Educational Innovations in Multimedia Systems*

Multimedia systems have emerged as one of the fastest growing segments of computing systems and thus need to be well integrated into a computer engineering curriculum. Fortunately the teaching and learning of multimedia systems can be aided with novel instructional techniques based on multimedia. The Multimedia Curriculum project at the University of Massachusetts Amherst is developing a unified set of instructional materials on the engineering techniques used in the design and test of hardware, software and networks for multimedia. This large project includes three facets: 1) multimedia instructional modules using web‐linked Digital Video Disks, 2) multimedia communication utilities to facilitate student interaction, and 3) multimedia component design projects. In this paper, we explain our approach to using multimedia as both content and instructional technology and briefly present preliminary results in each of the three facets.     

Analysis of optimized plates for buckling

This paper is concerned with the analysis of optimized plates for buckling. The Rayleigh-Ritz technique is used to solve variable thickness rectangular plates. A double sine series is used to represent the lateral displacements and convergence is attained for a six term series. The result yields a buckling load which is 44% higher than that of a uniform thickness plate having the same volume. The plate itself was optimized using variational calculus to obtain the optimality condition which states that the thickness is proportional to the strain energy density and a truncated Fourier series solution (one term) was used to obtain an optimal shape having a critical load 112% higher than the uniform thickness plate.     

Localization of human intestinal defensin 5 in Paneth cell granules

Antibiotic peptides of higher animals include the defensins, first discovered in phagocytic cells but recently also found to be produced by epithelial cells. We biosynthesized recombinant human intestinal defensin 5 (rHD-5) using the baculovirus-insect cell expression system. Since insect cells process defensin incompletely and secrete the precursor proHD-5, we substituted a methionine for an alanine at a likely processing site to allow selective chemical cleavage with cyanogen bromide, and rHD-5 was used to elicit polyclonal antibodies. By the immunoperoxidase-staining technique, the antibodies selectively stained Paneth cells of the normal adult small intestine. Immunogold electron microscopy further localized HD-5 to the Paneth cell secretory granules. Since some defensins exert activity cytotoxic to mammalian cells, we assayed the effect of rHD-5 on the human intestinal cell lines Caco2 and Int407. proHD-5 did not exert cytotoxic activity, and rHD-5 showed only minimal activity against Int407 and was inert against Caco2. Since Paneth cells release their granules adjacent to the mitotic cells of the intestinal crypts, HD could protect this cell population against invasion and parasitization by microbes.     

Tractable analytic models of demand assignment protocols innetworks with arbitrary buffer capacity

The authors introduce analytic models for evaluating demand assignment protocols in realistic finite-buffer/finite-station network configurations. A solution for protocols with gated and nongated service disciplines that enables one to model demand assignment protocols as found, for example, in local and metropolitan area networks and in satellite communication systems is presented. A tractable approximate solution based on linear equations whose number is also linear is given. It is demonstrated that in addition to its computational efficiency, the presented approach does not incur a significant penalty in terms of accuracy     

Possible existence of retinal vascular disease in relatives of diabetic patients and its metabolic correlation

The authors studied the possible presence of retinal vasculopathy in 31 patients with a diabetic father or mother. In 12 of them (38.7 per cent of the total number of patients) some degree of alteration in the glycemia curve and increased insulinemia were observed. Neither of these anomalies were related to sex of patients. Opthalmologic examination revealed diabetic retinopathy in 6.45 per cent of the patients, and the disease was only present in female patients. Among the 8 patients with diabetic glycemia curve (25.8 per cent of the total), only one (12.5 per cent of the diabetic patients, and 0.31 of the total) hand diabetic retinopathy. Diabetic retinopathy was not observed in any of the 4 non-diabetic patients with glucose load intolerance. I phase diabetic retinopathy was found in one subject (0.31 per cent of the total) with normal glucose and insulin tolerance.     

QoS Routing for Mesh-Based Wireless LANs

Wireless LANs with their increased data rate become an attractive technology for connecting mobile users to the Internet. Efficient deployment of wireless LANs will require the ability to extend the wireless LANs coverage without the need to deploy a very large number of access points. Mesh-based wireless LANs are an attractive solution to this problem. These networks extend wireless LAN coverage by using each node in the network as a router, resulting in a multihop topology. In this paper we introduce a novel routing algorithm, wireless mesh routing (WMR), that provides quality-of-service (QoS) support and accounts for the characteristics of both infrastructure-based wireless LANs and ad hoc networks. The algorithm is validated using the OPNET modeler. The simulation results show that the mesh network using WMR protocol can provide QoS support and react dynamically to the network status changes with low control overheads. Using the proposed software architecture the proposed routing protocol can be implemented with any MAC protocol, resulting in easy implementation in existing wireless nodes.     

Is the figural aftereffect an aftereffect? A review of its intensity, onset, decay, and transfer characteristics.

It has been shown how figural aftereffects might be generated by the lateral inhibitory effects of the inspection figure, in the manner of a simultaneous illusion. The present effort reviews some evidence suggesting that a figural aftereffect is a simultaneous illusion: (1) Varying the intensity of the inducing figure affects the simultaneous illusion and figural aftereffect in similar ways. (2) Temporal characteristics—onset and decay—of light adaptation, of afterimages, and of figural aftereffects are considered. It is shown that they obey similar empirical equations and that the constants in those equations have similar values. (3) The argument that the use of an interocular presentation of inducing and test figures eliminates the possible influence of afterimages is reviewed. It is concluded that figural aftereffects are very closely related to 3 visual phenomena: simultaneous contrast (the result of lateral inhibition), light and dark adaptation, and ocular tremor. (2 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)