Coding tools in MPEG-4 for interlaced video Panusopone, K.; Xuemin Chen; Eifrig, R. ...
IEEE transactions on circuits and systems for video technology,
08/2000, Letnik:
10, Številka:
5
Journal Article
Recenzirano
Previous developments in digital video compression, transmission, and displays have made object-based video viable for many applications, e.g., coding chroma-keyed video for digital TV and ...manipulating video objects on interactive multimedia terminals, etc. To facilitate these applications, there is a demand on international standards for coding methods and transmission formats for object-based natural and synthetic video. For the past few years, the Moving Picture Experts Group (MPEG) of the International Standards Organization (ISO), which successfully created the MPEG-1/2 standards, has been working to establish a new standard, called MPEG-4. MPEG-4 will provide standardized technological elements enabling the integration of the production, distribution, and content-access paradigms in four fields: wireless communication, digital TV, interactive graphics, and the World Wide Web. To meet the needs of interlaced video applications, MPEG-4 video adopted interlaced coding tools similar to those in MPEG-2 and features schemes to code multiple video objects. This paper provides an overview of MPEG-4 interlaced coding tools, and focuses in detail on the new shape and texture-coding algorithms for interlaced video.
Second order kinetics of the reaction of polymer-attached hydroxamic acids with substituted phenyl acetates (
k
pol) have been measured in aqueous solution at 25°C and shown to follow the following ...empirical rate law for degrees of ionisation (α) ranging from 0.1 to
1: k
pol
= a·α + b·
e
−
c
α
. The slopes of the plots of
k
pol against α measures the reactivity of the polymer (
k
react) at given values of α and these increase as α is increased.
The reactivity against substituted phenyl acetates at given α values increases with increasing cross-linking content of the microgel support. The reactivities at α = 0.1 and 0.9 obey the Brønsted equations:
logk
react
( α = 0.1) = −0.55±0.065
pK
ArOH
a+3.26±0.44 (n = 5; r = 0.9799)
logk
react
( α = 0.9) = −0.37±0.06
pK
ArOH
a+3.13±0.43 (n = 5; r = 0.9594)
The similarity between the Brønsted β values for the microgel-supported hydroxamate nucleophile at low degree of ionisation (α) and monomer hydroxamate ion is consistent with the microscopic medium of the transition-state's being water-like. At a high α value the less negative β value indicates a smaller charge change in the transition state; this result and the effect of cross-linking on reactivity supports the hypothesis that the substantial reactivity increases are due to hydroxamate ions buried in the microgel particle and electrophilic assistance of nucleophilic attack.
De-cinnamoylation of O-cinnamoylated microgel-supported hydroxamic acid is only some ten-fold less reactive to hydroxide ion than is the model
O-cinnamoyl-
N-benzoylhydroxylamine. The polymer deacylation possesses a significant water term which means that at low pH it is faster than that of the model reaction; intramolecular catalysis by carboxylate ions is held responsible for this acceleration.
MPEG-4 and H.263+ are the two latest video compression standards aimed towards the streaming video-over-Internet application. Both standars include advanced coding techniques to achieve high coding ...efficiency at low bit rates. They support several requirements of packet-based transmission on the Internet, e.g., scalable video coding and error resilience. MPEG-4 also supports object-based coding tools. It is widely expected that both MPEG-4 and H.263+ will be the two main standards used for delivering streaming video over the Internet. This paper compares the video coding performance of both MPEG-4 and H.263+ standards for this application. This paper also highlights the appropriate combinations of the tools (MPEG-4) and the options (H.263+) that provide good performance for streaming video applications. It is assumed that the reader is generally familiar with the coding tools used in these standards. A brief description of those tools is provided for the sake of completeness.PUBLICATION ABSTRACT
Summary
Ninety patients, divided into three groups of 30, were investigated to determine the incidence of gastric regurgitation during general anaesthesia administered via the laryngeal mask airway ...in the supine, Trendelenburg and lithotomy positions. Fifteen minutes before induction of anaesthesia each patient swallowed a 75mg methylene blue capsule. At the end of surgery, the LMA and the oropharynx were inspected for bluish discoloration which was considered to be a sign of gastric regurgitation. No blue dye was detected in the supine group but it was observed in one patient in each of the other two groups.
The
Mycobacterium tuberculosis UsfX protein is an anti-sigma factor which regulates its cognate sigma factor SigF. UsfX shares low sequence homology with other anti-sigma factors making it difficult ...to identify the nucleotide binding site and characterize its properties. We have identified that the NTP binding site occurs close to Trp106 and the area around the nucleotide binding site is predominantly negatively charged. UsfX binds to a variety of nucleotides unlike other reported anti-sigma factors and exhibits an unusual dual NTPase activity.
In silico computational experiments have identified a XG
SF
S motif close to the nucleotide binding site for metal ion binding. This motif is analogous to the DX
SX
S motif reported earlier in the human integrin CR3 protein superfamily. Overall, the experiments suggest that the
M. tuberculosis UsfX represents a distinct anti-sigma factor family with a novel nucleotide binding motif.
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