141 research outputs found
Phylogenetic placement and generic re-circumscriptions of the multilocular genera Arenifera, Octopoma and Schlechteranthus (Aizoaceae: Ruschieae): Evidence from anatomical, morphological and plastid DNA data
"Ruschieae is the largest tribe in the highly speciose subfamily Ruschioideae (Aizoaceae). A generic-level phylogeny for
the tribe was recently produced, providing new insights into relationships between the taxa. Octopoma and Arenifera are woody
shrubs with multilocular capsules and are distributed across the Succulent Karoo. Octopoma was shown to be polyphyletic in the
tribal phylogeny, but comprehensive sampling is required to confirm its polyphyly. Arenifera has not previously been sampled
and therefore its phylogenetic placement in the tribe is uncertain. In this study, phylogenetic sampling for nine plastid regions
(atpB-rbcL, matK, psbJ-petA, rpl16, rps16, trnD-trnT, trnL-F, trnQUUG-rps16, trnS-trnG) was expanded to include all species
of Octopoma and Arenifera, to assess phylogenetic placement and relationships of these genera. Three phylogenetic analyses
were carried out, maximum parsimony, maximum likelihood and Bayesian inference. Leaf anatomical sections were studied
to further inform generic circumscriptions. The phylogenies showed Octopoma to be polyphyletic, with the type, O. octojuge,
and the related O. nanum, resolved as sister to Zeuktophyllum and Smicrostigma, while the other species were placed in the
Conophytum-clade. Arenifera was also shown to be polyphyletic, with the type, A. pillansii, placed in the xeromorphic-clade,
and the remainder of the species recovered among the Octopoma species in the Conophytum-clade (forming the Octopoma
subglobosum-Arenifera spinescens subclade). Generic affinities of the O. subglobosum-A. spinescens subclade were assessed
in relation to the sister taxon Schlechteranthus. The leaf anatomy was found to be informative within the study group. Bladder
cells were observed in Arenifera pillansii, a hypodermis in Little Karoo Octopoma (O. octojuge, O. nanum, O. quadrisepalum)
and epidermal cells forming blunt papillae in Schlechteranthus and the O. subglobosum-A. spinescens subclade. Upon assessment
of the anatomical, morphological and phylogenetic data, Schlechteranthus is here expanded to include the species in
the O. subglobosum-A. spinescens subclade. Eight new combinations are made in Schlechteranthus. As a result, Arenifera is
again monotypic and the circumscription of Octopoma is refined to include three species restricted to the Little Karoo. Two
subgenera within Schlechteranthus s.l. (subg. Schlechteranthus, subg. Microphyllus) are erected to accommodate differences
in leaf size, capsule size, closing body size and locule number."Web of Scienc
A taxonomic revision of chamaecrista (caesalpinioideae, cassieae, cassiinae) in Southern Africa
The southern African species of Chamaecrista were all treated under Cassia in Gordon-Gray’s treatment for the Flora of Southern
Africa. However, given the subsequent generic recircumscriptions in the subtribe Cassiinae, and the expanded collections of these taxa, there is a
need to revisit the taxonomy of the group. The present study aimed to conduct a detailed taxonomic revision of the species of Chamaecrista indigenous to the flora of southern Africa region. Extensive fieldwork was carried out to study the taxa in their natural environment and morphological characters were additionally studied using herbarium material. The revision presented here includes comprehensive descriptions, a key to the
species, nomenclature, typifications, diagnostic characters with illustrations, and geographical distribution maps of all recognised taxa. Eleven
species of Chamaecrista are recognised for the flora of southern Africa, two of which are described as new, i.e. Chamaecrista grandiglandulata
and C. gordon-grayei. In addition, one new subspecies is described, namely C. gordon-grayei subsp. longipedicellata, while Chamaecrista comosa
var. capriconia is raised to the rank of subspecies, viz. Chamaecrista comosa subsp. capriconia. The typifications published here include lectotypes
designated for Chamaecrista plumosa and C. stricta, neotypes designated for C. capensis var. flavescens, C. comosa, and C. plumosa var. diffusa, and an
isolectotype designated for C. stricta
Felicia douglasii (Asteraceae-Astereae), a distinctive new species from the Cape Floristic Region, South Africa
Felicia Cass. (Asteraceae) is the largest of the African members of tribe Astereae, and comprises ±90 species from southern and tropical Africa to Arabia. As currently circumscribed, it is rather weakly diagnosed by the herbaceous or shrubby habit, mostly radiate capitula with epaleate receptacle, ± concolorous rays, mostly bisexual disc florets, and eglandular cypselas with several scabrid or barbellate pappus bristles (Grau, 1973; Herman et al., 2000; Manning and Goldblatt, 2012)
Othonna koos-bekkeri Van Jaarsv. is a synonym of Othonna cerarioides Magoswana & J.C.Manning (Asteraceae: Othonninae)
We thank Nick Helme for bringing to our attention the publication of Othonna koos-bekkeri Van Jaarsv. This work is based on research supported by the National Research Foundation of South Africa (Grant Number 118597) awarded through the Foundational Biodiversity Information Programme (FBIP), a joint initiative of the Department of Science and Technology (DST), the National Research Foundation and the South African National Biodiversity Institute. Additional funding was provided by Elizabeth Parker of Elandsberg. Thank you to Dr Cornelia Klak of the Bolus Herbarium for alerting us of the Namibian and additional collections of the species.Othonna koos-bekkeri Van Jaarsv. is recognised as a synonym of O. cerarioides Magoswana & J.C.Manning. Copyright: © 2021. The AuthorsSouth African National Biodiversity Institute
National Research Foundation 118597
Department of Science and Technology, Ministry of Science and Technology, India डीएसट
A taxonomic revision of the Pteronia camphorate group (Astereae, Asteraceae)
As a first step towards a comprehensive revision of Pteronia (Asteraceae, Astereae), we present here a taxonomic
treatment of the Pteronia camphorata group, in which we recognise three species. The group includes the type species
P. camphorata (an important medicinal plant) and is easily distinguished from the rest of the genus by the glabrous
rather than glandular or variously pilose cypselas. The lectotype of P. camphorata has involucral bracts with
entire margins and long acuminate apices, both diagnostic characters for P. stricta. As such P. stricta is here reduced
into synonymy with P. camphorata and the next available name, P. aspera Thunb, reinstated to accommodate the
species heretofore treated as P. camphorata. Three varieties within Pteronia camphorata had been previously
recognised (var. armata, var. laevigata and var. longifolia). The characters distinguishing var. armata were found to
be continuous with the variation observed within var. longifolia. The third infraspecific taxon, var. laevigata, was
however found to be distinct and is therefore recognised here as a new species, P. cederbergensis Bello, Magee &
Boatwr. It is readily distinguished by the glabrous branches, opposite to sub-opposite somewhat succulent leaves,
the 2-seriate pappus and larger, obclavate cypselas. Transverse sections of the leaves and cypselas were also examined
and provide additional differences between the three recognised species.IS
A decision support system for urban infrastructure inter-asset management employing domain ontologies and qualitative uncertainty-based reasoning
Urban infrastructure assets (e.g. roads, water pipes) perform critical functions to the health and well-being of society. Although it has been widely recognised that different infrastructure assets are highly interconnected, infrastructure management in practice such as planning, installation and maintenance are often undertaken by different stakeholders without considering these dependencies due to the lack of relevant data and cross-domain knowledge, which may cause unexpected cascading social, economic and environmental effects. In this paper, we present a knowledge based decision support system for urban infrastructure inter-asset management. By considering various infrastructure assets (e.g. road, ground, cable), triggers (e.g. pipe leaking) and potential consequences (e.g. tra c disruption) as a holistic system, we model each sub-domain using a modular ontology and encapsulate the interdependence between them using a set of rules. Moreover, qualitative likelihood is assigned to each rule by domain experts (e.g. civil engineers) to encode the uncertainty of knowledge, and an inference engine is applied to predict the potential consequences of a given trigger with location specific data and the encoded rules. A web-based prototype system has been developed based on the above concept and demonstrated to a wide range of stakeholders. The system can assist in the process of decision making by aiding data collation and integration, as well as presenting potential consequences of possible triggers, advising on whether additional information is needed or suggesting ways of obtaining such information. The work shows an intelligent approach to integrate and process multi-source data to pioneer a novel way to aid a complex decision process with a high social impact
Web-based Visualisation for Look-Ahead Ground Imaging in Tunnel Boring Machines
Tunnel Boring Machines (TBMs) are large multi-million pound machines used to excavate underground tunnels. In order to make best use of the high-speed performance of a TBM and guarantee the safety of excavation, it is important to know the local geology, structures and ground properties ahead of the TBM cutter head, especially in complex geological conditions (e.g. karst caves). By working with experienced geophysical experts, tunnelling engineers/consultants and TBM manufacturers, we propose a novel web-based visualisation platform to help TBM operators efficiently manage, process and visualise the TBM parameters, the geology map created by geo-experts based on boreholes, and especially the imaging data captured by an on-board ground imaging system for "seeing through" the ground beyond the excavation surface. Informative visualisation interfaces were designed to facilitate interpretation of the imaging data and adding annotation by users; algorithms were developed for automatic detection of features and probable events by fusion of radar and seismic imaging data; and a back-end database was designed to store all such relevant information for supporting more advanced interpretation in the future. The web-based architecture not only allows the visualisation platform to be directly linked to on-board sensors (e.g. ground penetrating radars, seismic sensors), but also allows users away from the job site to access the captured data using a standard web browser, enabling a collaborative interpretation process. The data processing, management and visualisation platform presented in this paper is flexible with respect to different imaging sensors and modalities, so it is highly adaptable for any other ground imaging systems for tunnel geology inspection, underground utility surveys, etc
An anomalous event detection and tracking method for a tunnel look-ahead ground prediction system
The complicated geological conditions and unexpected geological hazards beyond the face of a tunnel are challenging problems for tunnel construction, which can cause great loss of life and property. While the geological surveys conducted before tunnel construction can provide rough information of construction site, they are not sufficiently accurate for predicting the sudden geological condition changes in local areas. Within the EU NETTUN project, an on-board ground prediction system consisting of multiple ground penetrating radars (GPR) and seismic sensors were developed to “see through” the ground and provide the local ground information behind the excavation front surface of a TBM (Tunnel Boring Machine). In order to facilitate the interpretation of the imaging data captured by this system, an automatic event detection and tracking method is presented in this paper. Anomalous 2D features are detected on each radar profile and reconstructed into a 3D accumulator; then, probable 3D events are detected from the accumulator and tracked at subsequent locations based on the information from multiple sets of radar data. The detection results can be used to generate alarms or be sent to human operators for interactive interpretation. The proposed method was evaluated using two sets of GPR data captured in a designed test field. Experimental results show that the buried targets can be correctly detected by the proposed event detection and tracking method. The proposed method is sufficiently flexible to cope with variations on the spatial configuration of on-board sensors
Flight of the Bumblebee: the Early Excess Flux of Type Ia Supernova 2023bee revealed by , and Young Supernova Experiment Observations
We present high-cadence ultraviolet through near-infrared observations of the
Type Ia supernova (SN Ia) 2023bee in NGC~2708 ( Mpc), finding
excess flux in the first days after explosion relative to the expected
power-law rise from an expanding fireball. This deviation from typical behavior
for SNe Ia is particularly obvious in our 10-minute cadence light curve
and UV data. Compared to a few other normal SNe Ia with detected early
excess flux, the excess flux in SN 2023bee is redder in the UV and less
luminous. We present optical spectra of SN 2023bee, including two spectra
during the period where the flux excess is dominant. At this time, the spectra
are similar to those of other SNe Ia but with weaker Si II, C II and Ca II
absorption lines, perhaps because the excess flux creates a stronger continuum.
We compare the data to several theoretical models that have been proposed to
explain the early flux excess in SNe Ia. Interaction with either a nearby
companion star or close-in circumstellar material is expected to produce a
faster evolution than seen in the data. Radioactive material in the outer
layers of the ejecta, either from a double detonation explosion or simply an
explosion with a Ni clump near the surface, can not fully reproduce the
evolution either, likely due to the sensitivity of early UV observable to the
treatment of the outer part of ejecta in simulation. We conclude that no
current model can adequately explain the full set of observations. We find that
a relatively large fraction of nearby, bright SNe Ia with high-cadence
observations have some amount of excess flux within a few days of explosion.
Considering potential asymmetric emission, the physical cause of this excess
flux may be ubiquitous in normal SNe Ia.Comment: 21 pages, 12 figures. Accepted by the astrophysical journa
GUCY2C Opposes Systemic Genotoxic Tumorigenesis by Regulating AKT-Dependent Intestinal Barrier Integrity
The barrier separating mucosal and systemic compartments comprises epithelial cells, annealed by tight junctions, limiting permeability. GUCY2C recently emerged as an intestinal tumor suppressor coordinating AKT1-dependent crypt-villus homeostasis. Here, the contribution of GUCY2C to barrier integrity opposing colitis and systemic tumorigenesis is defined. Mice deficient in GUCY2C (Gucy2c−/−) exhibited barrier hyperpermeability associated with reduced junctional proteins. Conversely, activation of GUCY2C in mice reduced barrier permeability associated with increased junctional proteins. Further, silencing GUCY2C exacerbated, while activation reduced, chemical barrier disruption and colitis. Moreover, eliminating GUCY2C amplified, while activation reduced, systemic oxidative DNA damage. This genotoxicity was associated with increased spontaneous and carcinogen-induced systemic tumorigenesis in Gucy2c−/− mice. GUCY2C regulated barrier integrity by repressing AKT1, associated with increased junction proteins occludin and claudin 4 in mice and Caco2 cells in vitro. Thus, GUCY2C defends the intestinal barrier, opposing colitis and systemic genotoxicity and tumorigenesis. The therapeutic potential of this observation is underscored by the emerging clinical development of oral GUCY2C ligands, which can be used for chemoprophylaxis in inflammatory bowel disease and cancer
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