Showing papers by "University of Fribourg published in 2009"
TL;DR: In this paper, the authors empirically investigate a simple framework of link prediction on the basis of node similarity and propose a new similarity measure, motivated by the resource allocation process taking place on networks, which can remarkably enhance the prediction accuracy.
Abstract: Missing link prediction in networks is of both theoretical interest and practical significance in modern science. In this paper, we empirically investigate a simple framework of link prediction on the basis of node similarity. We compare nine well-known local similarity measures on six real networks. The results indicate that the simplest measure, namely Common Neighbours, has the best overall performance, and the Adamic-Adar index performs second best. A new similarity measure, motivated by the resource allocation process taking place on networks, is proposed and shown to have higher prediction accuracy than common neighbours. It is found that many links are assigned the same scores if only the information of the nearest neighbours is used. We therefore design another new measure exploiting information on the next nearest neighbours, which can remarkably enhance the prediction accuracy.
1,284 citations
University of Alberta1, ExxonMobil2, University of Houston3, Louisiana State University4, Queen's University5, University of Pretoria6, University of Nebraska–Lincoln7, University of Texas at Austin8, Dalhousie University9, New Mexico State University10, University of Texas at Arlington11, University of South Carolina12, University of Toronto13, Colorado School of Mines14, Chevron Corporation15, University of Saskatchewan16, University of Fribourg17, Durham University18, Royal Dutch Shell19
TL;DR: In this paper, a model-independent framework of genetic units and bounding surfaces for sequence stratigraphy has been proposed, based on the interplay of accommodation and sedimentation (i.e., forced regressive, lowstand and highstand normal regressive), which are bounded by sequence stratigraphic surfaces.
1,255 citations
University of Bayreuth1, Institut national de la recherche agronomique2, Canterbury of New Zealand3, Lund University4, Charles University in Prague5, Academy of Sciences of the Czech Republic6, Helmholtz Centre for Environmental Research - UFZ7, University of Tartu8, University of Fribourg9, Hungarian Academy of Sciences10, ETH Zurich11, University of Leeds12, CABI13, University of Bern14, Saint Petersburg State University15, National Academy of Sciences of Belarus16, Polish Academy of Sciences17, Joseph Fourier University18, Spanish National Research Council19, Potsdam Institute for Climate Impact Research20
TL;DR: It is emphasised that global warming has enabled alien species to expand into regions in which they previously could not survive and reproduce and management practices regarding the occurrence of 'new' species could range from complete eradication to tolerance.
Abstract: Climate change and biological invasions are key processes affecting global biodiversity, yet their effects have usually been considered separately. Here, we emphasise that global warming has enabled alien species to expand into regions in which they previously could not survive and reproduce. Based on a review of climate-mediated biological invasions of plants, invertebrates, fishes and birds, we discuss the ways in which climate change influences biological invasions. We emphasise the role of alien species in a more dynamic context of shifting species' ranges and changing communities. Under these circumstances, management practices regarding the occurrence of 'new' species could range from complete eradication to tolerance and even consideration of the 'new' species as an enrichment of local biodiversity and key elements to maintain ecosystem services.
1,138 citations
ExxonMobil1, University of Houston2, University of Pretoria3, University of Nebraska–Lincoln4, University of Texas at Austin5, New Mexico State University6, University of Texas at Arlington7, University of South Carolina8, University of Toronto9, University of the Balearic Islands10, Chevron Corporation11, University of Saskatchewan12, University of Fribourg13, Royal Dutch Shell14
TL;DR: Catuneanu et al. as discussed by the authors used a neutral approach that focused on model-independent, fundamental concepts, because these are the ones common to various approaches and this search for common ground is what they meant by "standardization", not the imposition of a strict, inflexible set of rules for the placement of sequence-stratigraphicsurfaces.
872 citations
TL;DR: These results are in line with animal studies indicating that central oxytocin facilitates approach and pair bonding behavior, and imply an involvement of oxytocIn in couple interaction and close relationships in humans.
686 citations
TL;DR: A local path index to estimate the likelihood of the existence of a link between two nodes, and a network model with controllable density and noise strength in generating links, as well as collect data of six real networks.
Abstract: Predictions of missing links of incomplete networks, such as protein-protein interaction networks or very likely but not yet existent links in evolutionary networks like friendship networks in web society, can be considered as a guideline for further experiments or valuable information for web users. In this paper, we present a local path index to estimate the likelihood of the existence of a link between two nodes. We propose a network model with controllable density and noise strength in generating links, as well as collect data of six real networks. Extensive numerical simulations on both modeled networks and real networks demonstrated the high effectiveness and efficiency of the local path index compared with two well-known and widely used indices: the common neighbors and the Katz index. Indeed, the local path index provides competitively accurate predictions as the Katz index while requires much less CPU time and memory space than the Katz index, which is therefore a strong candidate for potential practical applications in data mining of huge-size networks.
577 citations
TL;DR: Findings from stress research in couples that has practical significance and may inspire clinical work are summarized and future directions in research and clincial significance are suggested.
470 citations
TL;DR: It is reported that the yeast Rag GTPase homolog Gtr1, a component of the vacuolar-membrane-associated EGO complex (EGOC), interacts with and activates TORC1 in an amino-acid-sensitive manner and is regulated by the conserved guanine nucleotide exchange factor (GEF) Vam6.
420 citations
TL;DR: The data document for the first time the rising prevalence, spread and molecular basis of MDR populations in a major plant pathogen in agricultural environments and will increase the risk of grey mould rot and hamper the effectiveness of current strategies for fungicide resistance management.
Abstract: The grey mould fungus Botrytis cinerea causes losses of commercially important fruits, vegetables and ornamentals worldwide. Fungicide treatments are effective for disease control, but bear the risk of resistance development. The major resistance mechanism in fungi is target protein modification resulting in reduced drug binding. Multiple drug resistance (MDR) caused by increased efflux activity is common in human pathogenic microbes, but rarely described for plant pathogens. Annual monitoring for fungicide resistance in field isolates from fungicide-treated vineyards in France and Germany revealed a rapidly increasing appearance of B. cinerea field populations with three distinct MDR phenotypes. All MDR strains showed increased fungicide efflux activity and overexpression of efflux transporter genes. Similar to clinical MDR isolates of Candida yeasts that are due to transcription factor mutations, all MDR1 strains were shown to harbor activating mutations in a transcription factor (Mrr1) that controls the gene encoding ABC transporter AtrB. MDR2 strains had undergone a unique rearrangement in the promoter region of the major facilitator superfamily transporter gene mfsM2, induced by insertion of a retrotransposon-derived sequence. MDR2 strains carrying the same rearranged mfsM2 allele have probably migrated from French to German wine-growing regions. The roles of atrB, mrr1 and mfsM2 were proven by the phenotypes of knock-out and overexpression mutants. As confirmed by sexual crosses, combinations of mrr1 and mfsM2 mutations lead to MDR3 strains with higher broad-spectrum resistance. An MDR3 strain was shown in field experiments to be selected against sensitive strains by fungicide treatments. Our data document for the first time the rising prevalence, spread and molecular basis of MDR populations in a major plant pathogen in agricultural environments. These populations will increase the risk of grey mould rot and hamper the effectiveness of current strategies for fungicide resistance management.
299 citations
27 Mar 2009
TL;DR: The chapter starts with the features and advantages associated with multimodal interaction, with a focus on particular findings and guidelines, as well as cognitive foundations underlying multimodAL interaction, and focuses on the driving theoretical principles, time-sensitive software architectures and multimodals fusion and fission issues.
Abstract: The grand challenge of multimodal interface creation is to build reliable processing systems able to analyze and understand multiple communication means in real-time. This opens a number of associated issues covered by this chapter, such as heterogeneous data types fusion, architectures for real-time processing, dialog management, machine learning for multimodal interaction, modeling languages, frameworks, etc. This chapter does not intend to cover exhaustively all the issues related to multimodal interfaces creation and some hot topics, such as error handling, have been left aside. The chapter starts with the features and advantages associated with multimodal interaction, with a focus on particular findings and guidelines, as well as cognitive foundations underlying multimodal interaction. The chapter then focuses on the driving theoretical principles, time-sensitive software architectures and multimodal fusion and fission issues. Modeling of multimodal interaction as well as tools allowing rapid creation of multimodal interfaces are then presented. The article concludes with an outline of the current state of multimodal interaction research in Switzerland, and also summarizes the major future challenges in the field.
297 citations
TL;DR: The data suggest that miR-124, let-7d and mi-181a may be involved in a complex feedback loop with cocaine-responsive plasticity genes, highlighting the possibility that some miRNAs are key regulators of the reward circuit and may be implicated in addiction.
TL;DR: A new similarity measure, motivated by the resource allocation process taking place on networks, is proposed and shown to have higher prediction accuracy than common neighbours, which can remarkably enhance the prediction accuracy.
Abstract: Missing link prediction of networks is of both theoretical interest and practical significance in modern science. In this paper, we empirically investigate a simple framework of link prediction on the basis of node similarity. We compare nine well-known local similarity measures on six real networks. The results indicate that the simplest measure, namely common neighbors, has the best overall performance, and the Adamic-Adar index performs the second best. A new similarity measure, motivated by the resource allocation process taking place on networks, is proposed and shown to have higher prediction accuracy than common neighbors. It is found that many links are assigned same scores if only the information of the nearest neighbors is used. We therefore design another new measure exploited information of the next nearest neighbors, which can remarkably enhance the prediction accuracy.
TL;DR: It is demonstrated, on a test set of 80 conformationally stable molecules of various kinds carrying different functional groups, that, in contrast to what is claimed in the literature, large basis sets are not needed to obtain rather accurate predictions of (1)H NMR chemical shifts by quantum chemical calculations.
Abstract: The purpose of this paper is to convince practitioners of 1H NMR spectroscopy to consider simple quantum chemical calculations as a viable option to aid them in the assignment of their spectra. To this end, it is demonstrated, on a test set of 80 conformationally stable molecules of various kinds carrying different functional groups, that, in contrast to what is claimed in the literature, large basis sets are not needed to obtain rather accurate predictions of 1H NMR chemical shifts by quantum chemical calculations. On the other hand, modeling the solvent by an SCRF-type calculation may improve certain predictions significantly. The best accuracy/cost ratio is provided by GIAO calculations in chloroform as a solvent with the specially parametrized WP04 functional of Cramer et al. using the cc-pVDZ or 6-31G** basis set, closely followed by similar calculations with the ubiquitious B3LYP functional (both predict 1H chemical shifts with an average deviation of ca. 0.12 ppm, if the results are scaled linearly...
TL;DR: MeSA is dispensable for SAR in Arabidopsis, and SA accumulation in distant leaves appears to occur by de novo synthesis via isochorismate synthase, and it is shown that MeSA production induced by P. syringae depends on the JA pathway but that JA biosynthesis or downstream signaling is not required for SAR.
Abstract: Systemic acquired resistance (SAR) develops in response to local microbial leaf inoculation and renders the whole plant more resistant to subsequent pathogen infection. Accumulation of salicylic acid (SA) in noninfected plant parts is required for SAR, and methyl salicylate (MeSA) and jasmonate (JA) are proposed to have critical roles during SAR long-distance signaling from inoculated to distant leaves. Here, we address the significance of MeSA and JA during SAR development in Arabidopsis thaliana. MeSA production increases in leaves inoculated with the SAR-inducing bacterial pathogen Pseudomonas syringae; however, most MeSA is emitted into the atmosphere, and only small amounts are retained. We show that in several Arabidopsis defense mutants, the abilities to produce MeSA and to establish SAR do not coincide. T-DNA insertion lines defective in expression of a pathogen-responsive SA methyltransferase gene are completely devoid of induced MeSA production but increase systemic SA levels and develop SAR upon local P. syringae inoculation. Therefore, MeSA is dispensable for SAR in Arabidopsis, and SA accumulation in distant leaves appears to occur by de novo synthesis via isochorismate synthase. We show that MeSA production induced by P. syringae depends on the JA pathway but that JA biosynthesis or downstream signaling is not required for SAR. In compatible interactions, MeSA production depends on the P. syringae virulence factor coronatine, suggesting that the phytopathogen uses coronatine-mediated volatilization of MeSA from leaves to attenuate the SA-based defense pathway.
TL;DR: Recent progress in the study of homogeneous and heterogeneous crystal nucleation in colloids and the controlled growth of crystalline colloidal structures is reviewed, resulting in unprecedented insights into the early stage of nucleation.
Abstract: Despite progress in the understanding of crystal nucleation and crystal growth since the first theories for nucleation were developed, an exact quantitative prediction of the nucleation rates in most systems has remained an unsolved problem. Colloidal suspensions show a phase behavior that is analogous to atomic or molecular systems and serve accordingly as ideal model systems for studying crystal nucleation with an accuracy and depth on a microscopic scale that is hard to reach for atomic or molecular systems. Due to the mesoscopic size of colloidal particles they can be studied in detail on the single-particle level and their dynamics is strongly slowed down in comparison with atomic or molecular systems, such that the formation of a crystal nucleus can be followed in detail. In this review, recent progress in the study of homogeneous and heterogeneous crystal nucleation in colloids and the controlled growth of crystalline colloidal structures is reviewed. All this work has resulted in unprecedented insights into the early stage of nucleation and it is also relevant for a deeper understanding of soft matter materials in general as well as for possible applications based on colloidal suspensions.
TL;DR: A new depth-resolved technique for measuring the spin polarization of current-injected electrons in an organic spin valve is presented and the temperature dependence of the measured spin diffusion length is correlated with the device magnetoresistance.
Abstract: Electronic devices that use the spin degree of freedom hold unique prospects for future technology. The performance of these 'spintronic' devices relies heavily on the efficient transfer of spin polarization across different layers and interfaces. This complex transfer process depends on individual material properties and also, most importantly, on the structural and electronic properties of the interfaces between the different materials and defects that are common to real devices. Knowledge of these factors is especially important for the relatively new field of organic spintronics, where there is a severe lack of suitable experimental techniques that can yield depth-resolved information about the spin polarization of charge carriers within buried layers of real devices. Here, we present a new depth-resolved technique for measuring the spin polarization of current-injected electrons in an organic spin valve and find the temperature dependence of the measured spin diffusion length is correlated with the device magnetoresistance.
TL;DR: Advances in the understanding of a class of Ca2+-binding proteins usually referred to as “Ca2+ buffers” are reported, indicating that calbindin-D28k, possibly also calretinin and oncomodulin, the mammalian β parvalbumin, might have additional Ca2+.
Abstract: Advances in the understanding of a class of Ca2+-binding proteins usually referred to as “Ca2+ buffers” are reported. Proteins historically embraced within this group include parvalbumins (α and β), calbindin-D9k, calbindin-D28k and calretinin. Within the last few years a wealth of data has accumulated that allow a better understanding of the functions of particular family members of the >240 identified EF-hand Ca2+-binding proteins encoded by the human genome. Studies often involving transgenic animal models have revealed that they exert their specific functions within an intricate network consisting of many proteins and cellular mechanisms involved in Ca2+ signaling and Ca2+ homeostasis, and are thus an essential part of the Ca2+ homeostasome. Recent results indicate that calbindin-D28k, possibly also calretinin and oncomodulin, the mammalian β parvalbumin, might have additional Ca2+ sensor functions, leaving parvalbumin and calbindin-D9k as the only “pure” Ca2+ buffers.
TL;DR: A muon spin rotation study on SmFeAsO(1-x)F(x), with x=0-0.30 that shows that, as in the cuprates, static magnetism persists well into the superconducting regime, suggests that the proximity to magnetic order and associated soft magnetic fluctuations, rather than strong electronic correlations in the vicinity of a Mott-Hubbard transition, may be the key ingredients of high-Tc superconductors.
Abstract: In non-conventional superconductors, the competition of magnetic order and superconductivity seems to be a key element for the origin of superconductivity. Investigation of the newly discovered iron-pnictides superconductors challenges this picture, showing a coexistence of superconductivity and magnetism.
TL;DR: In this article, the same transcription factors are essential for the activation of jasmonic acid and ethylene (ET)-dependent defense mechanisms that counteract necrotrophic pathogens: the tga256 triple mutant is impaired in JA/ET-induced PDF1.2 and b-CHI expression, which correlates with a higher susceptibility against the necrotroph Botrytis cinerea.
Abstract: The three closely related Arabidopsis basic leucine zipper (bZIP) transcription factors TGA2, TGA5 and TGA6 are required for the establishment of the salicylic acid (SA)-dependent plant defense response systemic acquired resistance, which is effective against biotrophic pathogens. Here we show that the same transcription factors are essential for the activation of jasmonic acid (JA)- and ethylene (ET)-dependent defense mechanisms that counteract necrotrophic pathogens: the tga256 triple mutant is impaired in JA/ET-induced PDF1.2 and b-CHI expression, which correlates with a higher susceptibility against the necrotroph Botrytis cinerea. JA/ET induction of the trans-activators ERF1 and ORA59, which act upstream of PDF1.2, was slightly increased (ERF1) or unaffected (ORA59). PDF1.2 expression can be restored in the tga256 mutant by increased expression of ORA59, as observed in the tga256 jin1 quadruple mutant, which lacks the transcription factor JIN1/AtMYC2 that functions as a negative regulator of the JA/ET-dependent anti-fungal defense program. Whereas JA/ET-induced PDF1.2 expression is strongly suppressed by SA in wild-type plants, no negative effect of SA on PDF1.2 expression was observed in the tga256 jin1 quadruple mutant. These results imply that the antagonistic effects of TGA factors and JIN1/AtMYC2 on the JA/ET pathway are necessary to evoke the SA-mediated suppression of JA/ET-induced defense responses.
TL;DR: A major role of MKP1 and PTP1 is indicated in repressing salicylic acid biosynthesis in the autoimmune-like response caused by SNC1, which is largely the disease resistance gene homolog SUPPRESSOR of npr1-1, CONSTITUTIVE 1 that is absent in the Wassilewskija accession.
Abstract: Mitogen-activated protein (MAP) kinase phosphatases are important negative regulators of the levels and kinetics of MAP kinase activation that modulate cellular responses. The dual-specificity phosphatase MAP KINASE PHOSPHATASE1 (MKP1) was previously shown to regulate MAP KINASE6 (MPK6) activation levels and abiotic stress responses in Arabidopsis thaliana. Here, we report that the mkp1 null mutation in the Columbia (Col) accession results in growth defects and constitutive biotic defense responses, including elevated levels of salicylic acid, camalexin, PR gene expression, and resistance to the bacterial pathogen Pseudomonas syringae. PROTEIN TYROSINE PHOSPHATASE1 (PTP1) also interacts with MPK6, but the ptp1 null mutant shows no aberrant growth phenotype. However, the pronounced constitutive defense response of the mkp1 ptp1 double mutant reveals that MKP1 and PTP1 repress defense responses in a coordinated fashion. Moreover, mutations in MPK3 and MPK6 distinctly suppress mkp1 and mkp1 ptp1 phenotypes, indicating that MKP1 and PTP1 act as repressors of inappropriate MPK3/MPK6-dependent stress signaling. Finally, we provide evidence that the natural modifier of mkp1 in Col is largely the disease resistance gene homolog SUPPRESSOR OF npr1-1, CONSTITUTIVE 1 (SNC1) that is absent in the Wassilewskija accession. Our data thus indicate a major role of MKP1 and PTP1 in repressing salicylic acid biosynthesis in the autoimmune-like response caused by SNC1.
TL;DR: The present results demonstrate the presence of thalamic territories integrating different sensory modalities with motor attributes, and 4 distinct mechanisms of multisensory and sensorimotor interplay are proposed.
Abstract: Multisensory and sensorimotor integrations are usually considered to occur in superior colliculus and cerebral cortex, but few studies proposed the thalamus as being involved in these integrative processes. We investigated whether the organization of the thalamocortical (TC) systems for different modalities partly overlap, representing an anatomical support for multisensory and sensorimotor interplay in thalamus. In 2 macaque monkeys, 6 neuroanatomical tracers were injected in the rostral and caudal auditory cortex, posterior parietal cortex (PE/PEa in area 5), and dorsal and ventral premotor cortical areas (PMd, PMv), demonstrating the existence of overlapping territories of thalamic projections to areas of different modalities (sensory and motor). TC projections, distinct from the ones arising from specific unimodal sensory nuclei, were observed from motor thalamus to PE/PEa or auditory cortex and from sensory thalamus to PMd/PMv. The central lateral nucleus and the mediodorsal nucleus project to all injected areas, but the most significant overlap across modalities was found in the medial pulvinar nucleus. The present results demonstrate the presence of thalamic territories integrating different sensory modalities with motor attributes. Based on the divergent/convergent pattern of TC and corticothalamic projections, 4 distinct mechanisms of multisensory and sensorimotor interplay are proposed.
TL;DR: This analysis indicates that the antiferromagnetic order imprinted in the initial state vanishes exponentially and the corresponding relaxation time exhibits a minimum at the critical point, in contrast to the usual notion of critical slowing down, from which a maximum is expected.
Abstract: We study the unitary time evolution of antiferromagnetic order in anisotropic Heisenberg chains that are initially prepared in a pure quantum state far from equilibrium. Our analysis indicates that the antiferromagnetic order imprinted in the initial state vanishes exponentially. Depending on the anisotropy parameter, oscillatory or nonoscillatory relaxation dynamics is observed. Furthermore, the corresponding relaxation time exhibits a minimum at the critical point, in contrast to the usual notion of critical slowing down, from which a maximum is expected.
TL;DR: It is shown that the projections between different sensory and motor cortical areas and the thalamus enabled us to highlight the existence of thalamic nuclei that, by their connections, may represent an alternative pathway for information transfer between different Sensory and Motor cortical areas.
TL;DR: The anatomy and function of the larval dopaminergic system is analyzed, it is found that dopamine receptors are highly enriched in the mushroom bodies and that aversive and appetitive olfactory learning is strongly impaired in dopamine receptor mutants.
Abstract: Learning and memory is not an attribute of higher animals. Even Drosophila larvae are able to form and recall an association of a given odor with an aversive or appetitive gustatory reinforcer. As the Drosophila larva has turned into a particularly simple model for studying odor processing, a detailed neuronal and functional map of the olfactory pathway is available up to the third order neurons in the mushroom bodies. At this point, a convergence of olfactory processing and gustatory reinforcement is suggested to underlie associative memory formation. The dopaminergic system was shown to be involved in mammalian and insect olfactory conditioning. To analyze the anatomy and function of the larval dopaminergic system, we first characterize dopaminergic neurons immunohistochemically up to the single cell level and subsequent test for the effects of distortions in the dopamine system upon aversive (odor-salt) as well as appetitive (odor-sugar) associative learning. Single cell analysis suggests that dopaminergic neurons do not directly connect gustatory input in the larval suboesophageal ganglion to olfactory information in the mushroom bodies. However, a number of dopaminergic neurons innervate different regions of the brain, including protocerebra, mushroom bodies and suboesophageal ganglion. We found that dopamine receptors are highly enriched in the mushroom bodies and that aversive and appetitive olfactory learning is strongly impaired in dopamine receptor mutants. Genetically interfering with dopaminergic signaling supports this finding, although our data do not exclude on naive odor and sugar preferences of the larvae. Our data suggest that dopaminergic neurons provide input to different brain regions including protocerebra, suboesophageal ganglion and mushroom bodies by more than one route. We therefore propose that different types of dopaminergic neurons might be involved in different types of signaling necessary for aversive and appetitive olfactory memory formation respectively, or for the retrieval of these memory traces. Future studies of the dopaminergic system need to take into account such cellular dissociations in function in order to be meaningful.
TL;DR: In this article, the authors explore the potential of Web sites as an online communication tool of Swiss NPOs and find that most of them replied to information requests from potential donors and the media.
TL;DR: In this article, the main sources of national competitive advantages based on the Porter's diamond model are discussed, and the role of regional clusters of industries is explained, how MNCs can benefit from locating their operations in country markets with a high level of competitive advantage or in regional industry clusters.
Abstract: This Chapter gives an overview of the main sources of national competitive advantages, based on Porter’s diamond model, and discusses the role of regional clusters of industries. In this context it is explained, how MNCs can benefit from locating their operations in country markets with a high level of national competitive advantage or in regional industry clusters.
TL;DR: The results suggested that task completion time may be overestimated when a computer prototype is being used and users appeared to compensate for deficiencies in aesthetic design by overrating the aesthetic qualities of reduced fidelity prototypes.
TL;DR: Both conscientiousness and competence beliefs meaningfully predicted academic effort, irrespective of how academic effort was measured (single-measurement questionnaire or diary data).
Abstract: Conscientiousness and domain-specific competence beliefs are known to be highly important predictors of academic effort and achievement. Given their basis in distinct research traditions, however, these constructs have rarely been examined simultaneously. Three studies with 571, 415, and 1,535 students, respectively, found a moderate association between conscientiousness and competence beliefs. Both conscientiousness and competence beliefs meaningfully predicted academic effort, irrespective of how academic effort was measured (single-measurement questionnaire or diary data). The associations of competence beliefs with academic effort were highly domain specific, whereas conscientiousness was predictive of academic effort across a wide range of academic subjects. Conscientiousness and competence beliefs were also associated with academic achievement. Figural and verbal reasoning ability, although associated with academic achievement, only loosely predicted academic effort.
TL;DR: This study suggests that the invasive success of C. maculosa is partly due to preadaptation of the tetraploid cytotype in Europe to drier climate and possibly further adaptation to these conditions in the introduced range and the potential for earlier and longer seed production associated with the polycarpic life cycle constitutes an additional factor that may have led to the dominance of tetra ploidy over diploids in the introduce range.
Abstract: Polyploidy is often assumed to increase the spread and thus the success of alien plant species, but few empirical studies exist. We tested this hypothesis with Centaurea maculosa Lam., a species native to Europe and introduced into North America approximately 120 years ago where it became highly invasive. We analyzed the ploidy level of more than 2000 plants from 93 native and 48 invasive C. maculosa populations and found a pronounced shift in the relative frequency of diploid and tetraploid cytotypes. In Europe diploid populations occur in higher frequencies than tetraploids and only four populations had both cytotypes, while in North America diploid plants were found in only one mixed population and thus tetraploids clearly dominated. Our results showed a pronounced shift in the climatic niche between tetraploid populations in the native and introduced range toward drier climate in North America and a similar albeit smaller shift between diploids and tetraploids in the native range. The field data indicate that diploids have a predominately monocarpic life cycle, while tetraploids are often polycarpic. Additionally, the polycarpic life-form seems to be more prevalent among tetraploids in the introduced range than among tetraploids in the native range. Our study suggests that both ploidy types of C. maculosa were introduced into North America, but tetraploids became the dominant cytotype with invasion. We suggest that the invasive success of C. maculosa is partly due to preadaptation of the tetraploid cytotype in Europe to drier climate and possibly further adaptation to these conditions in the introduced range. The potential for earlier and longer seed production associated with the polycarpic life cycle constitutes an additional factor that may have led to the dominance of tetraploids over diploids in the introduced range.
TL;DR: It is suggested that modified true tracks and overtracks make up an important percentage of fossil footprints and that they may be as common as undertracks and that making unambiguous distinctions between poorly defined true tracks, modifiedtrue tracks, undertracks, and over tracks in the fossil record will remain a difficult task.
Abstract: This study concerns the formation, taphonomy, and preservation of human footprints in microbial mats of present-day tidal-flat environments. Due to differences in water content and nature of the microbial mats and the underlying sediment, a wide range of footprint morphologies was produced by the same trackmaker. Most true tracks are subjected to modification due to taphonomic processes, leading to modified true tracks. In addition to formation of biolaminites, microbial mats play a major role in the preservation of footprints on tidal flats. A footprint may be consolidated by desiccation or lithification of the mat, or by ongoing growth of the mat. The latter process may lead to the formation of overtracks. Among consolidated or (partially) lithified footprints found on present-day tidal flats, poorly defined true tracks, modified true tracks, and overtracks were most frequently encountered while unmodified and well-defined true tracks are rather rare. We suggest that modified true tracks and overtracks make up an important percentage of fossil footprints and that they may be as common as undertracks. However, making unambiguous distinctions between poorly defined true tracks, modified true tracks, undertracks, and overtracks in the fossil record will remain a difficult task, which necessitates systematic excavation of footprints combined with careful analysis of the encasing sediment.