Currently working at AINQA Health and IPPC. An applied mathematician interested in epidemiology. I have a passion in developing mathematical tools and algorithms to deliver analytical solutions to healthcare problems. My interest is in infectious disease modelling.
The Lancet Regional Health - Western Pacific, 2022
We report COVID-19 deaths by vaccine types (inactivated whole-virion SARS-CoV-2 [hereinafter inac... more We report COVID-19 deaths by vaccine types (inactivated whole-virion SARS-CoV-2 [hereinafter inactivated vaccine], BNT162b2, and ChAdOx1 vaccines), and vaccination status in Malaysia and further stratified the analysis by the presence of comorbidities. We used line list data on COVID-19 deaths until 14 September 2021, made available publicly by the Ministry of Health Malaysia.1 We limited the analysis from 24 February 2021 onwards, after COVID-19 vaccines were introduced. For all vaccine types, we defined individuals to be fully vaccinated 14 days after the final dose. We considered individuals who received only the first dose or died within 14 days after the final dose as partially vaccinated. We calculated the age-standardised mortality rate per 100,000 population (ASMR) by the direct method of standardisation using the Malaysian population2 and the World Health Organization (WHO) standard population as reference3 and their corresponding 95% confidence interval. Between 24 February 2021 and 14 September 2021, 20,823 COVID-19 deaths were recorded (Supplementary Table 1). The median age of people who died of COVID-19 was 61.0 years (interquartile range: 49–72). Most deaths (4,946/20,823 24%) occurred in the 60-69 years group (Supplementary Table 2). Males outnumbered females with a ratio of 1.33:1. More deaths occurred among Malaysians (87.5%) and those with comorbidities (72.3%). In comparison with vaccinated individuals, we observed higher mortality rates among those who were unvaccinated. The weekly ASMRs of fully vaccinated individuals were consistently lower than the partially vaccinated group throughout the study (Figure 1A). However, we found that individuals fully vaccinated with the inactivated vaccine had higher ASMRs than those who were partially vaccinated with the same vaccine after 25th August 2021. Nevertheless, we hypothesised that there was no difference between the mean ASMRs of those who were fully and partially vaccinated with the inactivated vaccine during the period of interest. We tested the hypothesis and the mean ASMRs did not differ significantly between the groups (Student's t-test, t(4)=-0.68, p>0.05). Figure 1 Download : Download high-res image (843KB)Download : Download full-size image Figure 1. COVID-19 age-standardised mortality rates by vaccine types and vaccination status in Malaysia, 24 February to 14 September 2021. (A) Time series plot of age-standardised mortality rates for unvaccinated, partially vaccinated, and fully vaccinated individuals by vaccine types. The line graphs represent the age-standardised mortality rates. The bar charts represent weekly COVID-19 positive cases. The dashed line represents the date when the Beta variant (1 April 2021) and Delta variant (26 May 2021) was first detected in Malaysia. (B) Interval plot of age-standardised mortality rates per 100000 population with 95% confidence interval by vaccine types, vaccination status, and presence of comorbidities. The total ASMRs for the unvaccinated group (47.5 per 100,000 population) were 43.2 times and 12.5 times higher than the ASMR of individuals fully vaccinated with BNT162b2 (1.1 per 100,000) and inactivated vaccines (3.8 per 100,000), respectively. Among those vaccinated (Figure 1B and Supplementary Table 3), the ASMRs of partially vaccinated individuals with comorbidities were higher than those without comorbidities across all vaccine types (BNT162b2: 3.6 times; inactivated vaccine: 2.4 times; and ChAdOx1: 3.1 times). The trends were similar for fully vaccinated individuals—the ASMRs for those with comorbidities were 8.9 times, 4.1 times, and 1.5 times higher than those without comorbidities among recipients of BNT162b2, inactivated vaccine, and ChAdOx1 vaccine, respectively. However, the difference in ASMRs of individuals fully vaccinated with the ChAdOx1 vaccine was small (by two deaths). Therefore, we could not conclude the effect of comorbidities on the mortality rates of ChAdOx1 vaccine recipients in this study. While we did not analyse immunological data in this study, the higher mortality rate among recipients of inactivated vaccines calls for close monitoring of breakthrough infections and deaths by vaccine types and further investigations into the recipients’ immunological profiles. Evidence from Hong Kong indicated differing concentrations of neutralising antibodies between the inactivated (lower) and BNT162b2 vaccine recipients (higher),4 highlighting potential differences in vaccine effectiveness. Our study findings also concur with the recent recommendations by the WHO to offer a third dose to persons aged ≥60 who received inactivated vaccines.5 In this study, we could not further describe the risk of death by the types of comorbidities. Nevertheless, other studies in Malaysia have reported that persons with diabetes, hypertension, kidney diseases, heart diseases, and cancer were at higher risk of COVID-19-related deaths.6,7 We could not infer vaccine effectiveness because we lack detailed information regarding those who received the vaccine but did not get infected/die. Vaccine allocation was not entirely random. Front line workers and older adults with comorbidities were prioritised for the BNT162b2 vaccine at first. However, subsequent allocation hinged predominantly on available stocks and supplies (Supplementary Table 4). Due to the concerns regarding the safety of the ChAdOx1 vaccine when it was introduced, Malaysia excluded it from the national vaccination programme and allowed voluntary opt-in through an online system. We opined that the recipients of the ChAdOx1 vaccine were likely to be younger and socioeconomically advantaged. Therefore, the outcome might be biased due to the populations’ lower risk of severe illness and death. This study highlighted that COVID-19 mortalities were associated with vaccination status, age, and comorbidities. The mortality rate among people who were vaccinated was consistently lower than those who were unvaccinated. Among vaccinated individuals, the mortality rate of those who received inactivated vaccines was higher than the recipients of the BNT162b2 and ChAdOx1 vaccines. Vaccination coverage, monitoring breakthrough hospitalisations and deaths, safeguarding hospital capacity, and evidence-based booster strategy is critical to prevent COVID-19 mortalities.
In Malaysia, COVID-19 were first detected as imported cases on 25 January and as local infection ... more In Malaysia, COVID-19 were first detected as imported cases on 25 January and as local infection on 4 February 2020. A surge of positive cases ensued by March 2020 which led to a series of countrywide containment and mitigation measures known as Movement Control Order (MCO). We study the direct effects of MCO on the course of epidemic by analyzing the cumulative and daily infection cases of COVID-19 up to 31 December 2020 in Malaysia and its states using piecewise linear regression and segment neighborhoods algorithm of change-point analysis, respectively. Through piecewise regression on nationwide cases, MCO were likely to almost flatten the epidemic curve in just one month after it was first initiated. While for stateswise cases, the average length of series of concave downward is six months before it turn to concave upward, indicating the period of which deceleration of new cases can be expected. However, the starting of this wave of COVID-19 can be relatively vary for three months in different states and federal territories. Together with change-point analysis on daily cases, the statewise epidemic phases could be subdivided into two to four regimes, whereby the majority of phase transitions fall in April and last quarter of 2020. Overall, the statistical modelling shows that the immediate effect of MCO appears to be effective.
Despite entering its fourth year, the rabies outbreak in the East Malaysian state of Sarawak has ... more Despite entering its fourth year, the rabies outbreak in the East Malaysian state of Sarawak has claimed another nine lives in 2020, culminating with a total of 31 laboratory-confirmed cases of human rabies as of 31 st December 2020. One of the outbreak control challenges faced by the authorities within a previously rabies-free area, such as in the case of Sarawak, is the lack of information regarding possible starting sources, notably hotspot locations of the outbreak. Identification of potential high-risk areas for rabies infection is a sine qua non for effective disease interventions and control strategies. Motivated by this and in preparation for future similar incidents, this paper presented a preliminary study on rabies hotspot identification. The modelling approach adopted the bipartite network where the two disjoint sets of nodes are the Location node and Dog (Bite Cases) node. The formulation of the network followed closely the Bipartite Modeling Methodology Framework. Thorough model verification was done in an attempt to show that such problem domain can be modelled using the Bipartite Modeling approach.
Since user-centered information about dengue is limitedly available to the local public and
even... more Since user-centered information about dengue is limitedly available to the local public and
even more limited in the Malaysian language, a need for centralized easy-understanding information
in the Malaysian languages (i.e. English and Malay) has evolved. On top of that, insufficient
communication may cause the lack of awareness within the Malaysian areas. A lot of people don’t
take precautions against mosquitoes and people living in risk areas often don’t know how to do this.
In addition, once people might suspect dengue, they hardly visit a doctor, which may cause risks and
dangerous situations that could have been prevented. On top of that, having dengue without knowing
or realising the risks may lead to an even faster spread of the virus. A centralized,
easy-understanding information system with a self-screening tool may increase awareness. The aim
of the current report is to describe an application to improve healthcare around dengue by early
detection, increasing knowledge and raising awareness. The application includes both a self-screening
tool as well as information on the virus, mosquitoes and protection. This will stimulate proper
treatment of dengue and will raise awareness to eventually prevent the virus spread.
2016 International Technical Meeting of The Institute of Navigation, 2016
Altitude data has long been deployed for aircraft vertical navigation (pilot) and separation (Air... more Altitude data has long been deployed for aircraft vertical navigation (pilot) and separation (Air Traffic Control (ATC)). Two types of altitude data are down-linked by radar; actual flight level (Mode C) and selected altitude (level). Selected altitude presents intent, and therefore cannot be used for separation purposes. Mode C indicates aircraft pressure altitude (barometric altitude) used by ATC for aircraft vertical separation. Emergence of satellite technology; Global Satellite Navigation System (GNSS) has introduced geometric altitude in the cockpit via GNSS receiver and to the ATC via Automatic Dependent Surveillance Broadcast (ADS-B) system broadcast. Literatures to date have identified many advantages of geometric altitude over barometric altitude. However, till today, the barometric altitude is still the only altitude data used for aircraft navigation and separation. This paper analyzes characteristics of geometric altitude data in the ADS-B messages. It then measures deviation of the geometric altitude from the barometric altitude data. Finally it identifies and discusses potential factors that may influence the variations. Findings showed obvious variation between the altitudes during different phases of flight. The barometric altitude displayed higher readings than geometric height especially while the aircraft is cruising. The discrepancies between the two altitudes were increasing during the climbing phase and decreasing during the descend phase. It is also found that the absolute difference between geometric height and barometric altitude ranges from 25 feet – 1325 feet with an average of 569 feet. Various statistical methods are used to analyze the sample data collected from ADS-B ground stations and aircraft avionics and make model information from airline.
In Air Traffic Control (ATC), aircraft altitude data is used to keep an aircraft within a specifi... more In Air Traffic Control (ATC), aircraft altitude data is used to keep an aircraft within a specified minimum distance vertically from other aircraft, terrain and obstacles to reduce the risk of collision. Two types of altitude data are downlinked by radar; actual flight level (Mode C) and selected altitude (Mode S). Flight level indicates pressure altitude, also known as barometric altitude used by controllers for aircraft vertical separation. ‘Selected altitude’ presents intent only, and hence cannot be used for separation purposes. The emergence of Global Navigation Satellite Systems (GNSSs) has enabled geometric altitude on board and to the controllers via the Automatic Dependent Surveillance-Broadcast (ADS-B) system. In addition, ADS-B provides quality indicator parameters for both geometric and barometric altitudes. Availability of this information will enhance Air Traffic Management (ATM) safety. For example, incidents due to Altimetry System Error (ASE) may potentially be avoided with this information. This work investigates the use and availability of these parameters and studies the characteristics of geometric and barometric data and other data that complement the use of these altitude data in the ADS-B messages. Findings show that only 8·7% of the altitude deviation is < 245 feet (which is a requirement of the International Civil Aviation Organization (ICAO) to operate in Reduced Vertical Separation Minimum (RVSM) airspace). This work provides an alert/guidance for future ground or airborne applications that may utilise geometric/barometric altitude data from ADS-B, to include safety barriers that can be found or analysed from the ADS-B messages itself to ensure ATM safety.
According to the World Health Organization (WHO), rabies is one of the 18 neglected tropical dise... more According to the World Health Organization (WHO), rabies is one of the 18 neglected tropical diseases, together with dengue, leprosy, and trachoma, among others. Despite being a vaccine-preventable disease, the latest estimate of annual human rabies mortality from a 2015 study is as high as 59,000 throughout 150 countries. In human rabies, more than 95% of the cases are due to dog bites, making the elimination of canine rabies a global priority by fighting the disease at its animal source. World Health Organization (WHO), World Organization for Animal Health (OIE), Food and Agriculture Organization (FAO) of the United Nations, and the Global Alliance for Rabies Control (GARC) have warranted the One Health framework with the objective of complete eradication of dog-related human rabies by the year 2030. In an effort to rationalise the One Health approach, this scoping review found 17 studies on assessing the effectiveness of control interventions of human and canine rabies. Different strategies were implemented based on the endemicity of rabies in a particular country. Overall, the combined strategies using the One Health approach, which allows effective participation and communication between different agencies, have shown promising results in reducing rabies cases. These strategies will hopefully realise the goal in the Global Strategic Plan to achieve zero canine-mediated human rabies death by the year 2030.
International Journal on Advanced Science, Engineering and Information Technology, 2019
There is a growing concern over the ongoing rabies epidemic in Sarawak that has remain unresolved... more There is a growing concern over the ongoing rabies epidemic in Sarawak that has remain unresolved ever since the outbreak began in July 2017. As of today, there has been 18 positive human rabies cases reported, which includes 17 fatalities, and one survivor who is now on life support after a severe neurological complications. Subsequently, the death rate now stands at approximately 94%. This paper is a preliminary report on the simulation of rabies transmission dynamics in Sarawak. At present, research is still lacking on the disease dynamics of rabies in Malaysia particularly in the state of Sarawak. We propose here a deterministic, compartmental model with SEIRS framework to fit actual data on the number of human infected rabies cases in Sarawak from June 2017 to January 2019. The simulation predicts that rabies in Sarawak will persist even with the current outbreak management and control efforts. Further, sensitivity analysis showed that dog vaccination rate is the most influential parameter and the basic reproduction number is estimated to be higher than 1. Henceforth, there is a need to increase the access to dog vaccines especially in remote rural areas with lack of health facilities. Our findings also suggest that controlling dog births could prevent the spread of rabies from perpetuating in the state. Neutering or using other fertility control methods would reduce the input of new susceptible domestic dogs into the population while Trap-Neuter-Vaccinate-Release (TNVR) method can be implemented to control new births of free-roaming strays. In summary, increasing the coverage of dog vaccination and reducing the number newborn dogs would be the more effective strategies to manage the current rabies outbreak in Sarawak.
The Lancet Regional Health - Western Pacific, 2022
We report COVID-19 deaths by vaccine types (inactivated whole-virion SARS-CoV-2 [hereinafter inac... more We report COVID-19 deaths by vaccine types (inactivated whole-virion SARS-CoV-2 [hereinafter inactivated vaccine], BNT162b2, and ChAdOx1 vaccines), and vaccination status in Malaysia and further stratified the analysis by the presence of comorbidities. We used line list data on COVID-19 deaths until 14 September 2021, made available publicly by the Ministry of Health Malaysia.1 We limited the analysis from 24 February 2021 onwards, after COVID-19 vaccines were introduced. For all vaccine types, we defined individuals to be fully vaccinated 14 days after the final dose. We considered individuals who received only the first dose or died within 14 days after the final dose as partially vaccinated. We calculated the age-standardised mortality rate per 100,000 population (ASMR) by the direct method of standardisation using the Malaysian population2 and the World Health Organization (WHO) standard population as reference3 and their corresponding 95% confidence interval. Between 24 February 2021 and 14 September 2021, 20,823 COVID-19 deaths were recorded (Supplementary Table 1). The median age of people who died of COVID-19 was 61.0 years (interquartile range: 49–72). Most deaths (4,946/20,823 24%) occurred in the 60-69 years group (Supplementary Table 2). Males outnumbered females with a ratio of 1.33:1. More deaths occurred among Malaysians (87.5%) and those with comorbidities (72.3%). In comparison with vaccinated individuals, we observed higher mortality rates among those who were unvaccinated. The weekly ASMRs of fully vaccinated individuals were consistently lower than the partially vaccinated group throughout the study (Figure 1A). However, we found that individuals fully vaccinated with the inactivated vaccine had higher ASMRs than those who were partially vaccinated with the same vaccine after 25th August 2021. Nevertheless, we hypothesised that there was no difference between the mean ASMRs of those who were fully and partially vaccinated with the inactivated vaccine during the period of interest. We tested the hypothesis and the mean ASMRs did not differ significantly between the groups (Student's t-test, t(4)=-0.68, p>0.05). Figure 1 Download : Download high-res image (843KB)Download : Download full-size image Figure 1. COVID-19 age-standardised mortality rates by vaccine types and vaccination status in Malaysia, 24 February to 14 September 2021. (A) Time series plot of age-standardised mortality rates for unvaccinated, partially vaccinated, and fully vaccinated individuals by vaccine types. The line graphs represent the age-standardised mortality rates. The bar charts represent weekly COVID-19 positive cases. The dashed line represents the date when the Beta variant (1 April 2021) and Delta variant (26 May 2021) was first detected in Malaysia. (B) Interval plot of age-standardised mortality rates per 100000 population with 95% confidence interval by vaccine types, vaccination status, and presence of comorbidities. The total ASMRs for the unvaccinated group (47.5 per 100,000 population) were 43.2 times and 12.5 times higher than the ASMR of individuals fully vaccinated with BNT162b2 (1.1 per 100,000) and inactivated vaccines (3.8 per 100,000), respectively. Among those vaccinated (Figure 1B and Supplementary Table 3), the ASMRs of partially vaccinated individuals with comorbidities were higher than those without comorbidities across all vaccine types (BNT162b2: 3.6 times; inactivated vaccine: 2.4 times; and ChAdOx1: 3.1 times). The trends were similar for fully vaccinated individuals—the ASMRs for those with comorbidities were 8.9 times, 4.1 times, and 1.5 times higher than those without comorbidities among recipients of BNT162b2, inactivated vaccine, and ChAdOx1 vaccine, respectively. However, the difference in ASMRs of individuals fully vaccinated with the ChAdOx1 vaccine was small (by two deaths). Therefore, we could not conclude the effect of comorbidities on the mortality rates of ChAdOx1 vaccine recipients in this study. While we did not analyse immunological data in this study, the higher mortality rate among recipients of inactivated vaccines calls for close monitoring of breakthrough infections and deaths by vaccine types and further investigations into the recipients’ immunological profiles. Evidence from Hong Kong indicated differing concentrations of neutralising antibodies between the inactivated (lower) and BNT162b2 vaccine recipients (higher),4 highlighting potential differences in vaccine effectiveness. Our study findings also concur with the recent recommendations by the WHO to offer a third dose to persons aged ≥60 who received inactivated vaccines.5 In this study, we could not further describe the risk of death by the types of comorbidities. Nevertheless, other studies in Malaysia have reported that persons with diabetes, hypertension, kidney diseases, heart diseases, and cancer were at higher risk of COVID-19-related deaths.6,7 We could not infer vaccine effectiveness because we lack detailed information regarding those who received the vaccine but did not get infected/die. Vaccine allocation was not entirely random. Front line workers and older adults with comorbidities were prioritised for the BNT162b2 vaccine at first. However, subsequent allocation hinged predominantly on available stocks and supplies (Supplementary Table 4). Due to the concerns regarding the safety of the ChAdOx1 vaccine when it was introduced, Malaysia excluded it from the national vaccination programme and allowed voluntary opt-in through an online system. We opined that the recipients of the ChAdOx1 vaccine were likely to be younger and socioeconomically advantaged. Therefore, the outcome might be biased due to the populations’ lower risk of severe illness and death. This study highlighted that COVID-19 mortalities were associated with vaccination status, age, and comorbidities. The mortality rate among people who were vaccinated was consistently lower than those who were unvaccinated. Among vaccinated individuals, the mortality rate of those who received inactivated vaccines was higher than the recipients of the BNT162b2 and ChAdOx1 vaccines. Vaccination coverage, monitoring breakthrough hospitalisations and deaths, safeguarding hospital capacity, and evidence-based booster strategy is critical to prevent COVID-19 mortalities.
In Malaysia, COVID-19 were first detected as imported cases on 25 January and as local infection ... more In Malaysia, COVID-19 were first detected as imported cases on 25 January and as local infection on 4 February 2020. A surge of positive cases ensued by March 2020 which led to a series of countrywide containment and mitigation measures known as Movement Control Order (MCO). We study the direct effects of MCO on the course of epidemic by analyzing the cumulative and daily infection cases of COVID-19 up to 31 December 2020 in Malaysia and its states using piecewise linear regression and segment neighborhoods algorithm of change-point analysis, respectively. Through piecewise regression on nationwide cases, MCO were likely to almost flatten the epidemic curve in just one month after it was first initiated. While for stateswise cases, the average length of series of concave downward is six months before it turn to concave upward, indicating the period of which deceleration of new cases can be expected. However, the starting of this wave of COVID-19 can be relatively vary for three months in different states and federal territories. Together with change-point analysis on daily cases, the statewise epidemic phases could be subdivided into two to four regimes, whereby the majority of phase transitions fall in April and last quarter of 2020. Overall, the statistical modelling shows that the immediate effect of MCO appears to be effective.
Despite entering its fourth year, the rabies outbreak in the East Malaysian state of Sarawak has ... more Despite entering its fourth year, the rabies outbreak in the East Malaysian state of Sarawak has claimed another nine lives in 2020, culminating with a total of 31 laboratory-confirmed cases of human rabies as of 31 st December 2020. One of the outbreak control challenges faced by the authorities within a previously rabies-free area, such as in the case of Sarawak, is the lack of information regarding possible starting sources, notably hotspot locations of the outbreak. Identification of potential high-risk areas for rabies infection is a sine qua non for effective disease interventions and control strategies. Motivated by this and in preparation for future similar incidents, this paper presented a preliminary study on rabies hotspot identification. The modelling approach adopted the bipartite network where the two disjoint sets of nodes are the Location node and Dog (Bite Cases) node. The formulation of the network followed closely the Bipartite Modeling Methodology Framework. Thorough model verification was done in an attempt to show that such problem domain can be modelled using the Bipartite Modeling approach.
Since user-centered information about dengue is limitedly available to the local public and
even... more Since user-centered information about dengue is limitedly available to the local public and
even more limited in the Malaysian language, a need for centralized easy-understanding information
in the Malaysian languages (i.e. English and Malay) has evolved. On top of that, insufficient
communication may cause the lack of awareness within the Malaysian areas. A lot of people don’t
take precautions against mosquitoes and people living in risk areas often don’t know how to do this.
In addition, once people might suspect dengue, they hardly visit a doctor, which may cause risks and
dangerous situations that could have been prevented. On top of that, having dengue without knowing
or realising the risks may lead to an even faster spread of the virus. A centralized,
easy-understanding information system with a self-screening tool may increase awareness. The aim
of the current report is to describe an application to improve healthcare around dengue by early
detection, increasing knowledge and raising awareness. The application includes both a self-screening
tool as well as information on the virus, mosquitoes and protection. This will stimulate proper
treatment of dengue and will raise awareness to eventually prevent the virus spread.
2016 International Technical Meeting of The Institute of Navigation, 2016
Altitude data has long been deployed for aircraft vertical navigation (pilot) and separation (Air... more Altitude data has long been deployed for aircraft vertical navigation (pilot) and separation (Air Traffic Control (ATC)). Two types of altitude data are down-linked by radar; actual flight level (Mode C) and selected altitude (level). Selected altitude presents intent, and therefore cannot be used for separation purposes. Mode C indicates aircraft pressure altitude (barometric altitude) used by ATC for aircraft vertical separation. Emergence of satellite technology; Global Satellite Navigation System (GNSS) has introduced geometric altitude in the cockpit via GNSS receiver and to the ATC via Automatic Dependent Surveillance Broadcast (ADS-B) system broadcast. Literatures to date have identified many advantages of geometric altitude over barometric altitude. However, till today, the barometric altitude is still the only altitude data used for aircraft navigation and separation. This paper analyzes characteristics of geometric altitude data in the ADS-B messages. It then measures deviation of the geometric altitude from the barometric altitude data. Finally it identifies and discusses potential factors that may influence the variations. Findings showed obvious variation between the altitudes during different phases of flight. The barometric altitude displayed higher readings than geometric height especially while the aircraft is cruising. The discrepancies between the two altitudes were increasing during the climbing phase and decreasing during the descend phase. It is also found that the absolute difference between geometric height and barometric altitude ranges from 25 feet – 1325 feet with an average of 569 feet. Various statistical methods are used to analyze the sample data collected from ADS-B ground stations and aircraft avionics and make model information from airline.
In Air Traffic Control (ATC), aircraft altitude data is used to keep an aircraft within a specifi... more In Air Traffic Control (ATC), aircraft altitude data is used to keep an aircraft within a specified minimum distance vertically from other aircraft, terrain and obstacles to reduce the risk of collision. Two types of altitude data are downlinked by radar; actual flight level (Mode C) and selected altitude (Mode S). Flight level indicates pressure altitude, also known as barometric altitude used by controllers for aircraft vertical separation. ‘Selected altitude’ presents intent only, and hence cannot be used for separation purposes. The emergence of Global Navigation Satellite Systems (GNSSs) has enabled geometric altitude on board and to the controllers via the Automatic Dependent Surveillance-Broadcast (ADS-B) system. In addition, ADS-B provides quality indicator parameters for both geometric and barometric altitudes. Availability of this information will enhance Air Traffic Management (ATM) safety. For example, incidents due to Altimetry System Error (ASE) may potentially be avoided with this information. This work investigates the use and availability of these parameters and studies the characteristics of geometric and barometric data and other data that complement the use of these altitude data in the ADS-B messages. Findings show that only 8·7% of the altitude deviation is < 245 feet (which is a requirement of the International Civil Aviation Organization (ICAO) to operate in Reduced Vertical Separation Minimum (RVSM) airspace). This work provides an alert/guidance for future ground or airborne applications that may utilise geometric/barometric altitude data from ADS-B, to include safety barriers that can be found or analysed from the ADS-B messages itself to ensure ATM safety.
According to the World Health Organization (WHO), rabies is one of the 18 neglected tropical dise... more According to the World Health Organization (WHO), rabies is one of the 18 neglected tropical diseases, together with dengue, leprosy, and trachoma, among others. Despite being a vaccine-preventable disease, the latest estimate of annual human rabies mortality from a 2015 study is as high as 59,000 throughout 150 countries. In human rabies, more than 95% of the cases are due to dog bites, making the elimination of canine rabies a global priority by fighting the disease at its animal source. World Health Organization (WHO), World Organization for Animal Health (OIE), Food and Agriculture Organization (FAO) of the United Nations, and the Global Alliance for Rabies Control (GARC) have warranted the One Health framework with the objective of complete eradication of dog-related human rabies by the year 2030. In an effort to rationalise the One Health approach, this scoping review found 17 studies on assessing the effectiveness of control interventions of human and canine rabies. Different strategies were implemented based on the endemicity of rabies in a particular country. Overall, the combined strategies using the One Health approach, which allows effective participation and communication between different agencies, have shown promising results in reducing rabies cases. These strategies will hopefully realise the goal in the Global Strategic Plan to achieve zero canine-mediated human rabies death by the year 2030.
International Journal on Advanced Science, Engineering and Information Technology, 2019
There is a growing concern over the ongoing rabies epidemic in Sarawak that has remain unresolved... more There is a growing concern over the ongoing rabies epidemic in Sarawak that has remain unresolved ever since the outbreak began in July 2017. As of today, there has been 18 positive human rabies cases reported, which includes 17 fatalities, and one survivor who is now on life support after a severe neurological complications. Subsequently, the death rate now stands at approximately 94%. This paper is a preliminary report on the simulation of rabies transmission dynamics in Sarawak. At present, research is still lacking on the disease dynamics of rabies in Malaysia particularly in the state of Sarawak. We propose here a deterministic, compartmental model with SEIRS framework to fit actual data on the number of human infected rabies cases in Sarawak from June 2017 to January 2019. The simulation predicts that rabies in Sarawak will persist even with the current outbreak management and control efforts. Further, sensitivity analysis showed that dog vaccination rate is the most influential parameter and the basic reproduction number is estimated to be higher than 1. Henceforth, there is a need to increase the access to dog vaccines especially in remote rural areas with lack of health facilities. Our findings also suggest that controlling dog births could prevent the spread of rabies from perpetuating in the state. Neutering or using other fertility control methods would reduce the input of new susceptible domestic dogs into the population while Trap-Neuter-Vaccinate-Release (TNVR) method can be implemented to control new births of free-roaming strays. In summary, increasing the coverage of dog vaccination and reducing the number newborn dogs would be the more effective strategies to manage the current rabies outbreak in Sarawak.
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Papers by Nur Asheila Taib