bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of culture conditions on the lipid composition of Phytophthora infestans
Authors: Griffiths Robert G. , Dancer Jane , O'Neill Elizabeth , Harwood John L. 
Published: December 2004

Summary

Phytophthora infestans is one of the most important of all plant pathogens and there is a demand for its more effective control. One target area for pesticides is lipid metabolism. To provide background information for studies with pesticides, we examined the lipids of P. infestans and how their composition is altered by culture conditions.
Phytophthora infestans was grown in a pea‐broth and three different minimal media. Acyl lipids were extracted, separated by thin‐layer chromatography, identified and quantified. Total fatty acid patterns and those in individual lipid classes were measured by gas–liquid chromatography.
Major polar lipids were the phosphoglycerides, phosphatidylcholine > phosphatidylethanolamine > phosphatidylinositol. The proportion of total polar lipids was reduced in minimal media. The similar fatty acid patterns of phosphatidylcholine and phosphatidylethanolamine were consistent with their metabolic relationship. Phytophthora infestans contained significant amounts of 22C unsaturated fatty acids, in addition to common fungal or oomycete fatty acids. Growth on minimal media caused changes in fatty acid patterns with increases in palmitate and linoleate and decreases in oleate being most obvious. Particular changes were also associated with the specific fatty acid patterns of individual lipids.
The changes found in total fatty acids and in the acyl profiles of individual lipids suggest that desaturase activities are altered by growth conditions. These results and the greater proportions of storage triacylglycerol in minimal media agree with data for some other lower plants or fungi.
Uptake and distribution of nickel and other metals in the hyperaccumulator Berkheya coddii
Authors: Robinson B. H. , Lombi E. , Zhao F. J. , McGrath S. P. 
Published: December 2004

Summary

Berkheya coddii is a fast‐growing, high biomass nickel (Ni) hyperaccumulator plant that has recently attracted attention for its possible use in the phytoextraction of Ni. The mechanisms of Ni accumulation, however, are not well understood in this plant.
Plants were grown hydroponically in varying Ni concentrations to assess the uptake and distribution of Ni, and other metals, at the whole plant level. X‐ray microanalyses (EDXA) of frozen hydrated tissues were conducted to determine the distribution of Ni at the cellular level in the leaves.
Most Ni was found in the shoots, especially in the leaves. Leaf Ni concentration increased with age, whereas older stem sections had lower Ni concentrations than new growth. EDXA analyses revealed that the cuticle of the upper epidermis had a significantly higher Ni concentration than the rest of the leaf. The Ni concentrations in the other leaf tissues were not significantly different.
This pattern of distribution contrasts sharply with some other hyperaccumulator species that commonly show a preferential accumulation of Ni and other metals in the vacuoles of the epidermal cells.
The ecological transition in speciation
Authors: Levin Donald A. 
Published: December 2004

SummaryEcological transitions are at the core of different modes of speciation. These transitions face both genetic and demographic hurdles. This paper focuses on how these hurdles are overcome, allowing ecological speciation and speciation via hybridization and/or polyploidy. Niche shifting is a two‐step process. First there is the establishment of ill‐adapted populations where ecological opportunity allows. This is followed by the genetic refinement of populations, which allows them to be integrated into novel communities and habitats. These steps are more readily accomplished in unsaturated floras, where competition is less intense. Ecological transitions in saturated floras may be facilitated by disturbance. Invasive species serve as heuristic model systems for understanding the early stages of speciation where niche shifts are involved.
Advances in the study of polyploidy sincePlant speciation
Authors: Soltis Douglas E. , Soltis Pamela S. , Tate Jennifer A. 
Published: December 2004

SummaryEnormous strides have been made in the study of polyploidy over the last 20 yr. Here, we highlight some of these discoveries and note where our understanding of polyploid evolution has changed. Genetic and genomic studies have dramatically altered the polyploidy paradigm. The estimated frequency of polyploidy has increased, and it is now recognized that multiple origins are the rule for most polyploids. Likewise, autopolyploidy is much more common than traditionally maintained. Rapid genomic rearrangements, genomic downsizing, movement of genetic elements across genomes, and the movement of foreign genetic materials into the polyploid genome illustrate the complex dynamics of polyploid genomes. Following polyploidization, both genetic and epigenetic mechanisms may play an important role in altering gene expression. Ecological studies reveal that plant polyploidy can have profound effects on interactions with animal herbivores and pollinators and that polyploidy may trigger changes in the reproductive biology of a species. Despite the recent advances in our understanding of polyploid evolution, many exciting aspects remain under‐investigated. Some of these include the consequences of genetic and genomic changes in natural polyploid populations, the physiological and ecological effects of polyploidy, and whether recurrent polyploidy prompts evolution to repeat itself.
ERP components associated with successful and unsuccessful stopping in a stop‐signal task
Authors: Kok Albert , Ramautar Jennifer R. , De Ruiter Michiel B. , Band Guido P. H. , Ridderinkhof K. Richard 
Published: December 2004

AbstractThe primary aim of this study was to examine how response inhibition is reflected in components of the event‐related potential (ERP), using the stop‐signal paradigm as a tool to manipulate response inhibition processes. Stop signals elicited a sequence of N2/P3 components that partly overlapped with ERP components elicited by the reaction stimulus. N2/P3 components were more pronounced on stop‐signal trials than on no‐stop‐signal trials. At Cz, the stop‐signal P3 peaked earlier on successful than on unsuccessful stop trials. This finding extends the horse race model by demonstrating that the internal response to the stop signal (as reflected in stop‐signal P3) is not constant, but terminates at different moments in time on successful and unsuccessful stop trials. In addition, topographical distributions and dipole analysis of high density EEG recordings indicated that different cortical generators were involved in P3s elicited on successful and unsuccessful stop‐signal trials. The latter results suggest that P3 on successful stop‐signal trials not only reflects stop‐signal processing per se, but also efficiency of inhibitory control.
A Novel Calcium Sensor Stimulating Inositol Phosphate Formation and [Ca2+]i Signaling Expressed by GCT23 Osteoclast‐Like Cells
Authors: Seuwen Klaus , Boddeke Hendrikus G.W.M. , Migliaccio Silvia , Perez Marie , Taranta Anna , Teti Anna 
Published: December 2004

Osteoclast activity is inhibited by elevated [Ca2+]o; however, the underlying molecular mechanism is unknown. We used the human osteoclast‐like cells GCT23 to elucidate their cation‐sensing properties. Cells responded to elevated [Ca2+]o with rpaaid concentration‐dependent [Ca2+]i transients (EC50 = 7.8 mm, time to peak 44 ± 4 sec) that were due to release from intracellular stores, followed by Ca2+ influx across the plasma membrane. Ca2+ store depletion by thpaasigargin, endothelin‐1, or bradykinin activated calcium entry pathways. Cells responded similarly to Ni2+ and Cd2+ with albeit slower kinetics (EC50 <10 μm and <100 μm, times to peak 140 ± 25 sec and 150 ± 24 sec, respectively). The three cations stimulated inositol phosphate production (two‐fold, p < .02) similar to bradykinin (2.5‐fold, p < .002), which activates a phospholipase C (PLC)‐coupled receptor in GCT23 cells. The cells did not respond to 0.1–1 mM Gd3+ or neomycin B, indicating that the parathyroid calcium receptor (PCaR) is not functionally expressed. In confirmation, PCaR could not be detected by reverse transcriptase polymerase chain reaction in GCT23 cells and in mouse osteoclasts, and the calcimimetic compound NPS R‐568 failed to produce the left shift of the concentration‐response curve characteristic for PCaR. Our data demonstrate for the first time that cation sensing by osteoclast‐like GCT23 cells is mediated by a PLC‐coupled receptor that is not identical to PCaR.
Aspects of the Care of People with HIV/AIDS in South Africa
Authors: Uys Leana R. 
Published: December 2004

Abstract  The study was aimed at exploring the realization of counseling, palliative care, and terminal care in the care of people with HIV/AIDS in seven settings in South Africa. A descriptive study was performed in seven sites where a model of home‐based care was implemented that links hospitals, clinics, and home‐based care in a continuum. Data was collected from people with HIV/AIDS (PWA), their caretakers, health care workers, and community members using semistructured interviews, observation, taping of onsite meetings, and completion of questionnaires. Descriptive and nonparametric statistics were used to analyze the quantitative data, and the template approach was used to analyze the qualitative data. There is a need to extend counseling before and after diagnostic testing to counseling about living with HIV/AIDS. There is also a need to equip counselors to deal with children. Fifty‐seven percent of patients died at home or in hospice. There is a significant relationship between a “good” death and dying at home. Palliative care in the formal health services was generally poor due mainly to lack of specific training in this field and the stigma associated with this diagnosis. Health care providers can change the experience of illness and death for PWA through adequate counseling, palliative care, and terminal care that meet professional standards.
Planning and Implementing a Reintroduction of Wolves to Yellowstone National Park and Central Idaho
Authors: Fritts Steven H. , Bangs Edward E. , Fontaine Joseph A. , Johnson Mark R. , Phillips Michael K. , Koch Edward D. , Gunson John R. 
Published: December 2004

AbstractThe Northern Rocky Mountain Wolf Recovery plan proposed reintroduction ofCanis lupus(gray wolf) to Yellowstone National Park and central Idaho as part of a wolf restoration plan for the northern Rocky Mountains of the United States. Strong opposition from some factions within the region forestalled the action for two decades. An environmental impact statement, conducted in 1992–1994 with extensive public input, culminated in a proposal to reintroduce wolves designated as “non‐essential—experimental” under Section 10 (j) of the federal Endangered Species Act. This approach, approved by the Secretary of the Interior in 1994, provided for wolf restoration while allowing management flexibility to deal with concerns of the local public. A reintroduction plan was developed in the summer and fall of 1994. Acquiring, holding, transporting, and releasing suitable wolves for reintroduction presented a myriad of technical and logistical challenges that required effective planning and coordination by all participants. In January 1995, 29 wolves were captured in Alberta and transported to Yellowstone National Park (14) and central Idaho (15). Idaho wolves were freed immediately upon arrival; Yellowstone wolves (three family groups) were held in acclimation pens in the park until late March. Most Idaho wolves traveled extensively within the area intended for them, averaging 82 km net distance away from release sites after 5 months (range = 30–220 km), and three male‐female pairs formed by July. After 5 months in the wild, at least 13 of 15 Idaho‐released wolves were alive within the intended area, as were 13 of 14 Yellowstone wolves; one wolf was known to have been illegally killed in each area. No livestock were killed. Wolves released into Yellowstone Park continued to live as packs, stayed closer to their release sites (x = 22 km at end of June), and settled into home ranges; two packs produced a total of nine pups. The progress of the reintroduction program in its first year far exceeded expectations. Reintroductions of about 15 wolves to each area for 2–4 more years are scheduled, but the project may be shortened because of early successes. Future reintroduction planners can expect sociocultural issues to pervade the effort, but they can be optimistic that, from a biological standpoint, reintroduction of wolves has strong potential as a restoration technique.
Woodland Restoration in the Western Australian Wheatbelt: A Conceptual Framework Using a State and Transition Model
Authors: Yates Colin J. , Hobbs Richard J. 
Published: December 2004

AbstractWoodlands dominated by Eucalyptus spp. in temperate southeastern and southwestern Australia have been extensively cleared for agriculture and are often badly degraded by livestock grazing. This has resulted in the loss of biodiversity and widespread land degradation. The continuing decline of these woodlands has become a concern for the conservation of biodiversity, and there is a growing interest among farmers, land managers, and researchers in developing techniques for restoring them. Currently few scientific guidelines exist for undertaking woodland restoration programs. We use a state and transition model to develop hypotheses on restoration strategies for salmon gum (Eucalyptus salmonophloia) woodlands. We consider that this approach provides a suitable framework for organizing knowledge and identifying areas where further information is needed, and hence provides a useful starting point for a restoration program. The model has the potential to provide a tool for land managers with which they can assess the action and effort needed to undertake woodland restoration in agricultural landscapes.
Biomass and Nutrient Accumulation During Natural Afforestation of Iron‐Smelting Slag
Authors: Smith Frances C. , Johnson Arthur H. , Dranoff Martin , Wibiralske Anne 
Published: December 2004

AbstractThis paper summarizes the accumulation of nutrient capital during the natural afforestation of iron‐smelting slag. The study site was the Beckley Furnace (North Caanan, Connecticut, U.S.A.) slag dump, which was abandoned around 1918. Currently, a Pinus strobus (white pine)‐dominated forest occupies the site. Our primary objective was to determine the relationships among stand development and belowground nutrient pools to evaluate controls on the rates at which nitrogen, calcium, magnesium, and potassium accumulate in the developing forest. Along a developmental gradient of increasing stand basal area, we measured (1) aboveground biomass, (2) root biomass, (3) above‐ground nutrient capital, (4) belowground nutrient capital, (5) soil weight, (6) soil organic carbon weight, (7) soil moisture, and (8) understory richness and density. Regression analysis suggests, as expected, that the addition of organic matter controls the accumulation of above‐ and belowground nutrients, soil water, and understory plant composition and distribution. The rather rapid rate of nitrogen accumulation suggests that allochthonous as well as autochthonous organic matter is an important source of nutrients for the developing forest soil and vegetation. Compared to those of other northeastern forests, soils in the most developed areas at the Beckley site have accumulated more than enough labile nutrient capital in 75 years to support a forest typical of the region. In the most developed stands, understory composition indicates mesic soil conditions, and that within the next 75 years or so the Beckley slag dump will be floristically very similar to the surrounding forest.
The Flora and Invertebrate Fauna of Abandoned Limestone Quarries in Derbyshire, United Kingdom
Authors: Wheater C. Philip , Cullen W. Rod 
Published: December 2004

AbstractAbandoned limestone quarries are hostile environments for plant and invertebrate colonization and establishment. The length of time taken for successful establishment by natural processes may be unacceptable for reclamation purposes; several techniques are used to reduce the time scales involved. A new technique, restoration blasting, aims to replicate natural daleside landforms by selective blasting of modern production quarry faces. We compare the flora and invertebrate fauna of restoration‐blasted sites, hydro‐seeded with daleside species, with naturally regenerating disused quarries and a natural daleside. Restoration‐blasted sites were found to have less plant cover, more bare ground, fewer orders of invertebrates, and generally fewer animals within each order than the other two types of site. The disused quarries tended to have intermediate characteristics between the restoration‐blasted sites and the natural daleside. The age of the site may be important in determining the plants and invertebrates occurring there. This may be related to the time available for establishment or a greater degree of settlement or stability within the biotic and abiotic components of the site. Although most of the results indicate that time since establishment may be important, some variations occur. In particular, the development of vegetation cover in areas grazed by rabbits is problematic. These results are important in the assessment of successful reclamation because the invertebrate fauna may contribute greatly to the overall system. Both plant and animal communities appear to be establishing well on the sites reclaimed by restoration blasting. Further monitoring will identify the speed at which such environments achieve the desired aim of replicating daleside communities and the communities best able to be sustained following this technique.
Existence of Detonations for Small Values of the Rate Parameter
Authors: Wood W. W. 
Published: December 2004

The simplified, one-dimensional, steady-state Navier-Stokes detonation problem formulated by Hirschfelder, Curtiss, et al. is examined with respect to the existence of solutions when the reaction rate is small compared to the molecular collision rate. The latter condition is necessary for the assumed unimolecular mechanism to be valid, but is also the condition where these authors were unable to find solutions by numerical integration of the differential equations. It is shown that solutions indeed exist for arbitrarily small values of the reaction rate, and that these solutions approach the von Neumann model of a shock preceding a deflagration. An asymptotic approximation to the solution is given which should be adequate for such small reaction rates.
In order to make the steady-state problem mathematically well defined, the usual difficulty of the very small reaction rate in the initial state is removed by imposing an ignition temperature. It is shown that if the reaction rate and Mach number are held fixed while the ignition temperature is raised slightly above the von Neumann spike temperature, the solution changes to a flame having the same hot boundary state, but with the detonation von Neumann spike state as its initial state.
United Grain Growers: Enterprise Risk Management and Weather Risk
Authors: Harrington Scott , Niehaus Greg 
Published: December 2004

AbstractIn August of 1999, Mike McAndless, the risk manager of United Grain Growers (UGG), was preparing for a meeting with the firm's chief financial officer, Peter Cox. Mike and Peter had spent considerable time over the past three years with representatives of the Willis Group Ltd., a large international insurance broker, identifying and measuring UGG's major sources of risk. The risk assessment process indicated that, although UGG hedged most of its currency and commodity price risk and purchased insurance against property and liability losses, the firm's earnings still exhibited substantial volatility. This volatility was, in large part, due to the weather. Mike and Peter had to decide whether to retain the risk or shift it to another party using one of two innovative contractual arrangements: weather derivatives or a new type of insurance contract.
Legitimacy Problems in Deliberative Democracy
Authors: Parkinson John 
Published: December 2004

The classic accounts of deliberative democracy are also accounts of legitimacy: ‘that outcomes are legitimate to the extent they receive reflective assent through participation in authentic deliberation by all those subject to the decision in question’ ( Dryzek, 2001, p. 651 ). And yet, in complex societies deliberative participation by all those affected by collective decision-making is extremely implausible. There are also legitimacy problems with the demanding procedural requirements which deliberation imposes on participants. Given these problems, deliberative democracy seems unable to deliver legitimate outcomes as it defines them. Focusing on the problem of scale, this paper offers a tentative solution using representation, a concept which is itself problematic. Along the way, the paper highlights issues with the legitimate role of experts, the different legitimate uses of statistical and electoral representation, and differences between the research and democratic imperatives driving current attempts to put deliberative principles into practice, illustrated with a case from a Leicester health policy debate. While much work remains to be done on exactly how the principles arrived at might be transformed into working institutions, they do offer a means of criticising existing deliberative practice.
Estimation of Bivariate and Marginal Distributions with Censored Data
Authors: Akritas Michael G. , Keilegom Ingrid Van 
Published: December 2004

SummaryConsider a pair of random variables, both subject to random right censoring. New estimators for the bivariate and marginal distributions of these variables are proposed. The estimators of the marginal distributions are not the marginals of the corresponding estimator of the bivariate distribution. Both estimators require estimation of the conditional distribution when the conditioning variable is subject to censoring. Such a method of estimation is proposed. The weak convergence of the estimators proposed is obtained. A small simulation study suggests that the estimators of the marginal and bivariate distributions perform well relatively to respectively the Kaplan–Meier estimator for the marginal distribution and the estimators of Pruitt and van der Laan for the bivariate distribution. The use of the estimators in practice is illustrated by the analysis of a data set.
Maximum Likelihood Estimation for the Proportional Hazards Model with Partly Interval-Censored Data
Authors: Kim Jong S. 
Published: December 2004

SummaryThe maximum likelihood estimator (MLE) for the proportional hazards model with partly interval-censored data is studied. Under appropriate regularity conditions, the MLEs of the regression parameter and the cumulative hazard function are shown to be consistent and asymptotically normal. Two methods to estimate the variance–covariance matrix of the MLE of the regression parameter are considered, based on a generalized missing information principle and on a generalized profile information procedure. Simulation studies show that both methods work well in terms of the bias and variance for samples of moderate size. An example illustrates the methods.
Inference for Clusters of Extreme Values
Authors: Ferro Christopher A. T. , Segers Johan 
Published: December 2004

SummaryInference for clusters of extreme values of a time series typically requires the identification of independent clusters of exceedances over a high threshold. The choice of declustering scheme often has a significant effect on estimates of cluster characteristics. We propose an automatic declustering scheme that is justified by an asymptotic result for the times between threshold exceedances. The scheme relies on the extremal index, which we show may be estimated before declustering, and supports a bootstrap procedure for assessing the variability of estimates.