Trends in incidence and histological pattern of thyroid cancer in Ho Chi Minh City, Vietnam (1996-2015): a population-based study.

BACKGROUND: The burden and trend of thyroid cancer in Vietnam have not been well documented. This study aimed to investigate the trends in incidence and histological pattern of thyroid cancer in Ho Chi Minh City from 1996 to 2015. METHODS: A population-based study retrieved data from the Ho Chi Minh City Cancer Registry during 1996-2015. Trends in the incidence of thyroid cancer were investigated based on age, gender, and histology for each 5-year period. Annual percentage change (APC) in incidence rates was estimated using Joinpoint regression analysis. RESULTS: In the study period, there were 5953 thyroid cancer cases (men-to-women ratio 1:4.5) newly diagnosed in Ho Chi Minh City with the mean age of 42.9 years (±14.9 years). The age-standardized incidence rate of thyroid cancer increased from 2.4 per 100,000 during 1996-2000 (95% confidence interval [95% CI]: 2.2-2.6) to 7.5 per 100,000 during 2011-2015 (95% CI: 7.3-7.9), corresponded to an overall APC of 8.7 (95% CI 7.6-9.9). The APC in men and women was 6.2 (95% CI: 4.2-8.2) and 9.2 (95% CI: 8.0-10.4), respectively. The incidence rate in the < 45 years age group was the highest diagnosed overall and increased significantly in both men (APC 11.0) and women (APC 10.1). Both genders shared similar distribution of subtype incidences, with papillary thyroid cancer constituted the most diagnosed (73.3% in men and 85.2% in women). The papillary thyroid cancer observed a markedly increase overall (APC of 10.7 (95% CI 9.3-12.0)). CONCLUSIONS: There were appreciable increases in the age-standardized incidence rate of thyroid cancer in both genders, mainly contributed by the papillary subtype. The age of patients at diagnosis decreased gradually. The widespread utilization of advanced diagnostic techniques and healthcare accessibility improvement might play a potential role in these trends. Further investigations are needed to comprehend the risk factors and trends fully.

Maximum Pseudolikelihood Estimation for Model-Based Clustering of Time Series Data.

Mixture of autoregressions (MoAR) models provide a model-based approach to the clustering of time series data. The maximum likelihood (ML) estimation of MoAR models requires evaluating products of large numbers of densities of normal random variables. In practical scenarios, these products converge to zero as the length of the time series increases, and thus the ML estimation of MoAR models becomes infeasible without the use of numerical tricks. We propose a maximum pseudolikelihood (MPL) estimation approach as an alternative to the use of numerical tricks. The MPL estimator is proved to be consistent and can be computed with an EM (expectation-maximization) algorithm. Simulations are used to assess the performance of the MPL estimator against that of the ML estimator in cases where the latter was able to be calculated. An application to the clustering of time series data arising from a resting state fMRI experiment is presented as a demonstration of the methodology.

A Block Successive Lower-Bound Maximization Algorithm for the Maximum Pseudo-Likelihood Estimation of Fully Visible Boltzmann Machines.

Maximum pseudo-likelihood estimation (MPLE) is an attractive method for training fully visible Boltzmann machines (FVBMs) due to its computational scalability and the desirable statistical properties of the MPLE. No published algorithms for MPLE have been proven to be convergent or monotonic. In this note, we present an algorithm for the MPLE of FVBMs based on the block successive lower-bound maximization (BSLM) principle. We show that the BSLM algorithm monotonically increases the pseudo-likelihood values and that the sequence of BSLM estimates converges to the unique global maximizer of the pseudo-likelihood function. The relationship between the BSLM algorithm and the gradient ascent (GA) algorithm for MPLE of FVBMs is also discussed, and a convergence criterion for the GA algorithm is given.

A Universal Approximation Theorem for Mixture-of-Experts Models.

The mixture-of-experts (MoE) model is a popular neural network architecture for nonlinear regression and classification. The class of MoE mean functions is known to be uniformly convergent to any unknown target function, assuming that the target function is from a Sobolev space that is sufficiently differentiable and that the domain of estimation is a compact unit hypercube. We provide an alternative result, which shows that the class of MoE mean functions is dense in the class of all continuous functions over arbitrary compact domains of estimation. Our result can be viewed as a universal approximation theorem for MoE models. The theorem we present allows MoE users to be confident in applying such models for estimation when data arise from nonlinear and nondifferentiable generative processes.

Mixture of time-dependent growth models with an application to blue swimmer crab length-frequency data.

Understanding how aquatic species grow is fundamental in fisheries because stock assessment often relies on growth dependent statistical models. Length-frequency-based methods become important when more applicable data for growth model estimation are either not available or very expensive. In this article, we develop a new framework for growth estimation from length-frequency data using a generalized von Bertalanffy growth model (VBGM) framework that allows for time-dependent covariates to be incorporated. A finite mixture of normal distributions is used to model the length-frequency cohorts of each month with the means constrained to follow a VBGM. The variances of the finite mixture components are constrained to be a function of mean length, reducing the number of parameters and allowing for an estimate of the variance at any length. To optimize the likelihood, we use a minorization-maximization (MM) algorithm with a Nelder-Mead sub-step. This work was motivated by the decline in catches of the blue swimmer crab (BSC) (Portunus armatus) off the east coast of Queensland, Australia. We test the method with a simulation study and then apply it to the BSC fishery data.

Comparing combined laser iridoplasty and surgical iridectomy with trabeculectomy in treatment of refractory acute primary angle closure without significant cataract: a randomized controlled trial.

OBJECTIVES: To compare the safety and efficacy of combined laser iridoplasty followed by surgical iridectomy (LI-SI) versus trabeculectomy in the management of medically unresponsive acute primary angle closure (APAC) with minimal cataract. PATIENTS AND METHODS: This was a randomized controlled trial conducted among patients with medically unresponsive APAC without significant cataract. Study participants were randomized into: LI-SI or unaugmented trabeculectomy. Primary outcome of the study was the rate of post-operative surgical complications in the first 3 months after surgery. Secondary outcome assessed at 1 year was whether treatment was completely successful (IOP < 21 mmHg without IOP lowering drops), or partially successful (IOP < 21 mmHg with IOP lowering drops). Failure was defined as IOP ≥ 21 mmHg with IOP lowering drops. RESULTS: The study included 67 eyes of 67 patients (59 females/8 males = 7.4/1) who were randomized into 2 groups: LI-SI (Group 1, 37 eyes), and trabeculectomy (Group 2, 30 eyes). There was no statistical difference between the two groups at baseline. Overall, there were more post-operative complications in Group 1 versus Group 2 (45.9% versus 33.3% - p = 0.23), although all responded well to medical treatment and resolved without sequelae. Complete success was found in 97.1% (34/35 eyes) in Group 1 and 92.6% in group 2 (p = 0.19, Fisher's exact test). CONCLUSIONS: There was a higher rate of post-operative complications after LI-SI compared to trabeculectomy performed for medically unresponsive APAC with minimal cataract. Both procedures had similar surgical outcomes at 1 year.

A method to detect influencers in social networks based on the combination of amplification factors and content creation.

A social network is one of the efficient tools for information propagation. The content is the bridge between the product and its customers. Evaluating the user's content creation is a valuable feature to improve information spreading on the social network. This paper proposes a method for extracting brand value with influencers by combining the user's amplification and content creation in influencer marketing. The amplification factors are studied based on the propagation of the posts on the social network in a duration time. Those factors are more valuable than before when using influencer marketing at a determined time. Moreover, the content creation score is also studied to measure content creation based on the passion point with a brand and its quality. The amplification factors and content creation score are combined to analyze posts' interest in detecting the emerging influent users for a product in the influencer marketing campaign. Using the amplification factors, the passion points, and the content creation score, a system to manage the influencer marketing on Facebook has been constructed and tested in the real-world campaign. The experimental results show that the proposed method's influencers bring the conversion rate's efficiency and revenue in the influencer marketing campaign.

Trends in colorectal cancer incidence in Ho Chi Minh City, Vietnam (1996-2015): Joinpoint regression and age-period-cohort analyses.

BACKGROUND: Little is known about the trends in colorectal cancer (CRC) in Vietnam. We aimed to investigate the trends in epidemiology and anatomical subsites of CRC in Ho Chi Minh City, Vietnam. METHODS: Based on the Ho Chi Minh City Cancer Registry data during 1996-2015, we calculated the average annual percent changes (AAPCs) of the age-standardized incidence rates (ASRs) by sex, age groups, and anatomical subsites, using joinpoint regressions analysis. We further performed age-period-cohort (APC) analysis using the United States National Cancer Institute's web-based statistical tool to explore the underlying reason for the incidence trend. RESULTS: Over 20 years the overall ASR of CRC increased from 10.5 to 17.9 per 100,000, a 1.7-fold increase. CRC incidence elevated more rapidly in men (AAPC 4.7, 95%CI 2.2-7.3) than in women (AAPC 2.6, 95%CI 0.6-4.8). The highest and lowest increasing rates of ASRs were observed in the 50-64-year-old age group (AAPC 5.3, 95%CI 2.8-7.9) and < 50-year-old age group (AAPC 1.1, 95%CI -0.7 to 2.9), respectively. Regarding subsites, rectal cancer had the highest rate of increase (AAPC 3.3, 95%CI 1.0-5.7). Furthermore, the APC analysis indicated significant increases in CRC incidence in birth cohorts after 1975 in both genders. CONCLUSIONS: The CRC incidence in Ho Chi Minh City increased, with the more prominent rates being among men and older populations, in rectal subsites, and in people born after 1975. The upward trend of CRC incidence in Ho Chi Minh City may be due to the adoption of a westernized lifestyle.

Refining the estimation of amphetamine consumption by wastewater-based epidemiology.

Consumption of amphetamine and methamphetamine, two common illicit drugs, has been monitored by wastewater-based epidemiology (WBE) in many countries over the past decade. There is potential for the estimated amount of amphetamine used to be skewed at locations where methamphetamine is also consumed, because amphetamine is also excreted to wastewater following methamphetamine consumption. The present study aims to review the available data in the literature to identify an average ratio of amphetamine/methamphetamine (AMP/METH) that is excreted to wastewater after methamphetamine consumption. This ratio could then be used to refine the estimation of amphetamine consumption in catchments where there is both amphetamine and methamphetamine use. Using data from more than 6000 wastewater samples from Australia where methamphetamine is the dominant illicit amphetamine-type substance on the market, we were able to subtract the contribution of legal sources of amphetamine contribution and obtain the median AMP/METH ratio in wastewater of 0.09. Using this value, the amphetamine derived from methamphetamine consumption can be calculated and subtracted from the total amphetamine mass loads in wastewater samples. Without considering the contribution of amphetamine from methamphetamine use, selected European catchments with comparable consumption of amphetamine and methamphetamine showed up to 83% overestimation of amphetamine use. For catchments with AMP/METH ratio greater than 1.00, the impact of amphetamine from methamphetamine would be negligible; for catchments with AMP/METH ratio in the range of 0.04-0.19, it will be difficult to accurately estimate amphetamine consumption.

Pedestrian overpass use and its relationships with digital and social distractions, and overpass characteristics.

Pedestrian deaths and injuries are a major health issue in both developed and developing countries. In Vietnam, pedestrians account for about 10-11% of all road traffic deaths, while their travel distance contributes to approximately 2.4% of the total distance travelled by all modes. This paper aims to explore the use of pedestrian overpasses and identify influencing factors, particularly with regards to social and digital distractions, and overpass characteristics. An observational survey was conducted in Hanoi, Vietnam, in March 2017 at ten pedestrian overpasses. Behaviours of 608 pedestrians, including those who used an overpass to cross and those who illegally crossed, were observed. The rates of overpass usage varied significantly, between 35.9% and 96.5%. Modelling results suggest that pedestrians tended to compensate for the risks of illegal crossing by forming group and avoiding digital and social distractions (i.e., calling, operating a mobile phone's screen, listening to music, or talking to other pedestrians while crossing). In addition, overpass usage decreased with taller overpasses, but increased with wider overpasses. Effects of gender, weather, and illegal crossing speed on overpass use were also discussed.

Whole-Volume Clustering of Time Series Data from Zebrafish Brain Calcium Images via Mixture Modeling.

Calcium is a ubiquitous messenger in neural signaling events. An increasing number of techniques are enabling visualization of neurological activity in animal models via luminescent proteins that bind to calcium ions. These techniques generate large volumes of spatially correlated time series. A model-based functional data analysis methodology via Gaussian mixtures is suggested for the clustering of data from such visualizations is proposed. The methodology is theoretically justified and a computationally efficient approach to estimation is suggested. An example analysis of a zebrafish imaging experiment is presented.

Statistical Evaluation of Labeled Comparative Profiling Proteomics Experiments Using Permutation Test.

Comparative profiling proteomics experiments are important tools in biological research. In such experiments, tens to hundreds of thousands of peptides are measured simultaneously, with the goal of inferring protein abundance levels. Statistical evaluation of these datasets are required to determine proteins that are differentially abundant between the test samples. Previously we have reported the non-normal distribution of SILAC datasets, and demonstrated the permutation test to be a superior method for the statistical evaluation of non-normal peptide ratios. This chapter outlines the steps and the R scripts that can be used for performing permutation analysis with false discovery rate control via the Benjamini-Yekutieli method.

Asymptotic Normality of the Maximum Pseudolikelihood Estimator for Fully Visible Boltzmann Machines.

Boltzmann machines (BMs) are a class of binary neural networks for which there have been numerous proposed methods of estimation. Recently, it has been shown that in the fully visible case of the BM, the method of maximum pseudolikelihood estimation (MPLE) results in parameter estimates, which are consistent in the probabilistic sense. In this brief, we investigate the properties of MPLE for the fully visible BMs further, and prove that MPLE also yields an asymptotically normal parameter estimator. These results can be used to construct confidence intervals and to test statistical hypotheses. These constructions provide a closed-form alternative to the current methods that require Monte Carlo simulation or resampling. We support our theoretical results by showing that the estimator behaves as expected in simulation studies.

False discovery rate control in magnetic resonance imaging studies via Markov random fields.

Magnetic resonance imaging (MRI) is widely used to study population effects of factors on brain morphometry. Inference from such studies often require the simultaneous testing of millions of statistical hypotheses. Such scale of inference is known to lead to large numbers of false positive results. Control of the false discovery rate (FDR) is commonly employed to mitigate against such outcomes. However, current methodologies in FDR control only account for the marginal significance of hypotheses, and are not able to explicitly account for spatial relationships, such as those between MRI voxels. In this article, we present novel methods that incorporate spatial dependencies into the process of controlling FDR through the use of Markov random fields. Our method is able to automatically estimate the relationships between spatially dependent hypotheses by means of maximum pseudo-likelihood estimation and the pseudo-likelihood information criterion. We show that our methods have desirable statistical properties with regards to FDR control and are able to outperform noncontexual methods in simulations of dependent hypothesis scenarios. Our method is applied to investigate the effects of aging on brain morphometry using data from the PATH study. Evidence of whole brain and component level effects that correspond to similar findings in the literature is found in our investigation.

Development and characterization of candidate rotavirus vaccine strains derived from children with diarrhoea in Vietnam.

In Vietnam, rotavirus infection accounts for more than one-half of all hospitalizations for diarrhoea among children less than 5 years of age. While new vaccines to prevent rotavirus diarrhoea have been developed and introduced into some countries by multinational manufacturers, the ability for developing countries such as Vietnam to introduce several new and important vaccines into the routine infant immunization schedule may be challenging. In order to be partially self-sufficient in vaccine production, Vietnam has pursued the development of several rotavirus strains as candidate vaccines using isolates obtained from Vietnamese children with diarrhoea. This paper describes the origin, isolation and characterization of 3 human rotavirus strains being considered for further vaccine development in Vietnam. The goal is to prepare a monovalent G1P [8] rotavirus vaccine using one of these strains obtained in Vietnam and naturally attenuated by multiple passages in cell culture. While this is an ambitious project that will require several years' work, we are using the lessons learned to improve the overall quality of vaccine production including the use of Vero cell techniques for the manufacture of other vaccines in Vietnam.

Influenza A H5N1 clade 2.3.4 virus with a different antiviral susceptibility profile replaced clade 1 virus in humans in northern Vietnam.

BACKGROUND: Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses. METHODS AND FINDINGS: Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found. CONCLUSION: In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended.