bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidemiology and impact of rotavirus diarrhoea in Poland
Authors: Mrukowicz JZ , Krobicka B , Duplaga M , Kowalska‐Duplaga K , Domañski J , Szajewska  , Kantecki M , Iwañczak F , Pytrus T
Published: April 2008

Hospital and laboratory data were analysed in three hospitals to estimate rotavirus disease burden in 1994‐96. Community acquired gastroenteritis was diagnosed in 757 children of whom 41% tested positive for rotavirus. A total of 196 children had rotavirus nosocomial infections (39% of all rotavirus community‐acquired and nosocomial cases) Infants less than 24 months old and children less than 3 months old comprised 74% and 11.9% of admissions for rotavirus, respectively. Almost 94% of children with rotavirus infection had severe gastroenteritis (score 11). The annual rate of rotavirus associated hospitalization in Poland in 1996 was 3.1/1000 children under the age of 60 months and 5.2/1000 infants under 24 months of age. The mean hospital stay was 9.5 d (±9.8 d). We estimated that 8918 children under 60 months of age were hospitalized for rotavirus gastroenteritis in 1996; they accounted for 84899 inpatient days. We conclude that rotavirus is a leading aetiological agent of severe gastroenteritis in young children in Poland and that the Burden of this infection is significant. Rotavirus vaccine could significantly decrease the hospitalization rate and the financial impact of rotavirus Gastroenteritis in Poland. □Acute diarrhoea, disease burden, epidemiology, gastroenteritis, rotavirus
Burden of human rotavirus‐associated hospitalizations in three geographic regions of Hungary
Authors: Szücs G , Új M , Mihály I , Deák
Published: April 2008

Data on hospital admissions and laboratory reports were used to estimate the number of hospitalizations of children aged 14 y or less in three geographic regions of Hungary due to group A rotavirus infection. Between January 1993 and December 1996, 9182 hospitalizations for gastroenteritis occurred, of which 1946 (21%) were associated with rotavirus infection. Most (90%) ofthe rotavirus detections were among children aged 4 y or less. By extrapolation, an estimated 5000 rotavirus‐related hospitalizations (8.4/1000 children aged 4 y or less/y) occurred in Hungary during the study period. Marked seasonality of rotavirus infections was observed, with a peak of incidence from December to February. Rotaviruses with “long” RNA electropherotypes predominated each year, but in 1995/1996 20% of electropherotypes in the Budapest area were “short”. Effective surveillance is required for all children hospitalized for diarrhoea as part of a rotavirus immunization program in Hungary. □Age group, burden, electropherotypes, Hungaiy, region, rotavirus, season
Impact of rotavirus disease in Spain: an estimate of hospital admissions due to rotavirus
Authors: Visser LE , Portero R Cano , Gay NJ , Navarro JF Martínez
Published: April 2008

The epidemiology of rotavirus infection in Spain was investigated using information from existing surveillance systems. Peports from laboratories and data on hospital admissions were used to estimate the number of hospital admissions due to rotavirus infection. Between January 1989 and December 1995 there were 8265 reports of rotavirus identificatión in the Sistema de Información Microbiológica, a voluntary national laboratory surveillance system. Where age was reported, 89.2% were in children under 5 y old. This represents 21.8% of all pathogens identified in faecal specimens in children of this age group. Between January and December 1994 there were 5639 admissions coded as “infectious intestinal disease” and 8225 as “non‐infective gastroenteritis” in children under 5 y of age in the Conjunto Minimo Básico de Datos, an obligatory hospital admissions surveillance system which covers 83% of publis hospitals. Using regression analysis of admission data and laboratory reports it was estimated that rotavirus infection accounted for 3159 (25.3%) of the hospital admissions. We estimate that 4239 admissions attributable to rotavirus occurred in children under 5 y of age in Spain in 1994, a rate of 2.5/1000 population in this age group. These estimates are lower than those published for other countries, where the burden of disease is considered high enough to warrant a national vaccination programme. A costeffectivenness study with Spanish information is essential before embarking on a national vaccination programme. □Rotavirus, surveillance, vaccination
Hypoglycaemia in children with type 1 diabetes mellitus
Authors: Chiarelli F , Verrotti A , Catino M , Sabatino G , Pinelli L
Published: April 2008

Hypoglycaemia is a frequent acute complication of IDDM and is usually defined as a blood glucose level below 3.0 mmol/l. Hypoglycaemia stimulates several neuroendocrine responses, such as secretion of glucagon, adrenaline, growth hormone and Cortisol, which are generally increased during this phenomenon. The true prevalence of hypoglycaemia is not known. Studies of the epidemiology of severe hypoglycaemia give prevalences ranging from 2.7 to 85.7 episodes per 100 patients per year. The major risk factor for severe hypoglycaemia is hypoglycaemia unawareness, which occurs particularly in patients with type 1 diabetes of long duration and in those with a history of frequent episodes of hypoglycaemia. The first step in the management of hypoglycaemia is to check blood glucose and to treat hypoglycaemia on the basis of symptoms. Hypoglycaemia requires urgent treatment with a fast‐acting carbohydrate or, if severe, with parenteral glucagon or intravenous glucose. Prevention measures should be instituted to prevent subsequent episodes, particularly in younger children with hypoglycaemic seizures or when seizures are recurrent, □Adolescents, children, hypoglycaemia, hypoglycaemia unawareness, type 1 diabetes
The role of nutrition in prevention of complications in insulin‐dependent diabetes mellitus
Authors: Pinelli L , Mormile R , Alfonsi L , Gonfiantini E , Piccoli R , Chiarelli F
Published: April 2008

Nutrition management is an integral part of overall diabetic treatment that includes insulin, physical activity, emotional support and guidance. The aim of the present study was to evaluate a dietary approach in line with the recommended dietary allowances in terms of protein, total and saturated fat, carbohydrates as well as fibre and polyunsaturated fatty acid. A correct dietary approach may help to prevent and to reduce to a minimum any risk of hyperglycaemia, hypoglycaemia and important long‐term complications such as obesity, hyperlipidaemia and hypertension, and at the same time normal growth development. □Complications, diet, insulin‐dependent diabetes mellitus, nutrition, prevention
Family management of insulin‐dependent diabetes mellitus: a practical problem‐solving approach
Authors: Kassiou K , Tsamasiros J
Published: April 2008

Insulin‐dependent diabetes mellitus (IDDM) as a chronic and potentially life‐threatening condition, may have a devastating acute and long‐term effect on the patient and his or her family. IDMM's management should include the following components: (a) establishment of a co‐operative relationship amongst the patient, his or her family and the members of the diabetes team, (b) emphasis on the promotion of problem‐solving strategies, (c) sufficient emotional and psychological support and proper education and training concerning diabetic control, provided not only to the patient but to all the family members involved in his or her care. The treatment regimen, as well as the above mentioned components of IDMM management should be tailored to the individual's specific needs, developmental stage and a level of adjustment. These facilitating conditions can have a positive and long‐standing effect on the individual's capacity to cope efficiently in order to improve quality of life and obtain adjustment. □Developmental stages, IDDM management, problem‐solving strategies, psychological complications, stages of adjustment
SIDS diagnosis should not be put to bed
Authors: Alm Bernt , Wennergren Göran , Lagercrantz Hugo
Published: April 2008

The finding that prone sleeping position and smoking are important risk factors for SIDS has considerably reduced the incidence. Although these risk factors can be found in many cases of SIDS, they cannot be regarded as causes of death.

Conclusion: The diagnosis of SIDS must be adhered to, and risk factors must not be confused with diagnoses. A structured follow‐up of all cases of SIDS can be a cost‐effective mean to ensure that parents and researchers are given adequate information.
What Can We Learn? Adult Outcomes in Children of Seriously Mentally Ill Mothers
Authors: O’Connell Kathleen LeClear
Published: April 2008

PROBLEM:  Information is lacking about the experiences, needs of, and interventions for children of seriously mentally ill mothers.

METHODS:  Quantitative and qualitative methods of inquiry were used to retrospectively explore the characteristics and needs of adult children of seriously mentally ill mothers. The sample (N = 40) was recruited by referral and media advertisements. Childhood variables related to attachment, family environment, and parenting were compared to adult well‐being outcomes of depression, quality of life, sense of coherence, and self‐esteem. Participants also responded to the question “What other question should have been included in this study about your experience as the child of a seriously mentally ill mother?” and, additionally, spontaneously added their own clarifications of their answers to the survey questions.

FINDINGS:  It was apparent that the childhoods of participants were disruptive and often painful. Over half of the sample reported having their own diagnosis of depression in adulthood. Despite these factors, most members of the study sample were functioning well in adulthood, most often as a result of their own initiative.

CONCLUSIONS:  A high rate of depression in adulthood and participants’ own descriptions of their painful memories and experiences of childhood identifies that more can and should be done to assist children of mentally ill mothers to cope with their environments. Interventions at various times in childhood are described.
Korean American Adolescent Depression and Parenting
Authors: Kim Eunjung , Cain Kevin C.
Published: April 2008

PROBLEM:  Korean American adolescents tend to experience more mental health problems than adolescents in other ethnic groups.

METHODS:  The goal of this study was to examine the association between Korean American parent–adolescent relationships and adolescents’ depressive symptoms in 56 families.

FINDINGS:  Thirty‐nine percent of adolescents reported elevated depressive symptoms. Adolescents’ perceived low maternal warmth and higher intergenerational acculturation conflicts with fathers were significant predictors for adolescent depressive symptoms.

CONCLUSIONS:  The findings can be used to develop a family intervention program, the aim of which would be to decrease adolescent depressive symptoms by promoting parental warmth and decreasing parent–adolescent acculturation conflicts.
Identification of the species in thePanicum capillarecomplex (Poaceae) from eastern Canada and adjacent New York State
Authors: Darbyshire S. J. , Cayouette J.
Published: April 2008

The Panicum capillare complex was examined in eastern Canada and New York State, United States. Uniform cultivation indicated distinctive growth habits for the five species. Univariate analysis of various morphological characters indicated some that were useful in species identification, especially when expressed as ratios. Discriminant function analysis of 4 floret characters in 128 samples and 13 morphological characters (including the 4 floret characters) in 48 samples indicated that floret characters, especially those related to overall size and shape (area and perimeter), were most informative. Various ecological and morphological characters useful for identification of the species are discussed. A key to the species is presented. Key words: Panicum capillare, identification, weeds.
Black stem galls on aspen: anatomy and histochemistry
Authors: Crane Patricia E. , Blenis P.V. , Hiratsuka Y.
Published: April 2008

Large black stem galls occur sporadically on trembling aspen (Populus tremuloides) in western Canada. Although little is known about their cause or structure, trees having these galls are less likely than surrounding aspen to have advanced decay caused by the fungus Phellinus tremulae. The anatomy and histochemistry of black galls and associated branch galls were studied and compared with normal wood and bark. Light microscopy showed that the cambium of black galls produces greater numbers of cells per growth ring and that growth rings are two to three times wider than normal. Vessel elements and fibers are unusually small and misshapen. Gall xylem has characteristics associated with wounding or infection: ray cells filled with phenolic deposits, and vessel elements occluded by tyloses and granular material. Frequent radial strands of undifferentiated callus tissue surrounded by necrophylactic periderms indicate sites of cambial damage of unknown cause. White areas within dark-colored gall xylem of some samples were free of most of these abnormalities, suggesting that a persistent agent is required for continuing tumor growth. Thickened outer bark harbored a variety of saprophytic fungi, especially hyphomycetes. Surface and internal morphology of black galls was also compared with similar stem galls caused by poplar budgall mites (Aceria parapopuli) and was found to be different. Bacteria, fungi, or mites were not obvious within living tissue, and further studies are necessary to determine the etiology of black galls. Key words: Populus tremuloides, poplar, black gall, wood anatomy.
Morphological effects of Epiccocum nigrum and its antibiotic flavipin on Monilinia laxa
Authors: Madrigal Carlos , Melgarejo Paloma
Published: April 2008

The influence of an isolate of Epicoccum nigrum and one of its antibiotics, flavipin, on the spores, mycelium, and germ tubes of Monilinia laxa in culture was studied using light and electron microscopy. Epicoccum nigrum and flavipin induced the development of stromata in cultures. Abundant clusters of microconidia of M. laxa were produced on the induced stromata exposed to E. nigrum and flavipin. Deformation of hyphae and germ tubes such as swellings, coilings, and abnormal ramifications were also noticeable under light and scanning electron microscopy after treatment with E. nigrum or flavipin. Transmission electron microscopy revealed cytoplasmic coagulation of the cells and abundant vacuoles and lipid bodies associated with membranes. In some cases alteration and disorganization of membranes was also apparent. Key words: antagonism, antibiosis, flavipin, biological control.
Aboveground growth habits of two Vaccinium species in relation to habitat
Authors: Tolvanen Anne
Published: April 2008

Ramet morphology in the deciduous Vaccinium myrtillus L. and the evergreen Vaccinium vitis-idaea L. was compared between the forest and open, clear-felled habitats. Growth habits were measured in terms of branching, shoot mass, bud type, branching angle, and vertical elevation of ramets. New ramets of both species were produced from buds on the below-ground stem. Branching occurred from buds on 1-year-old shoots in young ramets. Aging and flowering induced rejuvenation, i.e., production of new shoots from buds on older shoot generations within the ramets. Sympodial V. myrtillus ramets were more branched than the predominantly monopodial V. vitis-idaea ramets. In ramets of both species, vegetative shoots grew primarily from distal buds in the forest, whereas a greater number of lower buds were activated in the ramets in the open habitat. Vaccinium myrtillus ramets grew more horizontally and had wider branching angles to increase the intercepted radiation in the forest, whereas compact, vertically growing ramets prevailed in the open habitat, where light was not limited. No difference in branch orientation was observed between habitats in V. vitis-idaea. Production of flowers was greater in the open habitat than in the forest in both species. The observed differences in growth habits between forest and open habitat were assumed to indicate high morphological plasticity in both species, allowing the plants to respond rapidly to changed environmental conditions. Key words: architecture, branching, growth habit, shrub, Vaccinium.
Effet de deux extraits biologiques sur l'embryogenèse somatique et sur la rétention des capacités de régénération chez les cals de blé (Triticum aestivum)
Authors: Zair I. , Chlyah B. , Chlyah H.
Published: April 2008

The effect of extracts of potato or immature wheat seeds, polyethylene glycol, or mannitol on the embryogenic capacity of calli derived from half or whole immature embryos of wheat (Triticum aestivum L.) has been studied. Calli initiated from embryo halves give the same yield of somatic embryos and regenerated plantlets as calli from whole embryo cultures. Compared to control cultures, calli initiated on potato extract are more embryogenic (> 70% embryogenic calli), form bigger embryos in a more reduced number, but that show a higher frequency of plant regeneration and longer retention of the regeneration capacity. The calli initiated on a wheat seed extract form less embryogenic calli and more but smaller somatic embryos; they have a shorter retention of their regeneration capacity. Increase in osmotic potential by addition of polyethylene glycol or mannitol to the culture medium did not improve somatic embryogenesis. Key words: Triticum aestivum, callus, embryogenesis, biological extracts.
Distribution of microfungi in the transitional zone of a subtropical lake in India
Authors: Mishra R. C.
Published: April 2008

Counts of CFU of microfungi, percent carbon, nitrogen, phosphorus, sodium, potassium, and calcium content, and pH were determined in upland, transect, and bottom soils, the transitional zone of Gujar Lake, a subtropical and eutrophic lake in India (25°58′N, 82°39′E). Microfungi in all zones were distributed in aggregate pattern, as evidenced by significant t values (P > 0.001) and F ratios (P > 0.001) of the variance–mean test and Morisita's index. A qualitative survey revealed that Alysidium sp., Arthrinium phaeospermum, Gliomastix murorum, Pythium sp., Tliermomyces sp., Thielavia terricola, Westerdykella multispora, and Varicosporium elodae were found specific to bottom soil of the lake. Key words: distribution, microfungi, transitional zone, subtropical, correlation.
The Utility of Light-Saturation Models for Estimating Marine Primary Productivity in the Field: A Comparison with Conventional "Simulated" In Situ Methods
Authors: Harrison W. G. , Platt T. , Lewis M. R.
Published: April 2008

Primary production rates derived from model photosynthesis–light (P–l) curves and daily solar radiation data were compared with direct measurements using "simulated" in situ incubations in arctic and temperate marine waters. On the average, model estimates were slightly higher in surface waters and significantly lower at the bottom of the euphotic zone (1% light level) than were the measured values. This could be partially explained by spectral differences in incubation light sources. However, areal production rates were statistically indistinguishable. Use of P-l models without a photoinhibition term and incorporating P-l pararmeters from mixed-layer populations gave the best overall agreement with directly measured production rates.
Stock Assessment Problems in Atlantic Herring (Clupea harengus) in the Northwest Atlantic
Authors: Sinclair M. , Anthony V. C. , Iles T. D. , O'Boyle R. N.
Published: April 2008

Total annual catches of Atlantic herring (Clupea harengus) in NAFO statistical areas 3–6 have declined steadily since 1968, and have not rebounded after management measures were implemented in the late 1970's (unlike demersal species in the area). The accuracy of the biomass estimates generated by sequential population analysis is evaluated by a retrospective analysis for 3 of the 10 management units for herring fisheries. In each case, the stock assessments have tended to seriously underestimate the declines in stock abundance and overestimate the upswings. Fishing mortalities have exceeded F0.1, but they have rarely exceeded Fmax, the level below which growth overfishing is prevented. Three assumptions in the stock assessment process are evaluated in relation to the 4WX management unit: (1) the various management units are in fact self-sustaining populations; (2) catchability (i.e. fishing mortality per unit of effort) is constant and independent of stock size; and (3) the population is in the stable age distribution. We conclude that at least part of the management failures are due to invalid assumptions in the stock assessment models. An approach that has prevented growth overfishing may well have caused recruitment overfishing. Atlantic herring should be managed on principles suited to salmon rather than those applied to groundfish.
Estuarine Growth of Juvenile Chinook Salmon (Oncorhynchus tshawytscha) as Inferred from Otolith Microstructure
Authors: Neilson John D. , Geen Glen H. , Bottom Daniel
Published: April 2008

The growth of juvenile chinook salmon (Oncorhynchus tshawytscha) in the Sixes River Estuary, Oregon, was inferred from otolith microstructure. Otolith increments appeared to be formed daily, on average, and a transition between those produced during freshwater residence and estuary residence was apparent. Otolith microstructure was also examined with respect to time series of water temperature, population density, and benthic standing crop data. While the results supported the hypothesis of food-limited growth, elevated water temperatures in midsummer may have decreased food conversion efficiencies, thus also contributing to an observed growth rate decline. It was also found that from counts of otolith increments formed during freshwater life, fish that hatched relatively late tended to spend less time in freshwater before moving downstream to the estuary.
Internal Zonations in Sections of Vertebrae from Atlantic Bluefin Tuna, Thunnus thynnus, and Their Potential Use in Age Determination
Authors: Prince Eric D. , Lee Dennis W. , Javech Joaquin C.
Published: April 2008

Internal zonations (bands) were observed in thin sections of vertebrae from 98% of the 200 Atlantic bluefin tuna, Thunnus thynnus, we examined between 49.5 and 284.5 cm fork length (FL). These zones occurred in the solid bone area of the sections corresponding to the outer margin of the vertebral cone surface. The remaining area of the section nearest the focus is characterized by spongy bone which obstructs internal zonations associated with early growth history. We present a modified method of determining vertebra age of Atlantic bluefin tuna by adopting a counting procedure which involves enumerating distal internal bands in the sections, as well as proximal external bands on the cone surface to assign ages. Accuracy of this methodology was assessed by evaluating fish where age was known from length frequency and tagging data. The accuracy and precision of estimating age of giant bluefin tuna [Formula: see text] was improved using our vertebral section method of age determination compared with the more traditional whole vertebra method of ageing. However, results of the vertebral section method in ageing medium tuna (146.0–208.9 cm FL) were inconclusive and this method overestimated age of school tuna (49.5–145.9 cm FL) and should not be used for juvenile age groups. The occurrence of internal zonations in vertebrae of teleosts other than bluefin tuna should be examined as a possible source of age and growth information.
A Bioeconomic Analysis of Sequential Fisheries: Competition, Coexistence, and Optimal Harvest Allocation Between Inshore and Offshore Fleets
Authors: Charles Anthony T. , Reed William J.
Published: April 2008

A bioeconomic model is developed to determine optimal harvest allocation between "offshore" and "inshore" fleets exploiting a single fish stock in sequential fisheries. The socially optimal policy for maximizing total discounted rent is determined in terms of optimal escapement levels in each fishery. Whether exclusion or coexistence of the two fleets occurs under open access and under optimal management is found to depend primarily on inshore/offshore price and cost ratios, together with biological parameters related to the age structure of the fish stock. We discuss how fishery regulations, such as separate landings taxes imposed on each fleet, can be used to jointly optimize open-access exploitation in sequential fisheries.
Comparison of Constant Effort Harvest Policies for Fish Stocks with Variable Recruitment
Authors: Hightower Joseph E. , Grossman Gary D.
Published: April 2008

Environmental variability may have a substantial influence on marine fish stocks, primarily by affecting survival to the time of recruitment. Simulation studies at low, intermediate, and high levels of variability in recruitment were used to compare alternative constant effort policies for anchovy (Engraulis capensis), Atlantic menhaden (Brevoortia tyrannus), and Pacific ocean perch (Sebastes alutus) fisheries. These policies were either to maintain effort at the level producing maximum sustainable yield (fMSY), or to permit levels of effort 25–100% greater than fMSY. An increase in effort of 25% above fMSY typically did not reduce annual yield significantly; however, a significant reduction in yield was apparent in all cases when effort increased by 75–100%. When recruitment is highly variable, comparable yields may be obtained at several levels of fishing effort. In such cases, environmental variability provides the fishery manager with considerable flexibility to enhance social or economic benefits without decreasing yields significantly.
Effects of Available Dietary Carbohydrate and Water Temperature on the Chronic Toxicity of Waterborne Copper to Rainbow Trout (Salmo gairdneri)
Authors: Dixon D. G. , Hilton J. W.
Published: April 2008

We used a factorial design to determine the effects of dietary carbohydrate content (0.1 or 25.6%) and temperature (10 or 15 °C) on the chronic toxicity of waterborne copper (0 or 144 μg Cu∙L−1) to rainbow trout (Salmo gairdneri) over a 12-wk period. Relative to those on the low-carbohydrate (LC) diet, trout reared on the high-carbohydrate (HC) diet developed enlarged, glycogen-filled livers and attained reduced final mean wet body weights. This response was more pronounced at 10 than at 15 °C. Whereas Cu exposure had no significant effect on the growth or mortality of either LC or HC fish at 15 °C, or LC fish at 10 °C, HC fish at 10 °C showed significantly reduced final weight and increased mortality. Trends toward reduced liver glycogen and increased serum glucose, characteristic of chronic stress, were apparent in all Cu-exposed fish. In Cu-free water, mean Cu concentrations in liver tissue of HC fish were significantly lower than those in LC fish at both temperatures. Copper exposure resulted in significant increases in liver Cu concentration for all diet treatments except HC at 10 °C. Elevated serum sorbitol dehydrogenase levels, indicative of hepatic damage, were apparent in Cu-HC fish at 15 °C and in HC, Cu-HC, and Cu-LC fish at 10 °C. No treatment effects on either serum protein or hematocrit were evident. The treatments during the growth period affected subsequent lethal tolerance of Cu. While the 96-h Cu LC50 was not significantly altered by diet alone at 15 °C, it was elevated in HC fish, relative to LC fish at 10 °C. The Cu LC50 of Cu preexposed fish was significantly elevated, relative to parallel groups held in Cu-free water, for LC fish at both 10 and 15 °C. This acclimation to Cu was not apparent in HC fish at either temperature: no significant elevation in LC50 occurred as a result of preexposure. We conclude that increased dietary carbohydrate can significantly increase the chronic toxicity of Cu to trout, and that the impact is enhanced by reduced water temperature.
Questions and Comments on the River Continuum Concept
Authors: Statzner Bernhard , Higler Bert
Published: April 2008

The River Continuum Concept (RCC) is a generalized conceptual framework for characterization of pristine running water ecosystems. Of the numerous tenets of the concept we particularly reevaluated the following: biological analogues of energy equilibrium and entropy in the physical system; maximization of energy consumption through continuous species replacement over a year; absence of succession in stream ecosystems, which can thus be viewed in a time-independent fashion; and maximization of biotic diversity in midreaches of streams as a result of the occurrence of highest environmental variability there together with spatial abundance shifts of insects, molluscs, and crustaceans. When emphasis is placed on rapid changes in the downstream hydraulics dependent on discharge and slope (both of which are expressed by stream order in the RCC and are key factors of the concept) and on results from tropical studies, some of these tenets are partly refuted or need extension. Some of them are in conflict with the current state of knowledge in other domains of stream ecology or are at least open to various interpretations. Therefore, we advocate modifications of the theoretical background of the RCC.
Relationship between Concentrations of Copper and Zinc in Water, Sediment, Benthic Invertebrates, and Tissues of White Sucker (Catostomus commersoni) at Metal-Contaminated Sites
Authors: Miller P. A. , Munkittrick K. R. , Dixon D. G.
Published: April 2008

The relationship of concentrations of copper (Cu) and zinc (Zn) in white sucker (Catostomus commersoni) tissues to concentrations of those metals in water, sediment, and benthic invertebrates (food) were investigated in a field study. Fish were collected from six northern Ontario lakes contaminated with mixed-metal mining wastes. The concentrations of Cu in invertebrates were correlated with water but not with sediment Cu concentrations. Conversely, Zn concentrations in invertebrates were correlated with sediment but not with water Zn concentrations. There were differences among fish from different lakes in the concentrations of Cu and Zn in liver, kidney, gill, and bone (Zn only). There were no significant correlations between tissue metal and invertebrate metal concentrations. This study suggests that liver and kidney are better indicators of chronic Cu and Zn exposure than muscle. Elevated Zn concentrations were reflected in bone tissue. For both metals, the water concentration was a better predictor of fish tissue contamination than the concentrations in either sediment or invertebrates.
Estimation of historical stock sizes and recruitment anomalies from relative abundance time series
Authors: Walters Carl
Published: April 2008

Often only simple relative abundance time series and basic growth and (or) survival estimates are available for assessing impacts of fishing and environmental factors. Assessment then involves fitting production models to the series, while forcing the model with observed catch or effort series. A key uncertainty in this approach is how to deal with recruitment variations due to factors other than stock size. A dynamic programming algorithm can be used to compute maximum likelihood estimates of the recruitment anomaly sequence, given prior knowledge of growth parameters, the natural survival rate, and proportion of the variation in the relative abundance index that is due to abundance measurement errors. The temporal pattern of anomaly estimates from the dynamic programming procedure is quite robust to uncertainties about the absolute stock size and average historical recruitment rate, so it can at least provide information for studies of factors affecting recruitment in cases where the abundance index measurement error is small compared with recruitment process errors (<10% of total error). Further, the procedure can easily be embedded within a Bayesian or maximum likelihood estimation of stock size and surplus production.
Predator responses to prey population dynamics: an empirical analysis based on lake trout growth rates
Authors: Eby Lisa A. , Rudstam Lars G. , Kitchell James F.
Published: April 2008

Lake trout (Salvelinus namaycush) growth rates were lower in Lake Superior (with the lowest prey density) than in Lakes Michigan and Ontario. In contrast, consumption rates (estimated using bioenergetics models) of lake trout were similar in Lakes Superior, Michigan, and Ontario because the primary prey in Lake Superior, rainbow smelt (Osmerus mordax), have a lower energy content than the primary prey in Lakes Michigan and Ontario, alewife (Alosa pseudoharengus). Estimated consumption rates did not respond to three-to five-fold changes in prey density within lakes and were similar across a 100-fold difference in prey density among lakes. These results demonstrate that lake trout are able to sustain high predation rates at low prey densities and a type II functional response fitted to these data rises very steeply at low prey densities. Two factors are implicated: the large search volume of these predators and disparity between the average density estimates of prey stock assessment and the spatial and temporal scaling appropriate for understanding predator–prey interactions. If prey are highly aggregated or predators can search large areas, then a decrease in whole-lake prey abundance will not necessarily result in a lower predation rate until prey populations are severely reduced.
The use of one-dimensional compression tests and elastic theory in predicting deformations of rockfill embankments
Authors: Charles J. A.
Published: April 2008

A laboratory investigation into the deformation behaviour of a rockfill material undergoing anisotropic compression at different stress ratios is described. The extent to which elastic parameters derived from one-dimensional compression can predict the behaviour of the rockfill at other stress ratios is considered. Stress paths encountered in embankments of cohesionless fill are examined and the relevance of elastic parameters derived from one-dimensional compression tests in analysing the deformations of such embankments is assessed.
Geotechnical design aspects for large gravity retaining structures under seismic loading
Authors: Thompson C. D. , Emery J. J.
Published: April 2008

Large wharf gravity retaining walls are often constructed in areas of Canada where seismic activity of a level that has damaged marine structures in other countries can be anticipated. From a geotechnical viewpoint, much of this damage is related to the liquefaction of sands and silts in foundations or backfills. It is critical that zones of potential liquefaction be detected, and this may require more extensive field and laboratory testing than for static designs. Simplified procedures for evaluating the liquefaction potential of sands and silts are presented, and some guidelines for sensitive clays are discussed. Since hydraulic fill is often used, remedial measures and specifications to avoid liquefaction of backfills are described. These include densification of the soil and provision of materials outside the gradation range that is most susceptible to liquefaction. While tsunamis arrive after the strong shaking, they can be the source of significant damage in areas where they might occur. Conservative earth pressure parameters are given for areas exposed to tsunamis, and these may be employed for initial assessment of potential problems from offshore earthquakes. The various geotechnical aspects considered must be closely related to other design factors such as seismic exposure, earth pressures, and allowable short-term safety factors.
La cartographie d'excavation en géologie urbaine—application à la région de Montréal
Authors: Durand Marc
Published: April 2008

Geological events dating back to the early Paleozoic (500 million years) have produced marked bedrock conditions in the Montreal area. The geological features are sometimes of importance to the execution and the cost of engineering works.Boreholes provide samples and data on the subsurface conditions, but cannot yield as much information as an open excavation. Detailed surveys of exposed cuts supplement the results of preliminary borings and confirm or modify their conclusions. These could sometimes mean appreciable savings on the construction cost or warnings of foundation designs not suited to actual site conditions. [Traduit par la revue]
The strain hardening behaviour of particulate media
Authors: Frydman S.
Published: April 2008

The strain increment resulting from an increment of stress applied to a particulate medium has been expressed in terms of its elastic and plastic components. The concepts of strain-hardening plasticity have been employed to develop an incremental stress–strain relation, based on a non-associated flow rule. The parameters appearing in the relation have been found using results of three-dimensional shear tests on sands and glass-microspheres. It is suggested that relations of the type developed in the paper could be beneficially incorporated into a finite-element program.
Deformation of the Deer Creek bridge by an active landslide in clay shale
Authors: Kelly A.J. , Sauer E. Karl , Barbour S.L. , Christiansen E.A. , Widger R.A.
Published: April 2008

Two parallel, concurrently active slip surfaces of a landslide in clay shale of the Cretaceous Lea Park Formation are causing deformation of a bridge structure across the North Saskatchewan River near Deer Creek, Saskatchewan. The upper slip occurs at the contact between the shale and glacial deposits, which is common in this region. However, the second slip occurs deep in the shale, 24 m below the upper slip zone. This multilevel landslide mechanism, not reported previously in this region, is resulting in a complex deformation pattern where components of the structure are moving at different rates. The multilevel slip mechanism is related to a unique combination of the hydrogeology and geologic structure at this site. Under an upward groundwater gradient, slip surfaces occur at discontinuities in available shearing resistance at different elevations in the shale. The discontinuities are gouge zones in the clay shale, which are the result of a combination of glacial shear and regional tectonism where parameters have been reduced to a residual state ([Formula: see text] and c′ = 0). The pore-water pressures for the slope stability analysis were generated from a site specific finite element seepage model using boundary conditions determined from a regional finite element seepage model. The groundwater models were calibrated from piezometer data and from hydrochemistry of water from farm wells, piezpmeters, and natural surface ponds. The hydrochemistry was used to delineate groundwater, discharge areas from recharge areas. The validity of the landslide mechanism is supported by a stability analysis integrated with the finite element seepage analysis, which demonstrates that two separate parallel slip surfaces at different depths can be at a state of limiting equilibrium concurrently. Key words : bridge deformation, Cretaceous shale, integrated models, residual strength, multilevel slips.
A new two point method of obtainingCvfrom a consolidation test
Authors: Prasad Yenumula V.S.N. , Rao S. Narasimha
Published: April 2008

The time factor, T, and the degree of consolidation, U, from Terzaghi's theory of consolidation can be shown to have a straight line relationship when plotted as log[– T/log (T/U)] versus log T. Oedometer tests were conducted on five soils with a wide variation in properties. The results obtained establish straight line variation between log[t/log(7/δ)] and log t plots. Using this property, a method is proposed to predict the compression (δ) versus time (t) behaviour of clayey soils by measuring the compression values of a soil specimen at only two time intervals in oedometer test. Variation of δ with t is predicted using the proposed method for some of the soils tested, and the computed values of Cvare compared with the actual experimental Cvvalues. Some of the published test results are used to validate the proposed method. Key words : coefficient of consolidation, clays, oedometer test, time–compression, settlements.
Derivative-assisted evaluation of well yields in a heterogeneous aquifer
Authors: Parks Kevin P , Bentley Laurence R
Published: April 2008

The evaluation of well yields conventional timedrawdown methods is based on the assumption of infinite-acting radial flow (IARF) of groundwater to a well. However, long-term well yields are controlled by heterogeneities and, as suggested here, by the presence of linear features and aquitard leakage, and the subsequent departures from IARF. Accurate prediction of long-term well yields therefore requires an evaluation of aquifer heterogeneities. Derivative techniques combined with aquifer geology and conventional methods aid in the evaluation of long-term well yields in the heterogenous aquifers. Our case study involves the estimation of long-term well yields from relatively short-term aquifer tests in an aquifer near Calgary, Alberta. The wells are completed in a gravel-floored cahnnel incised into bedrock. On the regional scale, the floor gravels appear to form a continuous and homogeneous aquifer. Aquifer-test responses indicate internal heterogeneity at a scale below the resolution attainable with the available well control. Reliable estimates of aquifer parameters are obtained by applying a derivative technique to the analysis of timedrawdown data. Derivative analysis allows us to isolate test segments for which the assumption of IARF is valid. Characteristic timedrawdown and derivative curves are then integrated with geology to identify the nature of heterogeneities and assess their impact on long-term aquifer response to pumping.

Key words: aquifer-test, derivative, heterogeneity, well yield, buried valley aquifer.
Natural-color and color-infrared photography for the identification of forest-stand density, height, and species composition
Authors: Morton Robert T. , Titus Stephen J. , Crown Peter H.
Published: April 2008

Natural-color and color-infrared aerial photography at scales of 1:30 000, 1:50 000, and 1:70 000 were evaluated for the interpretation of forest-stand density, height, and species class, for test areas in the boreal and foothills regions of Alberta. Accuracy was assessed by comparing photo interpreter identification to field measurements. When averaged over all scales, color film types did not differ in accuracy. Scale affected identification accuracy for density and species class. The 1:70 000 scale was most accurate for estimating density and least accurate for species class. Scale did not affect identification accuracy for 6-m height classes. Interpreter inventory experience and color-discrimination ability both affected accuracy for species class, but not density or height. Standard 1:15 000 scale black and white photography was not significantly more accurate than any of the other film–scale combinations for identification of density, height, or species class.
Accuracy of sequential sampling plans based on Wald's sequential probability ratio test
Authors: Fowler Gary W.
Published: April 2008

Monte Carlo operating characteristic (OC) and average sample number (ASN) functions were compared with Wald's OC and ASN equations for sequential sampling plans based on Wald's sequential probability ratio test (SPRT) using the binomial, negative binomial, normal, and Poisson distributions. This comparison showed that the errors inherent in Wald's equations as a result of "overshooting" the decision boundaries of the SPRT can be large. Relative errors increased for the OC and ASN equations as the difference between the null (θ0)) and alternative (θ1) test parameter values increased. Relative errors also increased for the ASN equation as the probabilities of type I (α) and type II (β) errors increased. For discrete distributions, the relative errors also increased as θ0 increased with θ1/θ0 fixed. Wald's equations, in general, overestimate the true error probabilities and underestimate the true ASN. For the values of θ0, θ1, α, and β used in many sequential sampling plans in forestry, Wald's equations may not be adequate. For those cases where the errors in Wald's equations are important compared with the other errors associated with the sampling plan, two alternative Monte Carlo OC and ASN functions are proposed.
Suppressed crown expansion and increased bud density after precommercial thinning in California Douglas-fir
Authors: Maguire Douglas A.
Published: April 2008

A densely regenerated Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantation in northern California was precommercially thinned from approximately 15 000 stems/ha to 740 stems/ha. Trees in an unthinned strip served as control for analyzing thinning responses. The terminal and lateral leader growth of "released" trees were significantly reduced after thinning, but the number of buds was significantly increased.
RANK FOUR SYMPLECTIC BUNDLES WITHOUT THETA DIVISORS OVER A CURVE OF GENUS TWO
Authors: HITCHING GEORGE H.
Published: April 2008

The moduli space [Formula: see text] of rank four semistable symplectic vector bundles over a curve X of genus two is an irreducible projective variety of dimension ten. Its Picard group is generated by the determinantal line bundle Ξ. The base locus of the linear system |Ξ| consists of precisely those bundles without theta divisors, that is, admitting nonzero maps from every line bundle of degree -1 over X. We show that this base locus consists of six distinct points, which are in canonical bijection with the Weierstrass points of the curve. We relate our construction of these bundles to another of Raynaud and Beauville using Fourier–Mukai transforms. As an application, we prove that the map sending a symplectic vector bundle to its theta divisor is a surjective map from [Formula: see text] to the space of even 4Θ divisors on the Jacobian variety of the curve.
ON EQUALITY CONDITION FOR TRACE JENSEN INEQUALITY IN SEMI-FINITE VON NEUMANN ALGEBRAS
Authors: HARADA TETSUO , KOSAKI HIDEKI
Published: April 2008

Let τ be a faithful semi-finite normal trace on a semi-finite von Neumann algebra, and f(t) be a convex function with f(0) = 0. The trace Jensen inequality states τ(f(a* xa)) ≤ τ(a* f(x)a) for a contraction a and a self-adjoint operator x. Under certain strict convexity assumption on f(t), we will study when this inequality reduces to the equality.
EXISTENCE OF COHERENT SYSTEMS
Authors: TEIXIDOR I. BIGAS MONTSERRAT
Published: April 2008

A coherent system of type (r, d, k) on a curve consists of a vector bundle of rank r and degree d together with a vector space of dimension k of the sections of this vector bundle. There is a stability condition depending on a positive real parameter α that allows to construct moduli spaces for these objects. This paper shows non-emptiness of these moduli spaces when k > r for any α under some mild conditions on the degree and genus.