On the efficiency of stochastic volume sources for the determination of light meson masses

We investigate the efficiency of single timeslice stochastic sources for the calculation of light meson masses on the lattice as one varies the quark mass. Simulations are carried out with Nf = 2 flavours of non-perturbatively O(a) improved Wilson fermions for pion masses in the range of 450 - 760 MeV. Results for pseudoscalar and vector meson two-point correlation functions computed using stochastic as well as point sources are presented and compared. At fixed computational cost the stochastic approach reduces the variance considerably in the pseudoscalar channel for all simulated quark masses. The vector channel is more affected by the intrinsic stochastic noise. In order to obtain stable estimates of the statistical errors and a more pronounced plateau for the effective vector meson mass, a relatively large number of stochastic sources must be used.Comment: 18 pages, 6 figure

Antigone, "cigoigne orde et vilz". L’histoire d’un portrait énigmatique dans l''Ovide Moralisé'

Le mythe d’Antigone transformée en cigogne a trouvé son chemin de l’Antiquité gréco-romaine vers le Moyen Âge occidental à travers les Métamorphoses ovidiennes, adaptés au XIVe siècle dans l’immense poème qu’est l’Ovide Moralisé. En retravaillant la matière mythologique dans le contexte chrétien, l’auteur de cette œuvre médiévale a fait de l’évocation succincte et anecdotique de la cigogne chez Ovide un discours moralisateur étendu qui multiplie les traits dépréciatifs attribués à l’oiseau blanc, en lui conférant une image foncièrement négative. La présente contribution tentera de mettre en lumière le cheminement et les possibles raisons de cette évolution, en examinant les différentes sources qui ont fourni des matériaux pour la composition du portrait tardo-médiévale de la cigogne moralisée

Morphology and angiosperm systematics in the molecular era

Several ways in which morphology is used in systematic and evolutionary research in angiosperms are shown and illustrated with examples: 1) searches for special structural similarities, which can be used to find hints for hitherto unrecognized relationships in groups with unresolved phylogenetic position; 2) cladistic studies based on morphology and combined morphological and molecular analyses; 3) comparative morphological studies in new, morphologically puzzling clades derived from molecular studies; 4) studies of morphological character evolution, unusual evolutionary directions, and evolutionary lability based on molecular studies; and 5) studies of organ evolution. Conclusions: Goals of comparative morphology have shifted in the present molecular era. Morphology no longer plays the primary role in phylogenetic studies. However, new opportunities for morphology are opening up that were not present in the premolecular era: 1) phylogenetic studies with combined molecular and morphological analyses; 2) reconstruction of the evolution of morphological features based on molecularly derived cladograms; 3) refined analysis of morphological features induced by inconsistencies of previous molecular and molecular phylogenetic analyses; 4) better understanding of morphological features by judgment in a wider biological context; 5) increased potential for including fossils in morphological analyses; and 6) exploration of the evolution of morphological traits by integration of comparative structural and molecular developmental genetic aspects (Evo-Devo); this field is still in its infancy in botany; its advancement is one of the major goals of evolutionary botan

How are Bayesian models really used? Reply to Frank (2013)

In response to the proposal that cognitive phenomena might be best understood in terms of cognitive theories (Endress, 2013), Frank (2013) outlined an important research program, suggesting that Bayesian models should be used as rigorous, mathematically attractive implementations of psychological theories. This research program is important and promising. However, I show that it is not followed in practice. I then turn to Frank's defense of the assumption that learners prefer more specific rules (the "size principle"), and show that the results allegedly supporting this assumption do not provide any support for it. Further, I demonstrate that, in contrast to Frank's criticisms, there is no circularity in an account of rule-learning based on "common-sense psychology", and that Frank's other criticisms of this account are unsupported. I conclude that the research program outlined by Frank is important and promising, but needs to be followed in practice. Be that as it might, the rule-learning experiments discussed by Frank are still better explained by simple psychological mechanisms

The Immense Diversity of Floral Monosymmetry and Asymmetry Across Angiosperms

Floral monosymmetry and asymmetry are traced through the angiosperm orders and families. Both are diverse and widespread in angiosperms. The systematic distribution of the different forms of monosymmetry and asymmetry indicates that both evolved numerous times. Elaborate forms occur in highly synorganized flowers. Less elaborate forms occur by curvature of organs and by simplicity with minimal organ numbers. Elaborate forms of asymmetry evolved from elaborate monosymmetry. Less elaborate form come about by curvature or torsion of organs, by imbricate aestivation of perianth organs, or also by simplicity. Floral monosymmetry appears to be a key innovation in some groups (e.g., Orchidaceae, Fabaceae, Lamiales), but not in others. Floral asymmetry appears as a key innovation in Phaseoleae (Fabaceae). Simple patterns of monosymmetry appear easily "reverted” to polysymmetry, whereas elaborate monosymmetry is difficult to lose without disruption of floral function (e.g., Orchidaceae). Monosymmetry and asymmetry can be expressed at different stages of floral (and fruit) development and may be transient in some taxa. The two symmetries are most common in bee-pollinated flowers, and appear to be especially prone to develop in some specialized biological situations: monosymmetry, e.g., with buzz-pollinated flowers or with oil flowers, and asymmetry also with buzz-pollinated flowers, both based on the particular collection mechanisms by the pollinating bees. Floral monosymmetry has developed into a model trait in evo-devo studies, whereas floral asymmetry to date has not been tackled in molecular genetic studie

The 'Reopen Churches' Conversation : Disabilities and the Margins

Peer reviewedPublisher PD

Synorganisation without organ fusion in the flowers of Geranium robertianum (Geraniaceae) and its not so trivial obdiplostemony

Background and Aims Synorganisation of floral organs, an important means in angiosperm flower evolution, is mostly realized by congenital or post-genital organ fusion. Intimate synorganisation of many floral organs without fusion, as present in Geranium robertianum, is poorly known and needs to be studied. Obdiplostemony, the seemingly reversed position of two stamen whorls, widely distributed in core eudicots, has been the subject of much attention, but there is confusion in the literature. Obdiplostemony occurs in Geranium and whether and how it is involved in this synorganisation is explored here. Methods Floral development and architecture were studied with light microscopy based on microtome section series and with scanning electron microscopy. Key Results Intimate synorganisation of floral organs is effected by the formation of five separate nectar canals for the proboscis of pollinators. Each nectar canal is formed by six adjacent organs from four organ whorls. In addition, the sepals are hooked together by the formation of longitudinal ribs and grooves, and provide a firm scaffold for the canals. Obdiplostemony provides a guide rail within each canal formed by the flanks of the antepetalous stamen filaments. Conclusions Intimate synorganisation in flowers can be realized without any fusion, and obdiplostemony may play a role in this synorganisatio

Carpels in Brasenia (Cabombaceae) are Completely Ascidiate Despite a Long Stigmatic Crest

• Background and Aims The morphological structure of anthetic carpels of Brasenia (Cabombaceae), a member of the phylogenetically basal ANITA grade, has not been studied before. The carpel has a long stigmatic crest on the ventral side and could give the impression of a conduplicate structure. This is in contrast to the carpel structure in other genera of the ANITA grade. Therefore, a study of carpel development and carpel structure at anthesis was carried out. • Methods Carpels of Brasenia schreberi were studied at different developmental stages up to anthesis by means of microtome section series and SEM to analyse and reconstruct the outer and inner carpel morphology. • Key Results Carpels of Brasenia are extremely ascidiate up to anthesis. The elongate stigma originates around the mouth of the young carpel, which is slightly curved toward the centre of the flower. Subsequently, the stigmatic zone below the mouth expands by massive intercalary elongation. • Conclusions In their ascidiate shape, carpels of Brasenia are similar to carpels of Cabomba, the other genus of Cabombaceae, which, in contrast, has a short stigma restricted to the tip of the carpel. Thus, the morphological structure is independent of the extent (and one-sidedness) of the stigma. The outer shape of carpels at anthesis does not allow the inference of the inner morphological surface. If an angiosperm carpel has a one-sided stigma it can be extremely conduplicate or extremely ascidiate. Therefore, caution has to be used in the interpretion of the structure of fossil carpel