832 research outputs found
Correlation between Subjective Nasal Patency and Intranasal Airflow Distribution
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
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
To evaluate whether virtual surgery (VS) performed on 3D nasal airway models can predict post-surgical, biophysical parameters obtained by computational fluid dynamics (CFD)
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Comparison of industry payments to psychiatrists and psychiatric advanced practice clinicians in the USA, 2021: A cross-sectional study
Objectives: To compare industry payment patterns among US psychiatrists and psychiatric advanced practice clinicians (APCs) and determine how scope of practice laws has influenced these patterns. Design: Cross-sectional study. Setting: This study used the publicly available US Centers for Medicare and Medicaid Services Sunshine Act Open Payment database and the National Plan and Provider Enumeration System (NPPES) database for the year 2021. Participants: All psychiatrists and psychiatric APCs (subdivided into nurse practitioners (NPs) and clinical nurse specialists (CNSs)) included in either database. Primary and secondary outcome measures: Number and percentage of clinicians receiving industry payments and value of payments received. Total payments and number of transactions by type of payment, payment source and clinician type were also evaluated. Results: A total of 85 053 psychiatric clinicians (61 011 psychiatrists (71.7%), 21 895 NPs (25.7%), 2147 CNSs (2.5%)) were reviewed; 16 240 (26.6%) psychiatrists received non-research payment from industry, compared with 10 802 (49.3%) NPs and 231 (10.7%) CNSs (p United States Dollars (US) 1000 (5.3% vs 4.1%; IRR, 1.29 (1.20 to 1.38); p US$ 10 000 (0.4% vs 1.0%; IRR, 0.39 (0.31 to 0.49); p Conclusions: Psychiatric NPs were nearly two times as likely to receive industry payments as psychiatrists, while psychiatric CNSs were less than half as likely to receive payment. Stricter scope of practice laws increases the likelihood of psychiatric NPs receiving payment, the opposite of what was found in a recent specialty agnostic study.</p
The Origin of the Brightest Cluster Galaxies
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 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
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
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
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
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Association of thyroid status prior to transition to end-stage renal disease with early dialysis mortality.
BackgroundAdvanced chronic kidney disease (CKD) patients, including those receiving dialysis, have a high prevalence of thyroid dysfunction. Although hypothyroidism is associated with higher death risk in end-stage renal disease (ESRD) patients, no studies have examined whether thyroid status in the pre-ESRD period impacts mortality after dialysis initiation.MethodsAmong US veterans with CKD identified from the national Veterans Affairs database that transitioned to dialysis over the period from October 2007 to September 2011, we examined the association of pre-ESRD serum thyrotropin (TSH) levels averaged over the 1-year pre-dialysis ('prelude') period with all-cause mortality in the first year following dialysis initiation.ResultsAmong 15 335 patients in the 1-year prelude cohort, TSH levels >5.0 mIU/L were associated with higher mortality in expanded case-mix Cox models (reference: TSH 0.5-5.0 mIU/L): adjusted hazard ratio (aHR) [95% confidence interval (CI) 1.20 (1.07-1.33). Similar findings were observed for TSH >5.0 mIU/L and mortality in the 2- and 5-year cohorts: aHRs (95% CI) 1.11 (1.02-1.21) and 1.15 (1.07-1.24), respectively. Analyses of finer gradations of TSH in the 1-year prelude cohort demonstrated that incrementally higher levels >5.0 mIU/L were associated with increasingly higher mortality in expanded case-mix models (reference: TSH 0.5-3.0 mIU/L): aHRs (95% CI) 1.18 (1.04-1.33) and 1.28 (1.03-1.59) for TSH levels >5.0-10.0 mIU/L and >10.0 mIU/L, respectively. In the 2- and 5-year cohorts, mortality associations persisted most strongly for those with TSH >10.0 mIU/L, particularly after laboratory covariate adjustment.ConclusionsAmong new ESRD patients, there is a dose-dependent relationship between higher pre-ESRD TSH levels >5.0 mIU/L and post-ESRD mortality. Further studies are needed to determine the impact of TSH reduction with thyroid hormone supplementation in this population
Predicting Postsurgery Nasal Physiology with Computational Modeling: Current Challenges and Limitations
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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