bluuebunny/crossref_metadata_2025_split huggingface dataset:
The origin and nature of seismic reflections of sharp‐based shoreface deposits (upper Jurassic Siliciclastics, northern France)
Authors: Braaksma H. , Drijkoningen G.G. , Filippidou N. , Kenter J.A.M. , Proust J.N. 
Published: February 2006

ABSTRACTIn order to advance understanding of the relationship between geological properties and their physical expression in reflection images, this study has focused expertise in reflection geophysics, petrophysics and sedimentology on the same geological object, in this case a succession of Upper Jurassic sharp‐based shoreface deposits embedded in offshore marine shales in northern France. This integrated approach to determine firstly the origin and nature of seismic reflections (calibration) and secondly to provide a means of extracting geological information from seismic imagery (inverse calibration) was built on the following analytical steps.Firstly, detailed and extensive petrophysical analyses of outcrop (plug) samples, continuous core and sonic well logs, in combination with a quantification of mineralogical and textural properties, allowed a direct conversion of acoustic properties (impedance) into sedimentological properties, resulting in a quantitative physical sequence stratigraphic model.Secondly, the integration of scale‐dependent acoustic measurements, ranging from 0.01 m and 320 kHz on cores up to the wavelength of field seismic data was established using an averaging algorithm (an effective‐medium‐theory type) as an upscaling approach. This alternative to a VSP or check shot allows an optimized depth–time conversion and hence determination of the origin of the seismic reflections with previously unattainable accuracy.Finally, the shape and scale dependence of impedance contrasts were integrated into so‐called singularity parameters that directly link depositional changes with information from seismic reflections: depositional changes in the shallow‐water domain are generally characterized by step functions, whereas those in more distal depositional environments are represented by spiky functions. This approach allows the recognition of the associated reflection events and, vice versa, it provides a unique opportunity to extract the character of impedance changes, and thus changes in depositional environment, from seismic reflection records in general.This integrated and multiscale characterization of sharp‐based shoreface deposits calibrates the typical reflection patterns for such sedimentary units. These include continuous high‐amplitude smooth and flat tops, discontinuous sharp basal reflections with variable amplitude, and complex sigmoidal high‐amplitude reflections within the compound shoreface deposits. In addition, the results of this study, by detailing the effects of scale and frequency on impedance changes, improve the identification of similar deposits in subsurface seismic data and the extraction of maximum amounts of geological information beyond seismic resolution.
Assessing the impact of Impatiens glandulifera on riparian habitats: partitioning diversity components following species removal
Authors: HULME PHILIP E. , BREMNER ELEANOR T. 
Published: February 2006

Summary

Attempts to quantify the impact of non‐native plants on the vegetation of invaded habitats have often been criticized because of the frequent use of observational assessments (invaded/uninvaded comparisons) focused on local‐ rather than community‐level effects. This study highlights how removal experiments combined with partitioning of diversity components across spatial scales can provide key insights into invasive species’ impacts.
Impatiens glandulifera (Balsaminaceae) is a widespread invasive riparian weed, yet few quantitative assessments of its impact on natural vegetation exist. Thus replicated experiments were used to compare the impact of Impatiens removal on α, β, γ components of species richness, diversity and evenness in open riparian habitats in north‐east England.
Plant community response to Impatiens removal was rapid, with a significant increase in seedling recruitment resulting in an average increase of four species m−2. The impact of Impatiens invasion was most marked for light‐demanding species. Eight non‐native species (in addition to Impatiens) occurred in the community and these responded proportionally more to Impatiens removal than native species. As a result the proportion of non‐native species in removal plots was higher than in invaded plots.
The increase in α richness and diversity following Impatiens removal was matched by a similar increase in the γ components. Thus the effect of Impatiens was significant at both the local plot scale and at the scale of the riparian community, although the former effect was more marked. Species accumulation curves suggested that extensive Impatiens stands may reduce species richness by as much as 25%.
Synthesis and applications. Removal experiments appear particularly well suited to assess the impacts of herbaceous non‐native plants on ruderal communities. By partitioning diversity components, impacts were consistently assessed at local and community scales and, when combined with analysis of species accumulation curves, provided a comprehensive assessment of impact on the plant community. The approach adopted in this study highlights that although Impatiens reduces native species diversity in open and frequently disturbed riparian vegetation, many of the species negatively influenced by Impatiens are widespread ruderal species. Furthermore, management may lead to a compensatory increase in the abundance of other non‐native species and thus fail to achieve desired conservation goals.
Correlates of biological soil crust abundance across a continuum of spatial scales: support for a hierarchical conceptual model
Authors: BOWKER MATTHEW A. , BELNAP JAYNE , DAVIDSON DIANE W. , GOLDSTEIN HARLAND 
Published: February 2006

Summary

Desertification negatively impacts a large proportion of the global human population and > 30% of the terrestrial land surface. Better methods are needed to detect areas that are at risk of desertification and to ameliorate desertified areas. Biological soil crusts are an important soil lichen‐moss‐microbial community that can be used toward these goals, as (i) bioindicators of desertification damage and (ii) promoters of soil stability and fertility.
We identified environmental factors that correlate with soil crust occurrence on the landscape and might be manipulated to assist recovery of soil crusts in degraded areas. We conducted three studies on the Colorado Plateau, USA, to investigate the hypotheses that soil fertility [particularly phosphorus (P), manganese (Mn) and zinc (Zn)] and/or moisture limit soil crust lichens and mosses at four spatial scales.
In support of the soil fertility hypothesis, we found that lichen–moss crusts were positively correlated with several nutrients [Mn, Zn, potassium (K) and magnesium (Mg) were most consistent] at three of four spatial scales ranging from 3·5 cm2 in area to c. 800 km2. In contrast, P was negatively correlated with lichen–moss crusts at three scales.
Community composition varied with micro‐aspect on ridges in the soil crust. Three micro‐aspects [north‐north‐west (NNW), east‐north‐east (ENE) and TOP] supported greater lichen and moss cover than the warmer, windward and more xeric micro‐aspects [west‐south‐west (WSW) and south‐south‐east (SSE)]. This pattern was poorly related to soil fertility; rather, it was consistent with the moisture limitation hypothesis.
Synthesis and application. Use of crusts as desertification bioindicators requires knowledge of a site's potential for crust cover in the absence of desertification. We present a multi‐scale model of crust potential as a function of site properties. Future quantitative studies can use this model to guide sampling efforts. Also, our results suggest new directions in restoration research: enhancement of moisture residence time and fertilization with key nutrients (Mn, Zn, K and Mg). Re‐establishment of soil crusts in desertified lands will help regain lost soil stability and fertility, and facilitate plant re‐establishment.
Using spatial heterogeneity to extrapolate species richness: a new method tested on Ecuadorian cloud forest birds
Authors: O'DEA NIALL , WHITTAKER ROBERT J. , UGLAND KARL I. 
Published: February 2006

Summary

For most ecological assemblages, compiling complete inventories of species is difficult, if not impossible. Various methods have been developed to estimate total species richness based on the pattern of richness and relative abundance reflected in a limited sample.
We assessed the performance of a recently developed technique, the total‐species (T‐S) accumulation method, in estimating bird species richness for cloud forest reserves in north‐west Ecuador. This technique explicitly integrates the spatial heterogeneity of samples into the estimate of species richness for large areas by grouping samples into subsets based on shared environmental characteristics.
We compared the technique's performance with that of more traditional methods of species richness estimation: non‐parametric estimators and extrapolations from species‐accumulation curves. Existing bird species records for the Ecuadorian cloud forest reserves served as the independent measure of total species richness.
Non‐parametric estimators of species richness significantly underestimated total species richness. In contrast, extrapolation from the semi‐log approximation of T‐S curves, using subdivision by habitat type, altitude and first axis detrended correspondence analysis scores, overestimated total species richness, while extrapolation from null T‐S models and the standard species‐accumulation curve produced the most accurate results.
The T‐S method overestimated species richness for our ‘hyper‐diverse’ assemblage. This was probably because it adjusted the estimates upwards to account for beta‐diversity, when this diversity was already captured in the design of the site selection scheme. Nevertheless, it provided a quantitative measure of the beta‐diversity produced by environmental and compositional gradients. Moreover, our test indicated that factors such as sampling effort and species abundance distributions may be more important for accurate species richness estimation than heterogeneity in the spatial distribution of species.
Synthesis and applications. Our analysis demonstrates significant differences in the accuracy of different methods for estimating total species richness from a limited sample. Our work highlights the importance of knowing what an estimator is estimating so that when we characterize or compare sites, whether in ecological or conservation research, we do so with explicit knowledge of the potential biases in our chosen methodology.
Mannan‐Binding Lectin in Children with Chronic Gastritis
Authors: Ba̧k‐Romaniszyn L. , Cedzyński M. , Szemraj J. , St. Świerzko A. , Zeman K. , Kałuz̊yński A. , Płaneta‐Małecka I. 
Published: February 2006

AbstractThe involvement of mannan‐binding lectin (MBL) insufficiency in the pathogenesis of chronic gastritis (CG) in children was investigated. Blood samples were collected from 78 paediatric patients suffering from CG associated with Helicobacter pylori infection (group Hp+) and from 41 with the disease not associated with such an infection (group Hp–). Control group consisted of 77 children. The frequency of mbl‐2 gene mutations and serum protein concentrations did not differ significantly in both groups as compared with controls. An expression of mbl‐2 gene in gastric biopsies of CG patients was demonstrated. It was found to be stronger in H. pylori‐infected children. The results presented in this paper suggest that MBL deficit/dysfunction probably does not contribute to an increased risk of CG (both associated and not associated with H. pylori infection) in children. However, MBL opsonic effect and/or the lectin pathway of complement activation may be taken into account as possible host defence mechanisms in gastric patients.
Enhanced arsenate reduction by a CDC25‐like tyrosine phosphatase explains increased phytochelatin accumulation in arsenate‐tolerant Holcus lanatus
Authors: Bleeker Petra M. , Hakvoort Henk W.J. , Bliek Mattijs , Souer Erik , Schat Henk 
Published: February 2006

SummaryDecreased arsenate [As(V)] uptake is the major mechanism of naturally selected As(V) hypertolerance in plants. However, As(V)‐hypertolerant ecotypes also show enhanced rates of phytochelatin (PC) accumulation, suggesting that improved sequestration might additionally contribute to the hypertolerance phenotype. Here, we show that enhanced PC‐based sequestration in As(V)‐hypertolerant Holcus lanatus is not due to an enhanced capacity for PC synthesis as such, but to increased As(V) reductase activity. Vacuolar transport of arsenite‐thiol complexes was equal in both ecotypes. Based on homology with the yeast As(V) reductase, Acr2p, we identified a Cdc25‐like plant candidate, HlAsr, and confirmed the As(V) reductase activity of both HlAsr and the homologous protein from Arabidopsis thaliana. The gene appeared to be As(V)‐inducible and its expression was enhanced in the As(V)‐hypertolerant H. lanatus ecotype, compared with the non‐tolerant ecotype. Homologous ectopic overexpression of the AtASR cDNA in A. thaliana produced a dual phenotype. It improved tolerance to mildly toxic levels of As(V) exposure, but caused hypersensitivity to more toxic levels. Arabidopsis asr T‐DNA mutants showed increased As(V) sensitivity at low exposure levels and enhanced arsenic retention in the root. It is argued that, next to decreased uptake, enhanced expression of HlASR might act as an additional determinant of As(V) hypertolerance and As transport in H. lanatus.
Outcome after anaesthesia and emergency surgery in patients over 100 years old
Authors: Konttinen N. , Rosenberg P. H. 
Published: February 2006

Background:  Deteriorated organ function and reduced stress response in very old patients may cause post‐operative morbidity and mortality. We wanted to identify immediate and longer‐term outcome after anaesthesia and surgery in the oldest of the old patients.Methods:  We analysed retrospectively anaesthesia and hospital records of patients who were over 100 years old when undergoing major emergency surgery in our hospital during 1990–2004.Results:  Altogether, 12 patients (median age 101 years) underwent 14 operations (nine for hip fracture, four for lower extremity circulatory problems and one for peritonitis). During anaesthesia, invasive arterial pressure was monitored in eight patients while central venous pressure (CVP) was monitored in only one patient. Spinal anaesthesia with bupivacaine was given as a continuous technique in six and as single‐shot spinal anaesthesia in five cases. Both spinal (11) and general (3) anaesthesias were characterized by marked drops in arterial pressure. Haemodynamics was managed with intravenous (i.v.) fluids and vasopressors. Five patients had post‐operative delirium. Mortality at 30 days, 6 months and 1 year was 25%, 42% and 50%, respectively. Within 15 days of the operation, three patients had died (pneumonia, cerebral infarction and myocardial infarction). Nine patients returned home and six of them lived in their pre‐operative mental and physical state for at least a year.Conclusion:  Independently of the anaesthetic method, marked drops in blood pressure occurred, requiring pharmacological intervention. We assume that in most of the patients, hypovolaemia explains the intra‐operative haemodynamic instability. A 25%, 30‐day mortality may be regarded as acceptable and, overall, these very old patients tolerated emergency surgery quite well.
Regional pulmonary pressure volume curves in mechanically ventilated patients with acute respiratory failure measured by electrical impedance tomography
Authors: Hinz J. , Moerer O. , Neumann P. , Dudykevych T. , Frerichs I. , Hellige G. , Quintel M. 
Published: February 2006

Background:  We hypothized, that in mechanically ventilated patients with acute respiratory failure, regional pressure volume curves differ markedly from conventional global pressure volume curves of the whole lung.Methods:  In nine mechanically ventilated patients with acute respiratory failure during an inspiratory low‐flow manoeuvre, conventional global pressure volume curves were registered by spirometry and regional pressure volume curves in up to 912 regions were assessed simultaneously using electrical impedance tomography. We compared the lower (LIP) and upper (UIP) inflection points obtained from the conventional global pressure volume curve and regional pressure volume curves.Results:  We identified from the conventional global pressure volume curves LIP [3–11 (8) cmH2O] in eight patients and UIP [31–39 (33) cmH2O] in three patients. Using electrical impedance tomography (EIT), LIP [3–18 (8) cmH2O] in 54–264 (180) regions and UIP [23–42 (36) cmH2O] in 149–324 (193) regions (range and median) were identified. Lung mechanics measured by conventional global pressure volume curves are similar to the median of regional pressure volume curves obtained by EIT within the tomographic plane. However, single regional pressure volume curves differ markedly with a broad heterogeneity of lower and upper inflection points.Conclusion:  Lower and upper inflection points obtained from conventional global pressure volume curves are not representative of all regions of the lungs.
Qualitative analysis of unanticipated difficult airway management
Authors: Rosenstock C. , Hansen E. G. , Kristensen M. S. , Rasmussen L. S. , Skak C. , Østergaard D. 
Published: February 2006

Background:  Unanticipated difficult airway management (DAM) is a major challenge for the anaesthesiologist and is associated with a risk of severe patient damage. We analysed 24 cases of unanticipated DAM for actual case management and anaesthesiologists knowledge, technical and non‐technical skills. Anaesthesiologists' opinions, as well as environmental factors of importance for DAM proficiency, were also assessed.Methods:  Departments of Anaesthesiology in three Copenhagen University Hospitals participated in a prospective study of unanticipated DAM. Anaesthesiologists recorded the details of the cases on a data sheet. Qualitative data were collected in a semi‐structured interview if the value of the Intubation Difficulty Score (IDS) was more than five, if the value of the visual analogue scale score for mask ventilation was more than five or in the case of a registered complication. Transcripts were theme analysed independently by two analysts. Data sheets and interviews were used in the final evaluation.Results:  All 24 cases concerned difficult tracheal intubation, and this was associated with difficult mask ventilation on four occasions. Management in three cases demonstrated strict adherence to a DAM practice guideline. Anaesthesiologists lacked standards for DAM. Inadequate knowledge, training and training facilities were documented. Sudden re‐allocation of personnel and change of anaesthetic technique were potential risk factors for DAM. Insufficient airway assessment, insufficient patient information and registration of difficulties were demonstrated. Ethical issues were raised concerning the use of patients for skills practice.Conclusions:  Both personal and system failures resulted in unanticipated DAM. There was insufficient knowledge of DAM and anaesthesiologists lacked DAM training. Standards for DAM and curricula for continuing education in DAM are needed.
Individuality in Problem Solving: String Pulling in TwoCarduelisSpecies (Aves: Passeriformes)
Authors: Seibt Uta , Wickler Wolfgang 
Published: February 2006

AbstractThe research reported here was designed to study the individual peculiarities of birds in solving a problem. GoldfinchesCarduelis carduelisand siskinsC. spinuswere tested with the string‐pulling task: sitting on a perch from which a small food container is suspended by a string the test bird had to lift the container, using the bill to pull the string stepwise up and a foot to hold it, and repeat that until they could reach the food. Fifty‐two goldfinches and 29 siskins raised under controlled conditions were tested individually. Three groups became apparent: ‘inventors’ (23% of goldfinches; 62% of siskins) solved the problem by themselves; ‘imitators’ (25% of goldfinches; 10% of siskins) succeeded after seeing a performing conspecific; ‘duffers’ (52% of goldfinches, 28% of siskins) did not succeed either way. The species – but not the sexes – differed significantly in string‐pulling ability. The results of our experiments indicate that string pulling is an acquired combination of innate behaviour elements. An individual's string‐pulling competence may depend on prior experience of handling branchlets, on trial‐and‐error learning and on social learning (emulation). However, some individuals succeeded without these facilitating factors, while others did not succeed at all despite all of them present. Although functionally and motivationally related to feeding, the learned string pulling is often shown as a playful activity without an obvious reward.
Ontogeny of Anti‐Predator Behavioral Habituation in Cottonmouths (Agkistrodon piscivorus)
Authors: Glaudas Xavier , Winne Christopher T. , Fedewa Luke A. 
Published: February 2006

AbstractFew studies of venomous snakes have addressed how anti‐predator behavior may be affected by experience with a potential predator. Because defensive strikes may be costly to snakes, individuals with the ability to learn to discriminate among potentially harmful and non‐harmful predatory stimuli should be favored by natural selection. In large venomous snakes, adults are capable of successfully defending themselves against most potential predators, whereas neonates suffer higher predator‐induced mortality and are faced with a large diversity of predators. Consequently, we hypothesized that the relative costs of habituation to potential predatory stimuli should vary ontogenetically. This hypothesis predicts that adults should habituate rapidly to non‐harmful predatory stimuli, whereas neonates should consistently employ active defensive displays (e.g. striking) because they are at higher risk. To test this prediction, we examined daily changes in the defensive behavior of adult and neonate cottonmouths (Agkistrodon piscivorus) towards a standardized non‐harmful predatory stimulus. As predicted, adults and neonates differed in their tendencies to habituate: adults decreased defensiveness over days while neonates did not. Adults showed habituation of striking components but not of warning displays. Our results support the hypothesis that there may be ontogenetic differences in predator perception.