Russell Ackoff's Jerusalem

This brief article looks at the influence of russ Ackoff's work, using as a focus of attention a maxim of the poet and philosopher William Blake. In particular, it considers Ackoff s contribution to the development of community operational research.     

Euler's invention of integral transforms

Euler invented integral transforms in the context of second order differential equations. He used them in a fragment published in 1763 and in a chapter of Institutiones Calculi Integralis (1769). In introducing them he made use of earlier work in which a concept akin to the integral transform is implicit. It would, however, be reading too much into that earlier work to see it as contributing to the theory of the integral transform. Other work sometimes cited in this context in fact has different concerns.     

犹大·福克曼(1933～2008)——记科学家、外科医生和血管生成领域的开拓者

犹大·福克曼(Judah Folkman)常说:"科学在于你如何想象它"(Science goes where you imagine it).确实,很少有人能像福克曼那样在科学领域如此大胆想象.     

在面向实践的软件工程课程中锻造学生素质:来自实习教学的经验

Students who participate in industry placement as part of their software engineering curriculum gain knowledge that could never be taught to them in a class room.The knowledge and experience they learn allows them to focus and sharpen their skills in areas that industry craves expertise.The School of Computing in Dublin Institute of Technology provides the opportunity to students to gain industry experience with leading multi-national IT companies and this enables them to learn key transferable skills to satisfy the desired requirements in a knowledge-based economy.     

Forecasting high‐frequency financial data with the ARFIMA–ARCH model

Financial data series are often described as exhibiting two non‐standard time series features. First, variance often changes over time, with alternating phases of high and low volatility. Such behaviour is well captured by ARCH models. Second, long memory may cause a slower decay of the autocorrelation function than would be implied by ARMA models. Fractionally integrated models have been offered as explanations. Recently, the ARFIMA–ARCH model class has been suggested as a way of coping with both phenomena simultaneously. For estimation we implement the bias correction of Cox and Reid ( 1987 ). For daily data on the Swiss 1‐month Euromarket interest rate during the period 1986–1989, the ARFIMA–ARCH (5,d,2/4) model with non‐integer d is selected by AIC. Model‐based out‐of‐sample forecasts for the mean are better than predictions based on conditionally homoscedastic white noise only for longer horizons (τ > 40). Regarding volatility forecasts, however, the selected ARFIMA–ARCH models dominate. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects of rangefire on soil algal crusts in semiarid shrub-steppe of the Lower Columbia Basin and their subsequent recovery

Effects of rangefire on soil algae in sagebrush steppe in the Lower Columbia Basin were studied. Dynamics of recovery of the soil algal community in the first two years following the fire were also documented. The study site was on the Arid Lands Ecology Reserve managed by Battelle Pacific Northwest Laboratory. Fire decreased the numbers of algae by more than an order of magnitude. Species composition in burned plots was similar to that in unburned plots, although some cyanophyte algae, particularly Nostoc commune , were decimated by the fire. Algal recovery took place in the winter months of the second year. Ninety taxa of algae were identified during the course of the study, over half of which were chlorophytes. Seasonal changes in the algal flora were also noted.     

Reproductive ecology of bison on Antelope Island, Utah

Autumn musters of bison ( Bison bison ) on Antelope Island State Park, Utah, conducted annually since 1987, provided data on temporal and age-specific reproductive patterns and a basis to evaluate the efficacy of management measures implemented to elevate reproductive performance in the herd. Pregnancy rates were variable and low ( x = 46.2%) in comparison to other free-ranging, noncommercial bison herds in North America. Cows in the 3- and > 6-yr range age classes exhibited lower-than-expected pregnancy rates ( P r = 0.64, P = 0.047) linear decline of 2.5% per annum. Variance in distribution of fetal ages observed in 6 yr indicates substantial temporal fluctuation. Long-term reproductive performance of cohorts born prior to implementation of management measures did not differ from that of cohorts born subsequent to these changes.