What happens when an information technology (IT) division tries to introduce usability into its systems development process, especially in an organization whose core business is not software development? The result is usually an uphill battle to convince colleagues of the value of usability. This is an experience shared by countless usability practitioners. At industry conferences we gather together like self-help groups, sharing our experiences and frustration in trying to convince management of the benefits of usability. The constant complaint is "I just want to get on with my job, I'm tired of having to persuade people to 'do usability.'"

Hexavalent chromium (Cr(VI)) reduction using stannous chloride (SnCl 2 ) has emerged as a possible alternative to chromium treatment technologies such as strong base anion exchange. In an effort to target not only Cr(VI) reduction but, ultimately, total chromium (Cr(T)) removal, SnCl 2 addition followed by rapid sand filtration was tested at the pilot scale on a groundwater with a naturally occurring Cr(VI) concentration of 0.090 mg/L. A SnCl 2 dose of 1.5 mg/L, followed by filtration, was able to consistently remove Cr(T) to less than 0.010 mg/L following an initial ripening period, with limited head loss for 10 sequential 17-to 25-hr filter runs. Total tin and turbidity removal were similar, decreasing to below 0.050 mg/L and raw water levels, respectively. Analysis of filter sand following backwashes and three different material pipe segments that were exposed to unfiltered water dosed with SnCl 2 indicated the accumulation of Cr and Sn on surfaces, which remains a concern.

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We report some new observations on what could be regarded as the world’s simplest visual illusion—the autokinetic effect. When a single dim spot of light is viewed in a completely dark room, it moves vividly in random directions. During steady fixation, perhaps subtle eye movements cause the image to move and a failure to correct for this using eye movement command signals leads to motion perception. This is especially true because eye muscle fatigue can lead to miscalibration. However, if two dots are shown, they often move independently in different directions, which negate the eye movement theory. In addition, two lines defining a single cross sometimes uncouple and slide past each other and the fragments composing a hidden object move independently until they click in place and the whole object is perceived—implying that the illusion occurs relatively late in visual processing. Finally, the effect is modulated by vestibular stimulation; anchoring your sense of self may be a prerequisite for binding features into coherent objects.

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