On Automatic Reduction

Paper by John Alan Robinso

Acid Polishing of Lead Crystal Glass

The industrial partner manufactures high quality lead crystal glassware. The cutting of decorative features in the glass damages the surface and the cuts are optically opaque; to restore transparency, the glass is polished in a solution of hydrofluoric (HF) and sulphuric acid (H2 SO4 .) The polishing process comprises three stages: 1. immersion in a polishing tank containing acid; 2. rinsing in a tank containing water; and 3. settlement of the solid reaction products in a settlement tank. The manufacturer hopes to optimise its polishing process to • minimise the health/environmental impact of the process; • maximise throughput; • maintain the sharpness of the cut edges while still polishing to an acceptable level of transparency. The study group was asked to focus on modelling three aspects of the process: • the chemical reactions involved in the etching at the glass-acid solution interface; • the removal of reaction products in the settlement tank; • flow within the polishing tank

Structural role of Sfi1p–centrin filaments in budding yeast spindle pole body duplication

Centrins are calmodulin-like proteins present in centrosomes and yeast spindle pole bodies (SPBs) and have essential functions in their duplication. The Saccharomyces cerevisiae centrin, Cdc31p, binds Sfi1p on multiple conserved repeats; both proteins localize to the SPB half-bridge, where the new SPB is assembled. The crystal structures of Sfi1p–centrin complexes containing several repeats show Sfi1p as an α helix with centrins wrapped around each repeat and similar centrin–centrin contacts between each repeat. Electron microscopy (EM) shadowing of an Sfi1p–centrin complex with 15 Sfi1 repeats and 15 centrins bound showed filaments 60 nm long, compatible with all the Sfi1 repeats as a continuous α helix. Immuno-EM localization of the Sfi1p N and C termini showed Sfi1p–centrin filaments spanning the length of the half-bridge with the Sfi1p N terminus at the SPB. This suggests a model for SPB duplication where the half-bridge doubles in length by association of the Sfi1p C termini, thereby providing a new Sfi1p N terminus to initiate SPB assembly

SOCIAL SCIENCE COMPUTER REVIEW Robinson et al. / MASS MEDIA USE AND SOCIAL LIFE Mass Media Use and Social Life Among Internet Users

The mass media use and social life of heavy, light, and nonusers of the Internet and personal computers are compared based on a fall 1998 survey of 3,993 nationally representative respondents age 18 and older. As in previous surveys, no significant or consistent evidence of time displacement of such media or social activities was found. Indeed, Internet users showed signs of more active social lives than nonusers. These results reinforce the conclusion that personal computer/Internet use may have more in common with time-enhancing home appliances such as the telephone than they do with the timedisplacing technology of television. Keywords: Internet, personal computers, information technology, social impacts, time displacement, mass media use S ince the commercialization of the telegraph in the mid-19th century, telecommunications technology has gone through a series of transformations. Before the last decade, however, only two fundamentally distinct formats had crystallized. In the first format, we find a mode of switched, point-to-point, two-way communication, with capacity to initiate as well as reply; similar to personal face-to-face communication, it is also relatively equally dispersed. This produces a communication network with the distinctive structure of potential communications between any pair of points, without any central control. Switched, point-to-point communication was characteristic of the telegraph itself but is perhaps most clearly exemplified by the telephone. In contrast, the second broadcast format involves a unidirectional form of communication. Here, capacity to originate communication remains centralized, communication itself is not targeted to particular recipients, and capacity to receive communication is widely dispersed. Insofar as components of this format are arranged into a network capable of two-way communication, it is in the form of a central backbone linking originators of broadcasts; recipients of the broadcast are linked to one another only by their common receipt of a single message. Such highly centralized broadcast communication is characteristic of radio and cinema, but more prominently today of television

Surgery for Hilar cholangiocarcinoma: the Newcastle-upon-Tyne Liver Unit experience

Background: Hilar cholangiocarcinoma (HCCA) arises from the confluence of the common hepatic duct and has a poor prognosis. If resectable, an extended left (eLH) or right hemihepatectomy (eRH) is usually required to provide oncological clearance. We reviewed outcomes for patients with HCCA managed at our centre. Methods: Electronic records of patients referred to our centre for HCCA were retrospectively reviewed. The Kaplan–Meier method was used to estimate overall survival (OS) with the log rank test used for significance (p < 0.05). A Cox regression was performed to ascertain factors that may influence survival. Results: 156 HCCA patients were identified (44 resected versus 112 non-resected). Resected patients had longer OS compared to non-resected patients (50.3 versus 9.8 months, p < 0.001). Patients who underwent an eLH (n = 15) had significantly longer OS at 3 years compared to eRH patients (67.7 vs. 42.1%, respectively; p = 0.007). An eLH was an independent predictor of survival (HR 0.43, p = 0.04). Lymph node positivity (n = 23, hazard ratio 1.72, p = 0.027) and the presence of microvascular invasion (n = 28, hazard ratio 1.78, p = 0.047) were independent predictors of mortality. The frequency of lymph node positivity and microvascular invasion did not differ between eLH and eRH patients (p > 0.05). Conclusion: Patients undergoing an eLH for HCCA have significantly better long-term outcomes compared to those undergoing eRH, independent of other pathological variables. The functional liver remnant (FLR) is usually smaller following eRH, resulting in a higher risk of post-operative liver failure. Combining CT volumetry with PVE may result in better prediction and optimisation of the FLR in the context of eRH for HCCA. Novel findings: An extended left hemihepatectomy is an independent predictor of survival; investigation into the precise interaction between left- and right-sided resections and pre- and post-embolization liver volume is warranted

What the disjunctivist is right about

There is a traditional conception of sensory experience on which the experiences one has looking at, say, a cat could be had by someone merely hallucinating a cat. Disjunctivists take issue with this conception on the grounds that it does not enable us to understand how perceptual knowledge is possible. In particular, they think, it does not explain how it can be that experiences gained in perception enable us to be in ‘cognitive contact’ with objects and facts. I develop this chal- lenge to the traditional conception and then show that it is possible to accommo- date an adequate account of cognitive contact in keeping with the traditional conception. One upshot of the discussion is that experiences do not bear the explanatory burden placed upon them by disjunctivists

Ozone loss derived from balloon-borne tracer measurements and the SLIMCAT CTM

Balloon-borne measurements of CFC-11 (on flights of the DIRAC in situ gas chromatograph and the DESCARTES grab sampler), ClO and O3 were made during the 1999/2000 winter as part of the SOLVE-THESEO 2000 campaign. Here we present the CFC-11 data from nine flights and compare them first with data from other instruments which flew during the campaign and then with the vertical distributions calculated by the SLIMCAT 3-D CTM. We calculate ozone loss inside the Arctic vortex between late January and early March using the relation between CFC-11 and O3 measured on the flights, the peak ozone loss (1200 ppbv) occurs in the 440–470 K region in early March in reasonable agreement with other published empirical estimates. There is also a good agreement between ozone losses derived from three independent balloon tracer data sets used here. The magnitude and vertical distribution of the loss derived from the measurements is in good agreement with the loss calculated from SLIMCAT over Kiruna for the same days