581 research outputs found
Taxonomic and paleoclimatic significance of Late Cretaceous wood from the San Juan Basin, New Mexico.
Fossil wood has been demonstrated to be a powerful tool for studying past environments and biotas. Anatomical structure of silicified woods from Late Cretaceous sediments in northwestern New Mexico was used to conduct a taxonomic survey of plants with secondary growth and tree stature, as well as estimate paleoclimate. A total of 50 specimens compromising both gymnospermous and angiospermous remains were surveyed from deposits within the upper Fruitland and lower Kirtland formations of the San Juan Basin. Anatomical characters were used to designate distinct xylotypes, which were then linked to modern orders or families. Paleoclimate was estimated using three quantitative methods: the Mean Sensitivity statistic (MS), the Vulnerability Index (VI), and regression equations that link eudicot/magnoliid wood to mean annual temperature (MAT). The taxonomic results indicate an abundant but low diversity coniferous flora and less abundant by higher diversity angiosperm flora with xylotypes that have potential links to eight modern orders. These orders ranged from ancestral to derived within the angiosperm phylogeny, and two of the xylotpes represented new records of taxa. The paleoclimate results confirmed a warm, wet environment for the Late Cretaceous. VI values were comparable to modern day tropical trees, implying that water was not a limited resource in the floodplain. The regression equations generated an average MAT of 23.13 Ā± 5.22oC, a value statistically similar to MAT calculated by leaf physiognomy at 26.8 Ā± 2.24oC (Ī± = 0.05, p \u3c 0.001). Growth ring sequences analyzed by MS produced an average value of 0.47 Ā± 0.09, indicating that some of the trees experienced irregular growth. Due to the warm MAT and high VI values, the irregular growth recorded in the conifer wood was probably the result of environmental disturbances, such as flooding or volcanic events, capable of disrupting wood production. This study is the first comprehensive examination of wood from the Late Cretaceous San Juan Basin, and enhances our knowledge of the paleoecology of the region
Larva and pupa of Cernotina spicata
The first positively associated larva and pupa of Cernotina are described. Tentative diagnoses are provided for distinguishing them from those of other genera of Nearctic Polycentropodidae, especially Polycentropus s. lat., which Cernotina most strongly resembles
Caddisflies (Insecta: Trichoptera) of Fringing Wetlands of the Laurentian Great Lakes
Fringing wetlands of the Laurentian Great Lakes are subject to natural processes, such as water-level fluctuation and wave-induced erosion, and to human alterations. In order to evaluate the quality of these wetlands over space and time, biological communities are often examined. Ideally, the groups of organisms selected for these evaluations should be resident in the wetlands themselves. Fish are often sampled, but many species are not truly resident, visiting wetlands on an occasional basis to feed or on a seasonal basis to breed. Aquatic vascular plants are perhaps the most common group selected for evaluation. However, in some cases, aquatic plants give a false impression by providing photosynthetic capabilities and structural infrastructure but having greatly diminished herbivore and carnivore communities
Care Coordination as Part of the Discharge Plan to Support Community Reintegration of Individuals with Stroke Living in Appalachian Rural Communities
Studies indicate a high incidence of readmission within the first 12 months post-discharge home following stroke. In addition, there is a limited awareness of healthcare services, community resources, and lack of access to information in rural communities. Previous work from our group has demonstrated the need for community-based navigational support during community reintegration for survivors of stroke. The purpose of this study was to determine the effectiveness of providing community health navigation to facilitate continued communications with healthcare providers and linkages to services and community resources for survivors of stroke in Appalachian rural communities
The RoboCOS Study : Development of an international core outcome set for the comprehensive evaluation of patient, surgeon, organisational and population level impacts of robotic assisted surgery
ACKNOWLEDGEMENTS We would like to thank sincerely all those who contributed to the interviews, the focus group, the Delphi survey and the consensus meeting, and Paul Manson (Health Services Research Unit, University of Aberdeen) for helping to retrieve full text copies of reports identified by the literature search. We also thank HSRU (Health Services Research Unit) at University of Aberdeen for providing support for this work. Funding: The study was funded from NHS Grampian Endowment Fund and the University of Aberdeen. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Copyright: Ā© 2023 Robertson et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Peer reviewedPublisher PD
Hydrologic Variability and the Application of Index of Biotic Integrity Metrics to Wetlands: A Great Lakes Evaluation
Interest by land-management and regulatory agencies in using biological indicators to detect wetland degradation, coupled with ongoing use of this approach to assess water quality in streams, led to the desire to develop and evaluate an Index of Biotic Integrity (IBI) for wetlands that could be used to categorize the level of degradation. We undertook this challenge with data from coastal wetlands of the Great Lakes, which have been degraded by a variety of human disturbances. We studied six barrier beach wetlands in western Lake Superior, six drowned-river-mouth wetlands along the eastern shore of Lake Michigan, and six open shoreline wetlands in Saginaw Bay of Lake Huron. Plant, fish, and invertebrate communities were sampled in each wetland. The resulting data were assessed in various forms against gradients of human disturbance to identify potential metrics that could be used in IBI development. Our results suggested that the metrics proposed as potential components of an IBI for barrier beach wetlands of Lake Superior held promise. The metrics for Lake Michigan drowned-river-mouth wetlands were inconsistent in identifying gradients of disturbance; those for Lake Huron open embayment wetlands were yet more inconsistent. Despite the potential displayed by the Lake Superior results within the year sampled, we concluded that an IBI for use in Great Lakes wetlands would not be valid unless separate scoring ranges were derived for each of several sequences of water-level histories. Variability in lake levels from year to year can produce variability in data and affect the reproducibility of data collected, primarily due to extreme changes in plant communities and the faunal habitat they provide. Substantially different results could be obtained in the same wetland in different years as a result of the response to lake-level change, with no change in the level of human disturbance. Additional problems included limited numbers of comparable sites, potential lack of undisturbed reference sites, and variable effects of different disturbance types. We also evaluated our conclusions with respect to hydrologic variability and other major natural disturbances affecting wetlands in other regions. We concluded that after segregation of wetland types by geographic, geomorphic, and hydrologic features, a functional IBI may be possible for wetlands with relatively stable hydrology. However, an IBI for wetlands with unpredictable yet recurring influences of climate-induced, long-term high water periods, droughts, or drought-related fires or weather-related catastrophic floods or high winds (hurricanes) would also require differing scales of measurement for years that differ in the length of time since the last major natural disturbance. A site-specific, detailed ecological analysis of biological indicators may indeed be of value in determining the quality or status of wetlands, but we recommend that IBI scores not be used unless the scoring ranges are calibrated for the specific hydrologic history pre-dating any sampling year
CFHTLenS: Weak lensing constraints on the ellipticity of galaxy-scale matter haloes and the galaxy-halo misalignment
We present weak lensing constraints on the ellipticity of galaxy-scale matter
haloes and the galaxy-halo misalignment. Using data from the
Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), we measure the
weighted-average ratio of the aligned projected ellipticity components of
galaxy matter haloes and their embedded galaxies, , split by
galaxy type. We then compare our observations to measurements taken from the
Millennium Simulation, assuming different models of galaxy-halo misalignment.
Using the Millennium Simulation we verify that the statistical estimator used
removes contamination from cosmic shear. We also detect an additional signal in
the simulation, which we interpret as the impact of intrinsic shape-shear
alignments between the lenses and their large-scale structure environment.
These alignments are likely to have caused some of the previous observational
constraints on to be biased high. From CFHTLenS we find
for early-type galaxies, which is consistent with
current models for the galaxy-halo misalignment predicting . For late-type galaxies we measure
from CFHTLenS. This can be compared to the simulated results which yield
for misaligned late-type models.Comment: 21 pages, 3 tables, 9 figures. This replacement matches the version
accepted for publication in MNRA
Graphene Oxide Reduces the Hydrolytic Degradation in Polyamide-11
Graphene oxide (GO) was incorporated into polyamide-11 (PA11) via in-situ polymerization. The GO-PA11 nano-composite had elevated resistance to hydrolytic degradation. At a loading of 1 mg/g, GO to PA11, the accelerated aging equilibrium molecular weight of GO-PA11 was higher (33 and 34 kg/mol at 100 and 120 C, respectively) compared to neat PA11 (23 and 24 kg/mol at 100 and 120 C, respectively). Neat PA11 had hydrolysis rate constants (kH) of 2.8 and 12 ( 10(exp -2) day(exp -1)) when aged at 100 and 120 C, respectively, and re-polymerization rate constants (kP) of 5.0 and 23 ( 10(exp -5) day(exp -1)), respectively. The higher equilibrium molecular weight for GO-PA11 loaded at 1 mg/g was the result of a decreased kH, 1.8 and 4.5 ( 10(exp -2) day(exp -1)), and an increased kP, 10 and 17 ( 10(exp -5) day(exp -1)) compared with neat PA11 at 100 and 120 C, respectively. The decreased rate of degradation and resulting 40% increased equilibrium molecular weight of GO-PA11 was attributed to the highly asymmetric planar GO nano-sheets that inhibited the molecular mobility of water and the polymer chain. The crystallinity of the polymer matrix was similarly affected by a reduction in chain mobility during annealing due to the GO nanoparticles' chemistry and highly asymmetric nano-planar sheet structure
A soft selective sweep during rapid evolution of gentle behaviour in an Africanized honeybee
Africanized honey bees (AHB) are notoriously aggressive, but in Puerto Rico they have a āgentleā phenotype. Here, Avalos et al. show that there has been a soft selective sweep at several loci in the Puerto Rican AHB population and suggest a role in the rapid evolution of gentle behaviour
- ā¦