Performance analysis of a register insertion ring with a variable size buffer

There has been a recent revival of interest in the register insertion (RI) protocol because of its high throughput and low delay characteristics. Several variants of the protocol have been investigated with a view to integrating voice and data applications on a single local area network (LAN). In this paper the performance of an RI ring with a variable size buffer is studied by modelling and simulation. The chief advantage of the proposed scheme is that an efficient but simple bandwidth allocation scheme is easily incorporated. Approximate formulas are derived for queue lengths, queueing times, and total end-to-end transfer delays. The results are compared with previous analyses and with simulation estimates. The effectiveness of the proposed protocol in ensuring fairness of access under conditions of heavy and unequal loading is investigated.

Examining the effect of exit separation on aircraft evacuation performance during 90-second certification trials using evacuation modelling techniques

This paper examines the influence of exit separation, exit availability and seating configuration on aircraft evacuation efficiency and evacuation time. The purpose of this analysis is to explore how these parameters influence the 60-foot exit separation requirement found in aircraft certification rules. The analysis makes use of the airEXODUS evacuation model and is based on a typical wide-body aircraft cabin section involving two pairs of Type-A exits located at either end of the section with a maximum permissible loading of 220 passengers located between the exits. The analysis reveals that there is a complex relationship between exit separation and evacuation efficiency. A main finding of this work is that for the cabin section examined, with a maximum passenger load of 220 and under certification conditions, exit separations up to 170ft will result in approximately constant total evacuation times and average personal evacuation times. This practical exit separation threshold is decreased to 114ft if another combination of exits is selected. While other factors must also be considered when determining maximum allowable exit separations, these results suggest it is not possible to mandate a maximum exit separation without taking into consideration exit type, exit availability and aircraft configuration.

Issues in second language proficiency

Benati provides clarity about the characteristics and notion of language proficiency in the field of second language acquisition. He looks at four areas of research paradigmatically related to the role of proficiency: theorizing and measuring second language proficiency; the dimensions of L2 proficiency; factors contributing to the attainment of L2 proficiency and attaining L2 proficiency in the classroom. It also contains a variety of research accounts about the specific factors which have an effect on proficiency together with a theorised measurement of proficiency in second language research. It will be required reading for researchers in applied linguistics and second language acquisition.

Key terms in second language acquisition

Key Terms in Second Language Acquisition includes definitions of key terms within second language acquisition, and also provides accessible summaries of the key issues within this complex area of study. The final section presents a list of key readings in second language acquisition that signposts the reader towards classic articles and also provides a springboard to further study.

[Book Review] The role of formal features in second language acquisition - edited by J. Liceras, H. Zobl, and H. Goodluck

Book review of: J. Liceras, H. Zobl, and H. Goodluck (eds.), 2008, The Role of Formal Features in Second Language Acquisition. London/New York: Lawrence Erlbaum Associates, 577 pages, ISBN: 0-8058-5354-5.

Second language processing: an analysis of theory, problems and possible solutions

Second Language Processing examines the problems facing learners in the second language classroom from the theoretical perspectives of Processing Instruction (structured input) and Enhanced Input. These two theories are brought to bear on a variety of processing problems, such as the difficulty of connecting second language grammatical forms encoding tense and mood as well as noun-adjective agreement with their meaning. Empirical studies examine a range of languages including Japanese, Italian and Spanish, through which the authors suggest practical solutions to these processing problems.

Low temperature crystal structures of two rhodanine derivatives, 3-amino rhodanine and 3-methyl rhodanine: geometry of the rhodanine ring

Rhodanines (2-thio-4-oxothiazolidines) are synthetic small molecular weight organic molecules with diverse applications in biochemistry, medicinal chemistry, photochemistry, coordination chemistry and industry. The X-ray crystal structure determination of two rhodanine derivatives, namely (I), 3-aminorhodanine [3-amino-2-thio-4-oxothiazolidine], C3H4N2OS2, and (II) 3-methylrhodanine [3-methyl-2-thio-4-oxothiazolidine], C4H5NOS2, have been conducted at 100 K. I crystallizes in the monoclinic space group P2(1)/n with unit cell parameters a = 9.662(2), b = 9.234(2), c = 13.384(2) angstrom, beta = 105.425(3)degrees, V = 1151.1(3) angstrom(3), Z = 8 (2 independent molecules per asymmetric unit), density (calculated) = 1.710 mg/m(3), absorption coefficient = 0.815 mm(-1). II crystallizes in the orthorhombic space group Iba2 with unit cell a = 20.117(4), b = 23.449(5), c = 7.852(2) angstrom, V = 3703.9(12) angstrom(3), Z = 24 (three independent molecules per asymmetric unit), density (calculated) = 1.584 mg/m(3), absorption coefficient 0.755 mm(-1). For I in the final refinement cycle the data/restraints/parameter ratios were 2639/0/161, goodness-of-fit on F-2 = 0.934, final R indices [I > 2sigma(I)] were R1 = 0.0299, wR2 = 0.0545 and R indices (all data) R1 = 0.0399, wR2 = 0.0568. The largest difference peak and hole were 0.402 and -0.259 e angstrom(-3). For II in the final refinement cycle the data/restraints/parameter ratios were 3372/1/221, goodness-of-fit on F(2) = 0.950, final R indices [I > 2sigma(I)] were R1 = 0.0407, wR2 = 0.1048 and R indices (all data) R1 = 0.0450, wR2 = 0.1088. The absolute structure parameter = 0.19(9) and largest difference peak and hole 0.934 and -0.301 e angstrom(-3). Details of the geometry of the five molecules (two for I and three for II) and the crystal structures are fully discussed. Corresponding features of the molecular geometry are highly consistent and firmly establish the geometry of the rhodanine

Twentieth Century Society Spring lecture series: second lives for Twentieth Century masterpieces

The Twentieth Century Society’s Spring lecture series (six in total) looks at the restoration and refurbishment of key C20 buildings in Britain and the US. Buildings covered: BBC Broadcasting House in London (G Val Meyer 1930-32, MacCormac Jamieson Prichard 2000-09). Speaker: Mark Hines (Mark Hines Architects), was the project architect and is the author of The Story of Broadcasting House: Home of the BBC. 5 February 2009. Crown Hall, Chicago (Mies van der Rohe 1952), the Art and Architecture Building, Yale University, New Haven (Paul Rudolf 1961-63) and the former Wills head office in Bristol (SOM with YRM 1970-75). Speaker: Patrick Bellew (Atelier 10 Engineers), 12 February 2009. Center for British Art, Yale University, New Haven (Louis Kahn 1969-77). Speaker: Peter Inskip (Inskip and Jenkins Architects), 17 February 2009. Brunswick Centre London (Patrick Hodgkinson 1967-72; Levitt Bernstein with Patrick Hodgkinson 2006). Speaker: Stuart Tappin (Stand Consulting Engineers Ltd), 26 February 2009. De La Warr Pavilion, Bexhill-on-Sea (Mendelsohn and Chermayeff 1934-5, John McAslan and Partners 2000-05). Speaker: Mark Cannata (HOK Architects), 5 March 2009. Finsbury Health Centre London (Lubetkin & Tecton 1938, first phase of conservation work Avanti Architects 1995.). Speaker: John Allan of Avanti Architects, 12 March 2009.

Second site

An exhibition by four artists from Roma/Gypsy/Traveller communities. [From the press release]