bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early Cambrian food webs on a trophic knife‐edge? A hypothesis and preliminary data from a modern stromatolite‐based ecosystem
Authors: Elser James J. , Watts James , Schampel John H. , Farmer Jack 
Published: January 2006

AbstractHere we use the theory of ecological stoichiometry to propose and provide a preliminary test of a novel hypothesis that the Cambrian ‘explosion’ may have been triggered by changes in circulating P availability in the biosphere. We exposed living stromatolites from a spring‐fed stream in Mexico to a gradient of P enrichment to examine subsequent effects on stromatolite C : P ratio and on the primary grazer, an endemic snail. Consistent with a previously hypothesized stoichiometric ‘knife‐edge’, snail performance was maximal at intermediate P‐enrichment, indicating in situ stoichiometric constraints because of high stromatolite C : P ratio along with high sensitivity to excessive P intake. These results are consistent with the idea that stoichiometric constraints may have delayed the evolutionary proliferation of animals in ancient stromatolite‐dominated ecosystems and also suggest that high food P content can significantly impair consumers. We propose that ecosystem P availability may have impacted both the expansion and decline of animal taxa in the history of life.
Rising variance: a leading indicator of ecological transition
Authors: Carpenter S. R. , Brock W. A. 
Published: January 2006

AbstractRegime shifts are substantial, long‐lasting reorganizations of complex systems, such as ecosystems. Large ecosystem changes such as eutrophication, shifts among vegetation types, degradation of coral reefs and regional climate change often come as surprises because we lack leading indicators for regime shifts. Increases in variability of ecosystems have been suggested to foreshadow ecological regime shifts. However, it may be difficult to discern variability due to impending regime shift from that of exogenous drivers that affect the ecosystem. We addressed this problem using a model of lake eutrophication. Lakes are subject to fluctuations in recycling associated with regime shifts, as well as fluctuating nutrient inputs. Despite the complications of noisy inputs, increasing variability of lake‐water phosphorus was discernible prior to the shift to eutrophic conditions. Simulations show that rising standard deviation (SD) could signal impending shifts about a decade in advance. The rising SD was detected by studying variability around predictions of a simple time‐series model, and did not depend on detailed knowledge of the actual ecosystem dynamics.
Antagonistic effects of seed dispersal and herbivory on plant migration
Authors: Vellend Mark , Knight Tiffany M. , Drake John M. 
Published: January 2006

AbstractThe two factors that determine plant migration rates – seed dispersal and population growth – are generally treated independently, despite the fact that many animals simultaneously enhance plant migration rate via seed dispersal, and decrease it via negative effects of herbivory on population growth. Using extensive empirical data, we modelled the antagonistic effects of seed dispersal and herbivory by white‐tailed deer on potential migration rates of Trillium grandiflorum, a forest herb in eastern North America. This novel antagonistic interaction is illustrated by maximum migration rates occurring at intermediate, but low herbivory (< 15%). Assuming herbivory < 20% and favourable conditions for population growth during post‐glacial migration, seed dispersal by deer can explain rates of migration achieved in the past, in contrast to previous models of forest herb migration. However, relatively unfavourable conditions for population growth and increasingly intense herbivory by deer may compromise plant migration in the face of present and future climate change.
Anaerobic arsenite oxidation by novel denitrifying isolates
Authors: Rhine E. Danielle , Phelps Craig D. , Young L. Y. 
Published: January 2006

SummaryAutotrophic microorganisms have been isolated that are able to derive energy from the oxidation of arsenite [As(III)] to arsenate [As(V)] under aerobic conditions. Based on chemical energetics, microbial oxidation of As(III) can occur in the absence of oxygen, and may be relevant in some environments. Enrichment cultures were established from an arsenic contaminated industrial soil amended with As(III) as the electron donor, inorganic C as the carbon source and nitrate as the electron acceptor. In the active enrichment cultures, oxidation of As(III) was stoichiometrically coupled to the reduction of NO3–. Two autotrophic As(III)‐oxidizing strains were isolated that completely oxidized 5 mM As(III) within 7 days under denitrifying conditions. Based on 16S rRNA gene sequencing results, strain DAO1 was 99% related to Azoarcus and strain DAO10 was most closely related to a Sinorhizobium. The nitrous oxide reductase (nosZ) and the RuBisCO Type II (cbbM) genes were successfully amplified from both isolates underscoring their ability to denitrify and fix CO2 while coupled to As(III) oxidation. Although limited work has been done to examine the diversity of anaerobic autotrophic oxidizers of As(III), this process may be an important component in the biological cycling of arsenic within the environment.
Bacterial and archaeal phylotypes associated with distinct mineralogical layers of a white smoker spire from a deep‐sea hydrothermal vent site (9°N, East Pacific Rise)
Authors: Kormas Konstantinos A. , Tivey Margaret K. , Von Damm Karen , Teske Andreas 
Published: January 2006

SummaryA diffusely venting chimney spire from the East Pacific Rise (9°N) was analysed by petrographic thin sectioning and 16S rRNA gene cloning and sequencing in parallel, to correlate microbial community composition with mineralogy and inferred in situ conditions within the chimney mineral matrix. Both approaches indicated a zonation of the chimney spire into distinct microhabitats for different bacteria and archaea. The thermal gradient inferred from the mineral composition and porosity of the chimney was consistent with the distribution of bacterial and archaeal phylotypes in the chimney matrix. A novel phylogenetic lineage of euryarchaeota was found that co‐occurred with clones related to cultured hyperthermophilic archaea. A few phylotypes related to mesophilic bacteria were found in the hot core of the chimney, indicating that seawater influx during retrieval and cooling of these highly porous structures can entrain microorganisms into chimney layers that are not their native habitat.
Microbial community dynamics in a humic lake: differential persistence of common freshwater phylotypes
Authors: Newton Ryan J. , Kent Angela D. , Triplett Eric W. , McMahon Katherine D. 
Published: January 2006

SummaryIn an effort to better understand the factors contributing to patterns in freshwater bacterioplankton community composition and diversity, we coupled automated ribosomal intergenic spacer analysis (ARISA) to analysis of 16S ribosomal RNA (rRNA) gene sequences to follow the persistence patterns of 46 individual phylotypes over 3 years in Crystal Bog Lake. Additionally, we sought to identify linkages between the observed phylotype variations and known chemical and biological drivers. Sequencing of 16S rRNA genes obtained from the water column indicated the presence of phylotypes associated with the Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, TM7 and Verrucomicrobia phyla, as well as phylotypes with unknown affiliation. Employment of the 16S rRNA gene/ARISA method revealed that specific phylotypes varied independently of the entire bacterial community dynamics. Actinobacteria, which were present on greater than 95% of sampling dates, did not share the large temporal variability of the other identified phyla. Examination of phylotype relative abundance patterns (inferred using ARISA fragment relative fluorescence) revealed a strong correlation between the dominant phytoplankton succession and the relative abundance patterns of the majority of individual phylotypes. Further analysis revealed covariation among unique phylotypes, which formed several distinct bacterial assemblages correlated with particular phytoplankton communities. These data indicate the existence of unique persistence patterns for different common freshwater phylotypes, which may be linked to the presence of dominant phytoplankton species.
Use of microcosms to determine the survival of the fish pathogen Tenacibaculum maritimum in seawater
Authors: Avendaño‐Herrera Ruben , Irgang Rute , Magariños Beatriz , Romalde Jesús L. , Toranzo Alicia E. 
Published: January 2006

SummaryThe survival of the fish pathogen Tenacibaculum maritimum in different seawater microcosms was investigated during 160 days. The persistence of culturable cells was greater in sterile than in natural seawater. Standard plate counts showed that T. maritimum survived in sterile seawater for more than 5 months at concentration around 103 cfu ml−1. However, T. maritimum proved to be very labile in non‐sterile seawater, rendering culturable cells no longer than 5 days. These results were confirmed when DNA‐based methods were applied. Regardless of the microcosms used, epifluorescence microscopy counts remained at about 106 cells ml−1 throughout the experiment, even though we can not distinguish T. maritimum in the case of non‐sterile microcosms. Resuscitation assays with addition of fresh medium to non‐sterile microcosms did not favour the recovery of T. maritimum on solid media. Although morphological changes from filamentous to spheres were observed after 3 days in the non‐sterile microcosms, in the case of the sterile microcosms this change was observed at the sixth day. The biochemical, physiological, serological and genetic characteristics were unaffected in the sterile microcosms. The overall results contribute to a better understanding of the behaviour of T. maritimum in natural seawater and suggest that the aquatic bacterial population play an important role in the survival of this fish pathogen.
Determinants of How Managers Cope with Organisational Downsizing
Authors: Armstrong‐Stassen Marjorie 
Published: January 2006

201 cadres de deux services relevant du gouvernement fédéral qui ont été confrontés à une réduction d’effectifs ont constitué un panel en vue d’une étude longitudinale qui a porté sur la relation entre les ressources présentes avant la réduction du personnel (T1) et les contraintes et stratégies de traitement du problème évaluées pendant la période elle‐même (T2 et T3). Les contraintes en T2 (travail aliénant, absence perçue de succès professionnel à venir et conséquences jugées négatives de la contraction des effectifs) agissaient sur la relation entre les ressources disponibles en T1 et les stratégies déployées en T2. Les ressources relevant de l’individu (optimisme et sécurité perçue du travail) et celles relevant de l’organisation (le vécu du soutien apporté par le supérieur et l’organisation et l’implication affective dans l’organisation) étaient en relation avec une appréciation plus favorable des contraintes, ce qui, en retour, avaient des retombées sur la mise en œuvre des stratégies T2 de fuite et de contrôle. Les conduites T2 de contrôle étaient significativement corrélées de façon négative aux contraintes T3 tandis que les conduites de fuite T2 étaient significativement corrélées de façon positive à ces mêmes contraintes T3. Les futures recherches ne devraient pas seulement étudier le rôle des ressources exploitées par ceux qui affrontent victorieusement une contraction des effectifs, mais aussi identifier et tenir compte des contraintes qui peuvent contrecarrer ou inhiber l’usage de certaines stratégies de coping.Managers (N= 201) in two federal government departments undergoing downsizing participated in a longitudinal panel study examining the relationship among pre‐downsizing (T1) coping resources and coping constraints and coping strategies assessed during the downsizing period (T2, T3). T2 coping constraints (work alienation, perceived lack of future career success, and perceived negative downsizing effect) mediated the relationship between T1 coping resources and T2 coping strategies. Individual‐related (optimism and perceived job security) coping resources and organisation‐related (perceived organisational and supervisor support and organisational affective commitment) coping resources were associated with a more favourable evaluation of the coping constraints which, in turn, influenced the use of T2 control‐oriented and escape coping strategies. T2 control‐oriented coping was significantly negatively related to T3 coping constraints whereas T2 escape coping was significantly positively related to T3 coping constraints. Future research should not only examine the role of coping resources in how survivors cope with organisational downsizing but also identify and examine coping constraints that may restrict or inhibit the use of certain coping strategies.
Meeting Deadlines in Work Groups: Implicit and Explicit Mechanisms
Authors: Gevers Josette M.P. , Rutte Christel G. , Van Eerde Wendelien 
Published: January 2006

Nous nous sommes demandés, dans cette étude, si les groupes étaient mieux à même de respecter les délais quand leurs membres partageaient les mêmes cognitions temporelles, c’est‐à‐dire quand ils s’accordaient sur les dimensions temporelles de leur tâche. Dans une étude longitudinale portant sur 31 groupes, nous avons étudié l’effet des cognitions temporelles partagées sur le respect d’un délai et exploré deux antécédents des cognitions temporelles partagées: la cohérence des rythmes des membres du groupe et l’échange des rappels concernant le temps. Nos résultats montrent que ces deux facteurs ont un impact sur les cognitions temporelles partagées et cela à différentes étapes du travail collectif. De plus, il est apparu que les cognitions temporelles partagées pouvaient aussi bien faciliter que contrecarrer le respect des délais: cela dépend des rythmes des membres du groupe.In this study, we examined whether groups were better able to meet deadlines when group members had shared temporal cognitions, that is, when they agreed on the temporal aspects of their task. In a longitudinal study involving 31 groups, we studied the effect of shared temporal cognitions on meeting a deadline and explored two antecedents of shared temporal cognitions: the similarity in group members’ pacing styles and the exchange of temporal reminders. Our findings suggest that both antecedents are relevant to shared temporal cognitions, be it at different stages of group collaboration. Furthermore, we found that shared temporal cognitions may either facilitate or impede meeting a deadline, depending on the content of group members’ pacing styles.
Applying a Modified Moral Decision Making Model to Change Habitual Car Use: How Can Commitment be Effective?
Authors: Matthies Ellen , Klöckner Christian A. , Preißner Claudia L. 
Published: January 2006

Une intervention basée sur une théorie a été réalisée auprès d’un échantillon de 297 automobilistes pour tenter de lancer de nouvelles habitudes de déplacement (essayer de préférer les transports en commun plutôt que la voiture). Un modèle de modification d’une décision morale relevant de la théorie de Schwartz et Howard (1981) fut exploité dans la conception d’une intervention associant une technique de décristallisation des comportements antérieurs (remise provisoire d’une carte gratuite) avec une technique focalisée sur une norme (appel à l’implication). L’échantillon était constitué de 297 citoyens allemands pouvant utiliser facilement leur voiture et vivant dans des quartiers bien desservis par les transports en commun. Les participants ont été répartis au hasard dans quatre conditions (implication précédée par une carte gratuite, seulement l’implication, seulement la carte gratuite et groupe contrôle) et durent faire part de leur choix de transport pour un trajet précis et habituel (par exemple aller au travail) sur une durée de huit semaines suivie d’une période contrôle de deux semaines. En outre, les variables du modèle (la règle personnelle de réduction de l’utilisation de la voiture, les normes sociales, les coûts comportementaux ressentis et les habitudes) ont été enregistrées toutes les deux semaines. Bien que les effets globaux de l’intervention aient été faibles, les résultats montrent qu’une motivation morale est un prédicteur pertinent du choix d’un mode de transport qui peut être renforcé par une intervention portant sur l’implication précédée par un changement temporaire de la situation.A theory‐driven intervention was carried out to initiate the try‐out of a new travel mode behavior (try out taking public transport instead of car) in a sample of habitual car users (N= 297). A modified moral decision making model based on the theory of Schwartz and Howard (1981) served as background for the design of an intervention combining a habit‐defrosting technique (temporary gift of a free ticket) with a norm‐focused technique (plea for commitment). The sample consisted of 297 German citizens with good car access and living in areas with a convenient supply of public transportation. Participants were randomly assigned to four groups (commitment preceded by a free ticket, commitment only, free ticket only, and control) and had to report their travel mode choice for a particular, regular trip (e.g. trip to work) for a period of 8 weeks and a 2‐week follow‐up period. Additionally, model variables (personal norm to reduce car use, social norm, perceived behavioral costs, and habit) were recorded every 2 weeks. Although overall effects of the interventions were small, results indicate that a moral motivation is a relevant predictor for travel mode choices and can be stabilised by a commitment intervention preceded by a temporary change of the situation.
Having to Wait for Service: Customer Reactions to Delays in Service Delivery
Authors: Groth Markus , Gilliland Stephen W. 
Published: January 2006

Deux expériences ont évalué les conséquences d’informations portant sur la durée d’attente et d’explications concernant les raisons du délai sur les réactions de clients confrontés à un service remis à plus tard. Dans la première étude, 111 participants ont lu un scénario décrivant une attente dans un cabinet médical. Dans l’autre étude, 87 sujets ont vécu un réel retard dans un laboratoire. Dans les deux cas, les participants ont ensuite fait part de leurs réactions suite au retard et évalué le service. Les résultats montrent que la présentation d’une information innocentant celui qui fournit le service provoque les réactions les plus favorables de la part de la clientèle, tandis que l’absence d’explications entraîne des réactions plus positives qu’une explication mettant en cause le responsable. Donner une estimation de la durée d’attente n’a que des effets limités sur les réactions. Les résultats sont analysés à partir des théories du temps d’attente.Two experiments tested the effects of providing wait duration information and explanations for the reason for a delay on customer reactions to a delayed service delivery. In Study 1, 111 participants read a paper‐and‐pencil scenario about a wait for service at a doctor's office. In Study 2, 87 participants experienced an actual delay at a research facility. In both studies, participants were subsequently surveyed about their service evaluation and reactions to the delay. Results indicate that providing a provider‐not‐at‐fault explanation led to the most positive customer reactions, whereas providing no explanation led to more positive reactions than a provider‐at‐fault explanation. Providing waiting duration estimates had only limited effects on customers’ reactions. Results are discussed from the perspective of wait time theories.
Thinking Deeply May Sometimes Help: Cognitive Motivation and Role Effects in Negotiation
Authors: Schei Vidar , Rognes Jørn K. , Mykland Solfrid 
Published: January 2006

On étudie dans cet article la façon dont la motivation cognitive et le rôle de négociateur interagissent pour prédire les comportements et les résultats des négociations duelles. La motivation cognitive de 64 participants a été mesurée antérieurement à une simulation de négociation achatvente. Les résultats montrent que l’impact de la motivation cognitive sur la négociation dépend du rôle joué. Comme prévu, les paires pourvues de vendeur à la motivation cognitive élevée parvenaient bien plus facilement à un accord que celles dont le vendeur avait une motivation cognitive basse. Par contre, la motivation cognitive des acheteurs n’avait pas de retombées sur le déroulement de la négociation. L’analyse des transcriptions des négociations indiqua que l’information fournie avait une fonction d’interface entre la motivation cognitive des vendeurs et l’accord. On discute des conséquences théoriques et pratiques.This article examines how cognitive motivation and negotiation role interact to predict behavior and outcomes in integrative dyadic negotiations. The cognitive motivation of 64 participants was measured prior to a simulated buyer–seller negotiation. The results suggest that the effect of cognitive motivation in negotiation depends upon the role of the negotiator. As predicted, dyads with sellers who were high on cognitive motivation achieved much better joint outcomes than dyads with sellers low on cognitive motivation. By contrast, the cognitive motivation of the buyers did not affect negotiation outcomes. Mediational analyses of negotiation transcripts illustrated that the giving of information was a mediating factor between the cognitive motivation of the sellers and joint outcomes. Theoretical and practical implications are discussed.
Assessment of Functional Impairment in Spanish Children
Authors: Ezpeleta Lourdes , Granero Roser , Osa Nuria de la , Doménech Josep M. , Bonillo Albert 
Published: January 2006

Le pressent travaux vérifie l’applicabilité et la validité du CAFAS, un instrument pour évaluer l’incapacité fonctionnel dans une population espagnole. L’échantillon est formé par 441 malades ambulatoires psychiatriques d’entre 8 et 17 années et leurs parents, et aussi par un échantillon de 74 malades ambulatoires pédiatriques. On a applique différents instruments pour évaluer l’incapacité fonctionnel, la psychopathologie, et autres variables psychologiques. La fiabilité intra observateur varie entre modérée et bonne. L’accord entre les ponctuations obtenues avec l’information des parents et des infants varie entre faible et modérée. Les corrélations avec autres mesures d’incapacité et du fonctionnement sont significatives mais modérée. Les ponctuations CAFAS différencient significativement les enfants avec et sans psychopathologie. Les résultats obtenus avalisent l’utilisation du CAFAS pour les études en psychopathologie, en incapacité fonctionnel et pour planifier interventions et services de santé mental.The present work tests the applicability and validity of the CAFAS, an instrument for assessing functional impairment, in the Spanish population. The sample included 441 psychiatric outpatients from 8 to 17 years old and their parents, and a pediatric group of 74 outpatients. Different instruments for assessing functional impairment, psychopathology, and other related variables were used. Interrater reliability ranged from moderate to very good. Weak‐to‐moderate agreement between CAFAS scores based on information from parents and children was obtained. Correlations with other measures of impairment and functioning were moderate. CAFAS scores differentiated significantly between children with and without psychopathology. These results permit the use of the instrument for studies on psychopathology and functional impairment, and for planning intervention and mental health services.