584 research outputs found
Topographic and Base-level Control on Back-Barrier Lagoon Evolution: West Galveston Bay, TX
Estuaries are economically and ecologically significant regions that are highly sensitive to external forcing from sea-level rise, storm events, and anthropogenic change. West Galveston Bay (West Bay) is a back-barrier lagoon system located immediately landward of Galveston Island, Texas, and it represents a sub-system of the larger Galveston estuary complex in the Northern Gulf of Mexico (NGOM). Previous studies have documented the evolution of many large estuaries along the NGOM in response to Holocene sea-level rise. However, the prehistory of smaller estuaries like West Bay remain largely overlooked and poorly understood. The primary purpose of this study is to complete a paleoenvironmental reconstruction of West Bay in Texas using geophysical and sedimentological approaches. A total of 30 core samples and more than 160 km of CHIRP seismic data were collected from West Bay and neighboring Chocolate Bay, within which several unique lithofacies and seismic facies were identified. As with other regional studies, the Pleistocene unconformity presents as an impedance change in the seismic profiles, and is most likely the Beaumont Formation. Multiple incised channels were observed on the Pleistocene Unconformity that are most likely seaward extensions of the tributaries that flow into Chocolate Bay, and formed the basal surface of the accommodation available for Holocene infill.
Radiocarbon dating of salient lithologic and seismic transitions in a few key cores revealed that several flooding events related to Holocene sea-level rise caused the landward back-stepping and geographic reorganization of depositional environments within West Bay. The first flooding event occurred at ~7,600 Cal. yr. BP caused both fluvial-dominated sedimentation to cease and initiation of estuarine conditions. The next flooding event occurred at ~6,800 Cal. yr. BP tripled the spatially inundated area and created ideal brackish conditions for oyster reef proliferation. This was short lived, however, as reduced salinity and increased turbidity from the paleo-Brazos River that was flowing into the area between ~6,100 and ~4,400 Cal. yr. BP ceased oyster reef production. The final flooding event occurred at ~4,400 Cal. yr. BP, which possibly established the connection between Galveston Bay and West Bay. At this time, an ephemeral tidal inlet formed within the incised channels, and then migrated west until stabilizing in the paleo-Brazos River incised valley as the modern day San Luis Pass.
This study reveals how the antecedent topography and sea-level rise controlled the environmental changes within West Bay throughout the Holocene. It also provides insight into how a small coastal system responds to varying rates of sea-level rise. Additionally, it may be useful as a baseline for West Bay for predicting future flooding associated with accelerating rates of sea-level rise
Equine meniscal degeneration is associated with medial femorotibial osteoarthritis
Background: There is limited information available concerning normal equine meniscal morphology, its degeneration and role in osteoarthritis (OA).
Objectives: To characterise normal equine meniscal morphology and lesions and to explore the relationship between equine meniscal degeneration and femorotibial OA.
Study design: Ex vivo cadaveric study.
Methods: Menisci were harvested from 7 normal joints (n = 14 menisci) and 15 joints with OA (n = 30 menisci). A macroscopic femorotibial OA score (cartilage degeneration and osteophytosis) was employed to measure disease severity in each compartment. The femoral and tibial meniscal surfaces were scored for macroscopic fibrillation and tears (1–4). Histological sections (regions: cranial and caudal horn; body) were also scored for microscopic fibrillation and tears (0–3) and inner border degeneration (0–3).
Results: Partial meniscal tears were present on both femoral and tibial surfaces in all 3 regions and most frequently identified on the femoral surface of the cranial horn of the medial meniscus and body of the lateral meniscus. There was a significantly positive correlation between the global medial meniscal macroscopic scores and osteophyte (r = 0.7, P = 0.002) or cartilage degeneration (r = 0.5, P = 0.03) scores within the medial femorotibial joint. The global medial meniscal macroscopic score was greater (P = 0.004) in the advanced OA joints compared with control joints.
Main limitations: The menisci were principally from abattoir specimens without a known clinical history because of the challenge in obtaining a large number of specimens with a clinical diagnosis of femorotibial OA.
Conclusions: This study is the first to describe normal equine meniscal morphology and lesions. Meniscal lesions were identified in all segments and on both articular surfaces. Meniscal degeneration significantly correlated with OA severity in the equine medial femorotibial joint. The relationship between OA and meniscal pathology remains to be elucidated
Use of tobacco and e-cigarettes among youth in Great Britain in 2022: analysis of a cross sectional survey
Introduction: Although e-cigarettes can be an effective form of nicotine substitution for adults attempting to quit smoking, their use among children and young people is a concern. Accurate data about this are needed to inform debates over policy and regulation in the UK and elsewhere. Methods: Using data from an online survey of 2613 youth aged 11–18 years, conducted by the market research company YouGov in March 2022, we present prevalence estimates of e-cigarette and tobacco use. We use logistic regression models to assess differences in e-cigarette use, tobacco use and use of disposable e-cigarettes across a range of covariates including age, sex, tobacco smoking status, social class, and country. Results: Among the 18.0% of those surveyed who reported ever having smoked a cigarette, 83.9% were not regular (at least once per week) smokers and 16.1% were (15.1% and 2.9% of the total sample, respectively). Among the 19.2% of those surveyed who had ever used an e-cigarette, 79.2% were not regular users, while 20.8% were (15.2% and 4.0% of the total sample, respectively). Regular e-cigarette use was more common than regular tobacco smoking (4.0% vs 2.9%). E-cigarette use was more common among those who also smoked tobacco, with 9.0% of never e-cigarette users ever smoking tobacco, compared with 89.4% of regular e-cigarette users. Both smoking and e-cigarette use were associated with increasing age and use by others within the home, but not with social class. Use of disposable e-cigarettes was reported by 53.8% of those who have ever used an e-cigarette, and more common among females than males. Conclusions: Regular e-cigarette use is now more common than smoking in children and youth, though the majority of this is among those who have also smoked tobacco. Measures to reduce the appeal of both e-cigarettes and tobacco to children and young people are warranted
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Exploring flexible polynomial regression as a method to align routine clinical outcomes with daily data capture through remote technologies
Data Availability:
The data that support the findings of this study are available from Great Ormond Street Hospital, but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of Great Ormond Street Hospital.Copyright © The Author(s) 2023. Background: Clinical outcomes are normally captured less frequently than data from remote technologies, leaving a disparity in volumes of data from these different sources. To align these data, flexible polynomial regression was investigated to estimate personalised trends for a continuous outcome over time. Methods: Using electronic health records, flexible polynomial regression models inclusive of a 1st up to a 4th order were calculated to predict forced expiratory volume in 1 s (FEV1) over time in children with cystic fibrosis. The model with the lowest AIC for each individual was selected as the best fit. The optimal parameters for using flexible polynomials were investigated by comparing the measured FEV1 values to the values given by the individualised polynomial. Results: There were 8,549 FEV1 measurements from 267 individuals. For individuals with > 15 measurements (n = 178), the polynomial predictions worked well; however, with < 15 measurements (n = 89), the polynomial models were conditional on the number of measurements and time between measurements. The method was validated using BMI in the same population of children. Conclusion: Flexible polynomials can be used to extrapolate clinical outcome measures at frequent time intervals to align with daily data captured through remote technologies.UCL, GOSH and Toronto SickKids studentship. GD is supported by a Future Leaders Fellowship from UK Research & Innovation (UKRI), Grant reference: MR/T041285. All research at Great Ormond Street Hospital NHS Foundation Trust and UCL Great Ormond Street Institute of Child Health is made possible by the NIHR Great Ormond Street Hospital Biomedical Research Centre
Evaluating an extended rehabilitation service for stroke patients (EXTRAS): Study protocol for a randomised controlled trial
Background: Development of longer term stroke rehabilitation services is limited by lack of evidence of effectiveness for specific interventions and service models. We describe the protocol for a multicentre randomised controlled trial which is evaluating an extended stroke rehabilitation service. The extended service commences when routine 'organised stroke care' (stroke unit and early supported discharge (ESD)) ends. Methods/design: This study is a multicentre randomised controlled trial with health economic and process evaluations. It is set within NHS stroke services which provide ESD. Participants are adults who have experienced a new stroke (and carer if appropriate), discharged from hospital under the care of an ESD team. Discussion: The provision of longer term support for stroke survivors is currently limited. The results from this trial will inform future stroke service planning and configuration. Trial registration: This trial was registered with ISRCTN (identifier: ISRCTN45203373) on 9 August 2012
Radiative Electroweak Symmetry Breaking in a Little Higgs Model
We present a new Little Higgs model, motivated by the deconstruction of a
five-dimensional gauge-Higgs model. The approximate global symmetry is
, breaking to , with a gauged subgroup of
, breaking to . Radiative corrections produce an additional small vacuum misalignment,
breaking the electroweak symmetry down to . Novel features of this
model are: the only un-eaten pseudo-Goldstone boson in the effective theory is
the Higgs boson; the model contains a custodial symmetry, which ensures that
at tree-level; and the potential for the Higgs boson is generated
entirely through one-loop radiative corrections. A small negative mass-squared
in the Higgs potential is obtained by a cancellation between the contribution
of two heavy partners of the top quark, which is readily achieved over much of
the parameter space. We can then obtain both a vacuum expectation value of
GeV and a light Higgs boson mass, which is strongly correlated with the
masses of the two heavy top quark partners. For a scale of the global symmetry
breaking of TeV and using a single cutoff for the fermion loops, the
Higgs boson mass satisfies 120 GeV GeV over much of
the range of parameter space. For raised to 10 TeV, these values increase
by about 40 GeV. Effects at the ultraviolet cutoff scale may also raise the
predicted values of the Higgs boson mass, but the model still favors
GeV.Comment: 32 pages, 10 figures, JHEP style. Version accepted for publication in
JHEP. Includes additional discussion of sensitivity to UV effects and
fine-tuning, revised Fig. 9, added appendix and additional references
Characterizing College Science Assessments: The Three-Dimensional Learning Assessment Protocol
Citation: Laverty, J. T., Underwood, S. M., Matz, R. L., Posey, L. A., Carmel, J. H., Caballero, M. D., . . . Cooper, M. M. (2016). Characterizing College Science Assessments: The Three-Dimensional Learning Assessment Protocol. Plos One, 11(9), 21. doi:10.1371/journal.pone.0162333Many calls to improve science education in college and university settings have focused on improving instructor pedagogy. Meanwhile, science education at the K-12 level is undergoing significant changes as a result of the emphasis on scientific and engineering practices, crosscutting concepts, and disciplinary core ideas. This framework of "three-dimensional learning" is based on the literature about how people learn science and how we can help students put their knowledge to use. Recently, similar changes are underway in higher education by incorporating three-dimensional learning into college science courses. As these transformations move forward, it will become important to assess three-dimensional learning both to align assessments with the learning environment, and to assess the extent of the transformations. In this paper we introduce the Three-Dimensional Learning Assessment Protocol (3D-LAP), which is designed to characterize and support the development of assessment tasks in biology, chemistry, and physics that align with transformation efforts. We describe the development process used by our interdisciplinary team, discuss the validity and reliability of the protocol, and provide evidence that the protocol can distinguish between assessments that have the potential to elicit evidence of three-dimensional learning and those that do not
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