58,918 research outputs found
Aceclidine, brimonidine tartrate, and dapiprazole: comparison of miotic effect and tolerability under different lighting conditions.
No full textPurpose: To evaluate the effect on pupil diameter of three different miotic eye-drops: aceclidine, brimonidine tartrate 0.20% and dapiprazole, when applied topically in normal subjects
Methods: The eyes of 30 healthy volunteers were included in this study. Pupil diameter was measured under scotopic, mesopic (4 lux) and photopic (50 lux) conditions, using an infrared pupillometer, in conjunction with a CSOTM topographer. The first measurement was obtained before the sole instillation of the three different kinds of eye drops. Afterwards, measurements were performed after 30, 120 and 240 minutes. Each additional eye medication was tested further after at least a 10 day interval in order to avoid any possible drug interference. Every patient received a questionnaire to grade the tolerability of each kind of eye drops by a subjective scoring system.
Results:Aceclidine had an unimportant miotic effect. Brimonidine caused significant miosis within 30 and 120 minutes: then the effect reduced without reaching the initial baseline at the forth hour in all different luminance conditions. Dapiprazole had a quite similar miotic effect to brimonidine but it produced many side effects, including hyperemia and burning, which caused too much discomfort for most of patients. Conclusions: Brimonidine tartrate 0.20% seems to have the best miotic effect together with good patient tolerability in comparison with aceclidine and dapiprazole. The reproducible miotic effect of this eye drop under all lighting conditions might help postoperative refractive patients who report night-vision difficulties related with large pupils
The green leafhopper, cicadella viridis (hemiptera, auchenorrhyncha, cicadellidae), jumps with near-constant acceleration
No full textJumping insects develop accelerations that can greatly exceed gravitational acceleration. Although several species have been analysed using different tools, ranging from a purely physical to a morpho-physiological approach, instantaneous dynamic and kinematic data concerning the jumping motion are lacking. This is mainly due to the difficulty in observing in detail events that occur in a few milliseconds. In this study, the behaviour of the green leafhopper, Cicadella viridis, was investigated during the take-off phase of the jump, through high-speed video recordings (8000 frames s-1). We demonstrate that C. viridis is able to maintain fairly constant acceleration during overall leg elongation. The force exerted at the foot-ground interface is nearly constant and differs from the force expected from other typical motion models. A biomechanical model was used to highlight that this ability relies on the morphology of C. viridis hind legs, which act as a motion converter with a variable transmission ratio and use the time-dependent musculo-elastic force to generate a nearly constant thrust at the body-ground interface. This modulation mechanism minimizes the risk of breaking the substrate thanks to the absence of force peaks. The results of this study are of broad relevance in different research fields ranging from biomechanics to robotics. © 2013. Published by The Company of Biologists Ltd
Cheratoplastica lamellare profonda: una valida alternativa alla cheratoplastica perforante.
No full textTranslation initiation in the crenarchaeon Sulfolobus solfataricus: eukaryotic features but bacterial route.
No full textThe formation of the translation initiation complex represents the rate-limiting step in protein synthesis. Translation initiation in the crenarchaeon Sulfolobus solfataricus depends on several translation IFs (initiation factors), some of which have eukaryal but no bacterial counterparts. In the present paper, we review the current knowledge of the structure, function and evolution of the IFs in S. solfataricus in the context of eukaryotic and bacterial orthologues. Despite similarities between eukaryotic and S. solfataricus IFs, the sequence of events in translation initiation in S. solfataricus follows the bacterial mode
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