bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of okadaic acid—induced cytotoxic effects in CHO K1 cells
Authors: Huynh‐Delerme C. , Fessard V. , Kiefer‐Biasizzo H. , Puiseux‐Dao S.
Published: November 2003

This article reports the results of investigations into the process of cell death induced in the Chinese hamster ovary cell K1 subclone (CHO K1) by okadaic acid (OA), a hydrophobic polyether produced by marine dinoflagellates. The IC50 was about 13 nM OA after 24 h of treatment, as determined using neutral red. With the MTT assay, the IC50 was 25 nM, although in this case 25% of the initial staining was still observed at 100 nM. Hoechst staining showed that mitotic figures accumulated at 12 nM OA after a 24‐ or 48‐h treatment. In experiments limited to a 3‐day treatment without changing the medium, CHO K1 cells were engaged in the death process at 50 nM OA after about 20 h and at 10 nM OA after 48 h. In many cells nuclear fragmentation that resulted in the apparent appearance of vesicles correlated with increasing cellular volume. But additional cell fragmentation was not observed with any treatment, and the chromatin material seemed to progressively disappear inside the cells. DNA fragmentation was analyzed by electrophoresis and with the TUNEL technique. With both techniques, the DNA was fragmented by 48 h in both 25 and 50 nM OA. Electrophoresis showed that both adherent and nonadherent cells were affected. Annexin‐positive/ propidium iodide (PI)–negative cells were rarely observed after OA treatment. Some were seen under the scanning cytometer after 20 h at 50 nM OA or after 48 h at 10 nM OA, but they were never detected by flow cytometry. Most of the time scanning cytometry showed either unstained cells or PI‐positive (annexin‐positive or ‐negative) cells (48 h, 50 nM, or 72 h, 10 nM). Flow cytometry cytograms showed two cell subpopulations: one composed of a majority of smaller cells, the other of larger cells. The larger cells markedly decreased with time and OA treatment (50 and 100 nM). Stained‐cell counting showed that all cells that stained were both annexin‐ and PI positive and that most PI‐positive cells were smaller. Ki67 antigen labeling showed the proliferative activity of CHO K1 cultures but also demonstrated the loss of this activity in smaller cells treated with 50 nM OA for 48 h. We concluded that in our culture conditions the main OA target within CHO K1 cultures was dividing cells. Our results suggest that cells with disturbed metaphase–anaphase enter apoptosis, leading to necrotic daughter cells. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 383–394, 2003
A practical and user‐friendly toxicity classification system with microbiotests for natural waters and wastewaters
Authors: Persoone Guido , Marsalek Blahoslav , Blinova Irina , Törökne Andrea , Zarina Dzidra , Manusadzianas Levonas , Nalecz‐Jawecki Grzegorz , Tofan Lucica , Stepanova Nadejda , Tothova Livia , Kolar Boris
Published: November 2003

Various types of toxicity classification systems have been elaborated by scientists in different countries, with the aim of attributing a hazard score to polluted environments or toxic wastewaters or of ranking them in accordance with increasing levels of toxicity. All these systems are based on batteries of standard acute toxicity tests (several of them including chronic assays as well) and are therefore dependent on the culturing and maintenance of live stocks of test organisms. Most systems require performance of the bioassays on dilution series of the original samples, for subsequent calculation of L(E)C50 or threshold toxicity values. Given the complexity and costs of these toxicity measurements, they can only be applied in well‐equipped and highly specialized laboratories, and none of the classification methods so far has found general acceptance at the international level. The development of microbiotests that are independent of continuous culturing of live organisms has stimulated international collaboration. Coordinated at Ghent University, Belgium, collaboration by research groups from 10 countries in central and eastern Europe resulted in an alternative toxicity classification system that was easier to apply and substantially more cost effective than any of the earlier methods. This new system was developed and applied in the framework of a cooperation agreement between the Flemish community in Belgium and central and eastern Europe. The toxicity classification system is based on a battery of (culture‐independent) microbiotests and is particularly suited for routine monitoring. It indeed only requires testing on undiluted samples of natural waters or wastewaters discharged into the aquatic environment, except for wastewaters that demonstrate more than 50% effect. The scoring system ranks the waters or wastewaters in 5 classes of increasing hazard/toxicity, with calculation of a weight factor for the concerned hazard/toxicity class. The new classification system was applied during 2000 by the participating laboratories on samples of river water, groundwaters, drinking waters, mine waters, sediment pore waters, industrial effluents, soil leachates, and waste dump leachates and was found to be easy to apply and reliable. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 395–402, 2003.
Testing direct and indirect effects of sports participation on perceived health in Spanish adolescents between 15 and 18 years of age☆
Authors: Pastor Yolanda , Balaguer Isabel , Pons Diana , García‐Merita Marisa
Published: November 2003

This paper examines the direct and indirect effects of sports participation on perceived health. It is based on a representative sample of middle adolescents aged 15–18 (N=1038,Mage=16.31,s.d.=0.92; 510 boys and 528 girls) from the Valencian Community (Spain). This study used two different models; Model A is an adaptation of Thorlindsson, Vilhjalmsson and Valgeirsson's (Social Science and Medicine 31 (1990) 551) model which introduces smoking, alcohol use, feelings of anxiety, feelings of depression and psychophysiological symptoms as mediator variables; Model B is an extension of Model A with perceived physical fitness as an added mediator variable. Both models show a good fit to the data. Results showed that, in both models, sports participation affected perceived health directly and indirectly by decreasing smoking and alcohol consumption, feelings of depression and psychophysiological symptoms. In Model B, sport also affected perceived health via increased perceived physical fitness explaining almost 10% more of the variance.
Structural insights into the processivity of endopolygalacturonase I from Aspergillus niger
Authors: van Pouderoyen Gertie , Snijder Harm J , Benen Jacques A.E , Dijkstra Bauke W
Published: November 2003

Endopolygalacturonase I is a processive enzyme, while the 60% sequence identical endopolygalacturonase II is not. The 1.70 Å resolution crystal structure of endopolygalacturonase I reveals a narrowed substrate binding cleft. In addition, Arg96, a residue in this cleft previously shown to be critical for processivity, interacts with the substrate mimics glycerol and sulfate in several well‐defined conformations in the six molecules in the asymmetric unit. From this we conclude that both Arg96 and the narrowed substrate binding cleft contribute to retaining the substrate while it moves through the active site after a cleavage event has occurred.
Structural localization of disease‐associated sequence variations in the NACHT and LRR domains of PYPAF1 and NOD2
Authors: Albrecht Mario , Domingues Francisco S. , Schreiber Stefan , Lengauer Thomas
Published: November 2003

Several autoinflammatory diseases with distinct clinical manifestations have been associated with sequence variations in the gene products PYPAF1/CIAS1 and NOD2/CARD15. Both proteins belong to the PYD/CARD‐containing family of apoptosis regulators and activators of pro‐inflammatory caspases. To gain insight into the dysfunctional role of sequence alterations, we assembled a structure‐based multiple sequence alignment of family members and related proteins. This allowed us to analyze the putative effect of the alterations on the function of nucleotide‐binding (NACHT) and leucine‐rich repeat (LRR) domains shared by the family members. In support of this analysis, we carefully selected template structures for the NACHT and LRR domains and mapped the genetic variations onto 3D domain models. Additionally, we propose a model of the NACHT and LRR domain complex. Our study revealed that many of the disease‐associated sequence variants are located close to highly conserved sequence regions of functional relevance and are spatially adjacent in the predicted 3D structure. The implications on the domain functions such as NTP‐hydrolysis or oligomerization are discussed.
The CD99 signal enhances Fas‐mediated apoptosis in the human leukemic cell line, Jurkat
Authors: Jung Kyeong Cheon , Kim Nam Hyun , Park Weon Seo , Park Seong Hoe , Bae Youngmee
Published: November 2003

The CD99 antigen has been implicated in various cellular processes, including apoptosis in T cells. Previously, we reported two monoclonal antibodies that recognize different epitopes of the CD99 molecule, named DN16 and YG32. In this study, we investigated the role of each CD99 epitope in T cell apoptosis. Unlike the DN16 epitope, CD99 ligation via the YG32 epitope failed to induce T cell death. Surprisingly, however, the YG32 signal enhanced Fas‐mediated apoptosis in Jurkat T cells. Augmentation of Fas‐mediated apoptosis by YG32 ligation was inhibited by treatment with either of the caspase inhibitors z‐VAD‐fmk or z‐IETD‐fmk, and YG32 ligation appeared to induce Fas oligomerization. These results suggest that each CD99 epitope plays a distinct role in T cell biology, especially in T cell apoptosis.
The importance of the Q motif in the ATPase activity of a viral helicase
Authors: Gallivan J.-P , McGarvey Michael J
Published: November 2003

NS3 proteins of flaviviruses contain motifs which indicate that they possess protease and helicase activities. The helicases are members of the DExD/H box helicase superfamily and NS3 proteins from some flaviviruses have been shown to possess ATPase and helicase activities in vitro. The Q motif is a recently recognised cluster of nine amino acids common to most DExD/H box helicases which is proposed to regulate ATP binding and hydrolysis. In addition a conserved residue occurs 17 amino acids upstream of the Q motif (‘+17’). We have analysed full‐length and truncated NS3 proteins from Powassan virus (a tick‐borne flavivirus) to investigate the role that the Q motif plays in the hydrolysis of ATP by a viral helicase. The Q motif appears to be essential for the activity of Powassan virus NS3 ATPase, however NS3 deletion mutants that contain the Q motif but lack the ‘+17’ amino acid have ATPase activity albeit at a reduced level.
The effects of post‐translational processing on dystroglycan synthesis and trafficking1
Authors: Esapa Chris T. , Bentham Graham R.B. , Schröder Jörn E. , Kröger Stephan , Blake Derek J.
Published: November 2003

Dystroglycan is a component of the dystrophin glycoprotein complex that is cleaved into two polypeptides by an unidentified protease. To determine the role of post‐translational processing on dystroglycan synthesis and trafficking we expressed the dystroglycan precursor and mutants thereof in a heterologous system. A point mutant in the processing site, S655A, prevented proteolytic cleavage but had no effect upon the surface localisation of dystroglycan. Mutation of two N‐linked glycosylation sites that flank the cleavage site inhibited proteolytic processing of the precursor. Furthermore, chemical inhibition of N‐ and O‐linked glycosylation interfered with the processing of the precursor and reduced the levels of dystroglycan at the cell surface. Dystroglycan processing was also inhibited by the proteasome inhibitor lactacystin. N‐linked glycosylation is a prerequisite for efficient proteolytic processing and cleavage and glycosylation are dispensable for cell surface targeting of dystroglycan.
Enhanced permeability transition explains the reduced calcium uptake in cardiac mitochondria from streptozotocin‐induced diabetic rats
Authors: Oliveira Paulo J , Seiça Raquel , Coxito Pedro M , Rolo Anabela P , Palmeira Carlos M , Santos Maria S , Moreno António J.M
Published: November 2003

Cardiac dysfunction is associated with diabetes. It was previously shown that heart mitochondria from diabetic rats have a reduced calcium accumulation capacity. The objective of this work was to determine whether the reduction in calcium accumulation by cardiac mitochondria from diabetic rats is related to an enhanced susceptibility to induction of the mitochondrial permeability transition. Streptozotocin‐induced diabetic rats were used as a model to study the alterations caused by diabetes in the permeability transition, 21 days after streptozotocin administration. Heart mitochondria were isolated to evaluate respiratory parameters and susceptibility to the calcium‐dependent permeability transition. Our results show that streptozotocin diabetes facilitates the mitochondrial permeability transition in cardiac mitochondria, resulting in decreased mitochondrial calcium accumulation. We also observed that heart mitochondria from diabetic rats had depressed oxygen consumption during the phosphorylative state. The reduced mitochondrial calcium uptake observed in heart mitochondria from diabetic rats is related to an enhanced susceptibility to the permeability transition rather than to damage to the calcium uptake machinery.
Der Computerwissenstest CWIS-4: Befunde zur Reliabilität und Validität
Authors: Wagener Dietrich
Published: November 2003

Zusammenfassung. Der CWIS-4 dient der Erfassung allgemeinen computerbezogenen Wissens. Neben einer Globalskala mit 60 Items, zu der auch eine Kurzfassung mit 24 Items vorliegt, geben vier Subskalen Auskunft über die Kenntnisse in den Bereichen Anwendung, Internet, Hardware und Informatik. Ziel der Konstruktion war ein Verfahren, das sich für den Einsatz in bezüglich Wissensniveau sehr unterschiedlichen Teilnehmergruppen eignet und trotz der schnellen technischen Weiterentwicklung relativ langlebige Items enthält. Befunde aus zwei Stichproben mit zusammen N = 974 Testbearbeitungen erlauben die Beurteilung von Reliabilität, Konstruktvalidität und kriterienbezogener Validität der Testskalen. Zur Überprüfung der auf Vorüberlegungen basierenden Differenzierung in vier inhaltliche Subskalen dienen Faktorenanalysen und Korrelationen mit Selbstauskünften.
Vertrauen gegenüber Vorgesetzten und Akzeptanz von Entgeltsystemen
Authors: Kopp Thomas , Schuler Heinz
Published: November 2003

Zusammenfassung. Im Rahmen der dargestellten zweiteiligen Untersuchung wird ein Fragebogen zur Erhebung des interpersonalen Vertrauens vorgestellt, das Mitarbeiter ihren Führungskräften entgegenbringen. Es wird untersucht, ob das Vertrauen eines Mitarbeiters in seinen Vorgesetzten eine Rolle für die Akzeptanz bestimmter Entgeltkomponenten spielt. Außerdem wird die Beziehung zwischen den Wertorientierungen der Mitarbeiter und der Akzeptanz der Entgeltkomponenten analysiert. Der Vertrauensfragebogen bildet die fünf relevanten Faktoren Fürsorge, Zuverlässigkeit, Offenheit und Harmonie, Fähigkeit und Ambivalenz ab. Nach den in der Untersuchung gefundenen Ergebnissen haben Wertorientierungen keinen Einfluss auf die Akzeptanz von Entgeltkomponenten; Mitarbeiter mit mittlerem und hohem Vertrauen in ihren Vorgesetzten akzeptieren eher Entgeltsysteme, bei denen die Führungskraft Entscheidungsspielraum besitzt, als Mitarbeiter mit geringem Vertrauen in ihren Vorgesetzten.
Seismic velocity, anisotropy, and fluid pressure in the Barbados accretionary wedge from an offset vertical seismic profile with seabed sources
Authors: Hayward Nathan , Westbrook Graham K. , Peacock Sheila
Published: November 2003

The state of compaction and fluid pressure in the Barbados accretionary wedge near its toe, at Ocean Drilling Program Site 949, were investigated by modeling travel times of seismic waves from ocean bottom shots to a borehole geophone array. The model, constrained by a three‐dimensional seismic survey and well logs, shows (1) a velocity gradient of about 1–1.25 s−1 in the uppermost 180–230 m of the wedge; (2) a zone of variable, but no net change in, velocity between 230 and 350 m depth; (3) a low‐velocity zone 40–50 m thick just above the décollement at 391 m; and (4) a displacement of the low‐velocity zone by thrust faults. Pore fluid pressure sections derived from P wave velocity show that the upper half of the wedge is normally pressured while the lower half is overpressured. The ∼160 m thick, underconsolidated basal zone shows anisotropy, which increases downward. The lowest 40–50 m has velocity varying (1) azimuthally (3%), being fastest in the direction of plate convergence, and (2) in the vertical plane (2–5%), horizontal faster than vertical. After correction for the effect of anisotropy in the derivation of effective stress from seismic velocity the calculated pore fluid pressure ratio λ does not exceed 0.9 and in the lowest 40–50 m of the basal zone, is between 0.71 and 0.82, with λ* [(fluid pressure − hydrostatic)/(lithostatic pressure − hydrostatic)] between 0.5 and 0.65, in accordance with in situ measurements of fluid pressure in the décollement zone beneath. These indicate that the accretionary wedge is stronger and less overpressured than was previously supposed.
Late twentieth century Northern Hemisphere sea‐ice record from U.S. National Ice Center ice charts
Authors: Partington Kim , Flynn Tom , Lamb Doug , Bertoia Cheryl , Dedrick Kyle
Published: November 2003

Arctic sea ice plays a key role in the climate system, by acting as the interface between a warm ocean and a cold atmosphere. Establishing the true pattern of recent behavior of the sea ice in this region is critical to simulating the role of sea ice in future climate. Recently released operational ice charts from the U.S. National Ice Center provide insight into the late twentieth century behavior of Northern Hemisphere sea ice, providing more reliable ice concentrations during summer and freeze‐up than those available from the passive microwave record. The major winter and summer modes of ice concentration variability observed from empirical orthogonal function analysis covering the period 1972–1994 are shown to indicate, respectively, the 1‐year lagged response of the sea ice to the North Atlantic Oscillation and the winter preconditioning of summer sea ice coverage in the eastern Arctic by the North Atlantic Oscillation. Feedback to the atmosphere is suggested in each case by zero‐lag cyclone frequency relationships to these two sea ice modes of variability.
High time resolution determination of the tropical tropopause by the Equatorial Atmosphere Radar
Authors: Yamamoto Masayuki K. , Oyamatsu Masayuki , Horinouchi Takeshi , Hashiguchi Hiroyuki , Fukao Shoichiro
Published: November 2003

The Equatorial Atmosphere Radar (EAR) is located at the equator (0.20°S, 100.32°E) in West Sumatra, Indonesia. The capability of the EAR to observe short‐term variations of the tropopause altitude is shown. Near the tropopause, the EAR receives strong echoes caused by the rapid increase of hydrostatic stability with altitude. By applying this characteristic, the radar tropopause (RT) was determined. The RT agreed well with both the lapse‐rate tropopause (LRT) and the cold‐point tropopause (CPT) in altitude with a time resolution of 3 hours. The power spectrum of the RT altitude from 1 July to 18 December, 2001 showed a clear 1‐day peak. The amplitude of its diurnal cycle as revealed in composites is as small as ∼0.1 km. Nevertheless, the RT was able to reproduce the diurnal cycle in the LRT and the CPT well, which indicates that the EAR can observe short‐term variations of the tropical tropopause.
Mid‐depth circulation in the northwest Pacific during the last deglaciation: Evidence from foraminiferal radiocarbon ages
Authors: Ahagon Naokazu , Ohkushi Ken'ichi , Uchida Masao , Mishima Toshiaki
Published: November 2003

Sediment cores (MR01‐K03 PC4/PC5, 1366 m water depth) collected from off northern Japan were studied using coexisting planktonic and benthic foraminiferal radiocarbon measurements to reconstruct the history of mid‐depth circulation in the northwest Pacific. Reconstructed ventilation ages indicate that, consistent with data from a previous radiocarbon study at a shallower site, there was significant variation in mid‐depth circulation during the last deglaciation, especially in the Bølling‐Allerød (13–15 ka) and Younger Dryas (11.5–13 ka) intervals. Our record indicates that the ventilation changes in the North Pacific were antiphase to those of the North Atlantic, suggesting that atmospheric moisture transport associated with the Asian Monsoon might have played a great role in millennium‐scale ventilation changes in the North Pacific during the last deglaciation.
Capgras syndrome – out of sight, out of mind?
Authors: Dietl T. , Herr A. , Brunner H. , Friess E.
Published: November 2003

Objective:  Recent theoretical approaches emphasize a disorder of face processing in the pathogenesis of the Capgras syndrome. We report a patient with the Capgras syndrome developing in the physical absence of the person who is believed to be replaced and thus a limited role for a disorder of face processing.

Method:  The clinical phenomenology of a case of the Capgras syndrome is explored.

Results:  A disorder of face processing might not be a sufficient explanation of the course of the disorder in this patient.

Conclusion:  Face processing accounts, of the Capgras delusion, have to be supplemented by additional assumptions.
Clinical correlates of early medication adherence: West London first episode schizophrenia study
Authors: Mutsatsa S. H. , Joyce E. M. , Hutton S. B. , Webb E. , Gibbins H. , Paul S. , Barnes T. R. E.
Published: November 2003

Objective:  Little is known about factors that mediate adherence with medication during the early stages of antipsychotic treatment in schizophrenia. This study sought to identify factors that may be associated with medication adherence in first‐episode schizophrenia.

Method:  In 101 patients, adherence was assessed along with potentially relevant variables, including attitudes toward medication, insight, substance misuse, side effects and psychopathology.

Results:  In a linear regression analysis, negative attitudes toward medication and a relative lack of insight contributed significantly towards poor adherence. Although poorly adherent patients had significantly higher scores on negative and disorganization syndromes, these did not contribute significantly towards adherence. Adverse medication side effects, subjective well‐being and substance misuse showed no significant association with adherence.

Conclusion:  At the initiation of drug treatment, attitudes toward medication and insight appear more relevant to medication adherence than side effects. Adherence appears to reflect a complex interaction of influences, which may change over time.
Which individuals with affective symptoms seek help? Results from the Zurich epidemiological study
Authors: Burns T. , Eichenberger A. , Eich D. , Ajdacic‐Gross V. , Angst J. , Rössler W.
Published: November 2003

Objective:  Several factors influence whether individuals with affective disorders seek help. The Zurich cohort study provides an opportunity to explore patient‐based factors without confounding with problems of access. This study aims to identify features which predict help‐seeking behaviour in symptomatic individuals and to explore failure of help seeking in those who did not.

Method:  Characteristics of currently symptomatic 40‐year‐old individuals in a stratified epidemiological sample were tested against help‐seeking behaviour using bivariate statistics and logistic regression. Individual predictors were identified and interaction effects tested.

Results:  Thirty‐one per cent of the 364 subjects sought help in the preceding year. Past treatment and living alone were significantly associated with treatment. Total number of symptoms and several individual symptoms correlated with treatment in the bivariate analyses but regression analysis identified ‘unfounded self‐reproach’ and ‘hopelessness’ interacting with social support to predict the best treatment.

Conclusion:  Social support is strongly protective against needing help in the presence of distressing affective symptoms unless these symptoms become elaborated into conclusions about their meaning and prognostic significance.
Weather and suicide: the present state of knowledge on the association of meteorological factors with suicidal behaviour
Authors: Deisenhammer E. A.
Published: November 2003

Objective:  To review the available literature on the association between daily and longer‐term weather data and the incidence of attempted and completed suicide.

Method:  A computerized search supplemented by a cross‐check of the references sections of the thereby identified papers was performed.

Results:  A total of 27 studies looking for a relationship between attempted or completed suicide and weather or climate data were found. Most of the papers reported a statistical association of suicidal acts with at least one weather factor. However, the results are not conclusive and in part contradictory.

Conclusion:  Possibly due to the high variance in methodological approaches of the studies it is not possible to identify a specific weather condition associated with a generally higher risk for suicide. Weather and seasonal effects may interact with each other. Environmental effects on brain function and weather‐related interactions of people may be involved in the occurrence of suicidal behaviour.
Convergence Equations and Income Dynamics: The Sources of OECD Convergence, 1970–1995
Authors: De la fuente Angel
Published: November 2003

This paper illustrates how convergence equations can be used to analyse the dynamics of the income distribution using a simple extension of standard techniques. Using data for a sample of OECD countries, I estimate an equation that relates growth in income per capita to the standard growth theory variables, government size and labour market performance indicators. The estimated model and the underlying data are then used in a convergence accounting exercise that yields quantitative estimates of the contribution of each of these variables to the relative growth performance of each country and to observed convergence in the sample.
Size and School District Consolidation: Do Opposites Attract?
Authors: Brasington David M.
Published: November 2003

Municipalities sometimes retain separate police departments and park services while cooperating in public schooling services with neighboring municipalities. The theoretical model of Ellingsen (Journal of Public Economics, 68, 251–68, 1998) predicts that: (1) under Tiebout sorting, larger size differences make big municipalities more likely to consolidate with small ones, but small municipalities less likely to consolidate with big ones; (2) municipalities never excessively consolidate. The current study examines 298 pairs of municipalities that could consolidate schooling. The decision‐making process of the larger and smaller member of each pair is examined separately. The Poirier bivariate probit results are consistent with Ellingsen's predictions but contradict previous empirical findings.
Government Spending, Local Indeterminacy and Tax Structure
Authors: Raurich Xavier
Published: November 2003

This paper develops an endogenous growth model where sustained growth is due to the introduction of a public input. Consumers derive utility from consumption, leisure and a public good. The public input and the public good are the flow of government expenditures. These expenditures are financed by means of income taxes. With these assumptions, it is shown that the dynamic equilibrium may exhibit local indeterminacy when the tax rate on the labour income is large. The tax structure that maximizes growth and the optimal tax structure are characterized and compared.
Microplanning with Communicative Intentions: The SPUD System
Authors: Stone Matthew , Doran Christine , Webber Bonnie , Bleam Tonia , Palmer Martha
Published: November 2003

The process of microplanning in natural language generation (NLG) encompasses a range of problems in which a generator must bridge underlying domain‐specific representations and general linguistic representations. These problems include constructing linguistic referring expressions to identify domain objects, selecting lexical items to express domain concepts, and using complex linguistic constructions to concisely convey related domain facts.

In this paper, we argue that such problems are best solved through a uniform, comprehensive, declarative process. In our approach, the generator directly explores a search space for utterances described by a linguistic grammar. At each stage of search, the generator uses a model of interpretation, which characterizes the potential links between the utterance and the domain and context, to assess its progress in conveying domain‐specific representations. We further address the challenges for implementation and knowledge representation in this approach. We show how to implement this approach effectively by using the lexicalized tree‐adjoining grammar (LTAG) formalism to connect structure to meaning and using modal logic programming to connect meaning to context. We articulate a detailed methodology for designing grammatical and conceptual resources which the generator can use to achieve desired microplanning behavior in a specified domain.

In describing our approach to microplanning, we emphasize that we are in fact realizing a deliberative process of goal‐directed activity. As we formulate it, interpretation offers a declarative representation of a generator's communicative intent. It associates the concrete linguistic structure planned by the generator with inferences that show how the meaning of that structure communicates needed information about some application domain in the current discourse context. Thus, interpretations areplansthat the microplanner constructs and outputs. At the same time, communicative intent representations provide arich and uniform resourcefor theprocessof NLG. Using representations of communicative intent, a generator can augment the syntax, semantics, and pragmatics of an incomplete sentence simultaneously, and can work incrementally toward solutions for the various problems of microplanning.
Widespread foliage δ15N depletion under elevated CO2: inferences for the nitrogen cycle
Authors: BassiriRad Hormoz , Constable John V. H. , Lussenhop John , Kimball Bruce A. , Norby Richard J. , Oechel Walter C. , Reich Peter B. , Schlesinger William H. , Zitzer Stephen , Sehtiya Harbans L. , Silim Salim
Published: November 2003

Leaf 15N signature is a powerful tool that can provide an integrated assessment of the nitrogen (N) cycle and whether it is influenced by rising atmospheric CO2 concentration. We tested the hypothesis that elevated CO2 significantly changes foliage δ15N in a wide range of plant species and ecosystem types. This objective was achieved by determining the δ15N of foliage of 27 field‐grown plant species from six free‐air CO2 enrichment (FACE) experiments representing desert, temperate forest, Mediterranean‐type, grassland prairie, and agricultural ecosystems. We found that within species, the δ15N of foliage produced under elevated CO2 was significantly lower (P<0.038) compared with that of foliage grown under ambient conditions. Further analysis of foliage δ15N by life form and growth habit revealed that the CO2 effect was consistent across all functional groups tested. The examination of two chaparral shrubs grown for 6 years under a wide range of CO2 concentrations (25–75 Pa) also showed a significant and negative correlation between growth CO2 and leaf δ15N. In a select number of species, we measured bulk soil δ15N at a depth of 10 cm, and found that the observed depletion of foliage δ15N in response to elevated CO2 was unrelated to changes in the soil δ15N. While the data suggest a strong influence of elevated CO2 on the N cycle in diverse ecosystems, the exact site(s) at which elevated CO2 alters fractionating processes of the N cycle remains unclear. We cannot rule out the fact that the pattern of foliage δ15N responses to elevated CO2 reported here resulted from a general drop in δ15N of the source N, caused by soil‐driven processes. There is a stronger possibility, however, that the general depletion of foliage δ15N under high CO2 may have resulted from changes in the fractionating processes within the plant/mycorrhizal system.
Uncertainty in estimating land use and management impacts on soil organic carbon storage for US agricultural lands between 1982 and 1997
Authors: Ogle Stephen M. , Jay Breidt F. , Eve Marlen D. , Paustian Keith
Published: November 2003

Uncertainty was quantified for an inventory estimating change in soil organic carbon (SOC) storage resulting from modifications in land use and management across US agricultural lands between 1982 and 1997. This inventory was conducted using a modified version of a carbon (C) accounting method developed by the Intergovernmental Panel on Climate Change (IPCC). Probability density functions (PDFs) were derived for each input to the IPCC model, including reference SOC stocks, land use/management activity data, and management factors. Change in C storage was estimated using a Monte‐Carlo approach with 50 000 iterations, by randomly selecting values from the PDFs after accounting for dependencies in the model inputs. Over the inventory period, mineral soils had a net gain of 10.8 Tg C yr−1, with a 95% confidence interval ranging from 6.5 to 15.3 Tg C yr−1. Most of this gain was due to setting‐aside lands in the Conservation Reserve Program. In contrast, managed organic soils lost 9.4 Tg C yr−1, with a 95% confidence interval ranging from 6.4 to 13.3 Tg C yr−1. Combining these gains and losses in SOC, US agricultural soils accrued 1.3 Tg C yr−1 due to land use and management change, with a 95% confidence interval ranging from a loss of 4.4 Tg C yr−1 to a gain of 6.9 Tg C yr−1. Most of the uncertainty was attributed to management factors for tillage, land use change between cultivated and uncultivated conditions, and C loss rates from managed organic soils. Based on the uncertainty, we are not able to conclude with 95% confidence that change in US agricultural land use and management between 1982 and 1997 created a net C sink for atmospheric CO2.
Natural disturbances in the European forests in the 19th and 20th centuries
Authors: Schelhaas Mart‐Jan , Nabuurs Gert‐Jan , Schuck Andreas
Published: November 2003

This paper, based on a literature review, presents a quantitative overview of the role of natural disturbances in European forests from 1850 to 2000. Such an overview provides a basis for modelling the possible impacts of climate change and enables one to assess trends in disturbance regimes in different countries and/or periods. Over the period 1950–2000, an annual average of 35 million m3 wood was damaged by disturbances; there was much variation between years. Storms were responsible for 53% of the total damage, fire for 16%, snow for 3% and other abiotic causes for 5%. Biotic factors caused 16% of the damage, and half of this was caused by bark beetles. For 7% of the damage, no cause was given or there was a combination of causes. The 35 million m3 of damage is about 8.1% of the total fellings in Europe and about 0.15% of the total volume of growing stock. Over the period 1961–2000, the average annual area of forest fires was 213 000 ha, which is 0.15% of the total forest area in Europe. Most types of damage seem to be increasing. This is partly an artefact of the improved availability of information. The most likely explanations for an increase in damage from disturbances are changes in forest management and resulting changes in the condition of the forest. Forest area, average volume of growing stock and average stand age have increased considerably, making the forest more vulnerable and increasing the resources that can be damaged. Since forest resources are expected to continue to increase, it is likely that damage from disturbances will also increase in future.
North Sea cod and climate change – modelling the effects of temperature on population dynamics
Authors: Clark Robin A. , Fox Clive J. , Viner David , Livermore Matthew
Published: November 2003

In order to examine the likely impacts of climate change on fish stocks, it is necessary to couple the output from large‐scale climate models to fisheries population simulations. Using projections of future North Sea surface temperatures for the period 2000–2050 from the Hadley General Circulation Model, we estimate the likely effects of climate change on the North Sea cod population. Output from the model suggests that increasing temperatures will lead to an increased rate of decline in the North Sea cod population compared with simulations that ignore environmental change. Although the simulation developed here is relatively simplistic, we demonstrate that inclusion of environmental factors in population models can markedly alter one's perception of how the population will behave. The development of simulations incorporating environment effects will become increasingly important as the impacts of climate change on the marine ecosystem become more pronounced.
Impacts of changing climate and atmospheric deposition on N and S drainage losses from a forested watershed of the Adirondack Mountains, New York State
Authors: Park Ji‐Hyung , Mitchell Myron J. , McHale Patrick J. , Christopher Sheila F. , Meyers Tilden P.
Published: November 2003

Biogeochemical responses to changing climate and atmospheric deposition were investigated using nitrogen (N) and sulfur (S) mass balances, including dry deposition and organic solutes in the Arbutus Lake watershed in the Adirondack Mountains, New York State. Long‐term monitoring of wet‐only precipitation (NADP/NTN, 1983–2001) and dry deposition (AIRMoN, 1990–2001) at sites adjacent to the watershed showed that concentrations of SO42− in precipitation, SO42− in particles,and SO2 vapor all declined substantially (P<0.005) in contrast to no marked temporal changes observed for most N constituents (NH4+ in precipitation, HNO3 vapor, and particulate NO3−), except for NO3− in precipitation, which showed a small decrease in the late 1990s. From 1983 to 2001, concentrations of SO42− in the lake outlet significantly decreased (−2.1 μeq L−1 yr−1, P<0.0001), whereas NO3− and dissolved organic N (DON) concentrations showed no consistent temporal trends. With the inclusion of dry deposition and DON fluxes into the mass balance, the retained portion of atmospheric N inputs within the main subcatchment increased from 37% to 60%. Sulfur outputs greatly exceeded inputs even with the inclusion of dry S deposition, while organic S flux represented another source of S output, implying substantial internal S sources. A significant relationship between the annual mean concentrations of SO42− in lake discharge and wet deposition over the last two decades (r=0.64, P<0.01) suggested a considerable influence of declining S deposition on surface water SO42− concentrations, despite substantial internal S sources. By contrast, interannual variations in both NO3− concentrations and fluxes in lake discharge were significantly related to year‐to‐year changes in air temperature and runoff. Snowmelt responses to winter temperature fluctuations were crucial in explaining large portions of interannual variations in watershed NO3− export during the months preceding spring snowmelt (especially, January–March). Distinctive response patterns of monthly mean concentrations of NO3− and DON in the major lake inlet to seasonal changes in air temperature also suggested climatic regulation of seasonal patterns in watershed release of both N forms. The sensitive response of N drainage losses to climatic variability might explain the synchronous patterns of decadal variations in watershed NO3− export across the northeastern USA.
Detection of process‐related changes in plant patterns at extended spatial scales during early dryland desertification
Authors: Ares Jorge , Del Valle Héctor , Bisigato Alejandro
Published: November 2003

Arid and semiarid shrublands occupy extensive land areas over the world, are susceptible to desertification by anthropic use and can contribute to regional climate change. These prompt the interest to monitor and evaluate these lands adequately in order to detect early stages of degradation. Evaluation topics must refer to biology‐relevant characteristics of these systems, while simultaneously satisfying sampling consistency over extended landscape areas. We present an analysis of process‐relevant parameters related to changes in the spatial arrangement of the plant canopy of shrublands inferred from high‐resolution panchromatic aerial photos and Interferometric Synthetic Aperture Radar imagery. We obtained low‐altitude images systematically located along several gradients of land‐use intensity in a Patagonian Monte shrubland in Argentina. Images were digitized to spatial resolutions ranging from 0.09 to 0.72 m (pixel size) and the average values and an‐isotropic characteristics of the plant canopy patterns were quantified by means of a Fourier metric. We used radar‐derived imagery to overlay the panchromatic images on a digital elevation model in order to study the correspondence of potential runoff patterns and the spatial arrangement of plants. We related an‐isotropic features of the plant canopy images to the prevailing wind regime. Observed trends were further interpreted on the basis of a spatial‐explicit simulation model describing the dynamics of the main functional groups in the plant community. We conclude that early stages of anthropic‐driven dryland degradation in the Patagonian Monte can be characterized by the incipient un‐coupling of spatial vegetation patterns from those of runoff at a landscape scale, and a progressive coupling to the spatial pattern of the wind regime. The method and metrics we present can be used to quantify early desertification changes in other similar drylands at extended spatial scales.
Biotic and abiotic immobilization of ammonium, nitrite, and nitrate in soils developed under different tree species in the Catskill Mountains, New York, USA
Authors: Fitzhugh Ross D. , Lovett Gary M. , Venterea Rodney T.
Published: November 2003

Nitrogen retention in soil organic matter (SOM) is a key process influencing the accumulation and loss of N in forest ecosystems, but the rates and mechanisms of inorganic N retention in soils are not well understood. The primary objectives of this study were to compare ammonium (NH4+), nitrite (NO2−), and nitrate (NO3−) immobilization among soils developed under different tree species in the Catskill Mountains of New York State, and to determine the relative roles of biotic or abiotic processes in soil N retention. A laboratory experiment was performed, where 15N was added as NH4+, NO2−, or NO3− to live and mercury‐treated O horizon soils from three tree species (American beech, northern red oak, sugar maple), and 15N recoveries were determined in the SOM pool. Mercuric chloride was used to treat soils as this chemical inhibits microbial metabolism without significantly altering the chemistry of SOM. The recovery of 15N in SOM was almost always greater for NH4+ (mean 20%) and NO2− (47%) than for NO3− (10%). Ammonium immobilization occurred primarily by biotic processes, with mean recoveries in live soils increasing from 9% at 15 min to 53% after 28 days of incubation. The incorporation of NO2− into SOM occurred rapidly (<15 min) via abiotic processes. Abiotic immobilization of NO2− (mean recovery 58%) was significantly greater than abiotic immobilization of NH4+ (7%) or NO3− (7%). The incorporation of NO2− into SOM did not vary significantly among tree species, so this mechanism likely does not contribute to differences in soil NO3− dynamics among species. As over 30% of the 15NO2− label was recovered in SOM within 15 min in live soils, and the products of NO2− incorporation into SOM remained relatively stable throughout the 28‐day incubation, our results suggest that NO2− incorporation into SOM may be an important mechanism of N retention in forest soils. The importance of NO2− immobilization for N retention in field soils, however, will depend on the competition between incorporation into SOM and nitrification for transiently available NO2−. Further research is required to determine the importance of this process in field environments.
Ondansetron does not prevent pruritus induced by low‐dose intrathecal fentanyl
Authors: Korhonen A. M. , Valanne J. V. , Jokela R. M. , Ravaska P. , Korttila K.
Published: November 2003

Background:  Addition of an opioid to low‐dose spinal anesthesia with bupivacaine improves the quality and success of anesthesia. However, the intrathecal fentanyl‐induced pruritus is as high as 75%. We hypothesized that after administration of 4 or 8 mg of prophylactic IV ondansetron, the incidence of pruritus induced by low‐dose intrathecal fentanyl would be significantly lower than after placebo.

Methods:  In this double‐blind study, 90 outpatients undergoing knee arthroscopy received 3 mg of bupivacaine + 10 µg fentanyl intrathecally. Before spinal puncture, the patients received randomly either saline (P) or ondansetron 4 mg (O4) or 8 mg (O8) IV. They were asked about pruritus frequently, and they estimated its severity on a scale of 0–10.

Results:  There was no difference in the incidence of pruritus between the three groups: pruritus occurred in 17 (57%), in 21 (75%) and in 19 patients (70%) in P, O4 and O8 groups, respectively. The pruritus was mostly mild. Four patients in the placebo group, three in the O4 and four patients in the O8 groups considered it severe. One patient in each group requested treatment for pruritus; after IV naloxone their pruritus was relieved. Neither time to pruritus nor duration of pruritus differed between the groups. One patient in each group developed a long‐lasting (>10 h) pruritus.

Conclusions:  After prophylactic administration of 4 or 8 mg of ondansetron IV, the incidence, duration and severity of pruritus were similar to placebo. Ondansetron does not prevent pruritus induced by low‐dose intrathecal fentanyl.
Screening for mast cell tryptase and serum IgE antibodies in 18 patients with anaphylactic shock during general anaesthesia
Authors: Dybendal T. , Guttormsen A. B. , Elsayed S. , Askeland B. , Harboe T. , Florvaag E.
Published: November 2003

Background:  In the perioperative setting multiple agents can cause anaphylaxis. Often the reactions are dramatic, and due to their lifethreatening potential it is crucial that the responsible agent is identified in order to avoid future adverse reactions. The aim of the present study was to measure the concentration of serum mast cell tryptase (MCT), to investigate the prevalence of serum IgE antibodies against ammonium groups, choline, morphine, suxamethonium, thiopentone and latex and to perform skin prick tests (SPTs) in 18 patients experiencing an anaphylactic reaction during induction of general anaesthesia.

Methods:  Serum samples from 18 patients with an anaphylactic reaction during general anaesthesia were analyzed for MCT and specific IgE against ammonium groups, choline, morphine, suxamethonium, thiopentone and latex. Skin prick tests were performed in 11 out of 18 patients.

Results:  Ten patients had elevated MCT levels and specific IgE against ammonium ion, morphine and (with the exception of patient nos 3, 9 and 10) suxamethonium. Seven of these patients had positive SPTs to suxamethonium. One of the patients tested positive to latex in addition to suxamethonium. Two patients showed elevated MCT, while specific IgE against the drugs tested was not detected. Three patients tested positive to ammonium ion, morphine and suxamethonium, but negative to MCT. Three patients tested negative to both MCT and specific IgE.

Conclusions:  Fifteen out of 18 sera tested positive for MCT and/or specific IgE against neuromuscular blocking drugs (NMBDs). Ten of the 18 patients experienced an IgE‐mediated anaphylactic reaction to NMBDs during anaesthesia, verified by detection of specific IgE and elevated levels of MCT.