Olfactory Interference during Inhibitory Backward Pairing in Honey Bees

Background: Restrained worker honey bees are a valuable model for studying the behavioral and neural bases of olfactory plasticity. The proboscis extension response (PER; the proboscis is the mouthpart of honey bees) is released in response to sucrose stimulation. If sucrose stimulation is preceded one or a few times by an odor (forward pairing), the bee will form a memory for this association, and subsequent presentations of the odor alone are sufficient to elicit the PER. However, backward pairing between the two stimuli (sucrose, then odor) has not been studied to any great extent in bees, although the vertebrate literature indicates that it elicits a form of inhibitory plasticity. Methodology/Principal Findings: If hungry bees are fed with sucrose, they will release a long lasting PER; however, this PER can be interrupted if an odor is presented 15 seconds (but not 7 or 30 seconds) after the sucrose (backward pairing). We refer to this previously unreported process as olfactory interference. Bees receiving this 15 second backward pairing show reduced performance after a subsequent single forward pairing (excitatory conditioning) trial. Analysis of the results supported a relationship between olfactory interference and a form of backward pairing-induced inhibitory learning/ memory. Injecting the drug cimetidine into the deutocerebrum impaired olfactory interference. Conclusions/Significance: Olfactory interference depends on the associative link between odor and PER, rather than between odor and sucrose. Furthermore, pairing an odor with sucrose can lead either to association of this odor to PER or t

Physicians' Preferences for Active-controlled versus Placebo-controlled Trials of New Antihypertensive Drugs

To evaluate physicians' preferences for referring patients to, and using information from, active-controlled trials (ACTs) versus placebo-controlled trials (PCTs) of new antihypertensive drugs. DESIGN AND SETTING Nationwide mailed survey, with telephone contact of nonresponders to assess nonresponse bias. PARTICIPANTS: One thousand two hundred primary care physicians randomly selected from the American Medical Association's Master File. Of 1,154 physicians eligible to respond, 651 (56.4%) returned completed questionnaires. MEASUREMENTS AND MAIN RESULTS: We measured physicians' stated willingness to encourage hypertensive patients to enroll in ACTs and PCTs of new antihypertensive drugs, their views of the relative merits of ACTs versus PCTs, their stated willingness to prescribe new drugs tested in ACTs or PCTs, and their views regarding the overall justifiability of the 2 designs. Physicians were significantly more likely to indicate they would encourage their patients to enroll in ACTs than in PCTs ( P < .0001). Physicians thought ACTs provided more valuable information for their practices, were more likely to lead to a public health benefit, offered enrolled patients greater opportunity for personal benefit, and were less likely to expose enrolled patients to unnecessary risks (all P < .0001). Physicians were more likely to prescribe new drugs that had been compared in ACTs ( P < .0001), and viewed ACTs as a more justifiable method for testing new antihypertensive drugs ( P < .0001). There was no evidence of nonresponse bias for these main results. CONCLUSIONS: Although PCTs remain the standard method for testing new antihypertensive drugs, physicians strongly prefer ACTs. Using ACTs to test new antihypertensive drugs may enhance the efficiency of patient recruitment and more strongly influence physicians' prescribing practices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73302/1/j.1525-1497.2002.11024.x.pd

Colloidal Semiconductor Nanocrystals for Artificial Photosynthesis

Light-driven reactions for solar fuels have been receiving tremendous interest, leading of the possibility to store solar energy, our biggest and cleanest renewable energy source. Efficient solar to fuel conversion needs photosynthetic materials with strong absorption and high photocatalytic properties. Colloidal semiconductor nanocrystals are cutting-edge materials for this application, thanks to their tunable optical and electronic properties through size, composition, morphology, and assembly. In this chapter, some insights on the challenges to improve photocatalytic performance are reported, followed by an overview of different parameters that can be controlled to cope with these limitations. Finally, some devices at the forefront are illustrated