Performance evaluation of MPEG-4 video streaming over UMTS networks using an integrated tool environment

Universal Mobile Telecommunications System (UMTS) is a third-generation mobile communications system that supports wireless wideband multimedia applications. This paper investigates the video quality attained in streaming MPEG-4 video over UMTS networks using an integrated tool environment, which comprises an MPEG-4 encoder/decoder, a network simulator and video quality evaluation tools. The benefit of such an integrated tool environment is that it allows the evaluation of real video sources compressed using an MPEG-4 encoder. Simulation results show that UMTS Radio Link Control (RLC) outperforms the unacknowledged mode. The latter mode provides timely delivery but no error recovery. The acknowledged mode can deliver excellent perceived video quality for RLC block error rates up to 30% utilizing a playback buffer at the streaming client. Based on the analysis of the performance results, a self-adaptive RLC acknowledged mode protocol is proposed

The Health Care Safety Net and Crowd-Out of Private Health Insurance

There is an extensive literature on the extent to which public health insurance coverage through Medicaid induces less private health insurance coverage. However, little is known about the effect of other components of the health care safety net in crowding out private coverage. We examine the effect of Medicaid and uncompensated care provided by clinics and hospitals on insurance coverage. We construct a long panel of metropolitan area and state-level data on hospital uncompensated care and free and reduced price care offered by Federally Qualified Health Centers. We match this information to individual level data on coverage from the Current Population Survey for two distinct groups: children aged 14 and under and single, childless adults aged 18 to 64. Our results provide mixed evidence on the extent of crowd-out. Hospital uncompensated care does not appear to crowd-out health insurance coverage and health center uncompensated care appears to crowd-out private coverage for adults and, in some specifications, children.

How Did SCHIP Affect the Insurance Coverage of Immigrant Children?

The State Children's Health Insurance Program (SCHIP) significantly expanded public insurance eligibility and coverage for children in "working poor" families. Despite this success, it is estimated that over 6 million children who are eligible for public insurance remain uninsured. An important first step for designing strategies to increase enrollment of eligible but uninsured children is to determine how the take-up of public coverage varies within the population. Because of their low rates of insurance coverage and unique enrollment barriers, children of immigrants are an especially important group to consider. We compare the effect of SCHIP eligibility on the insurance coverage of children of foreign-born and native-born parents. In contrast to research on the earlier Medicaid expansions, we find similar take-up rates for the two groups. This suggests that state outreach strategies were not only effective at increasing take-up overall, but were successful in reducing disparities in access to coverage.

The Buffalo Housing Court: A Special Court for Special Needs

The purposes of this brief Article are neither to sound the trumpets of ultimate success in discovering a solution to housing problems nor to compare and analyze the many housing courts now in existence; rather, this study focuses on the Housing Court of the City of Buffalo, how it came about, what it is today, and where it appears to be headed

Performance of TCP over UMTS common and dedicated channels

Universal Mobile Telecommunications System (UMTS) is a third-generation cellular network that enables high-speed wireless Internet access. This paper investigates the performance of Transmission Control Protocol (TCP) over UMTS utilizing a common and four dedicated transport channels with bit rates up to 2 Mb/s. The performance of TCP was examined under varying channel conditions. Bulk data transfer and interactive traffic was considered in the simulation. The simulation results show that the behaviour of TCP is closely coupled to the UMTS radio link control layer. A maximum TCP throughput is achievable for transport channels with bit rates up to 384 kb/s. The gain in request-response time for interactive traffic is relatively small for high bit rate channels because the UMTS radio interface is latency limited for small object sizes

Optimal eavesdropping on QKD without quantum memory

We consider the security of the BB84, six-state and SARG04 quantum key distribution protocols when the eavesdropper doesn't have access to a quantum memory. In this case, Eve's most general strategy is to measure her ancilla with an appropriate POVM designed to take advantage of the post-measurement information that will be released during the sifting phase of the protocol. After an optimization on all the parameters accessible to Eve, our method provides us with new bounds for the security of six-state and SARG04 against a memoryless adversary. In particular, for the six-state protocol we show that the maximum QBER for which a secure key can be extracted is increased from 12.6% (for collective attacks) to 20.4% with the memoryless assumption.Comment: 7 pages, 3 figures. Analysis of six-state and SARG04 QKD protocols adde

Innovation as Guided Coevolution: The Trend Micro Case (1998 – 2005)

Innovation is considered crucial for firms to compete effectively. The extant research on innovation has provided significant insights, but, however, the majority examined innovation in the context of technology. Only a few exceptions have explored how social and behavioral factors influence firms in the innovation processes. Based on the coevolution perspective, this study examines innovation process of a software firm participating in the ever-changing information security software industry. We focused on how the firm guided its offerings to coevolve with new technologies and relevant changes among different groups of human actors. Our data reveals that the firm developed different offerings in different periods to cope with the changing driving forces—technologies, users, and hackers—in each period. Effectively identifying the driving forces and guided its offerings to coevolve with them, the firm successfully sustained its competitive advantage in the period characterized with turbulence in the environment.Keywords: innovation, coevolution, software, high-tec