Publications

Journal Article
R. S. Gabud, J. Gayline F. Manalang, R. B. L. Chua, E. R. Mendoza, and J. P. Lozano-Kühne, “

An assessment of chronotype and social jetlag among Filipinos

,” International Journal of Philippine Science and Technology, vol. 8, no. 1, pp. 31-40, 2015. Link to the fulltextAbstract
Chronotype is a measure of an individual’s timing of sleep and wakefulness. It describes the relationship between an external time and a person’s internal biological time. The chronotype has been used to characterize human circadian trait. Differences in chronotypes are believed to be related to genetic variation, location, geographic and cultural factors. Determination of chronotype using quantitative approaches has been done in Europe for more than a decade now through the Munich Chronotype Questionnaire (MCTQ). In this approach, the chronotype is quantified by the midpoint time between the start and end of sleep during free days, corrected for sleep duration on work days. The calculated time classifies whether an individual has an early or late chronotype. In the Philippines, there is no existing data for chronotypes as well as social jetlag – the discrepancy between an individual’s internal time and social clock. In this study, we provide a quantitative description of chronotypes and social jetlag among Filipinos. We present preliminary results based on the 895 non-shift worker respondents of the PhilMCTQ, a language variant of the MCTQ for the Philippine population. Using this set of data, we determined the association of chronotype and social jetlag against certain factors, i.e., age, gender, self- assessed exposure to natural light, type of location (whether living in the urban or rural area), travel time to/from work, sleep duration, and body mass index. Observations concerning the relationship of chronotype and gender, age and social jetlag that have been previously reported in other populations are also seen in our data. Increased social jetlag has been observed among people with late chronotypes among our respondents. There were also some differences in chronotypes between genders, age groups, dwelling locations and consumers of stimulants (i.e., beer, liquor and cigarettes). Both Metro City and Non-Metro City residents similarly experience social jetlag. The data show that as commuting time becomes longer, social jetlag slightly increases. Differences in social jetlag have been observed between age groups and certain stimulants (e.g., smoking, coffee drinking) have been shown to be associated with social jetlag. Other factors such as gender, dwelling location, time spent outdoors and body mass index did not show sufficient evidence of association or correlation with social jetlag among the study participants.
J. P. Lozano-Kühne, M. E. R. Aguila, J. Gayline F. Manalang, R. B. L. Chua, R. S. Gabud, and E. R. Mendoza, “

Shift Work Research in the Philippines: Current State and Future Directions

,” Philippine Science Letters, vol. 5, no. 3, pp. 17-29, 2012. Publisher's VersionAbstract
Shift work has been reported to affect the worker’s health and well-being. However, the many interacting factors involved in shift work make it difficult to understand the mechanism underlying its effects. The currently rising demand for shift workers in the Philippine business process outsourcing (BPO) industry, particularly in the contact center sector, has spurred increased interest in research on the effects of shift work on Filipino workers. The fact that shift work affects employees’ health and well-being, and in turn affects economic productivity, gives enough reason for doing shift work studies. In this paper, we review research publications, project reports and theses (graduate and undergraduate) to determine the current state of knowledge on shift work in the Philippines and to define future research directions. Results of this review indicate that many aspects of shift work have been explored in studies in the Philippines, but there is still a big gap in knowledge that needs to be addressed. While there are studies that investigated health effects, job satisfaction, job performance, lifestyle, risk behaviors and other topics, the number of studies done in the country is still quite limited and the variables investigated do not allow comparison with situations in other countries. There is still a need for more detailed studies to be able to provide empirical evidence on shift work’s effects on Filipino workers and to be able to make relevant interventions to improve the workers’ health and well-being. In terms of research questions, there are no local studies that looked into chronic diseases such as cardiovascular diseases and cancer. There are also no published studies yet that investigated the Filipino chronotype in relation to shift work. The chronotype characterizes how an individual’s internal biological clock synchronizes to the external clock. The importance of chronotype in shift work research has been shown in studies in other countries. However, the chronotype variation among Filipinos is not yet known. Other untapped topics on shift work research in the Philippines include light and shift work, speech ability and shift work, actual physical work load and time pressure, exposure to heat, dust or other hazards during shift work, dermatological problems related to shift work, genes and shift work, social and psychological aspects of shift work and long term effects of shift work. We also included here a framework of research approaches on how to thoroughly investigate the effects of shift work on the worker’s health and well-being. The framework was adopted from the European project consortium called ClockWORK which aimed to optimize the individual’s structure of work, free time and sleep. An offshoot of the ClockWORK project is the PhilSHIFT initiative. PhilSHIFT is an interdisciplinary group of researchers from the University of the Philippines and the Ludwig-Maximilians-Universität München studying chronotype variation among Filipinos and shift work in the Philippines.
R. B. L. Chua and J. D. L. Caro, “

Competitive Online Scheduling with Fixed Number of Queues

,” Philippine Computing Journal, vol. 3, no. 1, pp. 18-25, 2008. Publisher's VersionAbstract
One of the complex parts of an operating system design is CPU scheduling, where the OS schedules a sequence of arriving jobs to use the CPU, without knowledge of the time and number of arriving jobs and their execution times. One of the measures of performance of a scheduling algorithm is the average flow time. For a long time, most operating systems, like Windows and UNIX used a scheduling algorithm based on the Multilevel Feedback scheduling algorithm. In this research, we present the Randomized Multilevel Feedback 2 (RMLF2) scheduling algorithm, which is a version of the RMLF algorithm proposed by Kalyanasundaram and Pruhs, and show that it has a competitive ratio of O(ln n) in terms of minimizing flow time against an online adaptive adversary. Since this obtains the Ω(log n) lower bound for randomized algorithm, it has a tight competitive ratio of ϴ(ln n).
Conference Proceedings
R. B. L. Chua and J. D. L. Caro, “

Competitive Online Scheduling with Fixed Number of Queues

,” Proceedings of the 8th Philippine Computing Science Congress. Computing Society of the Philippines, pp. 161-168, 2008. Publisher's VersionAbstract
One of the complex parts of an operating system design is CPU scheduling, where the OS schedules a sequence of arriving jobs to use the CPU, without knowledge of the time and number of arriving jobs and their execution times. One of the measures of performance of a scheduling algorithm is the average flow time. For a long time, most operating systems, like Windows and UNIX used a scheduling algorithm based on the Multilevel Feedback scheduling algorithm. In this research, we present the Randomized Multilevel Feedback 2 (RMLF2) scheduling algorithm, which is a version of the RMLF algorithm proposed by Kalyanasundaram and Pruhs, and show that it has a competitive ratio of O(ln n) in terms of minimizing flow time against an online adaptive adversary. Since this obtains the Ω(log n) lower bound for randomized algorithm, it has a tight competitive ratio of ϴ(ln n).
R. B. L. Chua and P. R. Florentino, “

Online Medical Training System for Simulated Cataract Surgery

,” Transactions of the National Academy of Science and Technology Philippines, vol. 28, no. 1. National Academy of Science and Technology, pp. 161, 2006.
R. B. L. Chua, M. S. A. Magboo, and N. S. Quiming, “

OrganicBuilder: A Java Program That Displays the 3-D Molecular Structure of an Organic Compound Given its IUPAC Name

,” Transactions of the National Academy of Science and Technology Philippines. National Academy of Science and Technology, 2004.
Book Chapter
J. A. Malinao, et al., “

A Metric for User Requirements Traceability in Sequence, Class Diagrams, and Lines-Of-Code via Robustness Diagrams

,” in Theory and Practice of Computation, vol. 7, S. -ya Nishizaki, M. Numao, J. D. L. Caro, and M. T. Suarez, Ed. Springer Japan, 2013, pp. 50-63. Publisher's VersionAbstract
In this work, we propose a metric based on the ICONIX paradigm to calibrate the consistency, completeness, and correctness of commonly used dynamic and static models of software design with a pre-specified set of user requirements expressed as Use Case Texts. A depth-first search-based algorithm is presented to extract scenarios and describe the temporal aspect of software development-related tasks embedded in the Robustness Diagram of ICONIX to derive results needed to perform further verification of these models. A procedure to perform a similar verification of a software’s set of Lines-of-Codes is also proposed. Finally, we perform empirical tests on real-world data and report the results.