Development of a photosynthesis model with an emphasis on ecological applications

A physiologically based steady-state model of whole leaf photosynthesis (WHOLEPHOT) is detailed which describes the functional dependence of net photosynthesis in C 3 leaves on [CO 2 ], [O 2 ], incident radiant flux (PhAR), and leaf temperature. The model simulates among other phenomena a) observed [CO 2 ], [O 2 ], and temperature effects on the initial slope of light response curves, b) a C 3 type temperature response curve of net photosynthesis, c) a shift of the optimum temperature of net photosynthesis to higher temperatures with increasing light intensity, and d) observed temperature and [O 2 ] effects on the CO 2 compensation point. Model parameters are derived from published response data of several C 3 species. Simulations also demonstrate that parameter changes based on literature data result in acclimation-like changes in net photosynthesis response with respect to light intensity and temperature. The advantages of this model are that the number of parameters is minimized in order to focus on environmental effects and that all parameters can be determined from measured net photosynthesis responses.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47727/1/442_2004_Article_BF00344999.pd

Revisiting the Dexamethasone Suppression Test in unipolar major depression: an exploratory study

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International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS

Thiopentone elimination in newborn infants: exploring Michaelis-Menten kinetics.

Background: Thiopentone elimination has been described using Michaelis-Menten pharmacokinetics in adults after prolonged infusion or overdose, but there are few reports of elimination in neonates. Methods: Time-concentration profiles for neonates (n=37) given single-dose thiopentone were examined using both first-order (constant clearance) and mixed-order (Michaelis-Menten) elimination processes using nonlinear mixed effects models. These profiles included a 33-week post-menstrual age (PMA) neonate given an overdose. A two-compartment mamillary model was used to fit data. Parameter estimates were standardized to a 70 kg person using allometric models. Results: There were 197 observations available for analysis from neonates with a mean post-menstrual age of 35 (SD 4.5) weeks and a mean weight of 2.5 (SD 0.9) kg. They were given a mean thiopentone dose of 3 (SD 0.4) mg/kg as a rapid bolus. Clearance at 26 weeks PMA was 0.015 l/min/70 kg and increased to 0.119 l/min/70 kg by 42 weeks PMA. The maximum rate of elimination (V(max) ) at 26 weeks PMA was 0.22 mg/min/70 kg and increased to 4.13 mg/min/70 kg by 42 weeks PMA. These parameter estimates are approximately 40% adult values at term gestation. The Michaelis constant (K(m) ) was 28.3 [between subject variability (BSV) 46.4%, 95% confidence interval (CI) 4.49-99.2] mg/l; intercompartment clearance was 0.44 (BSV 97.5%, 95% CI 0.27-0.63) l/min/70 kg; central volume of distribution was 46.4 (BSV 29.2%, 95% CI 41.7-59.8) l/70 kg; peripheral volume of distribution was 95.7 (BSV 70.3%, 95% CI 61.3-128) l/70 kg. Conclusions: Both first-order and mixed-order processes satisfactorily described elimination. First-order elimination adequately described the time-concentration profile in the premature neonate given an overdose. Clearance is immature in the pre-term neonate although there is rapid maturation around 40 weeks PMA, irrespective of post-natal age