Extra unit-speed machines are almost as powerful as speedy machines for flow time scheduling

We study online scheduling of jobs to minimize the flow time and stretch on parallel machines. We consider algorithms that are given extra resources so as to compensate for the lack of future information. Recent results show that a modest increase in machine speed can provide very competitive performance; in particular, using O(1) times faster machines, the algorithm SRPT (shortest remaining processing time) is 1-competitive for both flow time [C. A. Phillips et al., in Proceedings of STOC, ACM, New York, 1997, pp. 140-149] and stretch [W. T. Chan et al., in Proceedings of MFCS, Springer-Verlag, Berlin, 2005, pp. 236-247] and HDF (highest density first) is O(1)-competitive for weighted flow time [L. Becchetti et al., in Proceedings of RANDOM-APPROX, Springer-Verlag, Berlin, 2001, pp. 36-47]. Using extra unit-speed machines instead of faster machines to achieve competitive performance is more challenging, as a faster machine can speed up a job but extra unit-speed machines cannot. This paper gives a nontrivial relationship between the extra-speed and extra-machine analyses. It shows that competitive results via faster machines can be transformed to similar results via extra machines, hence giving the first algorithms that, using O(1) times unit-speed machines, are 1-competitive for flow time and stretch and O(1)-competitive for weighted flow time. © 2008 Society for Industrial and Applied Mathematics.published_or_final_versio

The Hong Kong Museum of Medical Sciences

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Dynamic dictionary matching and compressed suffix trees

Recent breakthrough in compressed indexing data structures has reduced the space for indexing a text (or a collection of texts) of length n from O(n log n) bits to O(n) bits, while allowing very efficient pattern matching. Yet the compressed nature of such indices also makes them difficult to update dynamically. This paper presents the first O(n)-bit representation of a suffix tree for a dynamic collection of texts whose total length is n, which supports insertion and deletion of a text T in O(|T| log2 n) time, as well as all suffix tree traversal operations, including forward and backward suffix links. This work can be regarded as a generalization of the compressed representation of static texts. Our new suffix tree representation serves as a core part in a compact solution for the dynamic dictionary matching problem, i.e., providing an O(d)-bit data structure for a dynamic collection of patterns of total length d that can support the dictionary matching query efficiently. When compared with the O(d log d)-bit suffix tree based solution of Amir et al., the compact solution increases the query time by roughly a factor of log d only. In the study of the above results, we also derive the first O(n)-bit representation for maintaining n pairs of balanced parentheses in O(log n/log log n) time per operation, matching the time complexity of the previous O(n log n)-bit solution.published_or_final_versio

Assessment of intervention measures for the 2003 SARS epidemic in Taiwan by use of a back-projection method

OBJECTIVES. To reconstruct the infection curve for the 2003 severe acute respiratory syndrome (SARS) epidemic in Taiwan and to ascertain the temporal changes in the daily number of infections that occurred during the course of the outbreak. METHOD. Back-projection method. RESULTS. The peaks of the epidemic correspond well with the occurrence of major infection clusters in the hospitals. The overall downward trend of the infection curve after early May corresponds well to the date (May 10) when changes in the review and classification procedure were implemented by the SARS Prevention and Extrication Committee. CONCLUSION. The major infection control measures taken by the Taiwanese government over the course of the SARS epidemic, particularly those regarding infection control in hospitals, played a crucial role in containing the outbreak. © 2007 by The Society for Healthcare Epidemiology of America. All rights reserved.published_or_final_versio

A time-dependent transit equilibrium assignment model for congested transit network

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Low-band-gap, sublimable rhenium(I) diimine complex for efficient bulk heterojunction photovoltaic devices

The fabrication of efficient bulk heterojunction photovoltaic cells using the chlorotricarbonyl rhenium(I) diimine complex as photosensitizer was discussed. The complex has a lower band gap, which can be adjusted easily by changing the structure of the ligand. The electric properties of the complex were studied using time-of-flight analysis. It was observed that the rhenium complex showed bipolar charge transport character with relatively high electron and hole mobilities.published_or_final_versio

Quantitative analysis of four rapid antigen assays for detection of pandemic H1N1 2009 compared with seasonal H1N1 and H3N2 influenza A viruses on nasopharyngeal aspirates from patients with influenza

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The changing epidemiology of varicella and herpes zoster in Hong Kong before universal varicella vaccination in 2014.

In Hong Kong, universal varicella vaccination started in July 2014. Before this, children could receive varicella vaccine via the private market. We analysed the epidemiology of varicella and zoster before universal vaccination. We estimated varicella vaccination coverage through surveys in preschool children. We estimated the burden of varicella and zoster with varicella notifications from 1999/00 to 2013/14, Accident and Emergency Department (A&E) attendance and inpatient admissions to public hospitals from 2004/05 to 2013/14. We fitted a catalytic model to serological data on antibodies against varicella-zoster virus to estimate the force of infection. We found that varicella vaccination coverage gradually increased to about 50% before programme inception. In children younger than 5 years, the annual rate of varicella notifications, varicella admission and zoster A&E attendance generally declined. The annual notification, A&E attendance and hospitalisation rate of varicella and zoster generally increased for individuals between 10 and 59 years old. Varicella serology indicated an age shift during the study period towards a higher proportion of infections in slightly older individuals, but the change was most notable before vaccine licensure. In conclusion, we observed a shift in the burden of varicella to slightly older age groups with a corresponding increase in incidence but it cannot necessarily be attributed to private market vaccine coverage alone. Increasing varicella vaccination uptake in the private market might affect varicella transmission and epidemiology, but not to the level of interrupting transmission

Exploring the key risks and risk mitigation measures for guaranteed maximum price and target cost contracts in construction

Author name used in this manuscript: Patrick T.I. LamAuthor name used in this manuscript: Joseph H.L. Chan2010-2011 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Application of next generation sequencing to CEPH cell lines to discover variants associated with FDA approved chemotherapeutics

After publication of this work [1], it has come to our attention that there is an error in the author list of the initial version of this manuscript; rather than Ernest J Lam, the second author of the manuscript should be listed as Ernest T Lam