133 research outputs found

    The apparatus composition and architecture of Erismodus quadridactylus and the implications for element homology in prioniodinin conodonts

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    The apparatus composition and architecture of prioniodinin conodonts is poorly understood, largely because few prioniodinin taxa are represented by articulated oral feeding apparatuses (natural assemblages) in the fossil record, but also due to the highly variable gradational morphology of their constituent elements that makes apparatus reconstruction problematic. We describe here a natural assemblage of Erismodus quadridactylus (Stauffer), a prioniodinin, from the Sandbian (Late Ordovician) of North Dakota, USA. The assemblage demonstrates that the apparatus architecture of Erismodus is similar to those of late Palaeozoic prioniodinins namely, Kladognathus Rexroad and Hibbardella Bassler, but also has similarities with ozarkodinin apparatuses. In addition, there is evidence to suggest that E. quadridactylus shares topological similarities to balognathid architecture, with respect to the position of its inferred P elements. The apparatus composition and architecture presented here indicate that, at least with respect to the M–S array, an ‘ozarkodinin‐type’ bauplan is probably more widely representative across prioniodontids. The assemblage demonstrates that element morphotypes traditionally considered to lie within the S array are M elements, whereas others traditionally interpreted as P elements are found in the S array. These observations are used as a basis for refining concepts of element homology among prioniodinin conodonts and their closest relatives

    Broad-line region in NGC 4151 monitored by two decades of reverberation mapping campaigns. I. Evolution of structure and kinematics

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    We report the results of long-term reverberation mapping (RM) campaigns of the nearby active galactic nuclei (AGN) NGC 4151, spanning from 1994 to 2022, based on archived observations of the FAST Spectrograph Publicly Archived Programs and our new observations with the 2.3m telescope at the Wyoming Infrared Observatory. We reduce and calibrate all the spectra in a consistent way, and derive light curves of the broad Hβ\beta line and 5100\,{\AA} continuum. Continuum light curves are also constructed using public archival photometric data to increase sampling cadences. We subtract the host galaxy contamination using {\it HST} imaging to correct fluxes of the calibrated light curves. Utilizing the long-term archival photometric data, we complete the absolute flux-calibration of the AGN continuum. We find that the Hβ\beta time delays are correlated with the 5100\,{\AA} luminosities as τHβL51000.46±0.16\tau_{\rm H\beta}\propto L_{5100}^{0.46\pm0.16}. This is remarkably consistent with Bentz et al. (2013)'s global size-luminosity relationship of AGNs. Moreover, the data sets for five of the seasons allow us to obtain the velocity-resolved delays of the Hβ\beta line, showing diverse structures (outflows, inflows and disks). Combining our results with previous independent measurements, we find the measured dynamics of the Hβ\beta broad-line region (BLR) are possibly related to the long-term trend of the luminosity. There is also a possible additional \sim1.86 years time lag between the variation in BLR radius and luminosity. These results suggest that dynamical changes in the BLR may be driven by the effects of radiation pressure.Comment: Accepted for publication in MNRAS; comments welcome

    Monitoring AGNs with Hβ\beta Asymmetry. IV. First Reverberation Mapping Results of 14 AGNs

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    We report first-time reverberation mapping results for 14 AGNs from the ongoing Monitoring AGNs with Hβ\beta Asymmetry campaign (MAHA). These results utilize optical spectra obtained with the Long Slit Spectrograph on the Wyoming Infrared 2.3m Telescope between 2017 November-2023 May. MAHA combines long-duration monitoring with high cadence. We report results from multiple observing seasons for 9 of the 14 objects. These results include Hβ\beta time lags, supermassive black hole masses, and velocity-resolved time lags. The velocity-resolved lags allow us to investigate the kinematics of the broad-line region.Comment: 35 pages, 19 figures, accepted for publication in ApJ Supplemen

    Vermiform Burrows and Rate of Sedimentation in the Lower Greensand

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    SOME MIDDLE SILURIAN REEFS OF GOTLAND

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    Remarks on two brachiopod species described by Linnaeus

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    Repetitive elements of the Mycoplasma hominis adhesin p50 can be differentiated by monoclonal antibodies

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    The gene encoding p50, an adhesin of Mycoplasma hominis, was identified, cloned, and sequenced. Comparison of the derived amino acid sequence with the N-terminal amino acids sequenced by the Edman reaction of the native protein revealed that p50 is expressed as a 467-amino-acid precursor. Posttranslational modification leads to a 441-amino-acid lipoprotein with an extended, predominantly helical structure and a leucine zipper. Computer analysis of the amino acid sequence identified a threefold-repetitive sequence motif comprising approximately three-quarters of the total protein. Different regions of the p50 polypeptide chain were expressed in Escherichia coli. Western blot (immunoblot) analysis of the E. coli lysates revealed that the epitopes of four p50-specific monoclonal antibodies were localized in the middle and C-terminal part of the protein. Epitope mapping by exonuclease III digestion showed that all of the four monoclonal antibodies bound within the same region of the threefold-repetitive amino acid sequence motif. The repeats, which were highly homologous but not identical in structure, could be differentiated by the monoclonal antibodies.</jats:p
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