Perching and takeoff of a robotic insect on overhangs using switchable electrostatic adhesion.

For aerial robots, maintaining a high vantage point for an extended time is crucial in many applications. However, available on-board power and mechanical fatigue constrain their flight time, especially for smaller, battery-powered aircraft. Perching on elevated structures is a biologically inspired approach to overcome these limitations. Previous perching robots have required specific material properties for the landing sites, such as surface asperities for spines, or ferromagnetism. We describe a switchable electroadhesive that enables controlled perching and detachment on nearly any material while requiring approximately three orders of magnitude less power than required to sustain flight. These electroadhesives are designed, characterized, and used to demonstrate a flying robotic insect able to robustly perch on a wide range of materials, including glass, wood, and a natural leaf.

A survey of prescribing preferences in the treatment of refractory depression: recent trends.

The objective of this study was to gather data from a large group of clinicians on antidepressant prescribing practices in the treatment of refractory depression. Eight hundred and thirty-five clinicians about to attend the annual Massachusetts General Hospital psychopharmacology review course were asked to respond to a brief questionnaire regarding a hypothetical clinical case vignette. The case was of a patient who suffered from a new onset, unipolar, nonpsychotic, severe major depressive episode. Three hundred and four (36%) clinicians agreed to participate and filled out our questionnaire. Of the respondents, 260 (85.5%) indicated their preference for an initial treatment that combined medication and psychotherapy, as opposed to either modality alone. Furthermore, given this patient's nonresponse to two adequate selective serotonin reuptake inhibitor (SSRI) trials and one atypical antidepressant trial over an 8-month period, 39.8% of respondents indicated venlafaxine monotherapy as their next choice, whereas combining antidepressants (20.1%) and augmentation (18.4%) were the second and third most preferred treatment choices at this time point. Further on in the course of treatment, with the patient not having responded to any interventions during a 16-month period, 80.9% of survey respondents indicated electroconvulsant therapy (ECT) as their next preference. Among 304 clinicians surveyed, a combination of therapy and medication is the most preferred choice for treating severely depressed outpatients with new onset depression. Switching to venlafaxine, using two antidepressants together, and augmentation of an antidepressant regimen with a second agent accounted for 78.3% of respondents' preferences when faced with treating a depressed patient who had not responded to two adequate SSRI trials and one adequate atypical antidepressant trial. Of the respondents, 80.9% indicated ECT as a treatment preference after 16 months of multiple failed medication trials and nonresponse to psychotherapy. Further research is necessary to elucidate the factors that influence clinicians' reasoning for selecting one strategy over another.

Acoustical performance of an electrostrictive polymer film loudspeaker

A new type of loudspeaker that generates sound by means of the electrostrictive response of a thin polymer film is described. Electrostrictive polymer film (EPF) loudspeakers are constructed with inexpensive, lightweight materials and have a very low profile. The films are typically silicone and are coated with compliant electrodes to allow large film deformations. Acoustical frequency response measurements from 5 x 5 cm (planar dimensions) prototype EPF loudspeakers are presented. Measurements of harmonic distortion are also shown, along with results demonstrating reduced harmonic distortion achieved with square-root wave shaping. Applications of EPF loudspeakers include active noise control and general-purpose flat-panel loudspeakers.

High-speed electrically actuated elastomers with strain greater than 100%

Electrical actuators were made from films of dielectric elastomers (such as silicones) coated on both sides with compliant electrode material. When voltage was applied, the resulting electrostatic forces compressed the film in thickness and expanded it in area, producing strains up to 30 to 40%. It is now shown that prestraining the film further improves the performance of these devices. Actuated strains up to 117% were demonstrated with silicone elastomers, and up to 215% with acrylic elastomers using biaxially and uniaxially prestrained films. The strain, pressure, and response time of silicone exceeded those of natural muscle; specific energy densities greatly exceeded those of other field-actuated materials. Because the actuation mechanism is faster than in other high-strain electroactive polymers, this technology may be suitable for diverse applications.

Cholecystokinin inhibits gastric emptying and contracts the pyloric sphincter in rats by interacting with low affinity CCK receptor sites.

The aim of these experiments was to characterize the receptor affinity state through which CCK produces pyloric contraction and inhibits gastric emptying in the rat using the novel CCK heptapeptide analog CCK-JMV-180. CCK-JMV-180 has been demonstrated to act as a functional agonist at high affinity pancreatic CCKA receptors but as a functional antagonist at CCKA low affinity receptors. CCK-8 (1, 3.2 and 10 nM) induced dose dependent tension increases in isolated pyloric segments. CCK-JMV-180 (3.2 microM) or vehicle failed to mimic this action when administered alone but blocked the ability of CCK-8 (3.2 nM) to induce tension increases. CCK-8 (2 micrograms/kg) also inhibited the gastric emptying of physiological saline. CCK-JMV-180 (320 and 1000 micrograms/kg) failed to inhibit emptying when administered alone but dose dependently antagonized CCK induced inhibition of gastric emptying. Thus, in both preparations CCK-JMV-180 acted as a functional CCK antagonist. This profile is consistent with the interpretation that the actions of CCK in pyloric contraction and the inhibition of gastric emptying are mediated through CCK's interactions with receptors functionally similar to pancreatic low affinity sites.