Growth and Competitive Effects of Centaurea stoebe Populations in Response to Simulated Nitrogen Deposition

Increased resource availability can promote invasion by exotic plants, raising concerns over the potential effects of global increases in the deposition of nitrogen (N). It is poorly understood why increased N favors exotics over natives. Fast growth may be a general trait of good invaders and these species may have exceptional abilities to increase growth rates in response to N deposition. Additionally, invaders commonly displace locals, and thus may have inherently greater competitive abilities. The mean growth response of Centaurea stoebe to two N levels was significantly greater than that of North American (NA) species. Growth responses to N did not vary among C. stoebe populations or NA species. Without supplemental N, NA species were better competitors than C. stoebe, and C. stoebe populations varied in competitive effects. The competitive effects of C. stoebe populations increased with N whereas the competitive effects of NA species decreased, eliminating the overall competitive advantage demonstrated by NA species in soil without N added. These results suggest that simulated N deposition may enhance C. stoebe invasion through increasing its growth and relative competitive advantage, and also indicate the possibility of local adaptation in competitive effects across the introduced range of an invader

Comparison Of The Effects Of Patient Controlled Analgesia (Pca) Using Dexmedetomidine And Propofol During Septoplasty Operations: A Randomized Clinical Trial

Introduction Septoplastical surgery to correct septum deviation can be performed under either local or general anesthesia. During local anesthesia, sedation helps to provide minimum anxiety/discomfort. Our aim was to evaluate the effects of patient-controlled analgesia using dexmedetomidine and propofol on sedation level, analgesic requirement, and patient satisfaction. Study design A prospective, randomized-parallel clinical study. Methods Fifty patients undergoing septoplastical surgery at our university hospital were randomized into two groups. A nasopharyngeal cotton tampon soaked in 0.25 % adrenaline solution was placed, and 1 mg midazolam and 1 mcg/kg fentanyl were applied 5 min before the injections of a surgical local anesthetic. Loading dose was 0.5 mg/kg propofol (Group I) and 1 mcg/kg dexmedetomidine (Group II). The sedation was sustained by a bolus dose of 0.2 mg/kg and continuous basal infusion dose of 0.5 mg/kg/h propofol in Group I, or by a bolus dose of 0.05 µg/kg and continuous basal infusion dose of 0.4 mcg/kg/h dexmedetomidine in Group II. The primary outcomes were patient satisfaction via patient-controlled anesthesia and analgesic demand. Secondary outcomes were sedation level of patients under local anesthesia. Results In Group II, SpO2 levels were significantly higher than in Group I. Intraoperative and postoperative analgesic requirements were lower in Group II than in Group I. There were no statistically significant differences in patient satisfaction, hemodynamic parameters, nausea and vomiting between the two groups. Conclusion Dexmedetomidine can be used safely as an analgesic and sedation drug in septoplastic surgery.PubMedWoSScopu