292 research outputs found
Weak compactness and essential norms of integration operators
Let be an analytic function on the unit disc and consider the integration
operator of the form . We show that on the
spaces and the operator is weakly compact if and only if it
is compact. In the case of this answers a question of Siskakis and Zhao.
More generally, we estimate the essential and weak essential norms of on
and
Productivity of Stump Harvesting for Fuel
The productivity of harvesting stump and root wood was studied in Norway spruce (Picea abies) stands. The objective was to create productivity models (m3/E0h) for stump wood extraction, stump wood forwarding, and site preparation, in addition to identifying work phases and improvement opportunities in the extraction and forwarding chain. Productivity models were based on time studies with professional operators. The independent variables in stump wood extraction were stump diameter (cm) and the number of stumps per hectare. For forwarding, the independent variables were volume of stump wood removed (m3/ha) and forwarding distance (m). When removing 350 stumps per ha with an average diameter of 40 cm, productivity was estimated at 7.9 m3/E0h. Increasing the number of stumps removed from 350 to 800 stumps per ha, increased productivity to 10.8 m3/E0h. Forwarding productivity was 7.8 m3/E0hwithaforwardingdistanceof250mandaload size of 7.0 m3 when removing 60 m3 of stumps per ha
Rigidity of composition operators on the Hardy space H-P
Let phi be an analytic map taking the unit disk ID into itself. We establish that the class of composition operators f bar right arrow C-phi(f) = f o phi exhibits a rather strong rigidity of non-compact behaviour on the Hardy space H-P, for 1 H-P, (ii) C-phi fixes a (linearly isomorphic) copy of l(P) in H-P, but C-phi does not fix any copies of l(2) in H-P, (iii) C-phi fixes a copy of l(2) in H-P. Moreover, in case (iii) the operator C-phi actually fixes a copy of L-P(0, 1) in H-P provided p > 1. We reinterpret these results in terms of norm-closed ideals of the bounded linear operators on H-P, which contain the compact operators k(H-P). In particular, the class of composition operators on H-P does not reflect the quite complicated lattice structure of such ideals. (C) 2017 Elsevier Inc. All rights reserved.Peer reviewe
Voriconazole greatly increases the exposure to oral buprenorphine
PurposeBuprenorphine has low oral bioavailability. Regardless of sublingual administration, a notable part of buprenorphine is exposed to extensive first-pass metabolism by the cytochrome P450 (CYP) 3A4. As drug interaction studies with buprenorphine are limited, we wanted to investigate the effect of voriconazole, a strong CYP3A4 inhibitor, on the pharmacokinetics and pharmacodynamics of oral buprenorphine.MethodsTwelve healthy volunteers were given either placebo or voriconazole (orally, 400mg twice on day 1 and 200mg twice on days 2-5) for 5days in a randomized, cross-over study. On day 5, they ingested 0.2mg (3.6mg during placebo phase) oral buprenorphine. We measured plasma and urine concentrations of buprenorphine and norbuprenorphine and monitored their pharmacological effects. Pharmacokinetic parameters were normalized for a buprenorphine dose of 1.0mg.ResultsVoriconazole greatly increased the mean area under the plasma concentration-time curve (AUC(0-18)) of buprenorphine (4.3-fold, PPeer reviewe
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