Normalized histogram of the state variable of first-order digital filters with two’s complement arithmetic

In this letter, the normalized histogram of the state variable of first-order digital filters with two’s complement arithmetic is investigated. When the pole of the digital filter is between 1 and 2, it is found that the possibility of occurrence of the state variable in certain region is close to zero no matter what the initial condition is. Some analytic results are given to account for this phenomenon

Prompts or proximity? Recycling old techniques for a new population

Sign posting and container proximity manipulations have been shown to be effective methods of increasing recycling in university and corporate settings. The generalizability of these methods to other populations is unknown. The current study used an ABCDEAB reversal design to examine recycling behavior in an adult mental health population at a local socialization center. During baseline (A), the amount of recyclable materials placed in trash containers was monitored. Recycling containers were then introduced to the center. During intervention phases, recycling and trash containers were placed adjacent to each other without signs (B), 4 meters apart without signs (C), adjacent to each other with signs (D), and 4 meters apart with signs (E). A brief reversal to baseline was then implemented followed by reinstating the least intrusive-most effective treatment. Results indicated that placing recycling and trash containers in close proximity (with or without signage) yielded the greatest overall increase in recycling behavior. Moreover, patrons of the center were able to reliably assist in data collection and maintain the project following the withdrawal of intervention. Techniques for increasing recycling behavior can be extended to a novel population and setting, albeit with some unique challenges to data collection (e.g., can theft)

Solid-state semiconductors are better alternatives to arc-lamps for efficient and uniform illumination in minimal access surgery

Current arc-lamp illumination systems have a number of technical and ergonomic limitations. White light-emitting diodes (LEDs) are energy-efficient solid-state lighting devices which are small, durable and inexpensive. Their use as an alternative to arc-lamp light sources in minimal access surgery has not been explored. This study aims to develop an LED-based endo-illuminator and to determine its lighting characteristics for use in minimal access surgery. METHODS: We developed an LED endo-illuminator using a white LED mounted at the tip of a steel rod. Offline image analysis was carried out to compare the illuminated field using the LED endo-illuminator or an arc-lamp based endoscope in terms of uniformity, shadow sharpness and overall image intensity. Direct radiometric power measurements in light intensity and stability were obtained. Visual perception of fine details at the peripheral endoscopic field was assessed by 13 subjects using the different illumination systems. RESULTS: Illumination from the LED endo-illuminator was more uniform compared to illumination from an arc-lamp source, especially at the closer distance of 4 cm (0.0006 versus 0.0028 arbitrary units--lower value indicates more uniform illumination). The shadows were also sharper (edge widths of 16 versus 44 pixels for the first edge and 15 versus 61 pixels for the second edge). The overall mean image intensity was higher (127 versus 100 arbitrary units) when using the autoshutter mode despite the lower direct radiometric power, about one tenth of the arc-lamp endoscopic system. The illumination was also more stable with less flickering (0.02% versus 5% of total power in non-DC components). Higher median scores on visual perception was also obtained (237 versus 157, p < 0.001). CONCLUSION: The LED endo-illuminator provides more uniform illumination with sharper shadows, less flickering and better illumination for visual perception than the arc-lamp-based system currently used