1,223 research outputs found

    Phylogenetics of Alooideae (Asphodelaceae)

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    Phylogenetic and taxonomic uncertainty surround the succulent subfamily Alooideae (Asphodelaceae). Only recently have molecular phylogenetic methods been utilized to address some of the questions regarding alooid evolution. These initial studies,however, were not specifically designed to elucidate Alooideae phylogenetic patterns and were therefore incomplete. A thorough examination of the intergeneric relationships within Alooideae was performed in an attempt to determine the evolutionary history of the subfamily. Plastid sequence data (ndhF, trnL intron, and trnL-F intergenic spacer) was accumulated and analyzed using both parsimony and Bayesian reconstruction methods to develop a hypothesis of evolutionary relationships. One of the most unexpected results was the discovery that the genus Haworthia, as currently circumscribed, is polyphyletic. In addition, Gasteria may be derived from within Haworthia subgenus Hexangulares. The monotypic genus Chortolirion was found to be nested within a strongly supported monophyletic Aloe. The polyphyly of Haworthia and its phylogenetic distribution may have implications on Alooideae taxonomy and necessitate the reevaluation of structural character evolution within this group of succulent monocots

    Phylogenetics of Paniceae (Poaceae)

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    Paniceae demonstrate unique variability of photosynthetic physiology and anatomy, including both non-Kranz and Kranz species and all subtypes of the latter. This variability suggests hypotheses of independent origin or reversals (e.g., from C4 to C3). These hypotheses can be tested by phylogenetic analysis of independent molecular characters. The molecular phylogeny of 57 species of Paniceae was explored using sequences from the grass-specific insert found in the plastid locus rpoC2. Phylogenetic analyses confirmed some long-recognized alliances in Paniceae, some recent molecular phylogenetic results, and suggested new relationships. Broadly, Paniceae were found to be paraphyletic with Andropogoneae, Panicum was found to be polyphyletic, and Oplismenus hirtellus was resolved as the sister group to the remaining ingroup species. A particularly well-supported clade in the rpoC2 tree included four genera with non-Kranz species and three with distinctively keeled paleas. As previously suggested, the PCK (phosphoenol pyruvate carboxykinase) C4 subtype arose once within Paniceae. All clades with non-Kranz species had Kranz ancestors or sister taxa suggesting repeated loss of the Kranz syndrome

    Phylogeny of the Grasses (Poaceae) Revisited

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    The most robust previously published phylogeny for the overall structure of the grass family (Poaceae) shows three early diverging lineages and two major derived clades, the BEP clade and the PACCAD clade (Grass Phylogeny Working Group 2001). A few key taxa were incompletely sampled, however, and support for the BEP clade was moderate at best and relationships among the major lineages within the PACCAD clade remained unresolved. In addition, recent studies indicated that the sister group to Poaceae may be Joinvilleaceae and/or Ecdeiocoleaceae, the latter of which were not previously sampled. In this study, missing structural data were determined and analyzed as well as sequence data for ndhF and rbcL, the two most complete plastid sequence data sets. Sampling was increased with a particular focus on key taxa such as Danthoniopsis, Eriachne, Micraira, and Streptogyna and a representative of the outgroup, Ecdeiocoleaceae. A total of 61 ingroup and two outgroup taxa were analyzed using maximum parsimony for total data, and maximum parsimony, Bayesian inference, and neighbor joining for the molecular data. A strongly supported clade of ((Eriachneae, Isachne) Micraira) was recovered as a sister subfamily to Arundinoideae and excluded from Panicoideae. Arundinaria was strongly united with Bambusoideae. The position of Streptogyna was weakly supported among Ehrhartoideae, and is still unresolved. An outgroup effect on ingroup topology was observed, demonstrating that highly divergent outgroups may unpredictably alter ingroup relationships

    Childhood Sexual Abuse and Early Timing of Puberty

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    AbstractPurposeThe purpose was to examine whether the timing of puberty, indexed by breast development and pubic hair development, was earlier for sexually abused females compared with a matched comparison group of nonabused females, controlling for key alternative confounds.MethodsA cohort of sexually abused females and matched comparisons was followed longitudinally at mean ages 11 through 20 years. Sexually abused participants (N = 84) were referred by protective services. Comparison participants (N = 89) were recruited to be comparable in terms of age, ethnicity, income level, family constellation, zip codes, and nonsexual trauma histories. Stage of puberty was indexed at each assessment by nurse and participant ratings of breast and pubic hair development using Tanner staging—the gold standard for assessing pubertal onset and development. Cumulative logit mixed models were used to estimate the association between sexual abuse status and the likelihood of transitioning from earlier to later Tanner stage categories controlling for covariates and potential confounds.ResultsSexual abuse was associated with earlier pubertal onset: 8 months earlier for breasts (odds ratio: 3.06, 95% CI: 1.11–8.49) and 12 months earlier for pubic hair (odds ratio: 3.49, 95% CI: 1.34–9.12). Alternative explanations including ethnicity, obesity, and biological father absence did not eradicate these findings.ConclusionsThis study confirms an association between exposure to childhood sexual abuse and earlier pubertal onset. Results highlight the possibility that, due to this early onset, sexual abuse survivors may be at increased risk for psychosocial difficulties, menstrual and fertility problems, and even reproductive cancers due to prolonged exposure to sex hormones

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

    Development and validation of HERWIG 7 tunes from CMS underlying-event measurements

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    This paper presents new sets of parameters (“tunes”) for the underlying-event model of the HERWIG7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in HERWIG7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at s=0.9, 7, and 13Te. The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the dat

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Search for lepton-flavor violating decays of the Higgs boson in the mu tau and e tau final states in proton-proton collisions at root s=13 TeV

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    A search is presented for lepton-flavor violating decays of the Higgs boson to mu t and et. The dataset corresponds to an integrated luminosity of 137 fb(-1) collected at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. No significant excess has been found, and the results are interpreted in terms of upper limits on lepton-flavor violating branching fractions of the Higgs boson. The observed (expected) upper limits on the branching fractions are, respectively, B(H -> mu t) e tau) < 0.22(0.16)% at 95% confidence level.Peer reviewe

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe
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