ABSTRACT
The dielectric properties, tunability and figure-of-merit (FOM) of relaxor Pb0.9La0.1(Zr0.52Ti0.48)O3 (PLZT) films have been investigated. Dielectric measurements indicated that the dielectric constant (at zero-bias field), tunability and FOM are enhanced as the film thickness increases, which are mainly attributed to the presence of an interfacial layer near the film-electrode interface. Experimental results illustrated that a slight reduction is observed in both dielectric constant and tunability (-2%) in a wide-frequency range (10 kHz-1 MHz); meanwhile, the FOM value decreases significantly (-17%) with increasing frequency, arising from the higher dielectric loss value. The 1000-nm PLZT film shows the largest tunability of 94.6% at a maximum electric-field of 1450 kV/cm, while the highest FOM factor is 37.6 at 1000 kV/cm, due to the combination of medium tunability (88.7%) and low dielectric loss (0.0236). All these excellent results indicated that the relaxor PLZT films are promising candidates for specific applications in microwave devices.
ABSTRACT
Acetylcholine (ACh) neurotransmission is important for attention, while dopamine (DA) signaling modulates impulsive behavior. Prior studies have established an existing relationship between ACh and DA that mediates dopamine release in the prefrontal cortex of the brain in rats performing the 5-choice serial reaction time task (5-CSRTT). This study is aimed to identify cholinergic and dopaminergic interactions that govern attention and impulsive behavior, using adult Long-Evans rats of both sexes and a 5-CSRTT, with variable short and long cue delays. In Experiment 1, the effects of single cholinergic and dopaminergic drugs were evaluated on 5-CSRTT performance. Drugs like nicotinic ACh receptor (nAChR) agonist nicotine, amphetamine, and GBR12909 that increase the synaptic levels of ACh and DA respectively all increased impulsive behavior. In addition, amphetamine and GBR 12909 decreased attention while nicotine had no effect on attention. The antagonists mecamylamine, a general nAChR antagonist, flupenthixol a DA 1/2 receptor antagonist, and SCH 23390 a DA 1 receptor antagonist, all decreased impulsive behavior, with mixed effects on attention. In contrast, dihydro-ß-erythroidine hydrobromide (DHBE), an α4ß2 subunit-specific nAChR antagonist, had no significant effects on attention or impulsivity across doses administered. Eticlopride, a DA 2 receptor antagonist, decreased attention at the shortest cue delay but did not affect impulsivity. The acetylcholinesterase inhibitor donepezil decreased both attention and impulsive behavior. Subsequently in Experiment 2, effects of nicotine and amphetamine were determined after pretreatment with SCH 23390 or eticlopride. SCH 23390 attenuated the effects of nicotine and amphetamine to increase impulsivity, while eticlopride only attenuated the effect of nicotine on impulsivity. Minimal effects were seen on attention in the combination trials. This study confirms that dopamine D1 receptor plays an essential role in modulation of impulsive behavior, as measured by the 5-CSRTT. More importantly, it establishes that impulsive behavior is altered by interactions between cholinergic and dopaminergic neurotransmission.
Subject(s)
Attention/drug effects , Cholinergic Agents/pharmacology , Dopamine/pharmacology , Reaction Time/drug effects , Animals , Female , Male , Rats , Rats, Long-EvansABSTRACT
The authors reviewing their own experience of blepharoplasty (92 cases) over the last ten years, discuss the principal approaches used depending on the age of the patient, the amount of adipose tissue, the lower lid tarsal and muscular laxity and the quality of the skin excess. In the lower eyelid they emphasize the value of the transconjunctival approach in young and or coloured people and the use of a cutaneo-muscular flap in the classical technique. In the upper eyelid, they combine the skin excision with an orbicularis muscle strip and in old people with suspension of the lateral canthus. A wise selection of these various approaches avoids the rare complications (ectropion and scleral show) because blepharoplasty must be considered to be a "variable geometry" operation.
