Wireless Sensor Networks (WSNs) have existed for many years and had assimilated many interesting innovations. Advances in electronics, radio transceivers, processes of IC manufacturing and development of algorithms for operation of such networks now enable creating energy-efficient devices that provide practical levels of performance and a sufficient number of features. Environmental monitoring is one of the areas in which WSNs can be successfully used. At the same time this is a field where devices must either bring their own power reservoir, such as a battery, or scavenge energy locally from some natural phenomena. Improving the efficiency of energy harvesting methods reduces complexity of WSN structures. This survey is based on practical examples from the real world and provides an overview of state-of-the-art methods and techniques that are used to create energyefficient WSNs with energy harvesting.

The aim of the present study was to search for event-related potential (ERP) correlates of processing pictures commonly described as “funny” but not preceded by the apparent “context-setting” phase. Three pairs of stimuli were used: (1) famous cartoon characters and images of household objects, (2) pictures reminiscent of a recently seen joke and similar pictures that did not produce such associations, (3) funny caricatures and drawings of neutral human faces. ERP differences in each pair were analyzed in two experiments. In the first experiment, both stimuli were targets in an “oddball” procedure, presented among the more frequent green disks. In the second experiment, they were both nontargets whereas the green disks were task-relevant. Both experiments and all pairs of stimuli produced similar results. ERPs for funny pictures were consistently more positive within the broad latency windows, resembling the effects of emotional arousal. Negative deflections, typical for incongruity processing, were not found. Such results indicated that these types of “humorous” images belonged to the class of affective stimuli that produced attentional reallocation of processing resources. The cognitive phase during which incongruity is detected and resolved was probably reduced to minimum or even absent.