Validation of Computational Models of Auxiliary Ventilation Systems with Experimental Data

This paper reports the interim findings of a research program whose objective is to determine whether Computational Fluid Dynamic (CFD) models can be employed to accurately predict the airflow patterns within rapid development headings. In particular, the project aims to investigate the optimum set back distances for the ducts in order to adequately ventilate the face of the drivage. To validate the accuracy of the CFD model simulations measurements were obtained from a series of experiments performed on both scale models and within a full-scale surface gallery. The experimental scale-modeling program included making a series of pressure measurements across the face of the model for equivalent forcing duct setback distances of 5, 10 and 15 m (16, 33 and 50 ft). This pressure data was then plotted as contour plots and compared with the corresponding CFD predictions. A series of full-scale auxiliary ventilation trials were performed within a modified surface gallery. Three-dimensional velocity measurements were taken across a number of cross-sections using an ultrasonic anemometer. Velocity measurements were obtained for three forcing duct setback distances and for a typical force-exhaust overlap configuration

Renormalization group theory for finite-size scaling in extreme statistics

We present a renormalization group (RG) approach to explain universal features of extreme statistics, applied here to independent, identically distributed variables. The outlines of the theory have been described in a previous Letter, the main result being that finite-size shape corrections to the limit distribution can be obtained from a linearization of the RG transformation near a fixed point, leading to the computation of stable perturbations as eigenfunctions. Here we show details of the RG theory which exhibit remarkable similarities to the RG known in statistical physics. Besides the fixed points explaining universality, and the least stable eigendirections accounting for convergence rates and shape corrections, the similarities include marginally stable perturbations which turn out to be generic for the Fisher-Tippett-Gumbel class. Distribution functions containing unstable perturbations are also considered. We find that, after a transitory divergence, they return to the universal fixed line at the same or at a different point depending on the type of perturbation.Comment: 15 pages, 8 figures, to appear in Phys. Rev.

Controlling extended systems with spatially filtered, time-delayed feedback

We investigate a control technique for spatially extended systems combining spatial filtering with a previously studied form of time-delay feedback. The scheme is naturally suited to real-time control of optical systems. We apply the control scheme to a model of a transversely extended semiconductor laser in which a desirable, coherent traveling wave state exists, but is a member of a nowhere stable family. Our scheme stabilizes this state, and directs the system towards it from realistic, distant and noisy initial conditions. As confirmed by numerical simulation, a linear stability analysis about the controlled state accurately predicts when the scheme is successful, and illustrates some key features of the control including the individual merit of, and interplay between, the spatial and temporal degrees of freedom in the control.Comment: 9 pages REVTeX including 7 PostScript figures. To appear in Physical Review

Negative diffraction pattern dynamics in nonlinear cavities with left-handed materials

We study a ring cavity filled with a slab of a right-handed material and a slab of a left-handed material. Both layers are assumed to be nonlinear Kerr media. First, we derive a model for the propagation of light in a left-handed material. By constructing a mean-field model, we show that the sign of diffraction can be made either positive or negative in this resonator, depending on the thicknesses of the layers. Subsequently, we demonstrate that the dynamical behavior of the modulation instability is strongly affected by the sign of the diffraction coefficient. Finally, we study the dissipative structures in this resonator and reveal the predominance of a two-dimensional up-switching process over the formation of spatially periodic structures, leading to the truncation of the homogeneous hysteresis cycle.Comment: 8 pages, 5 figure

IMECE2008-67360 GASTROESOPHAGEAL REFLUX 2D AND 3D STEADY STATE CFD SIMULATIONS

ABSTRACT Gastro-Esophageal Reflux Disease (GERD) is a condition which affects up to 20% of the adult US population on a weekly basis. It is a condition where acid is allowed to flow from the stomach and into the esophagus where it causes damage to the local tissue. In chronic cases the condition can lead to cancer. Dysfunction of the Esophagogastric Junction is indicated as a primary cause. The recently developed Functional Lumen Imaging Probe (FLIP) is designed for assessment of the EGJ. It measures the cross sectional area at eight locations through the junction. This data has been used to construct a series of computational fluid dynamic simulations. These simulations showed a jet of fluid which squirts into the esophagus under the gastric pressure. This jet corresponds with previously gathered anecdotal evidence. The centerline velocities of this jet were measured and this suggested that the jet could travel up to 20 times the minimum diameter of the EGJ into the esophagus before decelerating to 25% of its original velocity. This means that if an EGJ was curved then this jet could impinge on the walls causing a localized area of increased damage to the mucosa compared to the surrounding tissue

Spatiotemporal communication with synchronized optical chaos

We propose a model system that allows communication of spatiotemporal information using an optical chaotic carrier waveform. The system is based on broad-area nonlinear optical ring cavities, which exhibit spatiotemporal chaos in a wide parameter range. Message recovery is possible through chaotic synchronization between transmitter and receiver. Numerical simulations demonstrate the feasibility of the proposed scheme, and the benefit of the parallelism of information transfer with optical wavefronts.Comment: 4 pages, 5 figure

The Diagnostic Accuracy and Clinimetric Properties of Screening Instruments to Identify Frail Older Adults Attending Emergency Departments: A Protocol for a Mixed Methods Systematic Review and Meta-Analysis

Background: Prompt and efficient identification and stratification of patients who are frail is important, as this cohort are at high risk of adverse healthcare outcomes. Numerous frailty screening tools have been developed to support their identification across different settings, yet relatively few have emerged for use in emergency departments (EDs). This protocol provides details for a systematic review aiming to synthesize the accumulated evidence regarding the diagnostic accuracy and clinimetric properties of frailty screening instruments to identify frail older adults in EDs. Methods: Six electronic databases will be searched from January 2000 to March 2021. Eligible studies will include adults aged ≥60 years screened in EDs with any available screening instrument to identify frailty (even if not originally designed for this purpose). Studies, including case-control, longi-tudinal, and cohort studies, will be included, where instruments are compared to a reference standard to explore diagnostic accuracy. Predictive accuracy for a selection of outcomes, including mor-tality, institutionalization, and readmission, will be assessed. Clinical and methodological heterogeneity will be examined, and a random effects meta-analysis performed if appropriate. Conclusion: Understanding whether frailty screening on presentation to EDs is accurate in identifying frailty, and predicting these outcomes is important for decision-making and targeting appropriate man-agement

Detection of primary melanoma in individuals at extreme high risk: a prospective 5-year follow-up study

IMPORTANCE: The clinical phenotype and certain predisposing genetic mutations that confer increased melanoma risk are established; however, no consensus exists regarding optimal screening for such individuals. Early identification remains the most important intervention in reducing melanoma mortality. OBJECTIVE: To evaluate the impact of full-body examinations every 6 months supported by dermoscopy and total-body photography (TBP) on all patients and sequential digital dermoscopy imaging (SDDI), when indicated, on detecting primary melanoma in an extreme-risk population. DESIGN, SETTING, AND PARTICIPANTS: Prospective observational study from February 2006 to February 2011, with patients recruited from Sydney Melanoma Diagnostic Centre and Melanoma Institute Australia who had a history of invasive melanoma and dysplastic nevus syndrome, history of invasive melanoma and at least 3 first-degree or second-degree relatives with prior melanoma, history of at least 2 primary invasive melanomas, or a CDKN2A or CDK4 gene mutation. EXPOSURES: Six-month full-body examination compared with TBP. For equivocal lesions, SDDI short term (approximately 3 months) or long term (≥6 months), following established criteria, was performed. Atypical lesions were excised. MAIN OUTCOMES AND MEASURES: New primary melanoma numbers, characteristics, and cumulative incidence in each patient subgroup; effect of diagnostic aids on new melanoma identification. RESULTS: In 311 patients with a median (interquartile range [IQR]) follow-up of 3.5 (2.4-4.2) years, 75 primary melanomas were detected, 14 at baseline visit. Median (IQR) Breslow thickness of postbaseline incident melanomas was in situ (in situ to 0.60 mm). Thirty-eight percent were detected using TBP and 39% with SDDI. Five melanomas were greater than 1 mm Breslow thickness, 3 of which were histologically desmoplastic; the other 2 had nodular components. The benign to malignant excision ratio was 1.6:1 for all lesions excised and 4.4:1 for melanocytic lesions. Cumulative risk of developing a novel primary melanoma was 12.7% by year 2, with new primary melanoma incidence during the final 3 years of follow-up half of that observed during the first 2 years (incidence density ratio, 0.43 [95% CI, 0.25-0.74]; P = .002). CONCLUSIONS AND RELEVANCE: Monitoring patients at extreme risk with TBP and SDDI assisted with early diagnosis of primary melanoma. Hypervigilance for difficult-to-detect thick melanoma subtypes is crucial. Copyright 2014 American Medical Association. All rights reserved

Using airborne LiDAR Survey to explore historic-era archaeological landscapes of Montserrat in the eastern Caribbean

This article describes what appears to be the first archaeological application of airborne LiDAR survey to historic-era landscapes in the Caribbean archipelago, on the island of Montserrat. LiDAR is proving invaluable in extending the reach of traditional pedestrian survey into less favorable areas, such as those covered by dense neotropical forest and by ashfall from the past two decades of active eruptions by the Soufrière Hills volcano, and to sites in localities that are inaccessible on account of volcanic dangers. Emphasis is placed on two aspects of the research: first, the importance of ongoing, real-time interaction between the LiDAR analyst and the archaeological team in the field; and second, the advantages of exploiting the full potential of the three-dimensional LiDAR point cloud data for purposes of the visualization of archaeological sites and features

Study of B meson decays to three-body charmless hadronic final states

We report results of a study of charmless B meson decays to three-body KPiPi, KKPi and KKK final states. Measurements of branching fractions for B decays to K+0Pi+Pi-, K+K+K-, K0K+K-, KsKsK+ and KsKsKs final states are presented. The decays B0=>K0K+K-, B+=>KsKsK+ and B0=>KsKsKs are observed for the first time. We also report evidence for B+=>K+K-Pi+ decay. For the three-body final states K0K+K-, KsKsPi+, K+K+Pi- and K-Pi+Pi+ 90% confidence level upper limits are reported. Finally, we discuss the possibility of using the three-body B0=>KsK+K- decay for CP violation studies. The results are obtained with a 78 fb^-1 data sample collected at the Y(4S) resonance by the Belle detector operating at the KEKB asymmetric energy e+e- collider.Comment: 15 pages, 6 figures. To be submitted to PR