bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methods for mid‐course corrections in clinical trials with survival outcomes
Authors: Cook Thomas D. 
Published: October 2003

AbstractInterim monitoring of randomized controlled clinical trials often requires that the assumptions under which the trial was designed be evaluated and that appropriate design modifications be made. Furthermore, if there is little hope of ultimately demonstrating benefit, the study may be terminated on either ethical or economic grounds. Design modifications may be made based on either blinded or unblinded analyses. Since observed patterns of recruitment and patient outcomes may differ from those required by standard methods, specialized tools may be required to perform the necessary computations. In this paper we demonstrate how the Markov chain model of Lakatos can accommodate arbitrary observed patterns of recruitment, hazard rates, and other design parameters for performing mid‐course corrections in trials with survival outcomes. Copyright © 2003 John Wiley & Sons, Ltd.
A study on predictability of human physiological strain in Buenos Aires City
Authors: Alessandro A P , de Garín A B 
Published: October 2003

AbstractHigh atmospheric temperature and humidity can cause discomfort and even death among people in high‐risk groups. Forecasting such meteorological situations can be a useful tool for public health managers. The predictability of discomfort is analysed using a time series of the relative strain index in Buenos Aires. Other authors have found that index values exceeding the thresholds of both nocturnal and diurnal comfort can increase mortality. This study finds that such situations are associated with index values over 0.20 at 14:00 h. local time (RSI14>0.20). Consequently, the meteorological conditions associated with RSI14≥0.20 are studied. The anomalies of the geopotential monthly mean fields show the passage of a low‐pressure system south of 45°S. This system is related to a trough, possibly of frontal character, moving across the province of Buenos Aires, and a simultaneous intensification of the northwestern low in Argentina. The synoptic situation is associated with a general northerly flow that brings heat and moisture from the tropics. On 81% of days with RSI14≥0.20, winds with a northerly component were recorded. This increases to 84.4% when at least one day with northerly wind is previously observed. The synoptic characteristics are examined using a combination of circulation indices: meridional (R), zonal (Z) and curvature (C). The daily sequence of the weighted averages of the anomalies obtained are ΔR<0,ΔZ>0 and ΔC>0. Some 67% of the days when RSI14≥0.20 correspond to this daily index pattern estimated at locations near Buenos Aires. Copyright © 2003 Royal Meteorological Society
Dispersion and habitat use by Myotis daubentonii and Myotis nattereri during the swarming season: implications for conservation
Authors: Parsons K. N. , Jones G. 
Published: October 2003

AbstractWe radio‐tracked 24 Myotis daubentonii and 35 Myotis nattereri during the swarming season to determine the catchment area of a swarming site and to study habitat preferences of the bats so that important foraging habitats within the catchment area could be identified. Sixty‐one percent of individuals were relocated and 39 day roosts were found for 31 bats. Maximum range from the swarming site was 26.7 km for M. daubentonii and 24.8 km for M. nattereri. Minimum convex polygons depicting the minimum catchment area of the swarming site measured 254 km2 for M. daubentonii and 497 km2 for M. nattereri. Including recoveries of ringed bats increases the area enclosed by the maximum range to at least 4118 km2. Compositional analysis of habitat used in relation to that available suggested selection of mixed agricultural areas by M. nattereri. Broad‐leaved woodland was preferred for foraging. Parkland, woodland and open‐water habitats were common around roosts of M. daubentonii. Such habitats should be conserved and enhanced to protect these species. Some individuals of both sexes returned to the swarming site of capture, but none visited another swarming site. Bats may be faithful to only one site and may be inflexible should that site be destroyed. Because the catchment area of swarming sites is large, such sites are probably important centres of outbreeding. Protection of these mating sites should be a conservation priority, and key habitats should be protected over a large area around swarming sites.
Effects of surface fires on understorey insectivorous birds and terrestrial arthropods in central Brazilian Amazonia
Authors: Haugaasen Torbjørn , Barlow Jos , Peres Carlos A. 
Published: October 2003

AbstractUnderstorey insectivorous birds are highly vulnerable to different forms of habitat disturbance in tropical forests. Here we examine the effects of an unprecedented surface fire on understorey insectivores and forest litter arthropods in a terra firme forest of central Brazilian Amazonia, and compare species and guild abundance both close to and far from the clearly distinguishable fireline separating burnt and unburnt forest. All six of the most abundant insectivorous foraging guilds examined were detrimentally affected by fire, with dead‐leaf gleaners and professional ant‐followers being the most heavily affected. While army ants were apparently absent from the burnt forest, results from pit‐fall traps showed that wildfires had only a limited effect on the abundance of most leaf‐litter invertebrates. The fireline appeared to be an abrupt barrier to many understorey insectivorous birds, and there was little evidence to suggest that primary forest species were recolonizing burnt forest up to 1 year after the fires. Factors affecting the capture frequency of insectivorous birds are discussed.
Cat eradication significantly decreases shearwater mortality
Authors: Keitt B. S. , Tershy B. R. 
Published: October 2003

AbstractIntroduced predators are a leading threat to seabird populations world‐wide and cats (Felis catus) have probably had the most universally damaging effect (Moors & Atkinson, 1984). Eradication of feral cat populations from seabird colonies is a conservation priority (Tershy et al., 2002) and there are many studies that demonstrate the benefits of these actions for seabirds (e.g. Forsell, 1982; Cooper et al., 1995). However, detailed estimates of the effects of cat predation on seabird population viability are lacking in spite of the fact that such data could provide important support for land managers attempting to promote eradication programmes for seabird restoration.
Translocation of an imperilled woodrat population: integrating spatial and habitat patterns
Authors: Gerber L. R. , Seabloom E. W. , Burton R. S. , Reichman O. J. 
Published: October 2003

AbstractMany species have strong habitat preferences that directly influence population viability. For successful reintroduction of threatened populations that rely on habitat structures, the correct placement of artificial structures is also important to population persistence. In this paper, we present a hierarchical approach to the problem of translocating animals that rely on permanent habitat structures, in which we first use population dynamics data to identify areas of suitable habitat, and then identify optimal configuration for habitat structures. We use data collected from a non‐endangered, conspecific population of the endangered riparian woodrat (Neotoma fuscipes riparia) to examine the degree to which the distribution of dens in translocation sites might influence the likelihood that animals persist in their new environment. We characterize the habitats in which dens occur, analyze their spatial clustering, and compare them to temporal changes in population status for sex and age classes. We compare the potential efficacy of translocation efforts using spatial analysis versus solely habitat‐based approaches and identify the optimal spatial configuration of dens that should be considered in this translocation effort. We found that patterns of habitat use were positively correlated with overstorey cover, and animal weight was positively correlated with understorey cover. Woodrats appear to select den locations on the basis of understorey cover, but also benefit from dense overstorey cover and distance to nearest tree. Our results suggest that in translocation efforts, artificial dens should be placed in clusters within a radius of 15 m, as values above and below this value showed negative correlations with body mass. Translocations should occur after reproductive events, which occur in April and August for woodrats in southern California. Our analyses provide practical guidelines in determining appropriate timing and spacing for translocation events in the context of animal condition, minimizing disease transmission, and reproduction.
Genetic variation and resistance to a bacterial infection in the endangered Gila topminnow
Authors: Giese Alan R. , Hedrick Philip W. 
Published: October 2003

AbstractWe tested the association between host genetic diversity and resistance to a novel pathogen using controlled experiments to compare bacterially induced mortality among four populations of the endangered Gila topminnow (Poeciliopsis occidentalis) with different levels of genetic diversity, and between nine lines of inbred topminnows and their respective (non‐inbred) source populations. We exposed fish in treatment groups to salinity shock and high concentrations of the bacterium Listonella (Vibrio) anguillarum, a causative agent of vibriosis in fish. Mortality associated with vibriosis (mortality) 1 to 6 days post‐exposure differed among the populations, and between inbred and non‐inbred samples. However, mortality was not associated with expected heterozygosity based on microsatellite loci diversity, nor was it associated with expected or observed heterozygosity at a major histocompatibility complex (MHC) class II locus. Neither was mortality related to the presence or absence of specific MHC alleles. Additionally, the effect of severe inbreeding was to reduce mortality in the inbred fish relative to the non‐inbred controls in every population. Taken in the context of other studies, we conclude that effects of genetic diversity may be context‐ and locus‐specific, environmental stress may be an important determinant of host immunity, and genetic diversity should be used cautiously to predict the potential response of a population to a specific environmental challenge.
Should children be screened to undergo early treatment for otitis media with effusion? A systematic review of randomized trials
Authors: Butler C. C. , Van Der Linden M. K. , MacMillan H. L. , Van Der Wouden J. C. 
Published: November 2003

AbstractBackground  Otitis media with effusion (OME) is the most common cause of acquired hearing loss in childhood and has been associated with delayed language development and behavioural problems. Some have argued that children should be screened and treated early if found to have clinically important OME. The aim of this review was to assess evidence from randomized controlled trials about the effectiveness of screening and treating children with clinically important OME in the first 4 years of their life. The primary outcome was language development.Methods  We searched the Cochrane Controlled Trials Register, MEDLINE and EMBASE and reference lists of all included studies in February 2003. We also contacted the first authors of the studies included in this review. Search terms included otitis media; otitis media with effusion; glue ear; OME; screen; children; treatment; language; and behaviour. Data extraction and methodological quality assessment were performed by at least two of us for each study independently, using methods described in the Cochrane Collaboration Handbook.Results  From the three included randomized controlled trials evaluating interventions among children with OME identified through screening, we found no evidence of clinically important benefit in language development.Conclusions  The identified randomized trials do not show an important benefit on language development from screening the general population of asymptomatic children in the first 4 years of life to undergo early treatment for OME. Screening asymptomatic children in the first 4 years of life for OME is not recommended.
Changes in feeding behaviour of the larvae of the damselfly Enallagma cyathigerum in response to stimuli from predators
Authors: KOPERSKI PAWEŁ 
Published: November 2003

1. The feeding rates, diet composition and diel periodicity in feeding activity among larvae of the damselfly Enallagma cyathigerum Charp., exposed to chemical, visual and mechanical stimuli from the predators Ranatra linearis (L.), Notonecta glauca L. and Rutilus rutilus (L.) were investigated.2. In response to chemical cues produced by all the predator species, larvae reduced their rate of feeding significantly (especially on large, sedentary prey).3. Small larvae reacted more strongly than large ones to the kairomone produced by N. glauca.4. The fish kairomone induced a reduction in feeding activity during daylight hours only. This reaction was more intense than the reaction to non‐chemical cues.5. Observed predator‐induced changes in diet composition, caused directly by reduced activity during feeding, are discussed as an antipredator behaviour of damselfly larvae.
Amphibian species richness and distribution in relation to pond water chemistry in south‐western Ontario, Canada
Authors: HECNAR STEPHEN , M’CLOSKEY ROBERT 
Published: November 2003

1. We assessed the patterns of amphibian species richness and distribution in relation to water chemistry over a large geographical area in 1992–94.2. Thirteen amphibian species were observed at 180 ponds, with mean species richness 3.5 ± 0.13 species per pond (range zero to nine). Water samples were collected from 143 ponds, analysed for fifteen chemical variables, and further analysed by multivariate statistical techniques.3. Water in the study area was hard, alkaline and well‐buffered against pH change, and most ponds were eutrophic. Amphibian species richness was negatively correlated with five chemical variables (chloride, conductivity, magnesium, total hardness, turbidity).4. Principle components analysis reduced the data set to four chemical components that explained 65.4% of the variance in the original variables. Principle component scores were retained for use in further multivariate tests. Multiple regression accounted for only 19.0% of the variance in amphibian species richness. Discriminant function analysis (DFA) was used to determine if water chemistry variables discriminated among species, but it was only able to classify 17.5% of cases correctly. DFA was also used to determine if water chemistry distinguished between used and unused sites for individual species. DFA was moderately successful, classifying 61–77% of cases correctly.5. General water chemistry appears to play only a minor part in affecting amphibian species richness in south‐western, Ontario. However, chemical variables may be helpful to distinguish between used and unused sites for some species.
Habitat partitioning in riverine macrophyte communities
Authors: FRENCH TODD , CHAMBERS PATRICIA 
Published: November 2003

1. Habitat partitioning has been extensively studied in terrestrial plant communities. By comparison, few studies have examined habitat partitioning in riverine macrophyte communities. Riverine environments are often highly heterogeneous with respect to current speed, depth, bottom sediment fertility and other biologically important properties. Thus, the potential for habitat partitioning in riverine macrophyte communities is great.2. The objective of this study was to investigate how, or if, macrophyte species are differentially distributed with respect to abiotic gradients in a large river in central British Columbia, Canada.3. A survey of macrophyte biomass and associated measures of current speed, depth and sediment texture showed that coexistence occurred both with and without habitat partitioning.4. Coexistence in the absence of habitat partitioning was depicted by Potamogeton gramineus, Potamogeton berchtoldii, Myriophyllum exalbescens, Callitriche hermaphroditica and Potamogeton pectinatus such that they had a minimum and average niche overlap (NO) of 65% and 84%, respectively, for all measured abiotic variables. Similarly, the spatial niche of E. canadensis was close to that of Ceratophyllum demersum and M. exalbescens.5. While several taxa seemed to occupy the same spatial niche, some taxa were distinguished from one another in terms of the types of microhabitats they utilized. Mosses, for example, were often the only occupants of sites having current speeds greater than 0.6 m s–1 and substrates of bare rock. Ranunculus aquatilis was most abundant at sites having current speeds between 0.4 and 0.6 m s–1 whereas most other taxa were restricted to slower waters. Habitat partitioning across depth contours, which occurred between several taxa, was most evident between P. pectinatus and C. demersum(NO = 17%), C. hermaphroditica and C. demersum (NO = 3%), C. demersum and P. richardsonii (NO = 19%) and C. hermaphroditica and E. canadensis (NO = 29%).
Predicting the outcome of trophic manipulation in lakes—a comment on Harris (1994)
Authors: SARNELLE ORLANDO 
Published: November 2003

1. Harris (Freshwater Biology, 32, 143–160, 1994) asserts that while empirical modelling of lake ecosystem properties has yielded general predictions and useful explanations, research into the effects of food‐web interactions has not. I provide an explicit example of a useful, quantitative prediction gleaned from experiments on food‐web effects—the relationship between total phosphorus and the magnitude of response of algal biomass.2. I further argue that Harris errs in asserting that food‐web effects will be ineffective in eutrophic lakes. This error stems from a misconception about the relevance of ecosystem behaviour in unmanipulated systems for predictions of how an ecosystem will respond to manipulation. I cite empirical evidence demonstrating that, contrary to Harris’s contention, the response of algal biomass to a change in food‐web structure increases as lakes are enriched.
Ceratophyllum demersum hampers phytoplankton development in some small Norwegian lakes over a wide range of phosphorus concentrations and geographical latitude
Authors: MJELDE MARIT , FAAFENG BJØRN 
Published: November 2003

1. Data on submerged and floating‐leafed macrophytes, phytoplankton, nutrients (N, P) and calcium were collected from twenty‐four small lakes ( 1 km2) over a wide range of latitudes in Norway. The majority of the investigated lakes were mesotrophic or eutrophic, and most of the lakes were markedly affected by diffuse and point‐source runoff from agriculture. According to their macrophyte species composition, the majority of the lakes can be classified as Potamogeton lakes or Chara lakes, or a combination of these.2. This study is consistent with the ‘two alternative stable states’ hypothesis. We observed clearwater lakes with dense macrophyte cover over a wider range of total P concentration than has been reported previously: from 30 to more than 700 mg P m–3. The clearwater state was only observed in lakes with mean depths of less than 1.9 m.3. Most clear lakes with high cover of submerged vegetation showed indications of N limitation.4. In this study nearly all the macrophyte‐dominated lakes with P concentrations above 30 mg m–3 had dense stands of Ceratophyllum demersum (L.). This indicates that Ceratophyllum may also play an important role in stabilizing and maintaining a clearwater state at high P concentrations.
Excretion of heptadecene‐1 into lake water by swarms of Polyphemus pediculus (Crustacea)
Authors: WENDEL THOMAS , JÜTTNER FRIEDRICH 
Published: November 2003

1. In the littoral zone of a mesotrophic freshwater lake (Lake Selent, Northern Germany) much higher concentrations of heptadecene‐1 were found within a swarm of Polyphemus pediculus than in lake water at some distance from the swarm. Polyphemus collected in the field produced large amounts of heptadecene‐1 when exposed to osmotic shock. Other volatile compounds were not detected.2. Heptadecene‐1 could be involved in the formation, maintenance and recognition of swarms of Polyphemus. It is the first report of the release of a volatile organic compound from a freshwater crustacean.
Phenotypic plasticity of Daphnia life history traits: the roles of predation, food level and toxic cyanobacteria
Authors: WALLS M. 
Published: November 2003

1. We studied the life history responses of Daphnia pulex under different biotic conditions. In a factorially designed experiment, we tested the impacts of water conditioned by the invertebrate predator Chaoborus, low and high food level (10 000 and 100 000 Scenedesmus cells ml–1), and exposure to toxic Microcystis (5000 cells ml–1) on twelve D. pulex clones originating from different habitats. Our aim was to compare the phenotypic plasticity of different clones, and to study the interactions among biotic factors.2. Individuals cultured in Chaoborus‐conditioned water started to reproduce at a larger size than individuals cultured in water not conditioned by the predators. We found interactions between food level and Chaoborus‐conditioned water on age at first reproduction and total offspring number. In addition, the impact of the Chaoborus treatment on the size at first reproduction was reduced by Microcystis exposure.3. Clonal differences were found in the degree of phenotypic plasticity of different life history traits. However, there was no obvious connection between the original habitat of the clone and the degree of plasticity.
PAT1, an evolutionarily conserved acetyltransferase homologue, is required for multiple steps in the cell cycle
Authors: Lin Rueyling , Allis C. David , Elledge Stephen J. 
Published: November 2003

Background: Acetylation has been implicated in many biological processes. Mutations in N‐terminal acetyltransferases have been shown to cause a variety of phenotypes in Saccharomyces cerevisiae including activation of heterochromatin, inability to enter G0, and lethality. Histone acetylation has been shown to play a role in transcription regulation, histone deposition and histone displacement during spermatogenesis, although no known histone acetyltransferase is essential. Results: Studies aimed at revealing a role for histone H1 in yeast have uncovered a mutation in a putative acetyltransferase, PAT1. The mutant (pat1‐1) cells can live only in the presence of vertebrate H1. PAT1 is essential for mitotic growth in S. cerevisiae; mutant cells depleted of the Pat1p show aberrant cellular and nuclear morphology. PAT1 is required for multiple cell cycle events, including passage through Start, DNA synthesis, and proper mitosis through a microtubule‐mediated process. The S. pombe PAT1 gene was cloned by complementation and shown to exist as part of a larger protein, the unique portion of which is homologous to a second S. cerevisiae gene. pat1 mutants show a variety of mitotic defects including enhanced chromosome loss, accumulation of multiple nuclei, generation of giant cells, and displays classical cut phenotypes in which cytokinesis occurs in the absence of proper nuclear division and segregation. Conclusion: PAT1 controls multiple processes in cell cycle progression which suggests an essential role for the acetylation of yet unknown substrate(s).