832 research outputs found

    Correlation between Subjective Nasal Patency and Intranasal Airflow Distribution

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    Objectives (1) Analyze the relationship between intranasal airflow distribution and subjective nasal patency in healthy and nasal airway obstruction (NAO) cohorts using computational fluid dynamics (CFD). (2) Determine whether intranasal airflow distribution is an important objective measure of airflow sensation that should be considered in future NAO virtual surgery planning. Study Design Cross-sectional. Setting Academic tertiary medical center and academic dental clinic. Subjects and Methods Three-dimensional models of nasal anatomy were created based on computed tomography scans of 15 patients with NAO and 15 healthy subjects and used to run CFD simulations of nasal airflow and mucosal cooling. Subjective nasal patency was quantified with a visual analog scale (VAS) and the Nasal Obstruction Symptom Evaluation (NOSE). Regional distribution of nasal airflow (inferior, middle, and superior) was quantified in coronal cross sections in the narrowest nasal cavity. The Pearson correlation coefficient was used to quantify the correlation between subjective scores and regional airflows. Results Healthy subjects had significantly higher middle airflow than patients with NAO. Subjective nasal patency had no correlation with inferior and superior airflows but a high correlation with middle airflow (|r| = 0.64 and |r| = 0.76 for VAS and NOSE, respectively). Anterior septal deviations tended to shift airflow inferiorly, reducing middle airflow and reducing mucosal cooling in some patients with NAO. Conclusion Reduced middle airflow correlates with the sensation of nasal obstruction, possibly due to a reduction in mucosal cooling in this region. Further research is needed to elucidate the role of intranasal airflow distribution in the sensation of nasal airflow

    Role of Virtual Surgery in Preoperative Planning: Assessing the Individual Components of Functional Nasal Airway Surgery

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    There are often multiple anatomic factors that contribute to nasal obstruction, creating difficulty in deciding which components to address for a successful outcome. The purpose of this pilot study is to demonstrate the effect of individual components of functional nasal airway surgery in a patient with multifactorial obstruction and discuss the potential benefit of computational fluid dynamics (CFD)-aided virtual surgery

    Toward Personalized Nasal Surgery Using Computational Fluid Dynamics

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    To evaluate whether virtual surgery (VS) performed on 3D nasal airway models can predict post-surgical, biophysical parameters obtained by computational fluid dynamics (CFD)

    The Origin of the Brightest Cluster Galaxies

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    Most clusters and groups of galaxies contain a giant elliptical galaxy in their centres which far outshines and outweighs normal ellipticals. The origin of these brightest cluster galaxies is intimately related to the collapse and formation of the cluster. Using an N-body simulation of a cluster of galaxies in a hierarchical cosmological model, we show that galaxy merging naturally produces a massive, central galaxy with surface brightness and velocity dispersion profiles similar to observed BCG's. To enhance the resolution of the simulation, 100 dark halos at z=2z=2 are replaced with self-consistent disk+bulge+halo galaxy models following a Tully-Fisher relation using 100000 particles for the 20 largest galaxies and 10000 particles for the remaining ones. This technique allows us to analyze the stellar and dark matter components independently. The central galaxy forms through the merger of several massive galaxies along a filament early in the cluster's history. Galactic cannibalism of smaller galaxies through dynamical friction over a Hubble time only accounts for a small fraction of the accreted mass. The galaxy is a flattened, triaxial object whose long axis aligns with the primordial filament and the long axis of the cluster galaxy distribution agreeing with observed trends for galaxy-cluster alignment.Comment: Revised and accepted in ApJ, 25 pages, 10 figures, online version available at http://www.cita.utoronto.ca/~dubinski/bcg

    Computed intranasal spray penetration: comparisons before and after nasal surgery

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    Quantitative methods for comparing intranasal drug delivery efficiencies pre- and postoperatively have not been fully utilized. The objective of this study is to use computational fluid dynamics techniques to evaluate aqueous nasal spray penetration efficiencies before and after surgical correction of intranasal anatomic deformities

    Effects of Anatomy and Particle Size on Nasal Sprays and Nebulizers

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    To study the effects of nasal deformity on aerosol penetration past the nasal valve (NV) for varying particle sizes using sprays or nebulizers

    Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium

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    We present age estimates for the newly discovered very r-process enhanced metal-poor star HE 1523-0901 ([Fe/H]=-2.95) based on the radioactive decay of Th and U. The bright (V=11.1) giant was found amongst a sample of bright metal-poor stars selected from the Hamburg/ESO survey. From an abundance analysis of a high-resolution (R=75,000) VLT/UVES spectrum we find HE 1523-0901 to be strongly overabundant in r-process elements ([r/Fe]=1.8). The abundances of heavy neutron-capture elements (Z>56) measured in HE 1523-0901 match the scaled solar r-process pattern extremely well. We detect the strongest optical U line at 3859.57 A. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/Eu and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523-0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.Comment: 7 pages, 2 figures. Accepted for publication in ApJ Letter

    Predicting Postsurgery Nasal Physiology with Computational Modeling: Current Challenges and Limitations

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    High failure rates for surgical treatment of nasal airway obstruction (NAO) indicate that better diagnostic tools are needed to improve surgical planning. This study evaluates whether computer models based on a surgeon’s edits of pre-surgery scans can accurately predict results from computer models based on post-operative scans of the same patient using computational fluid dynamics
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