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52. Enhancing Semantic Spaces with Event-Driven Context Interpretation.

Author

Gellersen, Hans W., Want, Roy, Schmidt, Albrecht, Tan, Joo Geok, Zhang, Daqing, Wang, Xiaohang, and Cheng, Heng Seng

Abstract

One important functionality provided by a context-aware infrastructure is to derive high-level contexts on behalf of context-aware applications. High-level contexts are summary descriptions about users' states and surroundings which are generally inferred from low-level, explicit contexts directly provided by hardware sensors and software programs. In Semantic Space, an ontology-based context-aware infrastructure, high-level contexts are derived using context reasoning. In this paper, we present another approach to deriving high-level contexts in Semantic Space, event-driven context interpretation. We show how event-driven context interpretation can leverage on the context model and dynamic context acquisition/representation in Semantic Space as well as easily integrate into Semantic Space. Differing from the context reasoning approach, our proposed event-driven context interpreter offers better performance in terms of flexibility, scalability and processing time. We also present a prototype of the event-driven context interpreter we are building within Semantic Space to validate the feasibility of the new approach. [ABSTRACT FROM AUTHOR]

Published
2005
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56. Risk Factors Associated with Subclinical Human Infection with Avian Influenza A (H5N1) Virus—Cambodia, 2006.

Author

Vong, Sirenda, Ly, Sowath, van Kerkhove, Maria D., Achenbach, Jenna, Holl, Davun, Buchy, Philippe, Sorn, San, Heng Seng, Uyeki, Timothy M., Sok, Touch, and Katz, Jacqueline M.

Subjects
AVIAN influenza, RETROVIRUS diseases, INFLUENZA, INFECTION, RESPIRATORY diseases, GLOBULINS, BLOOD proteins, ANTIGENS, ANTIBODY titer, DISEASE risk factors
Abstract

Background. We conducted investigations in 2 villages in Cambodia where outbreaks of influenza H5N1 occurred among humans and poultry to determine the frequency of and risk factors for H5N1 virus transmission. Methods. During May 2006, ∼7 weeks after outbreaks of influenza H5N1 among poultry occurred, villagers living near households of 2 patients with influenza H5N1 were interviewed about potential H5N1 exposures and had blood samples obtained for H5N1 serological testing by microneutralization assay. A seropositive result was defined as an influenza H5N1 neutralizing antibody titer of ⩾1:80, with confirmation by Western blot assay. A case-control study was conducted to identify risk factors for influenza H5N1 virus infection. Control subjects, who had seronegative results of tests, were matched with H5N1-seropositive persons by village residence, households with an influenza H5N1-infected poultry flock, sex, and age. Results. Seven (1.0%) of 674 villagers tested seropositive for influenza H5N1 antibodies and did not report severe illness; 6 (85.7%) were male. The 7 H5N1-seropositive persons, all of whom were aged ⩽18 years, were younger than participants who tested seronegative for H5N1 antibodies (median age, 12.0 years vs. 27.4 years; P = .03) and were more likely than were the 24 control subjects to report bathing or swimming in household ponds (71.4% vs. 20.8%; matched odds ratio, 11.3; P = .03). Conclusions. Avian-to-human transmission of influenza H5N1 virus remains low, despite extensive poultry contact. Exposure to a potentially contaminated environment was a risk factor for human infection. [ABSTRACT FROM AUTHOR]

Published
2009
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57. Low frequency of poultry-to-human H5NI virus transmission, southern Cambodia, 2005.

Author

Vong, Sirenda, Coghlan, Benjamin, Mardy, Sek, Holl, Davun, Heng Seng, Ly, Sovann, Miller, Megge J., Buchy, Philippe, Froehlich, Yves, Dufourcq, Jean Baptiste, Uyeki, Timothy M., Lim, Wilina, Sok, Touch, and Seng, Heng

Subjects
AVIAN influenza, POULTRY, IMMUNOGLOBULINS, VIRUS diseases
Abstract

To understand transmission of avian influenza A (H5N1) virus, we conducted a retrospective survey of poultry deaths and a seroepidemiologic investigation in a Cambodian village where a 28-year-old man was infected with H5N1 virus in March 2005. Poultry surveys were conducted within a 1-km radius of the patient's household. Forty-two household flocks were considered likely to have been infected from January through March 2005 because >60% of the flock died, case-fatality ratio was 100%, and both young and mature birds died within 1 to 2 days. Two sick chickens from a property adjacent to the patient's house tested positive for H5N1 on reverse transcription-PCR. Villagers were asked about poultry exposures in the past year and tested for H5N1 antibodies. Despite frequent, direct contact with poultry suspected of having H5N1 virus infection, none of 351 participants from 93 households had neutralizing antibodies to H5N1. H5N1 virus transmission from poultry to humans remains low in this setting. [ABSTRACT FROM AUTHOR]

Published
2006
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58. Effect of Sediment Density on Bed‐Load Transport

Author

Heng Seng Low

Subjects
Mechanical Engineering, Sediment, Geotechnical engineering, Sediment transport, Grain size, Geology, Water Science and Technology, Civil and Structural Engineering, Bed load
Abstract

Experiments on transport by water of synthetic lightweight sediments of specific gravities, 1.0

Published
1989
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59. Two clustered cases of confirmed influenza A(H5N1) virus infection, Cambodia, 2011

Author

Nima Asgari, Beat Richner, Nora Chea, C Penh, Philippe Buchy, Paul Kitsutani, Touch Sok, Sek Mardy, Vanra Ieng, Sovann Ly, Maria Concepcion Roces, S D Yi, Heng Seng, Arnaud Tarantola, Denis R. St. Laurent, and Sareth Rith

Subjects
Male, Pediatrics, medicine.medical_specialty, Epidemiology, Influenza A (H5N1) Virus, medicine.disease_cause, Virus, Birds, Young Adult, Fatal Outcome, Virology, Throat, Influenza, Human, medicine, Influenza A virus, Animals, Humans, Young adult, Influenza A Virus, H5N1 Subtype, Transmission (medicine), business.industry, Reverse Transcriptase Polymerase Chain Reaction, Public Health, Environmental and Occupational Health, Infant, Influenza A virus subtype H5N1, medicine.anatomical_structure, Influenza in Birds, Female, Autopsy, Contact Tracing, business, Cambodia, Sentinel Surveillance, Contact tracing
Abstract

In February 2011, a mother and her child from Banteay Meanchey Province, Cambodia, were diagnosed, postmortem, with avian influenza A(H5N1) virus infection. A field investigation was conducted by teams from the Cambodian Ministry of Health, the World Health Organization and the Institut Pasteur in Cambodia. Nasopharyngeal, throat and serum specimens collected from 11 household or three neighbour contacts including two suspect cases tested negative by reverse transcriptase-polymerase chain reaction (RT-PCR) for A(H5N1). Follow-up sera from the 11 household contacts also tested negative for A(H5N1) antibodies. Twenty-six HCW who were exposed to the cases without taking adequate personal protective measures self-monitored and none developed symptoms within the two following weeks. An unknown number of passengers travelling with the cases on a minibus while they were symptomatic could not be traced but no clusters of severe respiratory illnesses were detected through the Cambodian surveillance systems in the two weeks after that. The likely cause of the fatal infection in the mother and the child was common-source exposure in Preah Sdach District, Prey Veng Province. Human-to-human transmission of A(H5N1) virus was unlikely but genetic susceptibility is suspected. Clusters of A(H5N1) virus infection should be systematically investigated to rule out any human-to-human transmission.

60. Adaptive Automation: Using secondary task measurement to determine function allocation

Author

Moh, Heng Seng and Moh, Heng Seng

Abstract

The present study investigated the behaviour of secondary task performance in Adaptive Automation to determine whether it could be used as a sensitive index of operator’s mental workload to trigger changes in support system. The majority of this study is to verify the method that is been used in performance-based automation is appropriate for which it used secondary task measurement as an indicator to initiate changes in LOA to assist human operator in the right time with right amount. This investigation did not start a new experiment but used experiment data that was done by previous researchers. Previous experiment used simulation software called Automated Cabin Air Management System (AutoCAMS) which simulates a life support system in the operational context of spaceflight. During the simulation, participants were required to ensure system stabilization and repair all 10 faults when occurred. Meanwhile, participants also need to respond quickly to 2 secondary tasks. With the experiment data, two simple analyses were made which are identifying the pattern of secondary task performance around the occurrence of fault and determine the effectiveness of using detector in secondary task measurement to detect fault events. These analyses were based on secondary task performance should worsen whenever fault event occurred due to additional workload. However, the result from the analysis did not appear to be inclined with expectation that the patterns were random and the detector could not accurately detect fault event but some false alarm. It was concluded that secondary task performance could not correctly indicating operator’s mental workload that could be used to trigger initiation in support system. Based on the result, secondary task is very sensitive that could be easily disturbed by any variation within the system. One of the factors that was discussed is the interference issue caused by additional tasks that share the same input, output, and time which resulted in

61. Adaptive Automation: Using secondary task measurement to determine function allocation

Author

Moh, Heng Seng and Moh, Heng Seng

Abstract

The present study investigated the behaviour of secondary task performance in Adaptive Automation to determine whether it could be used as a sensitive index of operator’s mental workload to trigger changes in support system. The majority of this study is to verify the method that is been used in performance-based automation is appropriate for which it used secondary task measurement as an indicator to initiate changes in LOA to assist human operator in the right time with right amount. This investigation did not start a new experiment but used experiment data that was done by previous researchers. Previous experiment used simulation software called Automated Cabin Air Management System (AutoCAMS) which simulates a life support system in the operational context of spaceflight. During the simulation, participants were required to ensure system stabilization and repair all 10 faults when occurred. Meanwhile, participants also need to respond quickly to 2 secondary tasks. With the experiment data, two simple analyses were made which are identifying the pattern of secondary task performance around the occurrence of fault and determine the effectiveness of using detector in secondary task measurement to detect fault events. These analyses were based on secondary task performance should worsen whenever fault event occurred due to additional workload. However, the result from the analysis did not appear to be inclined with expectation that the patterns were random and the detector could not accurately detect fault event but some false alarm. It was concluded that secondary task performance could not correctly indicating operator’s mental workload that could be used to trigger initiation in support system. Based on the result, secondary task is very sensitive that could be easily disturbed by any variation within the system. One of the factors that was discussed is the interference issue caused by additional tasks that share the same input, output, and time which resulted in

62. Adaptive Automation: Using secondary task measurement to determine function allocation

Author

Moh, Heng Seng and Moh, Heng Seng

Abstract

The present study investigated the behaviour of secondary task performance in Adaptive Automation to determine whether it could be used as a sensitive index of operator’s mental workload to trigger changes in support system. The majority of this study is to verify the method that is been used in performance-based automation is appropriate for which it used secondary task measurement as an indicator to initiate changes in LOA to assist human operator in the right time with right amount. This investigation did not start a new experiment but used experiment data that was done by previous researchers. Previous experiment used simulation software called Automated Cabin Air Management System (AutoCAMS) which simulates a life support system in the operational context of spaceflight. During the simulation, participants were required to ensure system stabilization and repair all 10 faults when occurred. Meanwhile, participants also need to respond quickly to 2 secondary tasks. With the experiment data, two simple analyses were made which are identifying the pattern of secondary task performance around the occurrence of fault and determine the effectiveness of using detector in secondary task measurement to detect fault events. These analyses were based on secondary task performance should worsen whenever fault event occurred due to additional workload. However, the result from the analysis did not appear to be inclined with expectation that the patterns were random and the detector could not accurately detect fault event but some false alarm. It was concluded that secondary task performance could not correctly indicating operator’s mental workload that could be used to trigger initiation in support system. Based on the result, secondary task is very sensitive that could be easily disturbed by any variation within the system. One of the factors that was discussed is the interference issue caused by additional tasks that share the same input, output, and time which resulted in

63. Adaptive Automation: Using secondary task measurement to determine function allocation

Author

Moh, Heng Seng and Moh, Heng Seng

Abstract

The present study investigated the behaviour of secondary task performance in Adaptive Automation to determine whether it could be used as a sensitive index of operator’s mental workload to trigger changes in support system. The majority of this study is to verify the method that is been used in performance-based automation is appropriate for which it used secondary task measurement as an indicator to initiate changes in LOA to assist human operator in the right time with right amount. This investigation did not start a new experiment but used experiment data that was done by previous researchers. Previous experiment used simulation software called Automated Cabin Air Management System (AutoCAMS) which simulates a life support system in the operational context of spaceflight. During the simulation, participants were required to ensure system stabilization and repair all 10 faults when occurred. Meanwhile, participants also need to respond quickly to 2 secondary tasks. With the experiment data, two simple analyses were made which are identifying the pattern of secondary task performance around the occurrence of fault and determine the effectiveness of using detector in secondary task measurement to detect fault events. These analyses were based on secondary task performance should worsen whenever fault event occurred due to additional workload. However, the result from the analysis did not appear to be inclined with expectation that the patterns were random and the detector could not accurately detect fault event but some false alarm. It was concluded that secondary task performance could not correctly indicating operator’s mental workload that could be used to trigger initiation in support system. Based on the result, secondary task is very sensitive that could be easily disturbed by any variation within the system. One of the factors that was discussed is the interference issue caused by additional tasks that share the same input, output, and time which resulted in

65. Identification of Molecular Markers Associated with Alteration of Receptor-Binding Specificity in a Novel Genotype of Highly Pathogenic Avian Influenza A(H5N1) Viruses Detected in Cambodia in 2013.

Author

Rith, Sareth, Davis, C. Todd, Duong, Veasna, Sar, Borann, Horm, Srey Viseth, Savuth Chin, Sovann Ly, Laurent, Denis, Richner, Beat, Oboho, Ikwo, Yunho Jang, Davis, William, Thor, Sharmi, Balish, Amanda, Iuliano, A. Danielle, San Sorn, Holl, Davun, Touch Sok, Heng Seng, and Tarantola, Arnaud

Subjects
*BIOMARKERS, *PROTEIN binding, *AVIAN influenza A virus, *GENETIC mutation, *FERRETS as laboratory animals
Abstract

Human infections with influenza A(H5N1) virus in Cambodia increased sharply during 2013. Molecular characterization of viruses detected in clinical specimens from human cases revealed the presence of mutations associated with the alteration of receptor-binding specificity (K189R, Q222L) and respiratory droplet transmission in ferrets (N220K with Q222L). Discovery of quasispecies at position 222 (Q/L), in addition to the absence of the mutations in poultry/environmental samples, suggested that the mutations occurred during human infection and did not transmit further. [ABSTRACT FROM AUTHOR]

Published
2014
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66. Rapid metagenomic characterization of a case of imported COVID-19 in Cambodia.

Author

Manning JE, Bohl JA, Lay S, Chea S, Sovann L, Sengdoeurn Y, Heng S, Vuthy C, Kalantar K, Ahyong V, Tan M, Sheu J, Tato CM, DeRisi JL, Baril L, Duong V, Dussart P, and Karlsson EA

Abstract

Rapid production and publication of pathogen genome sequences during emerging disease outbreaks provide crucial public health information. In resource-limited settings, especially near an outbreak epicenter, conventional deep sequencing or bioinformatics are often challenging. Here we successfully used metagenomic next generation sequencing on an iSeq100 Illumina platform paired with an open-source bioinformatics pipeline to quickly characterize Cambodia's first case of COVID-2019.

Published
2020
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