bluuebunny/crossref_metadata_2025_split huggingface dataset:
Littoral flow rates within and around submersed macrophyte communities
Authors: LOSEE RICHARD F. , WETZEL ROBERT C. 
Published: May 2006

SUMMARY

The magnitude and range of water flow rates were measured within and adjacent to plant beds at different depths and among different dominant submersed plant species in the littoral zones of two lakes with contrasting morphometry.
There was very little variability in within‐bed flow rates, either for locations within or among beds. However, when significant differences occurred in within‐bed flow rates, the higher rates occurred predominately near the bottom of the Scirpus subterminalis bed where the plant surface area to water volume ratio was lowest.
Factors such as bed depth and dominant species had little effect on within‐bed flow rate variance. Flows external to the plant beds were dissipated within 10–15 cm of the outer plant‐bed boundary even under severe external flow‐rate conditions (flow rate ∼ 30cms−1).
The mean within‐bed flow rate was 0.07cms−1 and individual experiment means ranged from 0.03 to 0.46cms−1. These flow rates resulted in estimates of laminar flow boundary layer thickness, 1 mm from the leading edge of the leaf, ranging from 9.1 to 2.3mm. These estimates are much larger than submersed macrophyte leaf thicknesses themselves (<1 mm).
Stream community structure in relation to spatial and temporal variation: a habitat templet study of two contrasting New Zealand streams
Authors: SCARSBROOK MIKE R. , TOWNSEND COLIN R. 
Published: May 2006

SUMMARY

The physical characteristics of two contrasting streams, and habitat types within these streams, are described in terms of a two‐dimensional physical habitat templet in which disturbance frequency and the availability of spatial refugia are the temporal and spatial axes.
It is predicted that habitats experiencing a high disturbance frequency and low refuge availability will be characterized by a low invertebrate species diversity, a low biomass of epilithic algae and particulate organic matter and a community made up of mobile, weedy species. Habitats having a low disturbance frequency and high refuge availability will be characterized by a diverse community containing sedentary and specialist species, with high algal and particulate organic matter levels.
A lower median substrate particle size and higher shear stress regime in Timber Creek were indicative of a higher disturbance frequency than in the Kyeburn. Substrate diversity was lower in Timber Creek than in the Kyeburn and indicated that the availability of refugia was lower in Timber Creek. In both streams, pools were found to have a higher disturbance frequency and lower availability of refugia than riffles.
Invertebrate species diversity, the biomass of epilithic algae and particulate organic matter and the representation of sedentary species, filter feeders and shredders were higher in the more temporally stable and spatially heterogeneous Kyeburn. The community of Timber Creek, frequently disturbed and having low refuge availability, had a high proportion of mobile and weedy species, with the highly mobile, generalist‐feeding Deleatidium spp. (Ephemeroptera; Leptophlebiidae) being the most dominant organisms.
The predictions made about stream community structure and species characteristics in relation to disturbance frequency and the availability of spatial refugia are generally supported. Now a larger scale investigation is required to test the generality of the predictions. We conclude that the habitat templet approach offers a sound framework within which to pose questions in stream ecology.
Factors affecting litter processing by Anisocentropus kirramus (Trichoptera: Calamoceratidae) from an Australian tropical rainforest stream
Authors: NOLEN J.A. , PEARSON R.G. 
Published: May 2006

SUMMARY

Larvae of the caddisfly Anisocentropus kirramus are common leaf shredders in rainforest streams in tropical Queensland. Laboratory experiments were undertaken to examine the effects of (a) differences in leaf species, age and degree of conditioning, (b) leaf preferences, (c) temperature and (d) larval stage on processing of leaf litter by A. kirramus.
Leaf species (five tested), age (fresh v senescent) and condition (conditioned in stream v unconditioned) each had a significant effect on the amount of leaf material that was processed. For most species, conditioned leaves were processed faster but for one species unconditioned leaves were processed faster. Senescent leaves were processed more rapidly than green leaves in three species but not in the other two. Given a choice of leaf types A. kirramus actively selected leaves that were processed faster; no preference was shown between two different ‘fast’ leaves.
Processing occurred at all temperatures tested (10, 18 and 25°C), with the processing rate increasing with temperature. Younger instar larvae processed leaves at a greater rate per unit body weight (up to 343% day−1) than older instars. Final instar (5) larvae were capable of processing some tough leaves that younger instars did not process.
In rainforest streams, processing of leaves by A. kirramus takes place throughout the year. Its ability to process green leaves is important because of the high input of fresh green leaves into tropical streams, and because of the severe depletion of the supply of conditioned leaves and fine detritus after floods.
Filamentous algal communities related to pH in streams in The Trossachs, Scotland
Authors: KINROSS J.H. , CHRISTOFI N. , READ P.A. , HARRIMAN R. 
Published: May 2006

SUMMARY

A survey of acidified streams in the Loch Ard area of The Trossachs, Scotland, was carried out between 1986 and 1988, to determine the influence of physical and chemical factors on the distribution of benthic algae. Samples were taken on thirty‐five occasions from fifteen sites on ten streams. Forty‐nine operational taxa of filamentous algae were distinguished. Relative abundance of taxa in samples was scored on a seven‐point scale. Estimates of standing crop were made by pigment extraction and ash‐free dry weight (AFDW) determination from biomass developed on artificial substrata.
No evidence was found for seasonality in standing crop, nor for an increase in standing crop with a decrease in pH. Seasonality in relative abundance was evident for few taxa. Species richness and diversity were highly correlated with pH and correlated chemical variables.
Canonical correspondence analysis (CCA) carried out using the CANOCO program ordinates species and sites and relates them directly to environmental variables. The most important variable was found to be pH (or an acidification‐related variable that is highly correlated with pH), with percentage forest cover and total oxidized nitrogen being of secondary importance. The effect of subdividing the data set, using data based on presence‐absence as well as estimated relative abundance, was tested. A comparison of the effects on the distribution of site and species values on the pH vector showed that the results are robust, confirming the value of this semi‐quantitative sampling method for use with a difficult algal group. It was possible to infer pH from algal community structure using CANOCO.
The pH ranking of species derived from CCA revealed that larger cell diameter taxa do not predominate at low pH, implying that reduction of invertebrate grazing was not an important determinant of algal community composition.
Production and turnover ofHyalella aztecain central Ontario, Canada compared with other regions
Authors: FRANCE R.L. 
Published: May 2006

SUMMARY Hyalella azteca(Amphipoda) inhabiting macrophyte beds in eight Canadian Shield lakes were sampled during the ice‐free seasons of 1984 and 1985. These amphipods were found to be predominantly univoltine in contrast to suggestions from a previous study. Annual production determined by the size‐frequency method ranged from 1.21 to 2.77g dry wt m−2year−1, and are the highest rates recorded for this species in temperate waters. Turnover rates (P/B ratios) ranged from 2.27 to 3.48 and are among the lowest values that have been measured. A synthesis of these data indicates that H.aztecaturnover rates increase sigmoidally with degree‐days above 5°C.
Ecological effects of river ice break‐up: a review and perspective
Authors: SCRIMGEOUR GARRY J. , PROWSE TERRY D. , CULP JOSEPH M. , CHAMBERS PATRICIA A. 
Published: May 2006

SUMMARY1. Abiotic disturbances strongly modify spatial and temporal patterns of lotic ecosystem community structure and function. Such effects are produced because disturbances alter organic matter, nutrient and contaminant dynamics and the distribution and abundance of bacterial, algal, macroinvertebrate and fish communities.2. River ice break‐up is a seasonal disturbance in rivers at high altitudes and latitudes world‐wide and is characterized, in part, by large increases in current velocity, stage, water temperature, concentrations of suspended materials and substrate scouring.3. These abiotic factors are likely to have important effects on primary producers, consumers, and food‐web dynamics of river biota. Despite the potential importance of river ice break‐up on community structure and function, detailed information describing the magnitude of their effects and underlying causal mechanisms is scarce.4. The objective of this paper is to provide a hydrological and ecological review and perspective on the potential effects of ice break‐up on lotic ecosystems. Specifically, the potential importance of break‐up on water temperature, river sediments and geomorphology, riverine energy sources, contaminants, and its effects on river biota and food‐web dynamics are evaluated.
Life history plasticity of Nemoura trispinosa (Plecoptera: Nemouridae) along a permanent‐temporary water habitat gradient
Authors: WILLIAMS D. DUDLEY , WILLIAMS NANCY E. , HOGG IAN D. 
Published: May 2006

SUMMARY1. The life history of the small herbivorous stonefly Nemoura trispinosa Claassen was studied in a variety of small springs in southern Ontario, Canada. Nymphs generally were able to tolerate a wide range of environmental conditions and were found in 78% of habitats sampled, although population densities differed markedly.2. Life‐cycle patterns varied from a univoltine, slow seasonal type to a univoltine, fast seasonal type with extended egg development. In one, highly stable, spring the life cycle was semivoltine. Inter‐year variation was studied for 5 years in one spring and was found to be low relative to among‐spring variation.3. Differences in the life history traits of N. trispinosa populations from our spring series were most probably an expression of phenotypic plasticity rather than of genetic differentiation.4. Maximum annual water temperature was the factor most influential on nymphal growth rate (non‐linear relationship), whereas range in generation time was related to the degree of habitat permanence.
Growth, production and losses of phytoplankton in the lowland River Spree: carbon balance
Authors: KÖHLER JAN 
Published: May 2006

SUMMARY1. Phytoplankton carbon assimilation and losses (exudation, dark carbon losses) as well as oxygen release and dark community respiration were measured regularly for 2 years at four stations along the lower Spree (Germany). Carbon balance of river phytoplankton was estimated using measured assimilation, metabolic losses and variations in algal carbon along a stretch of river.2. The light/dark bottle method was modified to simulate vertical mixing.3. Waxing and waning of phytoplankton populations dominated the load of particulate organic carbon as well as the oxygen budget of the river.4. Phytoplankton assimilated 310–358 g C m−2 yr−1. A mean value of 586 mg C m−3 day−1 was fixed in photosynthesis, with 16.7 mg C being exuded during the day and 20.1 mg lost at night. The measured dark respiration was equivalent to only 28% of the daily gross oxygen production of the plankton community. Phytoplankton washed from upstream lakes and reservoirs was not measurably damaged by turbulent transport.5. In spring, 18–22% of assimilated carbon was used for net biosynthesis of phytoplankton along the river course. At this time, the carbon balance of this part of the Spree was dominated by autochthonous net production. During summer, however, total carbon losses exceeded the intensive carbon assimilation. The decline of algal biomass along the river course in summer was not explicable by measurable physiological losses. The importance of sedimentation and grazing losses is discussed.
The influence of water chemistry on the enzymatic degradation of leaves in streams
Authors: JENKINS CINDY C. , SUBERKROPP KELLER 
Published: May 2006

SUMMARY1. Aquatic hyphomycetes degrade leaf litter in both softwater and hardwater streams. During growth on leaves, these fungi secrete an array of extracellular polysaccharidases that are differentially affected by pH. Hydrolytic enzymes exhibit acidic pH optima, whereas pectin lyases have neutral to alkaline pH optima.2. Enzyme activities associated with microbial communities colonizing yellow poplar (Liriodendron tulipifera) leaves submerged in an acidic (pH 6.3), softwater stream were compared with those occurring in an alkaline (pH 8.2), hardwater stream. In addition to pH differences, the hardwater stream had higher nutrient concentrations and higher temperatures than the softwater stream. Conditions in the hardwater stream favoured greater microbial growth, fungal activity, rates of leaf breakdown and softening. However, activities of hydrolytic enzymes (xylanase, endocellulase, galacturonanase) were lower in the hardwater stream than in the softwater stream. Consequently, activities of these hydrolytic enzymes were not good indicators of leaf breakdown in these streams.3. In contrast, the activities of pectin lyase were higher in the hardwater stream than in the softwater stream, corresponding to the greater rates of leaf breakdown and softening that occurred in the hardwater stream. These results support previous findings that pectin lyase is closely associated with the softening and maceration of leaf detritus and suggest that pectin degradation is a key process in the initial stages of leaf breakdown.
Digital imaging of patterns of dental wear to diagnose bruxism in children
Authors: RESTREPO C. , PELÁEZ A. , ALVAREZ E. , PAUCAR C. , ABAD P. 
Published: May 2006

Summary.  Objective.  The aim of this study was to evaluate and compare the area, perimeter, and form (D factor and fractal dimension) of the dental wear among bruxist and nonbruxist children with mixed dentition in order to determine if the dental wear may be used as criteria to diagnose bruxism.Methods.  The children were 8 to 11 years old and were classified as bruxist or nonbruxist, according to anxiety level and temporomandibular disorders. Dental casts of the upper arch were obtained for the bruxist (n = 24) and the control (n = 29) group. The dental wear was measured in digital format and processed automatically. The complete and pathological dental wear was compared between the two groups, using the Student's t‐test and Mann–Whitney test.Results.  Statistically significant differences were observed between the two groups, with a higher area, perimeter, and more irregular form of the pathological dental wear among the bruxist group. Regarding complete dental wear, differences were only significant for the D factor (an un‐dimensional quantitative parameter which produces a relation between the area and the perimeter of an object).Conclusion.  Digital imaging of dental wear may be used as criteria to diagnose bruxism in children with mixed dentition after making an analysis of the area, perimeter, and irregularity of the form of pathological dental wear.
Trends and predictors of aggressive therapy for clinical locally advanced prostate carcinoma
Authors: DENBERG THOMAS D. , GLODÉ L. MICHAEL , STEINER JOHN F. , CRAWFORD E. DAVID , HOFFMAN RICHARD M. 
Published: May 2006

OBJECTIVETo determine the patterns and predictors of aggressive local therapies for patients with clinically advanced (cT3) prostate carcinoma, as the USA National Cancer Institute considers external beam radiotherapy (EBRT) to be the most appropriate treatment for these patients, and currently there is less evidence supporting the use of radical prostatectomy (RP).PATIENTS AND METHODSWe used the Surveillance, Epidemiology and End Results (SEER) cancer registries to identify patients diagnosed with cT3 disease between 1995 and 2001. Sociodemographic and clinical data included patient age, race/ethnicity, marital status, SEER registry, year of diagnosis, tumour stage and grade, and treatment. Multivariate logistic regression was used to identify significant predictors of receiving (i) RP vs EBRT, (ii) any aggressive local treatment (RP or EBRT) or no treatment.RESULTSBetween 1995 and 2001, the proportion of men receiving aggressive local therapy for cT3 disease increased by 11% (58.4% to 69.4%), with a 20% increase in EBRT (40.3% to 60.2%) but a decline by half in RP (18.1% to 9.3%). Younger age was the strongest predictor of receiving RP rather than EBRT, and younger age with being married being a predictor of receiving aggressive local therapy (adjusted relative risk for marriage 1.33, 95% confidence interval 1.18–1.87). Black men were significantly less likely than non‐Hispanic white men to receive aggressive therapy, with a relative risk of 0.56 (0.45–0.69).CONCLUSIONBy 2001, 70% of patients with cT3 disease were receiving aggressive local therapy, with EBRT 6.5 times more common than RP. Clinical trials are needed to rigorously assess the effects of different local treatment strategies on clinical outcomes in men with cT3 prostate carcinoma.
An audit of implanted penile prostheses in the UK
Authors: AGRAWAL VINEET , RALPH DAVID 
Published: May 2006

Associate EditorMichael G. WyllieEditorial BoardIan Eardley, UKJean Fourcroy, USASidney Glina, BrazilJulia Heiman, USAChris McMahon, AustraliaBob Millar, UKAlvaro Morales, CanadaMichael Perelman, USAMarcel Waldinger, NetherlandsOBJECTIVETo assess whether the outcome of implanting penile prostheses is related to the number of prostheses implanted by surgeons, as several reports showed that the outcome of a urological procedure is directly related to the experience of the surgeon.METHODSWe conducted a retrospective audit of 413 penile prostheses implanted over a 2‐year period in the UK by 76 surgeons.RESULTSAbout 80% of the surgeons implanted only one or two prostheses per year, usually of the malleable type, and usually on patients in the private sector. Only four surgeons implanted >20 prostheses per year. The overall revision rate for implantation in the UK, at 24%, is far higher than the worldwide average.CONCLUSIONSGuidelines are needed on the number of prostheses a surgeon should implant per year so that revision rates will decline to more acceptable levels and patients will be offered a genuine choice of product.
Inhibition of the canonical Wnt signaling pathway by apolipoprotein E4 in PC12 cells
Authors: Caruso Alessandra , Motolese Marta , Iacovelli Luisa , Caraci Filippo , Copani Agata , Nicoletti Ferdinando , Terstappen Georg C. , Gaviraghi Giovanni , Caricasole Andrea 
Published: May 2006

AbstractWe examined the effect of the three human isoforms of apolipoprotein E (ApoE2, ApoE3, and ApoE4) on the canonical Wnt signaling pathway in undifferentiated PC12 cells. Addition of recombinant ApoE4 reduced Wingless‐Int7a‐stimulated gene expression at concentrations of 80 and 500 nm. Recombinant ApoE2 and ApoE3 were virtually inactive. Recombinant ApoE4 also inhibited Wnt signaling when combined with very low density lipoproteins (VLDLs) or in cells over‐expressing the low density lipoprotein receptor‐related protein, LRP6. In contrast, the enforced expression of LRP5 unmasked an inhibition by ApoE2 and ApoE3, which, however, were less effective than ApoE4 in inhibiting Wnt signaling. We also transfected PC12 cells with constructs encoding for the three human ApoE isoforms to examine whether endogenously expressed ApoE isoforms could modulate the Wnt pathway. Under these conditions, all three ApoE isoforms were able to inhibit Wnt signaling, although ApoE4 showed the greatest efficacy. Only the conditioned medium collected from cultures transfected with ApoE4 induced a significant inhibition of Wnt7a‐stimulated gene expression, confirming that ApoE4 has an extracellular action that is not shared by the other ApoE isoforms. We conclude that ApoE4 behaves as an inhibitor of the canonical Wnt pathway in a context‐independent manner.
PATRON‐CLIENT RELATIONSHIPS IN SOUTHERN ITALY*
Authors: GRAZIANO LUIGI 
Published: May 2006

ABSTRACTPolitical clientelism in Southern Italy has shown great persistence and capacity for conditioning the entire Italian political development. Accounting for these characteristics, clientelism is better understood as the product of the incomplete capitalistic rationalization of the Southern economy. Throughout the 19th century in Sicily, the feudo remained the basis of the economic and social structure, while in the continental South the feudal system disintegrated more quickly and widely. The resulting different models of social relationships within the Mezzogiorno, make it meaningful for our purposes to distinguish between two types of clientele, which may be termed clientela mafiosa and Neopolitan clientele.The second part of the article is concerned with the dynamics of the clientelistic system in post‐1945 Southern Italy and more generally with the relationship between clientelism and political development. The transition from the clientelism of the notables to political party‐directed patronage is studied both at the local level and in the context of the whole South. It is then argued that clientelism is a very poor tool for political development since it has two effects on the social structure and the political process: these effects will be called disorganic integration and exclusivism.
THE POWERS THAT BE AND THE POWERS THAT DO: AN “ECONOMIC” APPROACH
Authors: BEACKON S.G. , GOODIN R.E. 
Published: May 2006

ABSTRACTRational choice models of bargaining power are usually held to justify the pluralist methodology of decision analysis. This paper rejects this view and argues that such models are able to combine the pluralists’ concern with overt behaviour and the operationalizability of the concept of power with their critics’ emphasis upon the systemic or structural features of power and its cognates. We overcome charges of conservative bias which tend to be directed at rational choice theories by deriving from the model reasons why a rational actor would object to concentrations of power within his community. A theory which provides us with a measure of power which is at least notionally empirical and is capable of determining why, and to what extent moral sensibilities are offended by power concentrations would, we feel, enable the discipline to throw off the straitjacket which has constrained the analysis of power over the past two decades.
THE DISTRIBUTION OF SEATS IN THE EUROPEAN PARLIAMENT AFTER DIRECT ELECTIONS: A SIMULATION STUDY *
Authors: RATTINGER HANS , ZÄNGLE MICHAEL , ZINTL REINHARD 
Published: May 2006

ABSTRACTThis article presents an overview of a project designed to simulate the distribution of seats in the European Parliament after the first direct elections in 1978. First, the data base and some basic assumptions are described which pertain to electoral systems, voter behavior, and realignments in party systems. Some illustrative results of simulation runs are summarized which proceed from voter preferences as expressed in the most recent national general elections in the nine member countries of the European Community. These findings are analyzed for individual parties and parliamentary fractions as well as with the chances for forming majority coalitions in mind. Finally, the effects of some likely shifts in voting patterns are considered assuming that current national electoral systems will be applied in 1978.