QoS impact on user perception and understanding of multimedia video clips

The widespread and increasing advent of multimedia technologies means that there must be a departure from the viewpoint that users expect a Quality of Service (QoS) which will only satisfy them perceptually. What should be expected of multimedia clips is that the QoS with which they are shown is such that it will enable the users to assimilate and understand the informational content of such clips. In this paper we present experimental results Iinking users’ understanding andperception of multimedia clips with the presentation QoS. Results show that the quality of video clips can be severely degraded without the user having to perceive any significant loss of informational content

Quality of perception: User quality of service in multimedia presentations

We define quality of perception (QoP) as representing the user side of the more technical and traditional quality of service. QoP encompasses not only a user’s satisfaction with the quality of multimedia presentations, but also his/her ability to analyze, synthesise and assimilate the informational content of multimedia displays.We found that significant reductions in frame rate and color depth does not result in a significant QoP degradation

The Validity of Charge Symmetry for Parton Distributions

Recent measurements of the Gottfried sum rule have focused attention on the possibility of substantial flavor symmetry breaking in the proton sea. This is confirmed by pp and pD Drell-Yan processes measured at FNAL. Theoretical models used to `prove' flavor symmetry breaking rely on the assumption of charge symmetric parton distributions. Substantial charge symmetry violation [CSV] could affect current tests of flavor symmetry. In this review we examine the possibility of CSV for parton distributions. We first give definitions for structure functions without making the usual assumption of charge symmetry. Next we make estimates of CSV for both valence and sea quark distributions. We list a set of relations which must hold if charge symmetry is valid, and review current experimental limits on CSV. We propose a series of experimental tests of charge symmetry. These tests could either detect CSV, or they could provide stronger upper limits on CSV effects. We discuss CSV contributions to sum rules, and we propose sum rules which could differentiate between flavor symmetry, and charge symmetry violation in nuclear systems.Comment: 74 pages, including 26 figure

Shock wave propagation in porous ice

We present data on shock wave propagation in porous ice under conditions applicable to the outer solar system. The equation of state of porous ice under low temperature and low pressure conditions agrees well with measurements under terrestrial conditions implying that data on terrestrial snow may be applicable to the outer solar system. We also observe rarefaction waves from small regions of increased porosity and calculate release wave velocities