedia of Genes and Genomes analysis displayed a significant decrease. In the validating RA cohort, the OGPC concentrations in remissive RA group and active RA group decreased compared with HC group. OGPC down-regulated IL-6 secretion and p-JAK2 expression in TNF-α-induced MH7A cells in vitro. In conclusion, glycerophospholipid metabolism is the main metabolic pathway associated with the differential IL-6 expression in RA patients. The down-regulated OGPC is a promoting factor for the increased IL-6 plasma level in RA patients, which further affects the downstream JAK signaling pathway.

Although Chinese Railways remains largely a government owned vertically integrated system, track access charges were implemented for passenger trains in 2005 and freight trains in 2017. In recent years, many joint venture railway companies and local railway companies have been set up to bring in funding from provincial governments, state-owned enterprises and private enterprises for the construction of new lines. The coexistence of different railway enterprises and the interconnected characteristic of the railway network make the proportion of inter-rail company traffic for both passenger and freight high in China. Therefore, Chinese railways have adopted a series of revenue/cost settlement regimes reforms, including new rail access charges regimes. This paper examines these reforms, finding that the current Chinese access charges are still mainly a way to balance the accounts of rail companies. Given the revenue model of joint venture railway companies in China, the level of rail access charges is crucial for their financial performance. Moreover, the Chinese government has announced its intention of permitting open access competition, so the level and structure of track access charges will become much more important in future. Finally, this paper produces recommendations about how to reform the Chinese rail access charges regime for better adapting to the market needs in the future, in the light of European and Japanese experience.

One year into the global COVID-19 pandemic, the focus of attention has shifted to the emergence and spread of SARS-CoV-2 variants of concern (VOCs). After nearly a year of the pandemic with little evolutionary change affecting human health, several variants have now been shown to have substantial detrimental effects on transmission and severity of the virus. Public health officials, medical practitioners, scientists, and the broader community have since been scrambling to understand what these variants mean for diagnosis, treatment, and the control of the pandemic through nonpharmaceutical interventions and vaccines. Here we explore the evolutionary processes that are involved in the emergence of new variants, what we can expect in terms of the future emergence of VOCs, and what we can do to minimise their impact., Otto et al. review the evolutionary processes that have led to the emergence of variants of concern during the COVID-19 pandemic and describe efforts that could limit the future emergence of variants that spread faster, are more severe, or better escape immune responses.

We consider a C 1 , α smooth flow in R d which is “strongly monotone” with respect to a cone C of rank k, a closed set that contains a linear subspace of dimension k and no linear subspaces of higher dimension. We prove that orbits with initial data from an open and dense subset of the phase space are either pseudo-ordered or convergent to equilibria. This covers the celebrated Hirsch's Generic Convergence Theorem in the case k = 1 , yields a generic Poincare-Bendixson Theorem for the case k = 2 , and holds true with arbitrary dimension k. Our approach involves the ergodic argument using the k-exponential separation and the associated k-Lyapunov exponent (that reduces to the first Lyapunov exponent if k = 1 ).

CsPbBr3 perovskite QDs are precipitated in a borosilicate glass matrix, while protects efficiently the QD from photo-induced and chemical degradation. We show that the CsPbBr3 QD doped glasses exhibit strong visible photoluminescence (PL), which is dependence on the concentration that can be controlled by heat treatment conditions. Due to the stabilization by the glass matrix, we are able to determine the nonlinear optical (NLO) properties with a Z-scan technique. We observe a cross-over from saturated absorption (SA) to reverse saturated absorption (RSA) by either increase the pumping intensity or the QD size, reminiscent of quantum size effect in the NLO response. The RSA is associated with two-photon absorption (TPA) that induces strong upconversion luminescence of QD doped glass samples. Our results imply that the glasses containing CsPbBr3 QDs may find potential applications from solid state lighting to ultrafast optical switches.

In this paper, we focus on testing for individual and time effects in the two-way error component model with time-invariant regressors. We present the so-called FEF estimators when time-invariant regressors are exogenous and the FEF-IV estimators when one or more of time-invariant variables are endogenous, and obtain their asymptotic properties under some mild conditions. In the light of the moment-based test methods of Wu and Li (2014), we construct several tests for the existence of individual and time effects in the two-way error component model with time-invariant regressors. The resulting tests can be shown to have some desired properties as follows: they do not need any distributional assumptions on the error components; they do not require any assumptions on the correlation among the two random effects and the time-varying regressors; they are robust to the presence of one effect when the other one is tested. Simulation study and real data analysis are carried out for illustration of the above.

Examine the associations of sleep problems with health-risk behaviors and psychological well-being in a representative sample of Canadian adults.Cross-sectional.The 2011-2012 Canadian Community Health Survey (CCHS, conducted by Statistics Canada).Of all individuals taking part in the 2011-2012 CCHS, 42,600 participants aged ≥18 years from five provinces/territories (Nova Scotia, Quebec, Manitoba, Alberta, and Yukon) who participated in the sleep survey module were selected for this study.Health conditions were self-reported. Sleep problems referred to extreme sleep durations (either5 or ≥10 hours) and insomnia symptom. Health-risk behaviors included physical inactivity, daily smoking, highly sedentary behavior, and insufficient fruit and vegetable consumption. Worse psychological well-being included having worse self-rated general health, worse self-rated mental health, and worse sense of belonging, and being dissatisfied with life.The participants represented 10,614,600 Canadian adults aged ≥18 years from the five abovementioned provinces/territories. A significantly higher prevalence of all health-risk behaviors and worse psychological well-being was found among participants with extreme sleep durations (than those with 7 to8 hours) and insomnia symptom (than those without insomnia symptom). After multivariate adjustment, extreme sleep durations and insomnia symptom were still independently associated with increased odds of all health-risk behaviors and worse psychological well-being.Both extreme sleep durations and insomnia symptom were independently associated with health-risk behaviors and worse psychological well-being among Canadian adults.

We consider the nonlinear propagation for a single species population in a shifting habitat subject to unbalanced resources. The population dynamics is modelled by a reaction-diffusion equation with an asymptotical monostable type nonlinearity. Complicated dynamical patterns, naturally depending on the velocity of the shifting resource and the propagation velocities of the limiting systems at both ∞ and −∞, emerge, and our focus is to characterize these patterns. We first characterize the persistence and extinction of an asymptotical Fisher-KPP type equation and then establish a key relationship between the asymptotical Fisher-KPP type and the asymptotical monostable type equations. These, together with comparison principles, enable us 1). to obtain asymptotic propagation behaviours of asymptotical monostable type equations and 2). to analyze and describe the influence of the velocity of the shifting resource and the propagation velocity of the limiting systems on the asymptotic propagations of the reaction-diffusion equation with an asymptotical monostable type nonlinearity.

Objectives In this systematic review, we synthesize the current evidence on health-related quality of life (HRQoL) for the two of the most relevant outcomes of Zika virus infection in humans, microcephaly and Guillain-Barre Syndrome (GBS). Methods We searched the following databases: MEDLINE, Embase, CINAHL, LILACS, WHO's ICTRP clinical trials registries database and PROSPERO. Search terms included quality of life, microcephaly, and Guillain-Barre Syndrome. We included primary studies where HRQoL was quantitatively assessed for microcephaly and GBS using validated instruments. We used the Joanna Briggs Institute Critical Appraisal Tools to assess the risk of bias of individual studies. Results From a total of 1,657 abstracts screened and 66 full texts reviewed, 21 studies met the eligibility criteria; one study for microcephaly and 20 for GBS. Adjusted disutilities for microcephaly compared to a normative childhood utility ranged from −0.745 to −0.820. For GBS, time traded-off the expected lifetime ranged from 16 days to 3 years. HRQoL follows the clinical course of GBS, with lower scores in the first months, recovery within the first year post onset, and stabilization after one year. Conclusions Included studies reported a wide range of HRQoL for GBS, due in part to a high level of heterogeneity in methods, inclusion criteria, follow-up and reporting of results. Opportunities exist for primary studies assessing the longitudinal HRQoL over the entire course of the diseases to inform clinical practice, economic evaluations and health policy.

Towards gaining a mechanistic understanding of the co-feeding transmission dynamics of tick-borne diseases, we develop a delay differential equation model for vector-host population dynamics. In addition to the intrinsic demographic dynamics of both vector and host populations, the model has the distribution dynamics of vector individuals on hosts governed by vector attachment and host grooming behaviour. We introduce the concept of basic infestation number, derive analytic formulae for calculating it and use these formulae to characterize the distribution patterns. We also show how some of these patterns naturally lead to bi-stability and nonlinear oscillations in the vector and host populations.

Country reported case counts suggested a slow spread of SARS-CoV-2 in the initial phase of the COVID-19 pandemic in Africa. However, due to inadequate public awareness, unestablished monitoring practices, limited testing, ineffective diagnosis, stigmas attached to being infected with SARS-CoV-2, self-medication, and the use of complementary/alternative medicine that are common among Africans for social, economic, and psychological reasons, there might exist extensive under-ascertainment and therefore an underestimation of the true number of cases, especially at the beginning of the novel epidemic. We developed a compartmentalized epidemiological model based on an augmented susceptible-exposed-infectious-recovered (SEIR) model to track the early epidemics in 54 African countries. Data on the reported cumulative number of cases and daily confirmed cases were used to fit the model for the time period with no or little massive national interventions yet in each country. We estimated that the mean basic reproduction number is 2.02 (SD 0.7), with a range between 1.12 (Zambia) and 3.64 (Nigeria), whereas the mean basic reproduction number for observed cases was estimated to be 0.17 (SD 0.17), with a range between 0 (Sao Tomé and Príncipe, Seychelles, Tanzania, South Sudan, Mozambique, Liberia, Togo) and 0.68 (South Africa). It was estimated that the mean overall report rate is 5.37% (SD 5.71%), with the highest 30.41% in Libya and the lowest 0.02% in Sao Tomé and Príncipe. An average of 5.46% (SD 6.4%) of all infected cases were severe cases and 66.74% (SD 17.28%) were asymptomatic ones, with Libya having the most (39.45%) fraction of severe cases and Togo the most (97.38%) fraction of asymptomatic cases. The estimated low reporting rates in Africa suggested a clear need for improved reporting and surveillance system in these countries.

The World Health Organization has declared the scalding, defeathering, evisceration, and chilling processing stages in industrial poultry slaughterhouses as sites of cross-contamination. In response, we develop a novel ordinary differential equation model describing the transfer and thermal inactivation of pathogens between carcasses in an industrial three-stage scalding tank. The model provides a link between the distribution of bacteria on carcasses before and after scalding using physical mechanisms of transfer and inactivation. A key feature of our model is that it directly quantifies cross-contamination, or microbial transfer between carcasses, via the scald water. We parametrize the model according to the specific pathogen C. jejuni, and then validate the model using numerical simulations against industrial scalding processing data. In particular, the calibrated model predicts a mean pathogen level on individual carcasses of [ 1.15 × 10 4 , 2.6 × 10 4 ] CFU/carcass, capturing the experimentally determined mean of 1.89 × 10 4 CFU/carcass in an industrial setting. We then demonstrate that our framework is amenable to application in quantitative microbial risk assessment and policymaking. In particular, using scalding configurations from an industrial poultry processor in Canada as well as the 2015 USDA-FSIS Campylobacter performance standards as a benchmark, we utilize the developed model to quantify the relationship between pre-scald prevalence and mean pathogen counts and the distribution of post-scald pathogen levels on carcasses.

Our study aimed to elucidate the role of metabolites, bacteria, and fungi in rheumatoid arthritis (RA) patients with bone destruction (BD(+)) and identify some biomarkers to predicate bone progression of RA.Plasma metabolites of the 127 RA patients and 69 healthy controls were conducted by using nontargeted liquid chromatography-mass spectrometry (LC-MS). The gut bacteria and fungi were assessed by 16S rRNA and internal transcribed spacer (ITS).Compared with RA patients without bone destruction (BD(-)), some metabolites, bacteria, and fungi were altered in BD(+). Seven metabolites were selected as key metabolites for classifying the BD(+) and BD(-) groups with moderate accuracy (AUC=0.71). Metabolites-groups, metabolites-metabolites, and metabolites-clinical factors had a certain correlation, and 7 metabolites were enriched in glycerophospholipid metabolism and L-arginine and proline metabolism pathways. The bacteria and fungi of the BD(+) group showed significant differences in composition and function compared with BD(-) group. The changed 4 bacteria and 12 fungi yielded accuracy (AUC=0.74 and AUC=0.87, respectively) for the two groups. Taking 7 metabolites, 4 bacteria, and 12 fungi as a panel for AUC analysis, an improved AUC of 0.99 significantly discriminated the two groups. The changed metabolites, gut bacteria, and fungi may affect the pathway related to L-arginine.Our nontargeted LC-MS, 16S rRNA, and ITS highlighted a novel link among the metabolites, bacteria, fungi, and pathology of BD(+), which could contribute to our understanding of the role of metabolites, bacteria, and fungi in BD(+) etiology and offered some novel biomarkers to predict the bone progression of RA.

Understanding the corrosion behavior of Fe-based amorphous coatings under wet-dry cyclic conditions is of pretty importance for coating applications in marine environments. In this paper, the corrosion evolutions of the coatings under wet-dry cyclic conditions were investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and transmission electron microscopy (TEM). Accurate charge transfer resistance ( R t ) was obtained through fitting EIS results using a modified transmission line equivalent circuit model and a landscape map of R t was constructed for a panoramic investigation on coating corrosion. The results show that the corrosion rate of the coating changes cyclically under wet-dry cyclic conditions. Corrosion within a single wet-dry cycle can be presented as four stages: an initial decrease of corrosion rate due to passivation or repassivation when the coating is wetted, then a slow increase due to concentrated aggressive ions with solution evaporation, followed by a rapid increment associated with fast oxygen transport under ultrathin solution film and finally a stable stage as solution dries out. It is deduced that an oxygen concentration gradient can form between the inside and the outside of coating pores when the solution film over the coating is very thin, which further promotes the localized corrosion in the pores. According to the landscape map of R t , the coating maintains its high corrosion resistance for the initial 33 wet-dry cycles. But its corrosion resistance decreases significantly in the 35th wet-dry cycle accompanied by the attack of localized corrosion. After 65 wet dry cycles, the coating fails due to the penetration of localized corrosion. The interparticle oxide layers are defective, which enhances the localized corrosion process.

This study aimed to explore the association between sleep problems and health-related quality of life (HRQoL) in Canadian adults with chronic diseases, and whether mental illness can mediate the association.Data were drawn from the Canadian Community Health Survey, 2015. A total of 10,900 participants aged ≥18 years and diagnosed with chronic diseases were enrolled in this study.Of these participants, 23.6% (95% CI 22.1, 25.2) suffered from severe impairment of HRQoL. Extreme sleep durations, including both short (5, 5 to6, and 6 to7 h) and long (9 to10, and ≥10 h) sleep durations, were significantly associated with severe impairment of HRQoL (compared to 7 to8 h). Insomnia was also independently associated with severe impairment of HRQoL when compared to those without insomnia. In the mediation analyses, mental illness was shown to partly mediate the associations of extreme sleep durations and insomnia with severe impairment of HRQoL.In conclusion, both extreme sleep durations and insomnia were independently associated with severe impairment of HRQoL in adults with chronic diseases, and mental illness partly mediated the association.

Kappa-opioid receptor (KOR) is a member of G-protein coupled receptors (GPCRs) expressed in serotonergic neurons and neuronal terminals. The involvement of KOR ligands in nociception, diuresis, emotion, cognition, and immune system has been extensively studied. Omics-based methods are preferable to understand the signaling cascade after KOR activation in a systematic manner. In this study, an in-depth quantitative phosphoproteomic analysis resulted in 305 phosphosites, which were significantly changed in three KOR-overexpressed cells upon treatment with two KOR agonists. The subsequent substrate-kinase prediction analysis revealed that 18 potential kinases might be activated under stimulation of the agonists. We found that phosphorylation of PAK1/2 (p21-activated kinase 1/2) was induced by KOR agonists, resulting in reduced actin stress fibers and cytoskeletal reorganization. In summary, this quantitative phosphoproteomics-based research studied the downstream phosphorylation events upon KOR activation, which may shed light on the investigations of KOR signaling pathway and targeted therapy for KOR-related diseases.

Landscape pattern critically affects hydrological cycling and the processes of non-point source nutrients pollution. However, little is known about the quantitative relationship between landscape characteristics and the river water quality, and very few studies have addressed the abrupt changes in river water quality with the gradient of landscape metrics. The present study was conducted in a typically intensive agriculture watershed of eastern China including 13 sub-watersheds with different landscape pattern metrics. We adopted redundancy analysis, nonparametric deviance reduction approach, bootstrap sampling and other statistical methods to reveal the quantitative relationship between landscape pattern metrics and water quality variables; then, the phenomenon of an abrupt change in river water quality was explored with different landscape pattern gradients. The results show that landscape pattern significantly affects river water quality, and this effect was quite different in dry and rainy seasons. In the studied watershed, landscape pattern metrics could respectively explain 71.1% and 55.3% of the total variance in the river water quality in dry and rainy seasons. The configuration metrics of landscape pattern had a stronger ability than their composition metrics to explain the variance in water quality. In the dry season, largest patch index of forestland (LPIfor), the most important landscape index, explained 37.9% of the total variance in water quality. While, in the rainy season, the most important landscape index was the largest patch index of farmland (LPIfar), and it could explain 32.4% of that variance. In the studied watershed, when the LPIfor was

Due to finite information transmission and processing time between agents, delays are inevitable and should therefore be incorporated into flocking modeling. To shed light on understanding the impacts of time delay on the dynamics of flock models, we incorporate a time delay to a two-agent flock model and study its flocking dynamics. When the product of the amplitude of the coupling strength and the time delay is relatively small, necessary and sufficient conditions are established for the two-agent flock model to exhibit flocking. We further show that as the delay increases, transcritical bifurcation and Hopf bifurcation may emerge resulting in rich and complex flocking dynamics.

This paper focuses on evaluating the observed and latent factors in macroeconomics and finance from a new angle. The null hypothesis is that some observed time series is not correlated with each latent factor. This issue is interesting since it can help us to detect irrelevant variables in possible proxies for the latent factors in the macroeconomics and finance field. In this sense, this paper can be seen as the preliminary work of Bai and Ng (2006b) or one of its supplements. Under the null hypothesis and some mild assumptions, the proposed statistic is asymptotically chi-squared distributed. Monte Carlo simulation study shows that the new method has desired performance. A real example is analyzed for illustration.

The breast milk of HIV infected women contains HIV virus particles, therefore children can become infected through breastfeeding. We develop a mathematical epidemiological model of HIV infection in infants, infected children and infected women that represents infection of an infant/child as a series of exposures, by incorporating within-host virus dynamics in the individuals exposed to the virus through breastfeeding. We show that repeated exposures of the infant/child via breastfeeding can cause bi-stability dynamics and, subsequently, infection persistence even when the epidemiological basic reproduction number R 0 is less than unity. This feature of the model, due to a backward bifurcation, gives new insight into the control mechanisms of HIV disease through breastfeeding.

In this paper, a projection-type dual-view holographic three-dimensional (3D) display consisting of a single spatial light modulator (SLM) and a grating light-guide plate is proposed and implemented. A synthetic phase-only hologram of two different 3D objects is calculated by the layer-based Fresnel diffraction method and uploaded onto the SLM for 3D reconstruction. A grating with special design and fabrication is used as the light-guide plate to re-direct the two reconstructed 3D images into the two separated viewing zones simultaneously. Optical experiments demonstrate that the proposed system can realize the function of dual-view holographic 3D display, and it can present 3D images to the human eye with sufficient depth cues, which enables the observers free of the accommodation-vergence conflict and visual fatigue problem. Furthermore, the proposed dual-view holographic 3D display system is applied to the see-through display for augmented reality (AR) applications, and the performance of this system is also tested in the experiments and the results show that the system can provide the dual-view AR 3D sensation successfully.

In this work we extend the SEIR model as in epidemic disease modeling to investigate the propagation dynamics of the information online. Here, we go one step further and takes the homepage effect into consideration, acting as the infectious sources in infectious diseases. Aside of the mathematical analysis, the results of simulation also show some managerial insights that are helpful for controlling the information spread. Furthermore, a case study, usingthe information propagation data in Digg.com , is carried out to examine the effectiveness of two propagation models. Our study could be a starting point for developing a more realistic model about the online propagation dynamics of multiple messages.

Aims: To identify the impact of the information consumption modalities related to the COVID-19 pandemic and its vaccine, on the vaccination decision among the social media users. Also to study the relationships between vaccination attitudes, and latent subgroups, socio-demographic variables, fear of COVID-19 and perceived stress. Method: A total of 723 subjects (male: n = 353; 48.8%; female: n = 370; 51.2%), aged 31.08 ± 10.77, participated in our survey prepared online on the Google Forms application via the platforms Twitter and Facebook. Results: Five latent classes were identified by the analysis: Class 1 (mixed consumers), class 2 (the largest consumers of social media), class 3 (consumers of official information), class 4 (low consumers of information on the vaccine) and class 5 (social media consumers information verifiers). Also, the subgroup that is knowledgeable about COVID-19 pandemic and its vaccine, and who consumes the most information about the vaccine from official sources, is the one with the highest vaccine acceptance rate. In addition, the hesitant attitude towards the COVID-19 vaccine was linked to gender and mask wearing, while refusal behavior was linked to age, female gender, education level, mask wearing, and fear of COVID-19. Conclusion: The results of the study suggest that specific interventions on social media are needed, to reduce hesitancy rates, and the refusal of vaccination, which is crucial in this period of prevailing of COVID-19 virus.

Background: Dupilumab (Dupixent®) is a monoclonal antibody that inhibits IL-4 and IL-13 signaling used for the treatment of allergic diseases. Whilst biological therapy is generally associated with an increased risk of infectious disease, prior studies have suggested Dupilumab may be protective. Objective: We investigated the link between Dupilumab therapy and SARS-CoV-2 infection. Methods: We carryied out a comprehensive data-mining and disproportionality analysis of the WHO global pharmacovigilance database. One asymptomatic COVID-19 case, 106 cases of symptomatic COVID-19, and 2 cases of severe COVID-19 pneumonia were found. Results: Dupilumab treated patients were at higher risk of COVID-19 (with an IC0.25 of 3.05), even though infections were less severe (IC0.25 of -1.71). The risk of developing COVID-19 was significant both among males and females (with an IC0.25 of 0.24 and 0.58, respectively). The risk of developing COVID-19 was significant in the age-group of 45-64 years (with an IC0.25 of 0.17). Limitations: Limitations include: the heterogeneous nature of the database sources. Furthermore, a direct causal relationship cannot be inferred from the current investigation. Conclusion: Dupilumab use was found to reduce COVID-19 related severity. Further studies are needed to better understand the immunological mechanisms and clinical implications of these findings.

It is imperative that resources are channeled towards programs that are efficient and cost effective in combating the spread of COVID-19, the disease caused by severe acute respiratory syndrome coronavirus 2 (SARSCoV-2). This study proposed and analyzed control strategies for that purpose. We developed a mathematical disease model within an optimal control framework that allows us to investigate the best approach for curbing COVID-19 epidemic. We address the question, what is the role of community compliance in as a measure for COVID-19 control? Analyzing the impact of community compliance of recommended guidelines by health authorities — examples, social distancing, face mask use, and sanitizing — couple with efforts by health authorities in areas of vaccine provision and effective quarantine — showed that the best intervention in addition to implementation of vaccination programs and effective quarantine measures, is the active incorporation of individuals’ collective behaviors, and that resources should also be directed towards community campaigns on the importance of face mask use, social distancing, and frequent sanitizing, and any other collective activities. We also demonstrated that collective behavioral response of individuals influences the disease dynamics; implying recommended health policy should be contextualized.

Background. Public Health interventions have succeeded marginally to flatten the COVID-19 epidemic curve of the most recent wave in many regions. Several highly transmissible COVID-19 Variants of Concern (VOCs) have emerged internationally, with variable virulence and as-yet unclear antigenicity. Growing public fatigue highlights the importance of accurately quantifying the speed at which VOCs can replace the resident strain, to inform precise decision-making in terms of both timing and scale of interventions. Methods. Using a simple Susceptible-Infected-Removed (SIR) model, we derive a formula calculating the duration for a VOC to increase its frequency from one level to another. We evaluate the impact of interventions on VOC-related variables. Findings. After introduction of a VOC with a higher transmissibility than the resident strain, its prevalence increases exponentially, leading to eventual replacement by the VOC. Even if the outbreak caused by the resident strain has previously been brought under control, the epidemic is eventually going to increase exponentially, possibly after a transient declining phase. The initial VOC frequency, epidemic mean generation time, and reproduction number of the resident strain all contribute to determining the speed of VOC replacement and the resulting epidemic growth. Interpretation. Following the introduction of a VOC, the risk of a sudden surge of the total cases is hidden behind a transient decline. Maintaining or enhancing Public Health interventions are vital to slowing down the VOC replacement, curbing the epidemic growth, and increasing VOC doubling time.