bluuebunny/crossref_metadata_2025 huggingface dataset:
Acceptability of flexible sigmoidoscopy screening in older adults in the United Kingdom
Authors: Taylor T. , Williamson S. , Wardle J. , Borrill J. , Sutton S. , Atkin W.
Published: October 2002

Objectives To assess the acceptability of bowel cancer screening using flexible sigmoidoscopy (FS).

Setting Adults aged 55 to 64 recruited from general practices in Welwyn Garden City and Leicester, which were the pilot and start up centres of a multicentred randomised controlled trial of FS screening (the ICRF/MRC Flexible Sigmoidoscopy Screening Trial).

Methods Screenees (n=4422) were sent a three month follow up questionnaire that included measures of satisfaction with information given before the test, facilities at the test unit, attitudes of the staff, and explanation of the results. Measures of pain, embarrassment, feelings of being “in control” during the test, willingness to encourage others to have the test, and gladness to have participated were also included. In addition, semistructured telephone interviews were conducted with 60 screenees, stratified by screening outcome and gender.

Results The follow up questionnaire was completed by 94% of screenees. Responses indicated a high level of satisfaction with the procedure: 99% were satisfied with the information given before the test, the facilities, the attitudes of the staff, and the explanation of their results; 91% reported only mild or no pain; 97% reported little or no embarrassment; and 99% were glad they had the test. Satisfaction ratings varied little by gender or outcome group. The quantitative results were reinforced by the qualitative data, which also revealed high acceptability.

Conclusion In the context of a clinical trial with dedicated trial staff, FS is a well tolerated procedure. There are high levels of satisfaction with service provision and positive attitudes towards the programme.
The effect of varying the screening interval on false positives and duration of undiagnosed disease in a screening programme for type 2 diabetes
Authors: Park P.J. , Griffin S.J. , Duffy S.W. , Wareham N.J.
Published: October 2002

Objectives The aims of this study were to quantify the proportion of people diagnosed as having type 2 diabetes by standard 75 g oral glucose tolerance test, in a hypothetical screening programme, who would actually be false positives (false positive percentage), and the effect on the false positive percentage of varying the time between repeat screens. We also calculated the duration in person years of exposure to undiagnosed disease in the population for each screening interval.

Setting Ely, Cambridgeshire, UK.

Methods We used the glucose tolerance data from 965 participants of the Ely Diabetes Project, who were tested 4.5 years apart, to calculate the population's between and within person variance for 2 hour plasma glucose, and constructed a probability matrix of observed v true glucose tolerance categories. The progression of the population between glucose tolerance categories was modelled assuming exponential times to progression.

Results After one year, 47.5% of test positives were disease free: almost half of those labelled with diabetes would not have the disease. For a 5 year interval, the false positive percentage was 27.6%, but the population would have been exposed to undiagnosed diabetes for 144 person years.

Conclusions Screening can be associated with both benefit and harm; the balance is dependent on characteristics of the disease and the screening programme. This study has quantified the trade off between exposure to undiagnosed diabetes and false positive results to inform the debate about screening for type 2 diabetes.
Does individual programme size affect screening performance? Results from the United Kingdom NHS breast screening programme
Authors: Blanks R.G. , Bennett R.L. , Wallis M.G. , Moss S.M.
Published: October 2002

Objective: The size (number of women screened) of the 95 individual NHS breast screening programmes (NHSBSPs) varies by a factor of 10. This study investigates the impact of size on the performance of individual programmes. Method: Data were collated from the 95 United Kingdom screening programmes on the standard statistical returns for the past 5 years (1 April 1995–31 March 2000). Additional information was obtained from questionnaires. The number of women screened between 1 April 1999 and 31 March 2000 determined the size of a programme. The bottom 25% were defined as small, the middle 50% as medium, and the top 25% as large. On average large programmes screened about four times as many women as small programmes and medium programmes about twice as many. Performance was evaluated using cancer detection rates, referral rates for assessment, and positive predictive value (PPV) of assessment using PPV referral diagrams. Results: The performance of smaller programmes was shown to be marginally poorer than medium and large sized programmes in that they detected fewer cancers and had a lower PPV. The smallest 25% of programmes had an invasive cancer detection rate 13% less than the medium and large programmes. However, if these programmes had an equivalent detection rate to the medium/large programmes the national detection rate would only increase by about 2%. This is because the 75% of programmes described as medium and large screen about 90% of all women. It is therefore important to place the clinical importance of these findings in context when considering any envisaged possible solutions. Conclusions: Although the performance of smaller programmes was shown to be poorer than that of the larger programmes, it is not clear from this study exactly why this is so. A likely contributory factor based on experience of evaluating the NHSBSP is that performance problems in larger programmes have been easier to detect by quality assurance staff. The size of the small programmes and the few screen detected cancers (and inherent statistical instability in detection rates) mean that problems are difficult to identify. As a consequence small programmes which are genuinely performing marginally below specific standards are likely to receive less attention than larger programmes, and even under close scrutiny the causes are less likely to be found.
Prevalence and risk factors of work related asthma by industry among United States workers: data from the third national health and nutrition examination survey (1988–94)
Authors: Arif A A , Whitehead L W , Delclos G L , Tortolero S R , Lee E S
Published: October 2002

Objectives:To estimate the prevalence of work related asthma and work related wheezing in United States workers. To identify high risk industries that could be targeted for future intervention. To determine the population attributable risk of work related asthma and work related wheezing.

Methods:The third national health and nutrition examination survey, 1988–1994 (NHANES III) was analyzed to determine the prevalence of work related asthma and wheezing and to identify initially defined industries at risk among United States workers aged 20 and older. Separate logistic models were developed with work related asthma and work related wheezing as outcomes. Work related asthma was defined as affirmative response to questions on self reported physician diagnosed asthma and work related symptoms of rhinitis, conjunctivitis, and asthma. Work related wheezing was defined as affirmative response to questions on self reported wheezing or whistling in the chest in the previous 12 months and work related symptoms of rhinitis, conjunctivitis, and asthma. All analyses were adjusted for age, sex, smoking, and atopy.

Results:The prevalence of work related asthma was 3.70% (95% confidence interval (95% CI) 2.88 to 4.52) and the prevalence of work related wheezing was 11.46% (95% CI 9.87 to 13.05). The main industries identified at risk of work related asthma and wheeze included the entertainment industry; agriculture, forestry, and fishing; construction; electrical machinery; repair services; and lodging places. The population attributable risk for work related asthma was 36.5% and work related wheezing was 28.5%.

Conclusions:The findings provide impetus for further research and actions by public health professionals which prioritise occupational asthma on the public health agenda. Future intervention strategies need to be developed for effective control and prevention of asthma in the workplace.
Sensitivity of Ulocladium atrum, Coniothyrium minitans, and Sclerotinia sclerotiorum to benomyl and vinclozolin
Authors: Li G Q , Huang H C , Acharya S N
Published: October 2002

Assays on mycelial growth and spore germination were carried out to determine the sensitivity of the biocontrol agents Ulocladium atrum and Coniothyrium minitans and the plant pathogen Sclerotinia sclerotiorum to benomyl and vinclozolin. Ulocladium atrum was more tolerant to these fungicides than C. minitans and S. sclerotiorum. The 50% effective concentration (EC50) of U. atrum based on the mycelial growth inhibition was 1467.3 µg active ingredient (a.i.)/mL for benomyl and 12.6 µg a.i./mL for vinclozolin, and the maximum inhibition concentration was higher than 4000 µg a.i./mL for both fungicides. For C. minitans and S. sclerotiorum, however, the EC50 based on mycelial growth inhibition was lower than 1 µg a.i./mL. After incubation for 24 h at 20°C, the germination rate of U. atrum conidia was 9099% on potato dextrose agar (PDA) amended with benomyl at 100500 µg a.i./mL or vinclozolin at 10500 µg a.i./mL. At these concentrations, germ tubes of U. atrum developed into long, branched hyphae in benomyl treatments, but they remained short and clustered in vinclozolin treatments. Pycnidiospores of C. minitans and ascospores of S. sclerotiorum germinated on PDA amended with benomyl at 100500 µg a.i./mL, but the germ tubes did not grow further. Spore germination of C. minitans and S. sclerotiorum was less than 3.2% on PDA amended with vinclozolin at 10500 µg a.i./mL after 24 h. This is the first report on the sensitivity of U. atrum and C. minitans to benomyl and vinclozolin. The results suggest that it is possible to control S. sclerotiorum using a combination of U. atrum and benomyl or vinclozolin.Key words: fungicides, mycelial growth, spore germination, integrated pest management.
Inter-parent distance affects reproductive success in two clonal dwarf shrubs,Vaccinium myrtillusandVaccinium vitis-idaea(Ericaceae)
Authors: Nuortila Carolin , Tuomi Juha , Laine Kari
Published: October 2002

Clonal propagation and limited dispersal of seeds lead to genetic population structures in which most potential mates are relatives. If the species suffers from inbreeding depression or is self-incompatible, the number of seeds matured per fruit may be limited by the lack of outcrossing by unrelated pollen. We tested for distance-related genetic structure by hand-pollinating plants at increasing distances and measuring fruit set (berries/pollinated flowers) and seed number per fruit in natural populations of bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.). Bagging of the flower buds without natural (pollination by insects) or hand-pollination yielded almost no fruit or seed, suggesting that the species are obligately insect pollinated. Self-pollination led to a significant reduction in seed number per fruit and increased seed abortion compared with cross-pollination. Moreover, seed number increased with increasing distance between the pollen donor and pollen recipient. Flight distances of bumblebees were estimated for bilberry by monitoring between-flower and, for lingonberry, between-inflorescence flight distances. About 90% of all flights were at distances of less than 1 m. At this distance, we observed less than the maximum seed number per fruit in hand-pollinations in both study species. Consequently, clonal growth is likely to be an important factor that constrains fruit and seed number in these species.Key words: bumblebee forage distance, clonal, hand-pollination, inter-parent distance, reproductive success, Vaccinium.
A new occurrence of Archaeoscyphia pulchra (Bassler) from the Ordovician of western Canada
Authors: Rigby J Keith , Nowlan Godfrey S , Rowlands Peter A
Published: October 2002

A few specimens of the ornate anthaspidellid demosponge, Archaeoscyphia pulchra (Bassler), have been collected from the Lower Ordovician Outram Formation or Skoki Formation, from a saddle at the head of South Rice Brook in northeastern British Columbia. This is the first report of the flanged-appearing annulate, steeply obconical sponge in western Canada, although it has been reported from the Mingan Islands of Quebec and was initially described from Nevada, in the western United States. The taxon has also been reported as other species of Archaeoscyphia from Ordovician rocks of Missouri and from the San Juan region of Argentina.
Natural mortality estimates of juvenile Pacific herring (Clupea pallasi) in Prince William Sound, Alaska
Authors: Stokesbury Kevin DE , Kirsch Jay , Patrick E Vincent , Norcross Brenda L
Published: October 2002

The densities of young-of-the-year and 1-year-old Pacific herring, Clupea pallasi, in Prince William Sound, Alaska, were estimated using acoustic surveys from June 1996 to March 1998. Four bays were surveyed with acoustic transects that were repeated three times in 24 h. Species composition and size structure were determined from net collections. Averaging over the 24-h period allowed the best use of all data, as observations between the three replicates were similar but sporadic, possibly resulting from the different seasonal daynight cycle in these northern latitudes. The average instantaneous natural mortality rates for young-of-the-year Pacific herring were 0.009 (standard deviation (SD) = 0.002) and 0.016 (SD = 0.012) for the 1996 and 1997 cohorts, respectively. The average instantaneous natural mortality rates for 1-year-old Pacific herring were 0.003 (SD = 0.007) and 0.008 (SD = 0.005) for the 1995 and 1996 cohorts, respectively. Combining our estimates with those in the primary literature for other life history phases of Pacific herring indicated a progressive decrease in instantaneous natural mortality with age. This study presents the first direct estimates of natural mortality for juvenile herring.
An improved method for estimating individual growth variability in fish, and the correlation between von Bertalanffy growth parameters
Authors: Pilling Graham M , Kirkwood Geoffrey P , Walker Stephen G
Published: October 2002

A new method for estimating individual variability in the von Bertalanffy growth parameters of fish species is presented. The method uses a nonlinear random effects model, which explicitly assumes that an individual's growth parameters represent samples from a multivariate population of growth parameters characteristic of a species or population. The method was applied to backcalculated length-at-age data from the tropical emperor, Lethrinus mahsena. Individual growth parameter variability estimates were compared with those derived using the current "standard" method, which characterizes the joint distribution of growth parameter estimates obtained by independently fitting a growth curve to each individual data set. Estimates of mean von Bertalanffy growth parameters from the two methods were similar. However, estimated growth parameter variances were much higher using the standard method. Using the random effects model, the estimated correlation between population mean values of L[Formula: see text] and K was 0.52 or 0.42, depending on the marginal distribution assumed for K. The latter estimate had a 95% posterior credibility interval of 0.62 to 0.17. These represent the first reliable estimate of this correlation and confirm the view that these parameters are negatively correlated in fish populations; however, the absolute correlation value is somewhat lower than has been assumed.
Avoidance of solar ultraviolet radiation by juvenile coho salmon (Oncorhynchus kisutch)
Authors: Kelly David J , Bothwell Max L
Published: October 2002

Shade-seeking behavior and avoidance of solar ultraviolet radiation (UVR) by newly emerged coho salmon (Oncorhynchus kisutch) alevins and two-month-old coho juveniles was documented in experimental trials in the Little Qualicum River, British Columbia, using outdoor chambers that provided the fish with a binary choice of photo environments. Under high solar intensities (i.e., midsummer, cloudless skies) coho of both age classes strongly preferred 50% neutral density shaded conditions to unattenuated full-spectrum (280700 nm) sunlight (t test, p < 0.025). In addition, coho alevins and juveniles showed a high selective avoidance of UVR (280400 nm) (t test, p < 0.05). Within the UVR spectrum, coho responded significantly to UVA (320400 nm) (t test, p = 0.028). Evidence of UVB (280320 nm) avoidance was confounded by higher visible and UVA irradiance levels under screens exposing coho to UVB. Under lower solar intensities (i.e., cloudy skies) coho showed no spectral preference and did not seek neutral density shade. Behavioral avoidance of high intensity UVR, particularly UVA, suggests that shade-seeking behavior of juvenile coho may be linked to avoiding potentially harmful UVR exposure.
Pacific herring respond to simulated odontocete echolocation sounds
Authors: Wilson Ben , Dill Lawrence M
Published: October 2002

There has been a long-running debate as to if and how clupeoid fish, such as herring (Clupea sp.), respond to anthropogenic sound. Anatomical and physiological investigations have shown that members of the clupeoid suborder have highly developed hearing extending into ultrasonic frequencies and behavioural studies suggest that they respond to many sounds. However, only recently have the selective forces that have driven the evolution of this keen sense and behavioural repertoire played a major part in the debate. One explanation is the adaptation to predation from echolocating cetaceans. In this study, we investigate the responses of adult Pacific herring (Clupea pallasii) to broadband biosonar-type sounds with high-frequency similarities to those produced by odontocete cetaceans. Exposures to these sounds in an indoor tank and sea cage caused feeding fish to cease, drop in the water column, and begin to school actively. Fish already schooling dropped in the water column and increased their swimming speed. Exposures to electronic silence and an acoustic deterrent device for marine mammals did not elicit such responses. We discuss the potential suitability of the observed manoeuvres for avoidance of foraging odontocetes and consider their relevance for human-related fishing activities.
Factors regulating nitrification in aquatic sediments: effects of organic carbon, nitrogen availability, and pH
Authors: Strauss Eric A , Mitchell Nicole L , Lamberti Gary A
Published: October 2002

We investigated the response in nitrification to organic carbon (C) availability, the interactive effects of the C: nitrogen (N) ratio and organic N availability, and differing pH in sediments from several streams in the upper midwestern United States. In addition, we surveyed 36 streams to assess variability in sediment nitrification rates. Labile dissolved organic carbon (DOC) additions of 30 mg C·L1 (as acetate) to stream sediments reduced nitrification rates (P < 0.003), but lower concentration additions or dilution of ambient DOC concentration had no effect on nitrification. C:N and organic N availability strongly interacted to affect nitrification (P < 0.0001), with N availability increasing nitrification most at lower C:N. Nitrification was also strongly influenced by pH (P < 0.002), with maximum rates occurring at pH 7.5. A multiple regression model developed from the stream survey consisted of five variables (stream temperature, pH, conductivity, DOC concentration, and total extractable NH4+) and explained 60% of the variation observed in nitrification. Our results suggest that nitrification is regulated by several variables, with NH4+ availability and pH being the most important. Organic C is likely important at regulating nitrification only under high environmental C:N conditions and if most available C is relatively labile.
The response of planktonic phosphate uptake and turnover to ultraviolet radiation in Lake Erie
Authors: Allen C D , Smith R E.H
Published: October 2002

The hypothesis that ambient ultraviolet radiation (UVR), at near-surface intensities, may diminish phosphorus availability to phytoplankton was tested in Lake Erie in July and August of 1998 and 1999. Relative to samples exposed to photosynthetically active radiation (PAR, 400700 nm) only, those exposed to ultraviolet-B (UVB, 280320) and (or) ultraviolet-A (UVA, 320400 nm) in natural sunlight, or kept in darkness, had diminished phosphate uptake rates at elevated (1 µM P) dissolved phosphate concentrations. By contrast, the specific uptake rate of dissolved phosphate at ambient concentrations (turnover rate) was not significantly affected by UVR or darkness. Turnover was usually dominated by particles smaller than 0.8 µm, whereas uptake from elevated concentrations was dominated by larger particles. The size distribution of turnover and uptake activity was not affected by radiation treatment. Chlorophyll a concentrations were decreased by sufficient exposure to UVB and (or) UVA and increased by deprivation of PAR (dark controls), but the concentration of bacterial cells was unaffected. The results showed that UVR inhibited the phosphate uptake potential of larger, probably algal, plankton but did not change the apparent severity of phosphate limitation at ambient concentrations.
Influence of trends in fishing power on bioeconomics in the North Sea flatfish fishery regulated by catches or by effort quotas
Authors: Ulrich Clara , Pascoe Sean , Sparre Per J , Wilde Jan-Willem De , Marchal Paul
Published: October 2002

Total allowable effort quotas (TAEs) are often considered as promising alternatives to single-species total allowable catch quotas (TACs) in fisheries management. However, implementing TAEs would primarily require converting nominal effort into fishing mortality rate, i.e., developing a relevant model of the dynamics of catchability. Assuming that trends in the catchability may occur through fishing-power creeping linked to increased capital invested and technology, we compare, by stochastic and dynamic simulation modelling, the relative biological and economic benefits and drawbacks of TAEs and TACs in the North Sea sole (Solea solea L.) and plaice (Pleuronectes platessa L.) fishery. Management targets are based on the Precautionary Approach and Harvest Control Rules developed by the International Council for the Exploration of the Sea (ICES). Fishermen are assumed to set their effort at the most (TAE) or least (TAC) conservative level. Overall, the outcomes are more sensitive to the catchability model when implementing TAEs, especially in the medium and long term, but the variability in catchability has a much greater impact on stock levels than on the fisheries profit.
Using reproductive values to define optimal harvesting for multisite density-dependent populations: example with a marine reserve
Authors: Brooks Elizabeth N
Published: October 2002

A new method for determining optimal harvest from age-structured populations with a density-dependent stock-recruit relationship is presented. The theoretical optimal harvest comes from removing the age-class with the smallest ratio of reproductive value to weight. The method is derived from considering the sensitivity of equilibrium egg production to harvest using results for density-dependent Leslie matrices. The method holds in both single- and multi-site contexts and is derived for both Ricker and BevertonHolt recruitment functions. I illustrate the method for a one-site model of Arcto-Norwegian cod (Gadus morhua) and obtain the same optimal strategy as previous methods, namely that age-class 6 should be harvested 45%. Including age-specific selectivities, the best constrained yields occur at a harvest rate of 11% on ages 512. This yield is 73% of the theoretical optimum. I considered the same model when a reserve is established and found that high transfer rates out of the reserve (where spawners attain a higher fecundity) produced greater yields that were 86% of the one-site (no reserve) yield. Also, if overfishing occurs at 1.5 and 2.0 times the optimal level in the one-site case, then most yields from the reserve model are greater than those from the one-site model.
Nitrogen and phosphorus relationships to benthic algal biomass in temperate streams
Authors: Dodds Walter K , Smith Val H , Lohman Kirk
Published: October 2002

Knowledge of factors limiting benthic algal (periphyton) biomass is central to understanding energy flow in stream ecosystems and stream eutrophication. We used several data sets to determine how water column nutrients and nonnutrient factors are linked to periphytic biomass and if the ecoregion concept is applicable to nutrientperiphyton relationships. Literature values for seasonal means of biomass of periphyton, nutrient concentrations, and other stream characteristics were collected for almost 300 sampling periods from temperate streams. Data for benthic chlorophyll and nutrient concentrations from a subset of 620 stations in the United States National Stream Water-Quality Monitoring Networks were also analyzed. The greatest portion of variance in models for the mean and maximum biomass of benthic stream algae (about 40%) was explained by concentrations of total N and P. Breakpoint regression and a two-dimensional KolmogorovSmirnov statistical technique established significant breakpoints of about 30 µg total P·L1 and 40 µg total N·L1, above which mean chlorophyll values were substantially higher. Ecoregion effects on nutrientchlorophyll relationships were weak. Ecoregion effects were cross-correlated with anthropogenic effects such as percent urban and cropland area in the watershed and population density. Thus, caution is necessary to separate anthropogenic effects from natural variation at the ecoregion level.
Simulations of the impact of different temporal and spatial allocations of fishing effort on fishing mortality in a lobster (Homarus americanus) fishery
Authors: Gendron Louise , Brêthes Jean-Claude
Published: October 2002

A spatially explicit model is proposed to assess the impact on fishing mortality of modifying effort patterns for an American lobster (Homarus americanus) fishery. A two-box (offshore and inshore grounds) model is developed for the 1995 lobster fishery season in the Magdalen Islands (Quebec). It considers lobster migration and fisher's temporal and spatial effort dynamics to estimate within-season catchability patterns and exchange rates between the two spatial units. Different management scenarios are simulated: reducing nominal fishing effort and changing its temporal (season's length) and spatial (area closures) allocations. Catchability showed a strong temporal trend, being highest during the first 3 weeks and declining regularly afterwards. The model indicated a continuous migration toward the inshore during the fishing season and that a significant amount of biomass remained offshore. As a result, reducing fishing effort at the beginning of the season would have the greatest impact on exploitation rate. Allowing less effort in the offshore area would also reduce the exploitation rate significantly. Restricting effort to the inshore area, as it was 25 years ago, reduced substantially the exploitation rate. This model represents the first attempt to analyze in-season fishery dynamics and should be useful to further assess the impact of management measures.
Nutrient, chlorophyll, and water clarity relationships in Florida's nearshore coastal waters with comparisons to freshwater lakes
Authors: Hoyer Mark V , Frazer Thomas K , Notestein Sky K , Canfield, Jr. Daniel E
Published: October 2002

Models relating chlorophyll to nutrients and Secchi depth to chlorophyll using data from nearshore coastal waters of Florida were successfully developed. The models suggest that phosphorus is the primary limiting factor for phytoplankton in the nearshore coastal waters of Florida and that total phosphorus concentration accounts for 81% of the variance in chlorophyll concentration. The models also show that chlorophyll is the dominant factor determining Secchi depth in nearshore coastal waters of Florida and that chlorophyll concentrations account for 68% of the variance in Secchi depth. Thus, these models are robust and should be useful for eutrophication management of Florida's coastal marine systems. The models developed with data from nearshore coastal waters of Florida are similar to models developed for freshwater lakes in Florida, but the amount of chlorophyll per unit of phosphorus and Secchi depth per unit of chlorophyll are both significantly less for marine samples. This suggests that the chlorophyll to biovolume ratios in the nearshore coastal waters of Florida are less than in freshwater systems of Florida. Therefore, nutrient to chlorophyll and chlorophyll to Secchi depth models developed for freshwater systems are probably ill suited for use in Florida's marine systems.
Characterizing catch variability in a multispecies fishery: implications for fishery management
Authors: van Oostenbrugge J A.E , Bakker E J , van Densen W L.T , Machiels M A.M , van Zwieten P A.M
Published: October 2002

Exploiting several fish species simultaneously reduces variability in daily catches. The reduction depends on the number of species, the catch-frequency distributions of individual species, and the level of co-occurrence of species in the catch. We explore theoretically the reduction of variability (coefficient of variation; CV) in the total catch by combining the distributions of daily catches of individual fish species, including zero catches, into a total catch frequency distribution. Theoretical findings are tested with an example from a stationary lift-net fishery for schooling small pelagic species around Ambon Island in the Central Moluccas, Indonesia. This fishery catches over 30 species, all with high daily variability (CV = 2.213.4). The reduction of variability in the total catch (CV = 1.7) is a result of the dominance and independent occurrence of the three main species. We conclude that in this fishery the information value of the total catch as an indicator of the catches of the individual species is low.
Effects of observer efficiency, arrival timing, and survey life on estimates of escapement for steelhead trout (Oncorhynchus mykiss) derived from repeat markrecapture experiments
Authors: Korman Josh , Ahrens Robert N.M , Higgins Paul S , Walters Carl J
Published: October 2002

Estimation of escapement for steelhead trout (Oncorhynchus mykiss) from periodic visual counts of spawners is complicated by extreme changes in observer efficiency over the migration period, low numbers of fish, pulsed arrival timing, and variable survey life. We present a maximum likelihood method to compute escapement and uncertainty that accounts for these difficulties using markrecapture data from radiotelemetry and snorkel surveys. Estimates of escapement were highly sensitive to assumptions about arrival dynamics and survey life, moderately sensitive to the assumed ending date of the run, and insensitive to assumptions about the form of observation error. Discharge and diver visibility explained between 69 and 78% of the variation in observer efficiency. Simulations revealed that declines in observer efficiency over the duration of the run increased bias and variability in escapement estimates but that this can be mitigated to a limited extent by increasing the number of surveys. The simulations also provided evidence that our likelihood approach was superior to the standard area-under-the-curve method for computing escapement when estimates of the numbers present over time are affected by substantial sampling error.
Rapid Communication / Communication RapideAcoustic seabed classification: improved statistical method
Authors: Legendre Pierre , Ellingsen Kari Elsa , Bjørnbom Erik , Casgrain Philippe
Published: October 2002

Huge amounts of money will be spent by industrialized nations during the next decades to obtain detailed maps of continental shelf seabeds. These maps, which will allow a more rational exploitation of the sea floor, are needed to assess the impact of anthropic activities. The statistical method of analysis of echosounder backscatter data described in this paper presents several improvements over existing techniques. The steps are as follows. (i) The backscatter data are decomposed mathematically into a number of quantitative variables, which are subjected to principal component analysis (PCA). (ii) Principal components representing 9599% of the variation are used in a K-means partitioning procedure. A statistical criterion indicates what the number of groups is that best reflects the variability of the data. (iii) The groups are then plotted on maps of the survey area. Insofar as the mathematical decomposition produces variables that reflect the variations of the physical nature and composition of the seabed, the classes of the partition will correspond to different seabed types. Free software (The Q Package) implementing this method is available at http://www.fas.umontreal.ca/biol/legendre/.
Rapid Communication / Communication RapideEmamectin benzoate induces molting in American lobster, Homarus americanus
Authors: Waddy S L , Burridge L E , Hamilton M N , Mercer S M , Aiken D E , Haya K
Published: October 2002

Emamectin benzoate (nominal dose 1 μg·g body weight1) caused female American lobster (Homarus americanus) to enter proecdysis and molt prematurely (44% vs. 0% of the control lobster, P < 0.001). Lobster bearing eggs when proecdysis was induced aborted their broods. This chemical is the active ingredient in a new feed additive being used to control sea lice (Lepeophtheirus salmonis and Caligus spp.) infestations on farmed salmon (predominantly Salmo salar). The response of the American lobster to emamectin benzoate was unexpected, as avermectins inhibit or delay ecdysis in insects. We hypothesize that emamectin benzoate is interfering with the neuropeptides that modulate the production of molting hormone in lobster and that the diametric response of insects and lobster to this chemical is due to the difference in the neuroendocrine control of the molting glands of these two groups of arthropods (inhibitory in crustaceans, but stimulatory in insects). This is the first report of a crustacean molting prematurely in response to chemical exposure and the first report that a GABAergic (γ-aminobutyric acid) pesticide can cause premature molting in an arthropod.
Biofiltration de l'air pollué par le xylène : observations expérimentales
Authors: Jorio Hasnaa , Viel Guy , Heitz Michèle
Published: October 2002

A new filtering material has been tested for its biofiltration performance for the treatment of air contaminated with the three isomers of xylene. The biofilter, operated at an empty bed residence time of 68 s and for xylene concentrations up to 6.7 g·m3, allowed a xylene load and reduction of more than 92% for concentrations up to 2 g·m3, and more than 65% for concentrations less than 6.7 g·m3. The maximum xylene elimination capacity is of 236 g·m3·h1. In general, the removal efficiency of meta-xylene is the highest whereas the removal efficiency of ortho-xylene is the lowest. At high xylene concentration, the increase of biodegradation intensity leads to the accumulation of a voluminous biofilm around the filtering particles, causing the clogging of the filter bed, the progressive retention of the nutritive solution in the superior parts of the bed, and the drying of the inferior parts of the bed. These observations have showed that a biofilter operating at high elimination capacities requires a meticulous control of the humidity of the filtering bed and a regular draining of the biomass excess. Key words: biofiltration, xylene, ortho, meta, and para isomers, carbon dioxide, biofilm, pressure drop, biomass excess.[Journal translation]
Contractor integrated technical information service in construction
Authors: Kim K J , Chin K H , Han Seung H , Woo S K , Cho Moon-young
Published: October 2002

The research described in this paper implements a U.S. Department of Defense protocol entitled contractor integrated technical information service (CITIS) in a construction industry application to provide an electronic communication environment for sharing construction information among project participants. CITIS is a contractor-developed service that provides electronic access to and (or) delivery of contractual data to users. For the implementation of the CITIS concept in the construction industry, this research performs process and data modeling on a road construction project, then implements and tests a prototype. This article also introduces an overall procedure to implement the concept of CITIS in construction and identifies some challenges such as the limitations in performing process modeling in the public sector, specifically public road construction projects, the lessons learned, and suggestions in overcoming these difficulties.Key words: construction management, continuous acquisition and life cycle support, contractor integrated technical information service.
NotePrediction of early age curling in thin concrete topping over wood floor systems
Authors: Lee Peter , Chui Ying H , Smith Ian , Mailvaganam Noel , Pernica Gerry
Published: October 2002

This paper presents finite element simulations of curling of unreinforced concrete topping laid over wood floor systems. The finite analysis consists of two parts. The first part calculates the relative moisture distribution with respect to the age of the concrete, while the second determines the topping curling deformation based on modulus of elasticity, density, and shrinkage of the concrete. With the finite element model the curling profile at any point in time can be predicted. Predictions agree reasonably well with measurements from a full-sized wood floor with a thin concrete topping. A model-based parametric study was performed. For the floor size investigated the results of the parametric study indicate that curling is greatly influenced by topping thickness and relative humidity of the surrounding air. Although the modelling as discussed is a preliminary approach, it provides a basis for further enhancements that will address factors such as creep and relaxation of concrete and deformation of the underlying floor system. Key words: finite element analysis, concrete topping, wood floor, curling, shrinkage.
Coupled microstrip filters on multilayered dielectric media
Authors: Koufogiannidis Ar. , Siakavara K
Published: October 2002

The work presented in this paper is an attempt to design filters with coupled microstrip lines on multilayered dielectric media using methods employed in other applications. A procedure was formulated for designing filters with the desired frequency response and smaller size using insertion loss method combined with the theory of multiconductor transmission lines. The frequency response was verified by considering that the filters act as cascaded four-port networks. The results were in a very good agreement with those expected from the theoretically design procedure.

PACS No.: 84.40D
Electrohydrodynamic instability in a horizontal viscoelastic fluid layer in the presence of internal heat generation
Authors: Othman M IA , Sweilam N H
Published: October 2002

Linear stability theory is applied to examine the effect of a vertical ac electric field on the stability of natural convection, which occurs in a dielectric viscoelastic fluid (Walters' liquid B' ) between two parallel horizontal plates with internal heat generation. The power-series method is used to obtain the eigenvalue equation, which is then solved numerically. Critical heat Rayleigh numbers and the critical wave number for the onset of instability are presented graphically as functions of the electric Rayleigh number for various values of the Prandtl number.

PACS No.: 47.15Fe
The run of a golf ball
Authors: Penner A R
Published: October 2002

The run, which includes both the bounce and the roll, of a golf ball landing on turf is modeled. The effect of launch speed, impact angle, backspin, and green firmness on the run for a variety of golf shots is considered. It is found that the dominant factor that determines the length of the run, in the case of drives, is the impact angle. It is also found that for high-lofted iron shots, where the golf ball is given sufficient backspin, the ball may, for firm enough greens, initially bounce forward before running backwards.

PACS No.: 01.80+b
Photoluminescence properties study of the Au/Au2S nanoshell
Authors: Diao J J , Qiu F S , Chen G D , Xi C , Song Y
Published: October 2002

Photoluminescence experimental results of the Au/Au2S nanoshell (a nanometer-scale Au2S core coated by a thin Au shell) are presented in this note. An enhanced photoluminescence peak of Au coated Au2S is obtained near the bluegreen region, compared with the photoluminescence region of bulk Au2S, which is near the orangered region. The quantum-size effect and the core/shell nanostructure caused the blueshift photoluminescence of the Au2S/Au nanoshell.

PACS Nos.: 81.05Ys, 78.55-m
Dirac's hole theory versus quantum field theory
Authors: Coutinho F AB , Kiang D , Nogami Y , Tomio L
Published: October 2002

Dirac's hole theory and quantum field theory are usually considered equivalent to each other. The equivalence, however, does not necessarily hold, as we discuss in terms of models of a certain type. We further suggest that the equivalence may fail in more general models. This problem is closely related to the validity of the Pauli principle in intermediate states of perturbation theory. PACS Nos.: 03.65-w, 11.10-z, 11.15Bt, 12.39Ba
Seismic horizontal pullout capacity of vertical anchors in sands
Authors: Kumar Jyant
Published: October 2002

The problem of finding the horizontal pullout capacity of vertical anchors embedded in sands with the inclusion of pseudostatic horizontal earthquake body forces, was tackled in this note. The analysis was carried out using an upper bound limit analysis, with the consideration of two different collapse mechanisms: bilinear and composite logarithmic spiral rupture surfaces. The results are presented in nondimensional form to find the pullout resistance with changes in earthquake acceleration for different combinations of embedment ratio of the anchor (λ), friction angle of the soil (φ;), and the anchor-soil interface wall friction angle (δ). The pullout resistance decreases quite substantially with increases in the magnitude of the earthquake acceleration. For values of δ up to about 0.250.5φ, the bilinear and composite logarithmic spiral rupture surfaces gave almost identical answers, whereas for higher values of δ, the choice of the logarithmic spiral provides significantly smaller pullout resistance. The results compare favorably with the existing theoretical data.Key words: anchors, earthquakes, failure, limit analysis, sands.
A model for slow motion of natural slopes
Authors: Cristescu N D , Cazacu O , Cristescu C
Published: October 2002

A new model for describing the slow movement of natural slopes is proposed. The geological material in the slope is modeled with a nonhomogeneous Bingham constitutive equation. This model describes the effect of gravitational consolidation on the material response and allows for a variation of density and yield stress with depth. A criterion for shear flow initiation is formulated and the ensuing motion is described. Velocity profiles for several slip conditions at the interface with the bedrock are given. The model is used to predict the observed field behavior of a natural slope (Villarbeney, Switzerland).Key words: natural slope, incipient shear flow, nonhomogeneous Bingham law, creep flow, gravitational consolidation.
Increased pigment and lipid content, lipid variety, and cell and population size of the microalgae Chlorella spp. when co-immobilized in alginate beads with the microalgae-growth-promoting bacterium Azospirillum brasilense
Authors: de-Bashan Luz E , Bashan Yoav , Moreno Manuel , Lebsky Vladimir K , Bustillos Jose J
Published: October 2002

Three strains of the freshwater microalgae used for wastewater treatment, Chlorella vulgaris and Chlorella sorokiniana co-immobilized separately in alginate beads with the microalgae-growth-promoting bacterium Azospirillum brasilense Cd, resulted in significant changes in microalgal-population size, cell size, cell cytology, pigment, lipid content, and the variety of fatty acids produced in comparison with microalgae immobilized in alginate without the bacterium. Cells of C. vulgaris UTEX 2714 did not change in size, but the population size within the beads significantly increased. On the other hand, C. vulgaris UTEX 395 cells grew 62% larger, but their numbers did not increase. The population of C. sorokiniana UTEX 1602 increased, but not their cell size. The content of pigments chlorophyll a andb, lutein, and violoaxanthin increased in all microalgal species. The lipid content also significantly increased in all three strains, and the number of different fatty acids in the microalgae increased from four to eight. This study indicates that the microalgae-growth-promoting bacterium induced significant changes in the metabolism of the microalgae.Key words: alginate, Azospirillum, Chlorella, bacterial immobilization, microalgae, wastewater.
Survival of the rhizosphere-competent biocontrol strainPseudomonas fluorescensNBRI2650 in the soil and phytosphere
Authors: Nautiyal C Shekhar , Johri J K , Singh H B
Published: October 2002

Pseudomonas fluorescens NBRI2650 was isolated after screening 360 bacterial strains from the rhizosphere of chickpea (Cicer arietinum L.) grown in fungal-disease-suppressive field soil. The strain was selected because of its high rhizosphere competence and ability to inhibit the growth of Fusarium oxysporum f.sp. ciceri, Rhizoctonia bataticola, and Pythium sp. under in vitro conditions. Survival and colonization of NBRI2650 in the phytosphere of chickpea, cotton (Gossypium hirsutum L.), cucumber (Cucumis sativus L.), and tomato (Lycopersicon seculentum Mill.) were monitored using a chromosomally located rifampicin-marked mutant P. fluorescens NBRI2650R. The strain showed variable ability to invade and survive in the phytosphere of different plants. Chickpea was used as a tester plant for further work, as it was not invaded by NBRI2650R. The interaction between NBRI2650R and F. oxysporum f.sp. ciceri was studied by both light microscopy and scanning electron microscopy. The lysis of the fungal cell wall by NBRI2650R was clearly demonstrated. Treatment of the chickpea seeds with NBRI2650R in prerelease experiments in the greenhouse using disease-conducive field soils from Jhansi and Kanpur resulted in increased plant growth and did not result in any perturbation of the indigenous microbial community that inhabited the rhizosphere of chickpea compared with nonbacterized seeds. Direct fermentation of diluted NBRI2650R on vermiculite without the need of expensive fermentors offers a reliable process for manufacturing bacterial inoculants in developing countries. Under field conditions, the horizontal and vertical movement of NBRI2650R was restricted to 30 and 60 cm, respectively, and the strain could not survive in the field during the 7 months before the chickpea could be planted for next cropping season. Field trials conducted at Jhansi, Kanpur, and Pantnagar resulted in higher grain yield increase in the bacteria-treated seed compared with the nonbacterized control. Seed and furrow treatment of the two chickpeas ('Radhey' and 'H-208') at Pantnagar resulted in significantly (P = 0.05) greater seedling mortality in nonbacterized seedlings compared with bacterized ones. The seed dry weight and yield for each variety were also significantly higher in bacterized seedlings than in nonbacterized ones. The population of NBRI2650R persisted throughout the growing season of chickpea in the range of 5.46.4 log10CFU/g root.Key words: chickpea, competition, rhizosphere, biocontrol, survival.