387 research outputs found

    Re-establishment of the genus Pseudalbizzia (Leguminosae, Caesalpinioideae, mimosoid clade): the New World species formerly placed in Albizia

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    Following recent mimosoid phylogenetic and phylogenomic studies demonstrating the non-monophyly of the genus Albizia, we present a new molecular phylogeny focused on the neotropical species in the genus, with much denser taxon sampling than previous studies. Our aims were to test the monophyly of the neotropical section Arthrosamanea, resolve species relationships, and gain insights into the evolution of fruit morphology. We perform a Bayesian phylogenetic analysis of sequences of nuclear internal and external transcribed spacer regions and trace the evolution of fruit dehiscence and lomentiform pods. Our results find further support for the non-monophyly of the genus Albizia, and confirm the previously proposed segregation of Hesperalbizia, Hydrochorea, Balizia and Pseudosamanea. All species that were sampled from section Arthrosamanea form a clade that is sister to a clade composed of Jupunba, Punjuba, Balizia and Hydrochorea. We find that lomentiform fruits are independently derived from indehiscent septate fruits in both Hydrochorea and section Arthrosamanea. Our results show that morphological adaptations to hydrochory, associated with shifts into seasonally flooded habitats, have occurred several times independently in different geographic areas and different lineages within the ingoid clade. This suggests that environmental conditions have likely played a key role in the evolution of fruit types in Albizia and related genera. We resurrect the name Pseudalbizzia to accommodate the species of section Arthrosamanea, except for two species that were not sampled here but have been shown in other studies to be more closely related to other ingoid genera and we restrict the name Albizia s.s. to the species from Africa, Madagascar, Asia, Australia, and the Pacific. Twenty-one new nomenclatural combinations in Pseudalbizzia are proposed, including 16 species and 5 infraspecific varietal names. In addition to the type species Pseudalbizzia berteroana, the genus has 17 species distributed across tropical regions of the Americas, including the Caribbean. Finally, a new infrageneric classification into five sections is proposed and a distribution map of the species of Pseudalbizzia is presented

    Filogenia de Lysiloma (Fabaceae), un género restringido a Megaméxico con especies atípicas en las Antillas y Florida

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    Background and Aims: Lysiloma is a Neotropical genus in the Fabaceae family that comprises eight species, six of which are widely distributed in Mexico, and two more that occur in the Antilles and Florida. Lysiloma is frequent in Megamexico’s dry forests. A previous phylogenetic study included three species of Lysiloma and Hesperalbizia occidentalis. Both genera are closely related, but their divergence has weak support. Our objectives were to test the monophyly of the genus, evaluate the sister relationships within the genus, and estimate the divergence times. Methods: A phylogenetic analysis based on morphological characters, molecular markers (ETS, matK, and trnK), as well as a combined analysis (morphology + molecules) was performed. The data matrices were analyzed both individually and concatenated (total evidence approach) with Bayesian inference and Maximum Parsimony. In addition, molecular divergence times were estimated from the ETS dataset with a Bayesian uncorrelated lognormal relaxed clock. Key results: The morphological analysis supports the monophyly of Lysiloma with Hesperalbizia as sister group. However, the individual and the combined molecular analyses do not provide resolution to clarify the relationships between Hesperalbizia occidentalis, Lysiloma sabicu, and core Lysiloma. The total evidence analysis (including morphology) supports the monophyly of Lysiloma, yet with low support. According to our molecular clock model, the clade Lysiloma+Hesperalbizia diverged from other members of the tribe Acacieae+Ingeae about 32 million years ago, and the diversification of the core of Lysiloma occurred during the Miocene. Conclusions: Lysiloma+Hesperalbizia is an early divergent clade of tribes Acacieae+Ingeae. There are enough morphological differences to recognize both linages. Morphological characters informally used for taxonomic delimitation seem to have evolved homoplasiously. The clade Lysiloma and Hesperalbizia separated from other members of the tribe Acacieae+Ingeae in the Oligocene, but the diversification of the core of the genus coincides with the expansion of the dry forest at the beginning of the Miocene.Antecedentes y Objetivos: Lysiloma es un género neotropical de la familia Fabaceae que comprende ocho especies, seis de las cuales se distribuyen ampliamente en México y dos más que ocurren en las Antillas y La Florida. Lysiloma es frecuente en los bosques secos de Megaméxico. Un estudio filogenético previo incluyó tres especies de Lysiloma y Hesperalbizia occidentalis. Ambos géneros están estrechamente relacionados, pero su divergencia tiene un apoyo débil. Nuestros objetivos fueron probar la monofilia del género, evaluar las relaciones de grupo hermano dentro del género y estimar los tiempos de divergencia. Métodos: Se realizó un análisis filogenético basado en caracteres morfológicos, marcadores moleculares (ETS, matK y trnK), así como un análisis combinado (morfología + moléculas). Las matrices de datos se analizaron tanto individualmente como concatenadas (enfoque de evidencia total) con inferencia Bayesiana y máxima parsimonia. Además, los tiempos de divergencia molecular se estimaron a partir del conjunto de datos ETS con un modelo de reloj bayesiano relajado lognormal no correlacionado. Resultados clave: El análisis morfológico respalda la monofilia del Lysiloma con Hesperalbizia como grupo hermano. Sin embargo, los análisis moleculares individuales y combinado no proporcionan resolución para aclarar las relaciones entre Hesperalbizia occidentalis, Lysiloma sabicu y el núcleo de Lysiloma. El análisis de evidencia total (incluida la morfología) respalda la monofilia de Lysiloma, pero con un bajo soporte. Según nuestro modelo de reloj molecular, el clado Lysiloma+Hesperalbizia se separó de otros miembros de la tribu Acacieae+Ingeae hace unos 32 millones de años y la diversificación del núcleo del Lysiloma se produjo a lo largo del Mioceno.Conclusiones: Lysiloma+Hesperalbizia es un clado de divergencia temprana de las tribus Acacieae+Ingeae. Existen suficientes diferencias morfológicas para reconocer ambos linajes. Los caracteres morfológicos utilizados informalmente para la delimitación taxonómica parecen haber evolucionado de manera homoplásica. El clado de Lysiloma y Hesperalbizia se separó de otros miembros de la tribu Acacieae+Ingeae en el Oligoceno, pero la diversificación del núcleo del género coincidió con la expansión del bosque seco a principios del Mioceno

    LA U INVESTIGA: Revista Científica. Facultad Ciencias de la Salud. Volumen 3. Número 2

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    En el presente volumen se distinguen varios ámbitos de la investigación en salud desde artículos asociados a la promoción de salud, prevención de enfermedades, así como investigaciones de casos clínicos que evidencia la experiencia del equipo de salud en patologías específicas. Hay que resaltar que muchos de los artículos presentados en el volumen actual corresponden a los resultados de investigaciones ejecutadas en la academia, propias de la Universidad Técnica del Norte y de otras.1._ Melanoma antebraquial derecho metastásico a pa¬red abdominal y pelvis presentación de un caso clínico. 2._ Carcinoma papilar de localizacion extratiroidea. 3._ Tumores del golfo de la yugular 4._ Estudio comparativo del desarrollo psicomotor en niños/as de 1 a 3 años del Centro Infantil del Buen Vivir “CENTRO PUCARA” y “GOTITAS DE AMOR” del cantón Antonio Ante de la provincia de Imbabura. 5._ Adaptaciones de las técnicas comunicacionales al proceso terapéutico de salud mental infantil. 6._ La dinámica de la investigación científica en la formación de los profesionales de enfermería: una aproximación al problema de investigación. 7._ Las agresiones en las parejas de enamorados en la adolescencia y el equilibrio emocional. 8._ Rasgos de personalidad y su influencia en la calidad de vida en los estudiantes de la Unidad Educativa” Las Américas” 9._ Estudio de la postura corporal y su relación con la obesidad y sobrepeso en niños de 6 a 12 años del cantón Antonio Ante de la provincia de Imbabura. 10._ Caracterización de cuidadores informales de personas con discapacidad de la provincia de Im¬babura. 11._ Intervención educativa sobre embarazo en la adolescencia en estudiantes del tercer año de bachillerato de la unidad educativa “Madre Tere¬sa Bacq” Imbabura-Ecuador. 12._ Acceso a la atención de consulta externa de los usuarios del centro de llamadas, que asisten al subcentro de salud San Antonio, Tanguarin Iba¬rra, ecuador 2016. 13._ Prevalencia de disfunción familiar en la parro¬quia urbana de Urcuquí

    Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

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    An embedding technique to determine ττ backgrounds in proton-proton collision data

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    An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

    Search for Physics beyond the Standard Model in Events with Overlapping Photons and Jets

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    Results are reported from a search for new particles that decay into a photon and two gluons, in events with jets. Novel jet substructure techniques are developed that allow photons to be identified in an environment densely populated with hadrons. The analyzed proton-proton collision data were collected by the CMS experiment at the LHC, in 2016 at root s = 13 TeV, and correspond to an integrated luminosity of 35.9 fb(-1). The spectra of total transverse hadronic energy of candidate events are examined for deviations from the standard model predictions. No statistically significant excess is observed over the expected background. The first cross section limits on new physics processes resulting in such events are set. The results are interpreted as upper limits on the rate of gluino pair production, utilizing a simplified stealth supersymmetry model. The excluded gluino masses extend up to 1.7 TeV, for a neutralino mass of 200 GeV and exceed previous mass constraints set by analyses targeting events with isolated photons.Peer reviewe

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

    Bose-Einstein correlations of charged hadrons in proton-proton collisions at s\sqrt s = 13 TeV

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    Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at s \sqrt{s} = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at s \sqrt{s} = 7 TeV, as well as with theoretical predictions.[graphic not available: see fulltext]Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at s=\sqrt{s} = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at s=\sqrt{s} = 7 TeV, as well as with theoretical predictions

    Search for dark matter in events with a leptoquark and missing transverse momentum in proton-proton collisions at 13 TeV

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    A search is presented for dark matter in proton-proton collisions at a center-of-mass energy of root s= 13 TeV using events with at least one high transverse momentum (p(T)) muon, at least one high-p(T) jet, and large missing transverse momentum. The data were collected with the CMS detector at the CERN LHC in 2016 and 2017, and correspond to an integrated luminosity of 77.4 fb(-1). In the examined scenario, a pair of scalar leptoquarks is assumed to be produced. One leptoquark decays to a muon and a jet while the other decays to dark matter and low-p(T) standard model particles. The signature for signal events would be significant missing transverse momentum from the dark matter in conjunction with a peak at the leptoquark mass in the invariant mass distribution of the highest p(T) muon and jet. The data are observed to be consistent with the background predicted by the standard model. For the first benchmark scenario considered, dark matter masses up to 500 GeV are excluded for leptoquark masses m(LQ) approximate to 1400 GeV, and up to 300 GeV for m(LQ) approximate to 1500 GeV. For the second benchmark scenario, dark matter masses up to 600 GeV are excluded for m(LQ) approximate to 1400 GeV. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe

    Search for an L-mu - L-tau gauge boson using Z -> 4 mu events in proton-proton collisions at root s=13 TeV

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    A search for a narrow Z' gauge boson with a mass between 5 and 70 GeV resulting from an L-mu - L-tau U (1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb(-1) recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z -> Z'mu mu -> 4 mu decays. The event yields are consistent with the standard model predictions. Upper limits of 10(-8)-10(-7) at 95% confidence level are set on the product of branching fractions B(Z -> Z'mu mu)B(Z' -> mu mu), depending on the Z' mass, which excludes a Z' boson coupling strength to muons above 0.004-0.3. These are the first dedicated limits on L-mu - L-tau models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z' gauge boson to muons. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe
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