bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precipitation Bragg Scatter in Radar Observations at Nadir
Authors: Jameson A. R. 
Published: April 2011

AbstractAs precipitation sediments and interacts with turbulence, spatial structures appear as the familiar “streamers” of precipitation sweeping across the road during a thunderstorm or like those so obvious in snow that is backlit. Some of these are at scales that resonate with the radar wavelength, and as a consequence they produce coherent backscatter (precipitation Bragg scatter). Recently, and in contrast to incoherent scattering, it was found that the power-normalized cross-correlation functions of backscattered complex amplitudes in neighboring range bins ρ12 averaged over time exist. Moreover, they are identical to the fractional contributions made by radar coherent backscatter in the radial direction to the total backscattered power in rain and snow. This coherent power can significantly affect some radar techniques for measuring precipitation intensity because it depends upon the square of the particle concentrations rather than the linear dependence in the case of incoherent backscatter. All of these observations were made by radars looking tangentially to the ground, however. Yet for many purposes, including the global measurements of precipitation from space, radar observations in precipitation are at or near nadir to the surface of the earth. A natural question, then, is: Can coherent backscattered power be found in observations in precipitation at nadir as well? Here, radar observations collected at nadir in a convective shower and snow are analyzed. It is found that ρ12 and, hence, precipitation Bragg scatter exist in these nadir observations. Moreover, the intensity of the Bragg scatter is independent of the size of sample volume. Reasons for these findings and some implications are discussed.
Wind-Driven Mixing below the Oceanic Mixed Layer
Authors: Grant Alan L. M. , Belcher Stephen E. 
Published: April 2011

AbstractThis study describes the turbulent processes in the upper ocean boundary layer forced by a constant surface stress in the absence of the Coriolis force using large-eddy simulation. The boundary layer that develops has a two-layer structure, a well-mixed layer above a stratified shear layer. The depth of the mixed layer is approximately constant, whereas the depth of the shear layer increases with time. The turbulent momentum flux varies approximately linearly from the surface to the base of the shear layer.There is a maximum in the production of turbulence through shear at the base of the mixed layer. The magnitude of the shear production increases with time. The increase is mainly a result of the increase in the turbulent momentum flux at the base of the mixed layer due to the increase in the depth of the boundary layer. The length scale for the shear turbulence is the boundary layer depth. A simple scaling is proposed for the magnitude of the shear production that depends on the surface forcing and the average mixed layer current. The scaling can be interpreted in terms of the divergence of a mean kinetic energy flux.A simple bulk model of the boundary layer is developed to obtain equations describing the variation of the mixed layer and boundary layer depths with time. The model shows that the rate at which the boundary layer deepens does not depend on the stratification of the thermocline. The bulk model shows that the variation in the mixed layer depth is small as long as the surface buoyancy flux is small.
Baroclinic Turbulence in the Ocean: Analysis with Primitive Equation and Quasigeostrophic Simulations
Authors: Venaille Antoine , Vallis Geoffrey K. , Smith K. Shafer 
Published: April 2011

Abstract
This paper examines the factors determining the distribution, length scale, magnitude, and structure of mesoscale oceanic eddies in an eddy-resolving primitive equation simulation of the Southern Ocean [Modeling Eddies in the Southern Ocean (MESO)]. In particular, the authors investigate the hypothesis that the primary source of mesoscale eddies is baroclinic instability acting locally on the mean state. Using local mean vertical profiles of shear and stratification from an eddying primitive equation simulation, the forced–dissipated quasigeostrophic equations are integrated in a doubly periodic domain at various locations. The scales, energy levels, and structure of the eddies found in the MESO simulation are compared to those predicted by linear stability analysis, as well as to the eddying structure of the quasigeostrophic simulations. This allows the authors to quantitatively estimate the role of local nonlinear effects and cascade phenomena in the generation of the eddy field.
There is a modest transfer of energy (an “inverse cascade”) to larger scales in the horizontal, with the length scale of the resulting eddies typically comparable to or somewhat larger than the wavelength of the most unstable mode. The eddies are, however, manifestly nonlinear, and in many locations the turbulence is fairly well developed. Coherent structures also ubiquitously emerge during the nonlinear evolution of the eddy field. There is a near-universal tendency toward the production of grave vertical scales, with the barotropic and first baroclinic modes dominating almost everywhere, but there is a degree of surface intensification that is not captured by these modes. Although the results from the local quasigeostrophic model compare well with those of the primitive equation model in many locations, some profiles do not equilibrate in the quasigeostrophic model. In many cases, bottom friction plays an important quantitative role in determining the final scale and magnitude of eddies in the quasigeostrophic simulations.
Conservative Transport Schemes for Spherical Geodesic Grids: High-Order Flux Operators for ODE-Based Time Integration
Authors: Skamarock William C. , Gassmann Almut 
Published: April 2011

Higher-order finite-volume flux operators for transport algorithms used within Runge–Kutta time integration schemes on irregular Voronoi (hexagonal) meshes are proposed and tested. These operators are generalizations of third- and fourth-order operators currently used in atmospheric models employing regular, orthogonal rectangular meshes. Two-dimensional least squares fit polynomials are used to evaluate the higher-order spatial derivatives needed to cancel the leading-order truncation error terms of the standard second-order centered formulation. Positive definite or monotonic behavior is achieved by applying an appropriate limiter during the final Runge–Kutta stage within a given time step. The third- and fourth-order formulations are evaluated using standard transport tests on the sphere. The new schemes are more accurate and significantly more efficient than the standard second-order scheme and other schemes in the literature examined by the authors. The third-order formulation is equivalent to the fourth-order formulation plus an additional diffusion term that is proportional to the Courant number. An optimal value for the coefficient scaling this diffusion term is chosen based on qualitative evaluation of the test results. Improvements using the higher-order scheme in place of the traditional second-order centered approach are illustrated within 3D unstable baroclinic wave simulations produced using two global nonhydrostatic models employing spherical Voronoi meshes.
The Characteristics of Numerically Simulated Supercell Storms Situated over Statically Stable Boundary Layers
Authors: Nowotarski Christopher J. , Markowski Paul M. , Richardson Yvette P. 
Published: April 2011

Abstract
This paper uses idealized numerical simulations to investigate the dynamical influences of stable boundary layers on the morphology of supercell thunderstorms, especially the development of low-level rotation. Simulations are initialized in a horizontally homogeneous environment with a surface-based stable layer similar to that found within a nocturnal boundary layer or a mesoscale cold pool. The depth and lapse rate of the imposed stable boundary layer, which together control the convective inhibition (CIN), are varied in a suite of experiments.
When compared with a control simulation having little surface-based CIN, each supercell simulated in an environment having a stable boundary layer develops weaker rotation, updrafts, and downdrafts at low levels; in general, low-level vertical vorticity and vertical velocity magnitude decrease as initial CIN increases (changes in CIN are due only to variations in the imposed stable boundary layer). Though the presence of a stable boundary layer decreases low-level updraft strength, all supercells except those initiated over the most stable boundary layers had at least some updraft parcels with near-surface origins. Furthermore, the existence of a stable boundary layer only prohibits downdraft parcels from reaching the lowest grid level in the most stable cases. Trajectory and circulation analyses indicate that weaker near-surface rotation in the stable-layer scenarios is a result of the decreased generation of circulation coupled with decreased convergence of the near-surface circulation by weaker low-level updrafts. These results may also suggest a reason why tornadogenesis is less likely to occur in so-called elevated supercell thunderstorms than in surface-based supercells.
Lightning and Severe Weather: A Comparison between Total and Cloud-to-Ground Lightning Trends
Authors: Schultz Christopher J. , Petersen Walter A. , Carey Lawrence D. 
Published: April 2011

Abstract
Many studies over the past several decades have attempted to correlate trends in lightning (e.g., rates, polarity) to severe weather occurrence. These studies mainly used cloud-to-ground (CG) lightning information due to the ease of data availability, high detection efficiency, and broad coverage across the United States, with somewhat inconclusive results. Conversely, it has been demonstrated that trends in total lightning are more robustly correlated to severe weather occurrence, with rapid increases in total lightning observed 10s of minutes prior to the onset of severe weather. Unfortunately, total lightning observations are not as numerous, or available over the same areal coverage domain, as provided by CG networks. Relatively few studies have examined concurrent trends in both total and CG lightning within the same severe thunderstorm, or even large sets of thunderstorms using an objective lightning jump algorithm. Multiple studies have shown that the total flash rate rapidly increases prior to the onset of severe weather. What is untested within the same framework is the use of CG information to perform the same task. Herein, total and CG lightning trends for 711 thunderstorms occurring in four regions of the country were examined to demonstrate the increased utility that total lightning provides over CG lightning, specifically within the framework of developing a useful lightning-based severe weather warning decision support tool. Results indicate that while both lightning datasets demonstrate the presence of increased lightning activity prior to the onset of severe weather, the use of total lightning trends was more effective than CG trends [probability of detection (POD), 79% versus 66%; false alarm rate (FAR), 36% versus 53%; critical success index (CSI), 55% versus 38%; Heidke skill score (HSS), 0.71 versus 0.55]. Moreover, 40% of false alarms associated with total lightning, and 16% of false alarms with CG lightning trends, occurred when a lightning jump associated with a severe weather “warning” was already in effect. If these false alarms are removed, the FAR drops from 36% to 22% for total lightning and from 53% to 44% for CG lightning. Importantly, average lead times prior to severe weather occurrence were higher using total lightning as compared with CG lightning (20.65 versus 13.54 min). The ultimate goal of this study was to demonstrate the increased utility of total lightning information that the Geostationary Lightning Mapper (GLM) will provide to operational meteorology in anticipation of severe convective weather on a hemispheric scale once Geostationary Operational Environmental Satellite-R (GOES-R) is deployed in the next decade.
The Real-Time Mesoscale Analysis at NOAA’s National Centers for Environmental Prediction: Current Status and Development
Authors: De Pondeca Manuel S. F. V. , Manikin Geoffrey S. , DiMego Geoff , Benjamin Stanley G. , Parrish David F. , Purser R. James , Wu Wan-Shu , Horel John D. , Myrick David T. , Lin Ying , Aune Robert M. , Keyser Dennis , Colman Brad , Mann Greg , Vavra Jamie 
Published: April 2011

Abstract
In 2006, the National Centers for Environmental Prediction (NCEP) implemented the Real-Time Mesoscale Analysis (RTMA) in collaboration with the Earth System Research Laboratory and the National Environmental, Satellite, and Data Information Service (NESDIS). In this work, a description of the RTMA applied to the 5-km resolution conterminous U.S. grid of the National Digital Forecast Database is given. Its two-dimensional variational data assimilation (2DVAR) component used to analyze near-surface observations is described in detail, and a brief discussion of the remapping of the NCEP stage II quantitative precipitation amount and NESDIS Geostationary Operational Environmental Satellite (GOES) sounder effective cloud amount to the 5-km grid is offered. Terrain-following background error covariances are used with the 2DVAR approach, which produces gridded fields of 2-m temperature, 2-m specific humidity, 2-m dewpoint, 10-m U and V wind components, and surface pressure. The estimate of the analysis uncertainty via the Lanczos method is briefly described. The strength of the 2DVAR is illustrated by (i) its ability to analyze a June 2007 cold temperature pool over the Washington, D.C., area; (ii) its fairly good analysis of a December 2008 mid-Atlantic region high-wind event that started from a very weak first guess; and (iii) its successful recovery of the finescale moisture features in a January 2010 case study over southern California. According to a cross-validation analysis for a 15-day period during November 2009, root-mean-square error improvements over the first guess range from 16% for wind speed to 45% for specific humidity.
Is a Single Miniplate at the Inferior Border Adequate in the Management of an Angle Fracture of the Mandible?
Authors: Singh Virendra , Gupta Manisha , Bhagol Amrish 
Published: April 2011

ObjectiveThis prospective study evaluates the efficacy of using a single miniplate at the inferior border in the management of a displaced angle fracture.Study DesignCase series with chart review.SettingPt. B.D. Sharma University of Health Sciences.Subjects and MethodsFifty‐two patients with angle fracture of the mandible were evaluated. All fractures were displaced. The displacement of fracture was assessed on panoramic radiography by measuring the displacement of the inferior alveolar canal. Fractures with displacement greater than 2 mm were included in the study. Fixation with a 4‐hole noncompression miniplate along the inferior border and 2 bicortical screws on each side of the fracture was done.ResultsAmong these 52 patients, 20 sustained isolated angle fracture, 2 sustained bilateral angle fracture, and 30 sustained angle fracture associated with contralateral parasymphysis or body fracture. Five patients (9.5%) experienced complications. All were considered minor and did not require hospitalization. Two had a slight occlusal discrepancy requiring selective occlusal grinding, and 2 minor infections were managed by incision and drainage. One patient suffered from paresis of the facial nerve that resolved itself after 3 months.ConclusionBased on this single study, at a single institution, we can conclude that outcomes are acceptable in our patients, but there is very limited ability to generalize the results to different practice settings. Because of these limitations, a multicenter study with an appropriate comparison group is required to substantiate a more generalizable conclusion of efficacy of this single miniplate at inferior border.
Transcervical Drainage for Descending Necrotizing Mediastinitis May Be Sufficient
Authors: Hsu Ruey‐Fen , Wu Pei‐Yin , Ho Chi‐Kung 
Published: April 2011

ObjectiveDescending necrotizing mediastinitis (DNM) is a serious form of mediastinitis with a high mortality rate. It is caused by the downward spread of an oropharyngeal or cervicofascial infection. The optimal surgical approach for this often fatal disease is controversial. This article describes the authors’ experience and characterizes the surgical strategies and treatment outcomes of patients with DNM.Study DesignCase series with chart review.SettingA tertiary referral medical center.Subjects and MethodsThis study conducted a retrospective chart review of patients with deep neck infections treated at a medical center from 1994 to 2007 and identified 29 patients with DNM. The clinical characteristics and outcomes were compared between patients treated with transcervical drainage alone (group I) and those with both cervical and thoracic drainage (group II).ResultsThere were 20 patients in group I and 9 patients in group II. The overall mortality rate was 10.3%. The mean duration of the hospital stay was 29.3 ± 15.5 days. There was no statistically significant difference in age, sex distribution, or duration from the appearance of symptoms to hospital admission between the 2 groups. The duration of hospital stay, tracheotomy rate, and mortality rate also did not differ significantly between the 2 groups. However, the numbers of surgeries were significantly higher in group II than in group I.ConclusionTransthoracic mediastinal drainage is not a compulsory therapy, but timely, aggressive, transcervical mediastinal drainage with extensive debridement is very important for a good outcome when treating DNM patients.
Resident Physicians’ Perspectives on Health Care Reform
Authors: Frake Paul C. , Cheng Alex Y. , Howell Rebecca J. , Patel Nitin J. 
Published: April 2011

ObjectiveTo investigate the perspectives of resident physicians, in otolaryngology and other specialties, with respect to various health care reform proposals. Also, to determine if these opinions vary between residents training to become general medical doctors versus surgeons and specialists and between those with various levels of educational debt.Study Design and ParticipantsSurvey of resident physicians across the United States.MethodsOpinions of participants were measured on a 5‐point Likert scale.ResultsOf the 1576 respondents, the majority agreed that tort reform and electronic medical records would improve quality of care and help contain health care costs. However, few residents agreed that bundling of services (BOS), hospital‐acquired conditions penalties (HACP), and quality‐based reimbursement (QBR) would improve the quality of care. Specialists and surgeons, in comparison to generalists, were (1) less likely to agree that BOS, HACP, or QBR would improve the quality of care; (2) more likely to agree that tort reform would help contain health care costs; and (3) more likely to believe that BOS, HACP, or QBR would decrease physician compensation. Higher educational debt burden was also an independent predictor of increased skepticism about health care reforms effects on physician compensation.ConclusionsResidents in general medicine and surgery/specialty training programs agreed that tort reform and electronic medical records would help improve the quality of health care and help contain costs. However, both groups expressed strong concern that certain elements of the Patient Protection and Affordable Care Act would not achieve these goals.
Curvature Inversion Technique
Authors: Yañez Carlos , Pirrón José Antonio , Mora Nallely 
Published: April 2011

ObjectiveTo assess the laser‐assisted curvature inversion technique for the treatment of patients with patulous Eustachian tube (PET).Study DesignCase series with planned data collection.SettingTertiary care medical center.Subjects and MethodsEleven patients with Eustachian tube dysfunction underwent laser‐assisted curvature inversion technique (CIT) of the medial and lateral lamina of the Eustachian tube. A KTP laser is used to cross‐hatch the medial and lateral lamina of the tube to modify the curvature and to alter the spring of the posterior cushion. A change in the direction of the cartilaginous structure curvature is created to promote full closure of the patulous gap without interfering with the tube’s muscular activity. None of the patients had any concurrent disease or additional surgical procedure.ResultsThere were no surgical complications. Following CIT, subjective symptoms of autophony on nasal breathing improved in 9 of 11 patients (81.8%), while voice autophony improved in 8 patients (72.7%); posterior cushion curvature became inverted and less wide, and the valve was seen more closed postoperatively on simple endoscopy and slow‐motion video‐endoscopic analysis. On otoscopy, abnormal tympanic membrane excursions disappeared in 10 of 11 patients (90.9%). Mean immittance changes in tympanometric measurements for the forced respiration conditions improved postoperatively at least 0.05 mmhos in 9 of 11 patients (81.1%; P =. 015). The follow‐up period was 24 months.ConclusionCIT appears to be a promising and relatively feasible technique for the treatment of PET.
A Multilayer Cartilaginous Tip‐Grafting Technique for Improved Nasal Tip Refinement in Asian Rhinoplasty
Authors: Jang Yong Ju , Min Jin‐Young , Lau Bedy Chung 
Published: April 2011

ObjectiveTip surgery remains the most difficult part of rhinoplasty in Asian patients because of the lower lateral cartilage characteristics and thick skin. The objective of this study was to evaluate the multilayer cartilaginous tip‐grafting technique used for tip refinement in Korean patients undergoing rhinoplasty.Study DesignCase series with chart review.SettingAcademic tertiary care medical center.Subjects and MethodsA retrospective study of 99 Korean patients who underwent open rhinoplasty involving multilayer cartilaginous tip‐grafting for tip refinement was performed. Autologous septal, conchal, costal, or homologous costal cartilage, or a combination of these materials was used as grafting materials. Preoperative and postoperative photographs were reviewed for objective and subjective assessment of aesthetic outcomes.ResultsAmong patients, 7 had undergone previous rhinoplasty (7.1%), and removal of the previously placed silicone graft was required in 5 patients (5.1%). Two (6.7%), 3 (61.5%), 4 (28.8%), and 5 (3.0%) layers of cartilaginous graft were used. Postoperative aesthetic outcomes were graded as excellent in 63.6%, fair in 28.3%, and no change/worse in 8.1% of cases. Preoperative and postoperative objective measurements showed that the procedure resulted in increased nasal tip projection (0.52 ± 0.06 vs 0.57 ± 0.05; P <. 05) and improved nasolabial angle (92.98° ± 9.95° vs 95.34° ± 8.20°; P <. 05). The overall complication rate was 12.1%, and 8 patients required revision surgery (8.1%). Complications included infection (5.1%), visible graft contour (1.0%), nostril deformity (1.0%), overprojection (2.0%), and visible hypertrophic scar at the marginal incision site (3.0%).ConclusionsThe multilayer cartilaginous tip‐grafting technique was found to be effective for aesthetic refinement of the nasal tip when used in rhinoplasty for Korean patients.