Impact of major changes in flow regime on the macroinvertebrate assemblages of four chalk stream sites, 1997–2001

The macroinvertebrate assemblages of three unshaded sites on the River Kennet and one shaded site on the River Lambourn in Berkshire, England, were sampled in summer 1997–2001. Quantitative samples were taken on gravel and on the dominant macrophyte at each site in each year and abundance data were recorded for 57 families of macroinvertebrates. The study commenced during a major drought (1997), but in subsequent years discharge prior to sampling was much higher, culminating in the exceptionally high flows of spring 2001. Both family richness and abundance varied significantly in relation to site, habitat and year. Multidimensional scaling ordination, based on Bray‐Curtis dissimilarities, also displayed significant differences between sites, habitats and years. Differences in composition between the Kennet sites were partly due to longitudinal zonation whilst on the Lambourn, faunal differences resulted from shading and the addition of families from nearby habitats, including marginal vegetation. Major changes took place in family composition and abundance between the drought year of 1997 and 1998, indicating that faunal recovery from drought was rapid. Thereafter, faunal changes between 1998 and 2000 were relatively limited. In 2001, following the prolonged period of exceptionally high discharge, overall family richness peaked on both habitats at the three Kennet sites and family abundance reached peak or second highest values on all four sites and both habitats. Thus, the recent high discharge regimes experienced by these perennial chalk stream sites have had no immediate detrimental consequences for the macroinvertebrate assemblages. Copyright © 2004 John Wiley & Sons, Ltd.     

Overview and performance of CCITT/ANSI embedded ADPCM algorithms

Embedded adaptive differential pulse coded modulation (ADPCM) algorithms quantize the differences between the input signal and the estimated signal into core bits and enhancement bits. CCITT Recommendation G.727, which describes embedded ADPCM encoding algorithms with 5, 4, 3, and 2 core bits, is virtually identical to the corresponding ANSI standard T1.310. The main features of G.727 and T1.310 and performance results are presented. A formal subjective evaluation of the speech performance of embedded ADPCM algorithms indicates that a midrise quantizer provides better voice transmission performance than its midtread counterpart when two core bits are used. The subjective data also show that the performance of the 40-kb/s midrise ADPCM algorithm with two feedback bits is indistinguishable from that of 64-kb/s pulse code modulation (PCM) for up to four tandem encodings. Embedded algorithms are therefore recommended for flexible congestion control of integrated traffic in multinode networks     

The Selective Oxidation of Methanol to Formaldehyde on Iron Molybdate Catalysts and on Component Oxides

The reaction of methanol with an industrial iron molybdate catalyst, and with Fe₂O₃ and with MoO₃, has been investigated with a pulsed flow reactor and temperature-programmed desorption (TPD). The molybdena-based samples show only formaldehyde in TPD as the carbon-containing product, arising from the decomposition of a surface methoxy species. In contrast, haematite yields no formaldehyde, only CO₂ and H₂, which evolve coincidently at 290 °C, and indicates the presence of a formate intermediate on the surface. In turn, the reactor work shows high selectivity to formaldehyde for the molybdate materials and zero for haematite. The iron molybdate sample is more active than the molybdena, conversion beginning at 150 °C for the former and 270 °C for the latter. These data are discussed in terms of a global mechanism for the reaction and a tentative reaction enthalpy profile is proposed. The main differences between the iron and molybdenum samples arise from the stronger binding of oxygen in the former and the higher concentration of cation sites.     

The Manchester heritage

The wider historical and scientific context of the development of computing at the University of Manchester, focusing on the relationship between the University and industry, is described. The role of the National Archive for the History of Computing in preserving this heritage is discussed     

Information ecology: open system environment for data, memories, and knowing

An information ecology provides a conceptual framework to consider data, the creation of knowledge, and the flow of information within a multidimensional context. This paper, reporting on a 1 year project to study the heterogeneity of information and its management within the Long Term Ecological Research (LTER) community, presents some manifestations of traditionally unreported ‘invisible work’ and associated elements of informal knowledge and unarticulated information. We draw from a range of ethnographic materials to understand ways in which data-information-knowledge are viewed within the community and consider some of the non-linear aspects of data-knowledge-information that relate to the development of a sustained, robust, persistent infrastructure for data collection in environmental science research. Taking data as the unit of study, the notion of long-term research and data holdings leads to consideration of types of memory and of knowledge important for design of cyberinfrastructures. Complexity, ambiguity, and nonlinearity are part of an information ecology and addressed today by exploring multiple types of knowledge, developing information system vocabularies, and recognizing the need for intermediation.     

Alterations in the sarcoplasmic protein fraction of beef muscle with postmortem aging and hydrodynamic pressure processing

Abstract: Capillary electrophoresis (CE) and reversed‐phase high performance liquid chromatography (RP‐HPLC) analyses were utilized to detect differences in the sarcoplasmic protein fractions of beef strip loins subjected to aging and hydrodynamic pressure processing (HDP) treatments. At 48 h postmortem, strip loins (n= 12) were halved and subjected to control or HDP treatments. Following treatment, each half was divided into 3 portions which were aged for 0, 5, and 8 d. After each aging period, steaks were removed for Warner–Bratzler shear force (WBSF) analysis and for the extraction of sarcoplasmic proteins which were analyzed by CE and RP‐HPLC. Aging by HDP interactions were not detected using either separation technique. With CE analysis, no HDP effects were observed; however, the relative peak area of 8 protein peaks ranging in size from 17 to >200 kDa were influenced by postmortem aging. Separation of proteins by RP‐HPLC demonstrated that HDP influenced the relative size of 2 protein peaks while postmortem aging effects were observed in 6 peaks. Alterations in the sarcoplasmic protein fractions detected by both CE and RP‐HPLC were correlated to WBSF measurements. Overall, data demonstrate that HDP has minimal effects on sarcoplasmic proteins and that aging related changes in the water soluble protein fractions of muscle may be useful as indirect indicators of beef tenderness. Practical Application: Using 2 different postmortem tenderization techniques, aging and hydrodynamic pressure processing, this study demonstrates that postmortem changes in the soluble protein fraction of beef may be useful as potential indicators of meat tenderness.     

Method of isolation, rate of postmortem metabolism, and myosin heavy chain isoform composition influence ATPase activity of isolated porcine myofibrils

The objective of this study was to determine the influence of myofibril isolation procedures and myosin heavy chain (MyHC) isoform composition on myofibrillar ATPase activity as related to postmortem muscle metabolism. Myofibrils from the red (RST) and white (WST) portions of semitendinosus muscles were isolated using two different methods (A and B) at 3 min and 24 h postmortem in control (NS) and electrically stimulated (ES) pork carcasses. Comparison of the relative MyHC isoform profiles between the two different myofibril isolation methods and myosin extracts from the RST and WST at 3 min showed that method B myofibrils were more similar to the myosin extract than method A. Myofibrillar ATPase activity remained constant or increased (P<0.01) from 3 min to 24 h postmortem in NS carcasses and decreased (P<0.0001) in ES carcasses. From the RST, method A myofibrils had higher (P<0.0001) ATPase activity compared to method B across sampling time and carcass treatment. In the WST, method A myofibrils had lower (P<0.01) activity at 3 min, were not different at 24 h in NS carcasses, but had higher (P<0.05) activity at 24 h in ES carcasses versus method B myofibrils. Compared to method B, isolation method A biased the isoform profile of myofibril samples more towards faster MyHC (2A and 2X) in the RST and towards MyHC 2X in the WST. Results suggest that the ATPase activity and MyHC isoform profile of isolated myofibril samples are influenced by method of myofibril isolation, postmortem sampling time, and the rate of postmortem metabolism. Thus, differences in MyHC isoform profile and method of myofibril isolation must be taken into account to determine accurately the relationship between myofibrillar ATPase activity and rate of postmortem metabolism.