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Search Results: 1 - 10 of 325245 matches for " S. Renner "
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Detection of Laplace-resonant three-planet systems from transit timing variations
A. -S. Libert,S. Renner
Physics , 2013, DOI: 10.1093/mnras/sts722
Abstract: Transit timing variations (TTVs) are useful to constrain the existence of perturbing planets, especially in resonant systems where the variations are strongly enhanced. Here we focus on Laplace-resonant three-planet systems, and assume the inner planet transits the star. A dynamical study is performed for different masses of the three bodies, with a special attention to terrestrial planets. We consider a maximal time-span of ~ 100 years and discuss the shape of the inner planet TTVs curve. Using frequency analysis, we highlight the three periods related to the evolution of the system: two periods associated with the Laplace-resonant angle and the third one with the precession of the pericenters. These three periods are clearly detected in the TTVs of an inner giant planet perturbed by two terrestrial companions. Only two periods are detected for a Jupiter-Jupiter-Earth configuration (the ones associated with the giant interactions) or for three terrestrial planets (the Laplace periods). However, the latter system can be constrained from the inner planet TTVs. We finally remark that the TTVs of resonant three or two Jupiter systems mix up, when the period of the Laplace resonant angle matches the pericenter precession of the two-body configuration. This study highlights the importance of TTVs long-term observational programs for the detection of multiple-planet resonant systems.
The worldwide holoparasitic Apodanthaceae confidently placed in the Cucurbitales by nuclear and mitochondrial gene trees
Natalia Filipowicz, Susanne S Renner
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-219
Abstract: Here we report a phylogenetic analysis of 16 accessions representing six species of Apodanthaceae from the United States, Chile, Iran, and Australia, using the mitochondrial matR gene and the nuclear 18S gene. Data matrices include 190 matR sequences from up to 95 families in 39 orders of flowering plants and 197 18S sequences from 101 families representing the 16 orders of rosids. Analyses were performed at the nucleotide and at the amino acid level. Both gene trees agree with angiosperm phylogenies found in other studies using more genes. Apodanthaceae and the seven families of the order Cucurbitales form a clade with 100% bootstrap support from matR and 56% from 18 S. In addition, the Apodanthaceae and Cucurbitales matR gene sequences uniquely share two non-synonymous codon changes and one synonymous change, as well as a codon insertion, already found by Barkman et al. (2007).Apodanthaceae belong in the Cucurbitales with which they share inferior ovaries, parietal placentation and a dioecious mating system, traits that are ancestral in Cucurbitales and which can now be interpreted as possible synapomorphies of an enlarged order Cucurbitales. The occurrence of Apodanthaceae in the Americas, Africa, the Near East, and Australia, and their adaptation to distantly related host species in the Fabaceae and Salicaceae suggest a long evolutionary history.Among the c. 450 families of angiosperms [1] are about 11 parasitic lineages [2] of which some have completely lost the ability to photosynthesize. Such non-photosynthetic parasites grow embedded within the host tissues (as endoparasites) and emerge only during sexual reproduction [3]. Molecular-phylogenetic studies in recent years have revealed the sister groups of most parasitic plants [e. g. [2,4-10]. Only the Apodanthaceae and the likewise holoparasitic Cynomoriaceae have not yet been placed with confidence, and the Apodanthaceae are also the only unplaced family-level clade in the latest classification of flowering
A dated phylogeny and collection records reveal repeated biome shifts in the African genus Coccinia (Cucurbitaceae)
Norbert Holstein, Susanne S Renner
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-28
Abstract: Nuclear and plastid gene trees included 35 or 65 accessions, representing up to 25 species. The data revealed four species groups, one in southern Africa, one in Central and West African rain forest, one widespread but absent from Central and West African rain forest, and one that occurs from East Africa to southern Africa. A few individuals are differently placed in the plastid and nuclear (LFY) trees or contain two ITS sequence types, indicating hybridization. A molecular clock suggests that the diversification of Coccinia began about 6.9 Ma ago, with most of the extant species diversity dating to the Pliocene. Ancestral biome reconstruction reveals six switches between semi-arid habitats, woodland, and forest, and members of several species pairs differ significantly in their tolerance of different precipitation regimes.The most surprising findings of this study are the frequent biome shifts (in a relatively small clade) over just 6 - 7 million years and the limited diversification during and since the Pleistocene. Pleistocene climate oscillations may have been too rapid or too shallow for full reproductive barriers to develop among fragmented populations of Coccinia, which would explain the apparently still ongoing hybridization between certain species. Steeper ecological gradients in East Africa and South Africa appear to have resulted in more advanced allopatric speciation there.Clades will typically retain their ecological characteristics, at least over moderate periods of evolutionary time [1,2], and where inherited climatic tolerances are narrow, this will limit species' geographic range expansion. As long as the inherited component of ecological preference is strong, species evolving in allopatry should initially have similar habitat requirements, and ecological differences between them should accumulate gradually [3]. These arguments set up expectations about how climate niches and species ranges in groups of related species should correlate with each oth
Phylogenetics of Cucumis (Cucurbitaceae): Cucumber (C. sativus) belongs in an Asian/Australian clade far from melon (C. melo)
Susanne S Renner, Hanno Schaefer, Alexander Kocyan
BMC Evolutionary Biology , 2007, DOI: 10.1186/1471-2148-7-58
Abstract: Analyses of combined chloroplast sequences (4,375 aligned nucleotides) for 123 of the 130 genera of Cucurbitaceae indicate that the genera Cucumella, Dicaelospermum, Mukia, Myrmecosicyos, and Oreosyce are embedded within Cucumis. Phylogenetic trees from nuclear sequences for these taxa are congruent, and the combined data yield a well-supported phylogeny. The nesting of the five genera in Cucumis greatly changes the natural geographic range of the genus, extending it throughout the Malesian region and into Australia. The closest relative of Cucumis is Muellerargia, with one species in Australia and Indonesia, the other in Madagascar. Cucumber and its sister species, C. hystrix, are nested among Australian, Malaysian, and Western Indian species placed in Mukia or Dicaelospermum and in one case not yet formally described. Cucumis melo is sister to this Australian/Asian clade, rather than being close to African species as previously thought. Molecular clocks indicate that the deepest divergences in Cucumis, including the split between C. melo and its Australian/Asian sister clade, go back to the mid-Eocene.Based on congruent nuclear and chloroplast phylogenies we conclude that Cucumis comprises an old Australian/Asian component that was heretofore unsuspected. Cucumis sativus evolved within this Australian/Asian clade and is phylogenetically far more distant from C. melo than implied by the current morphological classification.Knowing the closest relatives and natural composition of the genus Cucumis L. is important because of ongoing efforts by plant breeders worldwide to improve melon (C. melo) and cucumber (C. sativus) with traits from wild relatives [1]. Next to tomatoes and onion, melon and cucumber may be the most widely cultivated vegetable species in the world [2]. Economic interest from breeders also led to the sequencing of the complete chloroplast genome of C. sativus [3]. Evolutionarily, Cucumis organellar genomes are unusually labile [4-7], and major chrom
Large Hadron Collider constraints on a light baryon number violating sbottom coupling to a top and a light quark
B. C. Allanach,S. A. Renner
Physics , 2013, DOI: 10.1140/epjc/s10052-013-2707-0
Abstract: We investigate a model of R-parity violating (RPV) supersymmetry in which the right-handed sbottom is the lightest supersymmetric particle, and a baryon number violating coupling involving a top is the only non-negligible RPV coupling. This model evades proton decay and flavour constraints. We consider in turn each of the couplings lambda"_{313} and lambda"_{323} as the only non-negligible RPV coupling, and we recast two recent Large Hadron Collider (LHC) measurements and searches (CMS top transverse momentum p_T(t) spectrum and ATLAS multiple jet resonance search) in the form of constraints on the mass-coupling parameter planes. We delineate a large region in the parameter space of the mass of the sbottom (m_{b_R}) and the lambda"_{313} coupling that is ruled out by the measurements, as well as a smaller region in the parameter space of m_{b_R} and lambda"_{323}. A certain region of the m_{b_R}-lambda"_{313} parameter space was previously found to successfully explain the anomalously large ttbar forward backward asymmetry measured by Tevatron experiments. The entire region is excluded at the 95% CL by CMS measurements of the top p_T spectrum. We also present p_T(ttbar) distributions of the forward-backward asymmetry for this model.
Composite leptoquarks and anomalies in $B$-meson decays
Ben Gripaios,Marco Nardecchia,S. A. Renner
Physics , 2014,
Abstract: We attempt to explain recent anomalies in semileptonic $B$ decays at LHCb via a composite Higgs model, in which both the Higgs and an $SU(2)_L$-triplet leptoquark arise as pseudo-Goldstone bosons of the strong dynamics. Fermion masses are assumed to be generated via the mechanism of partial compositeness, which largely determines the leptoquark couplings and implies non-universal lepton interactions. The latter are needed to accommodate tensions in the $b \to s \mu \mu$ dataset and to be consistent with a discrepancy measured at LHCb in the ratio of $B^+ \to K^+ \mu^+ \mu^-$ to $B^+ \to K^+ e^+ e^-$ branching ratios. The data imply that the leptoquark should have a mass of around a TeV. We find that the model is not in conflict with current flavour or direct production bounds, but we identify a few observables for which the new physics contributions are close to current limits and where the leptoquark is likely to show up in future measurements. The leptoquark will be pair-produced at the LHC and decay predominantly to third-generation quarks and leptons, and LHC13 searches will provide further strong bounds.
Hint of Lepton Flavour Non-Universality in $B$ Meson Decays
Diptimoy Ghosh,Marco Nardecchia,S. A. Renner
Physics , 2014, DOI: 10.1007/JHEP12(2014)131
Abstract: The LHCb collaboration has recently presented their result on R_K = BR(B+ -> K+ mu+ mu-)/ BR(B+ -> K+ e+ e-) for the dilepton invariant mass bin m_{ll}^2 = 1-6 GeV^2 (l = mu, e). The measurement shows an intriguing 2.6 sigma deviation from the Standard Model (SM) prediction. In view of this, we study model independent New Physics (NP) explanations of R_K consistent with other measurements involving b -> s l l transition, relaxing the assumption of lepton universality. We perform a Bayesian statistical fit to the NP Wilson Coefficients and compare the Bayes Factors of the different hypotheses in order to quantify their goodness-of-fit. We show that the data slightly favours NP in the muon sector over NP in the electron sector.
A specific insertion of a solo-LTR characterizes the Y-chromosome of Bryonia dioica (Cucurbitaceae)
Ryan K Oyama, Martina V Silber, Susanne S Renner
BMC Research Notes , 2010, DOI: 10.1186/1756-0500-3-166
Abstract: We sequenced 2321 bp of the Y-chromosome in Bryonia dioica that flank a male-linked marker, BdY1, reported previously. Within this region, which should be suppressed for recombination, we observed a solo-LTR nested in a Copia-like transposable element. We also found other, presumably paralogous, solo-LTRs in a consensus sequence of the underlying Copia-like transposable element.Given that solo-LTRs arise via recombination events, it is noteworthy that we find one in a genomic region where recombination should be suppressed. Although the solo-LTR could have arisen before recombination was suppressed, creating the male-linked marker BdY1, our previous study on B. dioica suggested that BdY1 may not lie in the recombination-suppressed region of the Y-chromosome in all populations. Presence of a solo-LTR near BdY1 therefore fits with the observed correlation between retrotransposon accumulation and the suppression of recombination early in the evolution of sex chromosomes. These findings further suggest that the homomorphic sex chromosomes of B. dioica, the first organism for which genetic XY sex-determination was inferred, are evolutionarily young and offer reference information for comparative studies of other plant sex chromosomes.The origin and evolution of sex chromosomes from autosomes have long interested biologists. Dioecy, a precondition for sex chromosomes where the male and female functions are separated onto different individuals, is common in animals but relatively rare among flowering plants, occurring in only about 6% of species [1]. Sex chromosomes in flowering plants are even less common, with only a handful of species known to have them [2,3]. Molecular clock dating and the observation that some of these species (e.g., papaya) still have homomorphic gonosomes, suggest that plant sex chromosomes are evolutionarily young [4,5].Most of what we know about the evolution of sex chromosomes in flowering plants is derived from research on a few model systems. M
A Nuclear Ribosomal DNA Phylogeny of Acer Inferred with Maximum Likelihood, Splits Graphs, and Motif Analysis of 606 Sequences
Guido W. Grimm,Susanne S. Renner,Alexandros Stamatakis,Vera Hemleben
Evolutionary Bioinformatics , 2006,
Abstract: The multi-copy internal transcribed spacer (ITS) region of nuclear ribosomal DNA is widely used to infer phylogenetic relationships among closely related taxa. Here we use maximum likelihood (ML) and splits graph analyses to extract phylogenetic information from ~ 600 mostly cloned ITS sequences, representing 81 species and subspecies of Acer, and both species of its sister Dipteronia. Additional analyses compared sequence motifs in Acer and several hundred Anacardiaceae, Burseraceae, Meliaceae, Rutaceae, and Sapindaceae ITS sequences in GenBank. We also assessed the effects of using smaller data sets of consensus sequences with ambiguity coding (accounting for within-species variation) instead of the full (partly redundant) original sequences. Neighbor-nets and bipartition networks were used to visualize conflict among character state patterns. Species clusters observed in the trees and networks largely agree with morphology-based classifications; of de Jong’s (1994) 16 sections, nine are supported in neighbor-net and bipartition networks, and ten by sequence motifs and the ML tree; of his 19 series, 14 are supported in networks, motifs, and the ML tree. Most nodes had higher bootstrap support with matrices of 105 or 40 consensus sequences than with the original matrix. Within-taxon ITS divergence did not differ between diploid and polyploid Acer, and there was little evidence of differentiated parental ITS haplotypes, suggesting that concerted evolution in Acer acts rapidly.
Universal Multifractal Properties of the Small Scale Intermittency in Anisotropic and Inhomogeneous Turbulence
M. Alber,S. Lueck,C. Renner,J. Peinke
Physics , 2000,
Abstract: The notion of self-similar energy cascades and multifractality has long since been connected with fully developed, homogeneous and isotropic turbulence. We introduce a number of amendments to the standard methods for analysing the multifractal properties of the energy dissipation field of a turbulent flow. We conjecture that the scaling assumption for the moments of the energy dissipation rate is valid within the transition range to dissipation introduced by Castaing et al.(Physica D (46), 177 (1990)). The multifractal spectral functions appear to be universal well within the error margins and exhibit some as yet undiscussed features. Furthermore, this universality is also present in the neither homogeneous nor isotropic flows in the wake very close to a cylinder or the off-centre region of a free jet.
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