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61 results on '"Levi G."'

1. The Impact of Rotation on Tropical Climate, the Hydrologic Cycle, and Climate Sensitivity

Author

Levi G. Silvers, Alyssa M. Stansfield, and Kevin A. Reed

Subjects
tropical convection, idealized modeling, radiative convective equilibrium, hydrologic cycle, climate sensitivity, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract This work explores the impact of rotation on tropical convection and climate. As our starting point, we use the RCEMIP experiments as control simulations and run additional simulations with rotation. Compared to radiative convective equilibrium (RCE) experiments, rotating RCE (RRCE) experiments have a more stable and humid atmosphere with higher precipitation rates. The intensity of the overturning circulation decreases, water vapor is cycled through the troposphere at a slower rate, the subsidence fraction decreases, and the climate sensitivity increases. Several of these changes can be attributed to an increased flux of latent and sensible heat that results from an increase of near‐surface wind speed with rotation shortly after model initialization. The increased climate sensitivity results from changes of both the longwave cloud radiative effect and the longwave clear‐sky radiative fluxes. This work demonstrates the sensitivity of atmospheric humidity and surface fluxes of moisture and temperature to rotation.

Published
2024
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6. Clouds and Sensitivities Across a Hierarchy of GFDL CMIP6 Models

Author

David Paynter, Levi G. Silvers, and Ming Zhao

Subjects
Hierarchy, Radiative flux, Climatology, Radiative transfer, Environmental science, Global change, Climate model, Context (language use), Sensitivity (control systems), Atmospheric model
Abstract

The newest atmospheric climate model at GFDL, AM4, succeeded at significantly reducing the toa radiative flux biases as compared to CERES observations. Despite a relatively low top-of-atmosphere sensitivity to uniform warming of SSTs (Cess warming experiments), the corresponding coupled climate model, CM4, has high transient and equilibrium climate sensitivities. We will present a systematic picture of the modeled clouds across a hierarchy of model configurations which utilize this atmospheric model. This hierarchy includes the CFMIP Aquaplanet and AMIP experiments, fully coupled model experiments (using GFDL’s CM4 model) as well as additional AMIP-like experiments with particular SST patterns. This demonstrates the large range of sensitivities that are possible from a single atmospheric climate model. Looking at the global mean radiative feedbacks across the different model configurations as well as in the context of CMIP5 and CMIP6 models will allow us to assess to what extent the cloud feedbacks in the...

Published
2020

8. Obesity and perioperative complications in head and neck free tissue reconstruction

Author

Aru Panwar, Jeffrey B. Jorgensen, Katelyn Kaiser, W. Chad Spanos, Yelizaveta Shnayder, Colin A. Neumann, Nitin A. Pagedar, Collin Kitzerow, Samir S. Khariwala, Gabriel de la Garza, Oleg Militsakh, Tabitha L.I. Galloway, and Levi G. Ledgerwood

Subjects
medicine.medical_specialty, business.industry, Retrospective cohort study, Odds ratio, Perioperative, Free flap, medicine.disease, Logistic regression, Comorbidity, Obesity, Surgery, 03 medical and health sciences, 0302 clinical medicine, Otorhinolaryngology, 030220 oncology & carcinogenesis, Medicine, 030223 otorhinolaryngology, business, Body mass index
Abstract

Background Free tissue transfer is a mainstay in reconstruction of complex head and neck defects. The purpose of this study was to determine if perioperative complications were more common in patients with body mass index (BMI) >30 kg/m2 undergoing free flap reconstruction. Methods A multi-institutional retrospective cohort was created. Medical complications, surgical complications, and procedural variables were recorded. Logistic regression was used to investigate univariate and multivariate associations between outcomes and predictors. Results Of 582 cases, 128 patients (22%) had BMI >30. Surgical complications occurred in 153 cases (26.3%), with an adjusted odds ratio (OR) for association of surgical complications with BMI >30 of 0.92 (p = .71). Medical complications occurred in 178 cases (30.6%), with an adjusted OR of 0.78 (p = .26). Age and advanced comorbidity status (Adult Comorbidity Evaluation-27 [ACE-27] 2 or 3) were associated with medical complications (p 30 does not predict medical or surgical complications in patients undergoing head and neck free flap surgery. © 2015 Wiley Periodicals, Inc. Head Neck, 2015

Published
2015

9. Identifying scapholunate ligamentous injury

Author

Walter H. Short, Paula F. Rosenbaum, Levi G. Sutton, Frederick W. Werner, and Haoyu Wang

Subjects
business.industry, Motion simulator, Anatomy, Kinematics, Scapholunate ligament, Wrist, musculoskeletal system, Watson's test, Lunate, medicine.anatomical_structure, Cadaver, Ligament, Medicine, Orthopedics and Sports Medicine, business
Abstract

The first purpose of this study was to develop a noninvasive clinical tool that could predict whether the scapholunate interosseous ligament and other secondary stabilizing ligaments are injured in the presence of suspected scapholunate instability. The second purpose of this study was to determine which of those ligaments or ligament groups have been injured. Kinematic and three-dimensional (3D) meaurements from 62 cadaver wrists moved in a wrist joint motion simulator were used to develop various neural network predictive models. One group of models was based on angular changes in scaphoid and lunate motion before and after ligament sectioning (representing scapholunate instability). A second group of models was based on changes in the minimum distance between the scaphoid and lunate as well as other 3D gap measurements. The models, based on the scaphoid and lunate angular data, could predict with a 93% accuracy rate whether the wrist ligaments were intact. These models could also predict whether it was the dorsal ligaments or the volar ligaments that were sectioned 84% of the time. The models worked best using data with the wrist in 10 to 30 degrees of wrist flexion. The viability of a CT-based predictive model has been demonstrated by obtaining high prediction rates, sensitivity, specificity, and kappa statistic values.

Published
2008

10. CCR7 Expression Predicts Cervical Metastasis in Oral Squamous Cell Carcinoma

Author

D. Gregory Farwell, Levi G. Ledgerwood, Steven P. Tinling, and Regina F Gandour-Edwards

Subjects
Oncology, medicine.medical_specialty, Pathology, business.industry, C-C chemokine receptor type 7, medicine.disease, Primary tumor, Koilocyte, Staining, Chemokine receptor, medicine.anatomical_structure, Otorhinolaryngology, Internal medicine, medicine, Immunohistochemistry, Surgery, Lymph, business, Lymph node
Abstract

Objective: 1) Determine whether expression of the chemokine receptor CCR7 is associated with an increased likelihood of cervical lymph node metastasis in oral squamous cell carcinoma. 2) Explore the significance of CCR7 expression in the localization of squamous cell carcinoma cells within the primary tumor and metastatic lymph nodes.Method: Tissue samples from primary tumors and cervical metastases of patients with oral squamous cell carcinoma were compared for their expression of CCR7 through immunohistochemistry. CCR7 expression was assessed in 30 primary tumor samples from patients without cervical metastases and compared to 30 samples from patients with metastases.Results: CCR7 expression was found to be significantly higher in squamous cell carcinoma samples from patients with cervical lymph node metastases. Primary tumors of patients with cervical metastases showed significantly higher CCR7 staining, χ2 = 16.936, P < .001. N0 patients showed small foci of CCR7 positivity while tumors from N+ patien...

Published
2012

11. Obesity and perioperative complications in head and neck free tissue reconstruction

Author

de la Garza, Gabriel, primary, Militsakh, Oleg, additional, Panwar, Aru, additional, Galloway, Tabitha L., additional, Jorgensen, Jeffrey B., additional, Ledgerwood, Levi G., additional, Kaiser, Katelyn, additional, Kitzerow, Collin, additional, Shnayder, Yelizaveta, additional, Neumann, Colin A., additional, Khariwala, Samir S., additional, Chad Spanos, W., additional, and Pagedar, Nitin A., additional

Published
2015
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26. Medical students' contribution to the development of a smoke-free hospital policy in a university medical centre: a relevant learning experience

Author

Sperber, A D, primary, Geftler, A, additional, Goren, M, additional, Cohen, H, additional, Levi, G, additional, Raz, I, additional, Mor, Z, additional, Yachelevich, N, additional, Malik, T, additional, Shubin, A, additional, Kachel, E, additional, Perl, S, additional, Steinberg, A, additional, Sarov, B, additional, and Bearman, J, additional

Published
1995
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