Conditional stimuli (CS) that are paired with reward can be used to motivate instrumental responses. This process is called Pavlovian-instrumental transfer (PIT). A recent study in rats suggested that habitual responses are particularly sensitive to the motivational effects of reward cues. The current experiments examined this idea using ratio and interval training in mice. Two groups of animals were trained to lever press for food pellets that were delivered on random ratio or random interval schedules. Devaluation tests revealed that interval training led to habitual responding while ratio training produced goal-directed actions. The presentation of CSs paired with reward led to positive transfer in both groups, however, the size of this effect was much larger in mice that were trained on interval schedules. This result suggests that habitual responses are more sensitive to the motivational influence of reward cues than goal-directed actions. The implications for neurobiological models of motivation and drug seeking behaviors are discussed.
Nature has had millions of years to optimize photonic crystals -an endeavour mankind only really began in the 1980s. Often, we attempt to mimic and expand upon nature's designs in creating photonic structures that meet our technology-driven needs. While this strategy can be fruitful in fabricating novel architectures, one has to keep in mind that nature designed and optimized these structures for specific applications (e.g., colouration, camouflaging, signalling), but certainly not for use in photonic chips and optical circuits. To take full advantage of biological structures as blueprints for nanotechnology, it is important to understand the purpose and development of natural structural colours. In this review, we will discuss important aspects of the design, formation and evolution of the structures embedded in beetle exoskeletons that are responsible for their striking colouration. In particular, we will focus on the purpose of structural colours for camouflaging, mimicry and signalling. We will discuss their evolutionary and ecological development and compare the development of beetles with and without structural colours. Examples of non-colour-related structural functionalities will also be introduced and briefly discussed. Finally, a brief overview of nature's synthesis strategies for these highly evolved structures will be given, with particular focus on membrane assembly.
A total of 20 children with benign transient hyperphosphatasemia were prospectively evaluated with no additional investigations recommended except repeat serologic evaluation in 2-3 months. The average age of our patients was 2.5 years (range: 1 year 2 months-5 years 10 months). The serum levels of alkaline phosphatase averaged 2383 IU/L (range: 1013-5700 IU/L). Levels returned to normal within several months. This condition should be recognized by the clinician in order not to put patients through lengthy, expensive and unnecessary investigations.
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