PrimeTime: A Finite-Time Consensus Protocol for Open Networks

In distributed problems where consensus between agents is required but average consensus is not desired, it can be necessary for each agent to know not only the data of each other agent in the network, but also the origin of each piece of data before consensus can be reached. However, transmitting large tables of data with IDs can cause the size of an agent's message to increase dramatically, while truncating down to fewer pieces of data to keep the message size small can lead to problems with the speed of achieving consensus. Also, many existing consensus protocols are not robust against agents leaving and entering the network. We introduce PrimeTime, a novel communication protocol that exploits the properties of prime numbers to quickly and efficiently share small integer data across an open network. For sufficiently small networks or small integer data, we show that messages formed by PrimeTime require fewer bits than messages formed by simply tabularizing the data and IDs to be transmitted

Dispelling the myths of online education: learning via the information superhighway

There continues to be a perception that online education is inferior to traditional education. In the U.S. online learning is more developed than in the U.K. This paper provides insights into a U.S. provision and takes a close look at what are perceived as weaknesses of on line learning and argues that these are not necessarily inherent weaknesses of this form of educational delivery. Then, results of two major studies, undertaken in the U.S. are provided comparing the effectiveness of online education to traditional education as perceived by current MBA students and past graduates. Results of these studies suggest that students of MBA modules and MBA graduates perceive the quality and effectiveness of online education to be similar to, if not higher than, the quality and effectiveness of traditional modules and programmes

The time-dependent rearrangement of the epithelial basement membrane in human skin wounds

In 62 human skin wounds (surgical wounds, stab wounds and lacerations after surgical treatment) we analyzed the immunohistochemical localization of collagen IV in the epithelial basement membrane. In 27 of these wounds the distribution of collagen VII, which represents a specific component of the basement membrane of stratified epithelia, was also analyzed. We were able to demonstrate a virtually identical co-distribution of both collagen IV and VII in the wound area with no significant time-dependent differences in the appearance of both collagen types. Fragments of the epithelial basement membrane could be detected in the wound area from as early as 4 days after wounding and after 8 days a complete restitution of the epithelial basement membrane was observed. In all cases with a wound age of more than 21 days the basement membrane was completely reformed over the former lesional area. The period between 8 and 21 days after wounding was characterized by a wide variability ranging from complete restitution to deposition of basement membrane fragments or total lack of the epidermal basement membrane

Expression of type I collagen mRNA in glomeruli of rats with passive Heymann nephritis

Expression of type I collagen mRNA in glomeruli of rats with passive Heymann nephritis. In passive Heymann nephritis (PHN) glomeruli exhibit marked basement membrane expansion around subepithelial immune deposits but they fail to show any change in mRNA levels of type IV collagen, laminin or fibronectin by Northern and slot-blot analysis, or in the amount or distribution of type IV collagen or laminin by immunohistology for up to 12 weeks after disease onset. On the other hand, in situ hybridization (ISH) revealed the appearance of positive cells exhibiting mRNA for the α1 chain of rat type I collagen two to three weeks after the onset of PHN in all glomeruli of all rats. Positive cells persisted for at least eight weeks. In many glomeruli, the location of the clusters of silver grains suggested that they were in visceral epithelial cells. In controls injected with normal sheep IgG, and in early PHN (<11 days after sheep anti-Fx1A), glomeruli were negative but cells in the renal capsule and adventitia of vessels showed strong ISH and served as positive controls. RNAse pre-treatment and the “sense” probe gave appropriately negative results. RNA from PHN glomeruli contained an α1 type I collagen transcript of the same size as that from rat fibroblasts. These results show that the evolution of glomerular basement membrane expansion in rat membranous nephropathy coincides with the induction of a matrix gene that is not normally expressed in glomerular cells. Further, they suggest that the intercalation of ectopically-expressed matrix molecules may contribute to the production of a disorganized basement membrane

Selection of ground motion prediction equations for the global earthquake model

Ground motion prediction equations (GMPEs) relate ground motion intensity measures to variables describing earthquake source, path, and site effects. From many available GMPEs, we select those models recommended for use in seismic hazard assessments in the Global Earthquake Model. We present a GMPE selection procedure that evaluates multidimensional ground motion trends (e.g., with respect to magnitude, distance, and structural period), examines functional forms, and evaluates published quantitative tests of GMPE performance against independent data. Our recommendations include: four models, based principally on simulations, for stable continental regions; three empirical models for interface and in-slab subduction zone events; and three empirical models for active shallow crustal regions. To approximately incorporate epistemic uncertainties, the selection process accounts for alternate representations of key GMPE attributes, such as the rate of distance attenuation, which are defensible from available data. Recommended models for each domain will change over time as additional GMPEs are developed

Books

Current Ocular Therapy. Ed. by F. T. Fraunfelder, F. Hampton Roy and S. Martha Meyer. Pp. xiii + 792. Illustrated. £55. Nonhmead: WB Saunders. 1989.Dysfunctional Uterine Bleeding and Menorrhagia. Bailliere's Clinical Obstetrics and Gynaecolcgy: International Practice and Research, June 1989. Ed. by J. O. Drife. Pp. 217 + 428. Illustrated. £18,50. Northmead: WE Saunders.1989.Treatment of Cancer. 2nd ed. Ed. by Karol Sikora and Keith E. Halnan. Pp. ix + 916. Illustrated. Price £99,50. London: Chapman and Hall Medical. 1990.Ocular Syndromes and Systemic Diseases. 2nd edition. Ed. by F. Hampton Roy. Pp. xlvii + 470. £40. Northmead: WE Saunders. 1989.Non-invasive Cardiac Imaging. British Medical Bulletin. Vol. 45, No. 4. Ed. by D. G. Gibson. Pp. 830 + 1109. Illustrated. £25 (UK) or £31,50 (overseas). New York: Churchill Livingstone. 1989.Laparoscopic Surgery. Bailliere's Clinical Obstetrics and Gynaecology: International Practice and Research, September 1989. Ed. by C. J. G. Sunon. Pp. 429 + 686. Illustrated. £18,50. Northmead: WB Saunders. 1989.Management ofMinor Head Injuries. Ed. by I. J. Swann and D. W. Yates. Pp. x + 102. Illustrated: £14,95. Hampshire: Chapman &amp; Hall Medical. 1989.ABC of Child Abuse. Ed. by Roy Meadow. Pp. 59. Illustrated. London: BMJ. 1989.The Facts of Life. Ed. by Marina Petropulos. Pp. 1 + 222. Illustrated. R19,95 exc!. GST. Cape Town: Tafelberg. 1990.Physical Examination of the Heart and Circulation. 2nd ed. Ed. by Joseph K. Perloff. Pp. viii + 292. Illustrated. £17,95. Northmead: WB Saunders. 1989.Growth Regulation of Thyroid Gland and Thyroid Tumours: Frontiers ofHormone Research. Vo!. 18. Ed. by P. E. Goretzki, and H. D. Roher. Pp. viii + 163. Illustrated. £68,80. Basel: S. Karger. 1989.Topical Diagnosis in Neurology: Anatomy, Physiology, Signs, Symptoms. 2nd revised ed. Ed. by P. Duus. Pp. x + 337. Illustrated. DM 370. Stungart: Georg Thieme Verlag. 1989

Atomistic modelling of large-scale metal film growth fronts

We present simulations of metallization morphologies under ionized sputter deposition conditions, obtained by a new theoretical approach. By means of molecular dynamics simulations using a carefully designed interaction potential, we analyze the surface adsorption, reflection, and etching reactions taking place during Al physical vapor deposition, and calculate their relative probability. These probabilities are then employed in a feature-scale cellular-automaton simulator, which produces calculated film morphologies in excellent agreement with scanning-electron-microscopy data on ionized sputter deposition.Comment: RevTeX 4 pages, 2 figure

Rapid and Repeatable Shifts in Life-History Timing of \u3ci\u3eRhagoletis pomonella\u3c/i\u3e (Diptera: Tephritidae) Following Colonization of Novel Host Plants in the Pacific Northwestern United States

Host shifts of phytophagous insect specialists to novel plants can result in divergent ecological adaptation, generating reproductive isolation and potentially new species. Rhagoletis pomonellafruit flies in eastern North America underwent a host shift ~160 ya from native downy hawthorn (Crataegus mollis) to introduced, domesticated apple (Malus domestica). Divergent selection on diapause phenology related to the earlier fruiting time of apples versus downy hawthorns resulted in partial allochronic reproductive isolation between the fly races. Here, we test for how rapid and repeatable shifts in life-history timing are driving ecological divergence of R. pomonella in the Pacific Northwestern USA. The fly was introduced into the region via larval-infested apples 40–65 ya and now attacks native black hawthorn (Crataegus douglasii) and introduced ornamental hawthorn (Crataegus monogyna), in addition to early- and late-maturing apple varieties in the region. To investigate the life-history timing hypothesis, we used a field-based experiment to characterize the host-associated eclosion and flight activity patterns of adults, and the feeding times of larvae at a field site in Vancouver, Washington. We also assessed the degree to which differences in host-fruiting time generate allochronic isolation among apple-, black hawthorn-, and ornamental hawthorn-associated fly populations. We conclude that host-associated fly populations are temporally offset 24.4% to 92.6% in their seasonal distributions. Our results imply that R. pomonella possesses the capacity for rapid and repeatable shifts in diapause life history to match host-fruiting phenology, which can generate ecologically based reproductive isolation, and potentially biodiversity in the process