Efficient duration modelling in the hierarchical hidden semi-Markov models and their applications

Modeling patterns in temporal data has arisen as an important problem in engineering and science. This has led to the popularity of several dynamic models, in particular the renowned hidden Markov model (HMM) [Rabiner, 1989]. Despite its widespread success in many cases, the standard HMM often fails to model more complex data whose elements are correlated hierarchically or over a long period. Such problems are, however, frequently encountered in practice. Existing efforts to overcome this weakness often address either one of these two aspects separately, mainly due to computational intractability. Motivated by this modeling challenge in many real world problems, in particular, for video surveillance and segmentation, this thesis aims to develop tractable probabilistic models that can jointly model duration and hierarchical information in a unified framework. We believe that jointly exploiting statistical strength from both properties will lead to more accurate and robust models for the needed task. To tackle the modeling aspect, we base our work on an intersection between dynamic graphical models and statistics of lifetime modeling. Realizing that the key bottleneck found in the existing works lies in the choice of the distribution for a state, we have successfully integrated the discrete Coxian distribution [Cox, 1955], a special class of phase-type distributions, into the HMM to form a novel and powerful stochastic model termed as the Coxian Hidden Semi-Markov Model (CxHSMM). We show that this model can still be expressed as a dynamic Bayesian network, and inference and learning can be derived analytically.Most importantly, it has four superior features over existing semi-Markov modelling: the parameter space is compact, computation is fast (almost the same as the HMM), close-formed estimation can be derived, and the Coxian is flexible enough to approximate a large class of distributions. Next, we exploit hierarchical decomposition in the data by borrowing analogy from the hierarchical hidden Markov model in [Fine et al., 1998, Bui et al., 2004] and introduce a new type of shallow structured graphical model that combines both duration and hierarchical modelling into a unified framework, termed the Coxian Switching Hidden Semi-Markov Models (CxSHSMM). The top layer is a Markov sequence of switching variables, while the bottom layer is a sequence of concatenated CxHSMMs whose parameters are determined by the switching variable at the top. Again, we provide a thorough analysis along with inference and learning machinery. We also show that semi-Markov models with arbitrary depth structure can easily be developed. In all cases we further address two practical issues: missing observations to unstable tracking and the use of partially labelled data to improve training accuracy. Motivated by real-world problems, our application contribution is a framework to recognize complex activities of daily livings (ADLs) and detect anomalies to provide better intelligent caring services for the elderly.Coarser activities with self duration distributions are represented using the CxHSMM. Complex activities are made of a sequence of coarser activities and represented at the top level in the CxSHSMM. Intensive experiments are conducted to evaluate our solutions against existing methods. In many cases, the superiority of the joint modeling and the Coxian parameterization over traditional methods is confirmed. The robustness of our proposed models is further demonstrated in a series of more challenging experiments, in which the tracking is often lost and activities considerably overlap. Our final contribution is an application of the switching Coxian model to segment education-oriented videos into coherent topical units. Our results again demonstrate such segmentation processes can benefit greatly from the joint modeling of duration and hierarchy

An Algorithm for Mining High Utility Sequential Patterns with Time Interval

Mining High Utility Sequential Patterns (HUSP) is an emerging topic in data mining which attracts many researchers. The HUSP mining algorithms can extract sequential patterns having high utility (importance) in a quantitative sequence database. In real world applications, the time intervals between elements are also very important. However, recent HUSP mining algorithms cannot extract sequential patterns with time intervals between elements. Thus, in this paper, we propose an algorithm for mining high utility sequential patterns with the time interval problem. We consider not only sequential patterns' utilities, but also their time intervals. The sequence weight utility value is used to ensure the important downward closure property. Besides that, we use four time constraints for dealing with time interval in the sequence to extract more meaningful patterns. Experimental results show that our proposed method is efficient and effective in mining high utility sequential pattern with time intervals

Mapping for engagement: setting up a community based participatory research project to reach underserved communities at risk for Hepatitis C in Ho Chi Minh City, Vietnam

Background: Approximately 1. 07 million people in Vietnam are infected with hepatitis C virus (HCV). To address this epidemic, the South East Asian Research Collaborative in Hepatitis (SEARCH) launched a 600-patient cohort study and two clinical trials, both investigating shortened treatment strategies for chronic HCV infection with direct-acting antiviral drugs. We conducted ethnographic research with a subset of trial participants and found that the majority were aware of HCV infection and its implications and were motivated to seek treatment. However, people who inject drugs (PWID), and other groups at risk for HCV were under-represented, although injecting drug use is associated with high rates of HCV. Material and Methods: We designed a community-based participatory research (CBPR) study to engage in dialogues surrounding HCV and other community-prioritized health issues with underserved groups at risk for HCV in Ho Chi Minh City. The project consists of three phases: situation analysis, CBPR implementation, and dissemination. In this paper, we describe the results of the first phase (i.e., the situation analysis) in which we conducted desk research and organized stakeholder mapping meetings with representatives from local non-government and community-based organizations where we used participatory research methods to identify and analyze key stakeholders working with underserved populations. Results: Twenty six institutions or groups working with the key underserved populations were identified. Insights about the challenges and dynamics of underserved communities were also gathered. Two working groups made up of representatives from the NGO and CBO level were formed. Discussion: Using the information provided by local key stakeholders to shape the project has helped us to build solid relationships, give the groups a sense of ownership from the early stages, and made the project more context specific. These steps are not only important preliminary steps for participatory studies but also for other research that takes place within the communities

Исследование перфекционизма и субъективного благополучия среди студентов колледжа: стратегии преодоления стресса как посредника

Introduction. Previous studies pointed out that there is an important relationship between personality factors and an individual’s well-being. Aim. This study aims to investigate the relationships between adaptive/maladaptive perfection and subject well-being among college students. Besides, positive/avoidance stress coping strategies are used as a mediator in the relationship between adaptive/maladaptive perfectionism and subject well-being. Methodology and research methods. This study used a quantitative research method to investigate a population of college students. Questionnaires were also delivered to 350 students in colleges in Ho Chi Minh City, Vietnam. The authors used Structural Equation Modelling (SEM) via AMOS to test all the hypotheses. Results. The findings show that (1) adaptive perfectionism can positively predict subjective wellbeing through positive coping strategies and negatively predict subject well-being through avoidance coping strategies; (2) maladaptive perfectionism can negatively predict subjective well-being through positive coping strategies and positively through avoidance coping strategies; (3) adaptive/maladaptive perfectionism can directly predict subject well-being. Scientific novelty. This study gains more insights into the role of stress coping strategies as a mediator in the relationship between adaptive/maladaptive perfectionism and subject well-being among college students. Practical significance. The findings in this study suggest that teachers, mentors, and counsellors should give appropriate counselling to college students to help them obtain good learning development and physical and mental adaptation.Введение. Предыдущие исследования указывали на то, что существует важная связь между личностными факторами и благополучием человека. Цель. Эта работа направлена на изучение взаимосвязи между адаптивным/маладаптивным перфекционизмом и субъективным благополучием среди студентов колледжа. Кроме того, стратегии преодоления положительного/избегающего стресса используются в качестве посредника в указанных отношениях. Методология, методы и методики. Был использован количественный метод исследования для изучения выборки студентов колледжа. В анкетировании приняли участие 350 студентов колледжей в Хошимине, Вьетнам. Авторы использовали моделирование структурных уравнений (SEM) через AMOS для проверки всех гипотез. Результаты. Результаты показывают, что: 1) адаптивный перфекционизм может положительно влиять на субъективное благополучие с помощью позитивных стратегий преодоления последствий и негативно влиять на субъективное благополучие с помощью стратегий избегания преодоления последствий; 2) маладаптивный перфекционизм может негативно влиять на субъективное благополучие через позитивные стратегии преодоления последствий и положительно – через стратегии избегания преодоления последствий; 3) адаптивный/маладаптивный перфекционизм может непосредственно влиять на благополучие субъекта. Научная новизна. Это исследование позволяет глубже понять роль стратегий преодоления стресса в качестве посредника в отношениях между адаптивным/маладаптивным перфекционизмом и благополучием учащихся колледжей. Практическая значимость. Результаты этого исследования показывают, что преподаватели, наставники и консультанты должны давать соответствующее консультирование студентам колледжа, чтобы помочь им получить хорошее обучение и развитие, а также физическую и психическую адаптацию.Авторы благодарят Городской университет экономики и финансов Хошимина (UEF) за финансирование настоящей работы.The authors would like to thank Ho Chi Minh City University of Economics and Finance (UEF) (Vietnam) for funding this work

The CIPAZ study protocol: an open label randomised controlled trial of azithromycin versus ciprofloxacin for the treatment of children hospitalised with dysentery in Ho Chi Minh City, Vietnam

Background: Diarrhoeal disease remains a common cause of illness and death in children <5 years of age. Faecal-oral infection by Shigella spp. causing bacillary dysentery is a leading cause of moderate-to-severe diarrhoea, particularly in low and middle-income countries. In Southeast Asia, S. sonnei predominates and infections are frequently resistant to first-line treatment with the fluoroquinolone, ciprofloxacin. While resistance to all antimicrobials is increasing, there may be theoretical and clinical benefits to prioritizing treatment of bacillary dysentery with the azalide, azithromycin. In this study we aim to measure the efficacy of treatment with azithromycin compared with ciprofloxacin, the current standard of care, for the treatment of children with bacillary dysentery. Methods and analysis: We will perform a multicentre, open-label, randomized controlled trial of two therapeutic options for the antimicrobial treatment of children hospitalised with dysentery. Children (6–60 months of age) presenting with symptoms and signs of dysentery at Children’s Hospital 2 in Ho Chi Minh City will be randomised (1:1) to treatment with either oral ciprofloxacin (15mg/kg/twice daily for 3 days, standard-of-care) or oral azithromycin (10mg/kg/daily for 3 days). The primary endpoint will be the proportion of treatment failure (defined by clinical and microbiological parameters) by day 28 (+3 days) and will be compared between study arms by logistic regression modelling using treatment allocation as the main variable. Ethics and dissemination: The study protocol (version 1.2 dated 27th December 2018) has been approved by the Oxford Tropical Research Ethics Committee (47–18) and the ethical review boards of Children's Hospital 2 (1341/NĐ2-CĐT). The study has also been approved by the Vietnamese Ministry of Health (5044/QĐ-BYT). Trial registration: Clinicaltrials.gov: NCT03854929 (February 26th 2019)

Добро пожаловать на работу в Тайване! Исследование возможностей трудоустройства иностранных студентов

Introduction. Employment plays an important role in vocational development. However, not many studies of job search among international students have been reported. Aim. The current study aims to examine the relationship between self-efficacy, behavioural intentions, and perceived discrimination in the field of job search (JS). Methodology and research methods. The authors used Social Cognitive Model of Career Self-management (CSM) as the theoretical background to explain the relationships among the constructs of self-efficacy, behavioural intentions and perceived discrimination in JS. The study was conducted in a Chinese cultural context (Taiwan) with a sample of 301 international students from Southeast Asian countries. Structural Equation Modelling (SEM) was used to test the model about the relationships between the three variables in the study. Results and scientific novelty. The research findings show that self-efficacy strongly predicts behavioural intentions. Besides, self-efficacy partly mediates the influence of perceived discrimination on behavioural intentions. A quantitative research method was applied to investigate the population of international students, which has not been much reported in previous studies. This indicates that the influence of a contextual factor (e.g. perceived discrimination) on behavioural intentions is direct and indirect through self-efficacy. Practical significance. The research findings can be used by practitioners for enhancing self-efficacy and behavioural intentions as well as helping international students to cope with discrimination in the JS process.Введение. Трудоустройство играет важную роль в профессиональном развитии. Однако опубликовано не так много исследований по поиску работы иностранными студентами. Цель. Настоящее исследование направлено на изучение взаимосвязи между самоэффективностью, поведенческими намерениями и предполагаемой дискриминацией в области поиска работы. Методология и методы исследования. Авторы использовали социально-когнитивную модель карьерного самоуправления в качестве теоретической основы для объяснения связей между конструкциями самоэффективности, поведенческих намерений и предполагаемой дискриминации в области поиска работы. Исследование проводилось в китайском культурном контексте (Тайвань) с участием 301 иностранного студента из стран Юго-Восточной Азии. Моделирование структурных уравнений использовалось для проверки модели взаимосвязи между тремя переменными в исследовании. Результаты и научная новизна. Результаты проведенной работы показывают, что самоэффективность с большой степенью вероятности предсказывает поведенческие намерения. Кроме того, она частично опосредует влияние воспринимаемой дискриминации на поведенческие намерения. Авторы применили метод количественного исследования для изучения контингента иностранных студентов, о котором не так много сообщалось в предыдущих работах. Выяснилось, что влияние контекстуального фактора (например, предполагаемой дискриминации) на поведенческие намерения является прямым и косвенным посредством самоэффективности. Практическая значимость. Результаты настоящего исследования могут быть использованы специалистами для повышения самоэффективности и поведенческих намерений иностранных студентов, а также для оказания им помощи в преодолении дискриминации в процессе поиска работы.The authors would like to thank the students for their time and participation.Авторы выражают благодарность студентам за уделенное время и участие в исследовании

Neurocognition and quality of life after reinitiating antiretroviral therapy in children randomized to planned treatment interruption

Objective: Understanding the effects of antiretroviral treatment (ART) interruption on neurocognition and quality of life (QoL) are important for managing unplanned interruptions and planned interruptions in HIV cure research. Design: Children previously randomized to continuous (continuous ART, n=41) vs. planned treatment interruption (PTI, n=47) in the Pediatric European Network for Treatment of AIDS (PENTA) 11 study were enrolled. At study end, PTI children resumed ART. At 1 and 2 years following study end, children were assessed by the coding, symbol search and digit span subtests of Wechsler Intelligence Scale for Children (6-16 years old) or Wechsler Adult Intelligence Scale ( 6517 years old) and by Pediatrics QoL questionnaires for physical and psychological QoL. Transformed scaled scores for neurocognition and mean standardized scores for QoL were compared between arms by t-test and Mann-Whitney U test, respectively. Scores indicating clinical concern were compared (&lt;7 for neurocognition and &lt;70 for QoL tests). Results: Characteristics were similar between arms with a median age of 12.6 years, CD4 + of 830 cells/\u3bcl and HIV RNA of 1.7 log 10 copies/ml. The median cumulative ART exposure was 9.6 in continuous ART vs. 7.7 years in PTI (P=0.02). PTI children had a median of 12 months off ART and had resumed ART for 25.2 months at time of first assessment. Neurocognitive scores were similar between arms for all tests. Physical and psychological QoL scores were no different. About 40% had low neurocognitive and QoL scores indicating clinical concern. Conclusion: No differences in information processing speed, sustained attention, short-term memory and QoL functioning were observed between children previously randomized to continuous ART vs. PTI in the PENTA 11 trial

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p&lt;0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p&lt;0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Search for Physics beyond the Standard Model in Events with Overlapping Photons and Jets

Results are reported from a search for new particles that decay into a photon and two gluons, in events with jets. Novel jet substructure techniques are developed that allow photons to be identified in an environment densely populated with hadrons. The analyzed proton-proton collision data were collected by the CMS experiment at the LHC, in 2016 at root s = 13 TeV, and correspond to an integrated luminosity of 35.9 fb(-1). The spectra of total transverse hadronic energy of candidate events are examined for deviations from the standard model predictions. No statistically significant excess is observed over the expected background. The first cross section limits on new physics processes resulting in such events are set. The results are interpreted as upper limits on the rate of gluino pair production, utilizing a simplified stealth supersymmetry model. The excluded gluino masses extend up to 1.7 TeV, for a neutralino mass of 200 GeV and exceed previous mass constraints set by analyses targeting events with isolated photons.Peer reviewe