Falsification testing for usability inspection method assessment

We need more reliable usability inspection methods (UIMs), but assessment of UIMs has been unreliable [5]. We can only reliably improve UIMs if we have more reliable assessment. When assessing UIMs, we need to code analysts’ predictions as true or false positives or negatives, or as genuinely missed problems. Defenders of UIMs often claim that false positives cannot be accurately coded, i.e., that a prediction is true but has never shown up through user testing or other validation approaches. We show this and similar claims to be mistaken by briefly reviewing methods for reliable coding of each of five types of prediction outcome. We focus on falsification testing, which allows confident coding of false positives

Inspection based evaluations

Usability inspection methods (UIMs) remain an important discount method for usability evaluation. They can be applied to any designed artefact during development: a paper prototype, a storyboard, a working prototype (e.g., in Macromedia Flash™ or in Microsoft PowerPoint™), tested production software, or an installed public release. They are analytical evaluation methods, which involve no typical end users, unlike empirical methods such as user testing. UIMs only require availability of a designed artefact and trained analysts. Thus, evaluation is possible with low resources (hence discount methods). Although risks arise from low resources, well-informed practices disproportionately improve analyst performance, improving cost-benefit ratios. This chapter introduces UIMs, covering six and one further method, and provides approaches to assessing existing, emerging and future UIMs and their effective uses

The degradation of p53 and its major E3 ligase Mdm2 is differentially dependent on the proteasomal ubiquitin receptor S5a.

p53 and its major E3 ligase Mdm2 are both ubiquitinated and targeted to the proteasome for degradation. Despite the importance of this in regulating the p53 pathway, little is known about the mechanisms of proteasomal recognition of ubiquitinated p53 and Mdm2. In this study, we show that knockdown of the proteasomal ubiquitin receptor S5a/PSMD4/Rpn10 inhibits p53 protein degradation and results in the accumulation of ubiquitinated p53. Overexpression of a dominant-negative deletion of S5a lacking its ubiquitin-interacting motifs (UIM)s, but which can be incorporated into the proteasome, also causes the stabilization of p53. Furthermore, small-interferring RNA (siRNA) rescue experiments confirm that the UIMs of S5a are required for the maintenance of low p53 levels. These observations indicate that S5a participates in the recognition of ubiquitinated p53 by the proteasome. In contrast, targeting S5a has no effect on the rate of degradation of Mdm2, indicating that proteasomal recognition of Mdm2 can be mediated by an S5a-independent pathway. S5a knockdown results in an increase in the transcriptional activity of p53. The selective stabilization of p53 and not Mdm2 provides a mechanism for p53 activation. Depletion of S5a causes a p53-dependent decrease in cell proliferation, demonstrating that p53 can have a dominant role in the response to targeting S5a. This study provides evidence for alternative pathways of proteasomal recognition of p53 and Mdm2. Differences in recognition by the proteasome could provide a means to modulate the relative stability of p53 and Mdm2 in response to cellular signals. In addition, they could be exploited for p53-activating therapies. This work shows that the degradation of proteins by the proteasome can be selectively dependent on S5a in human cells, and that this selectivity can extend to an E3 ubiquitin ligase and its substrate

UIMS: Toward the Next Generation

First generation User Interface Management Systems (UIMS) have established themselves in both research and commercial areas. This paper discusses improved usability and extension of UIMS to include a broader whole system development life cycle as the basis for evolution of a second generation of UIMS. Problems of first generation UIMS, some informal empirical work that is leading toward an interface development life cycle and UIMS to directions for the anticipated evolution are presented

A grammatical specification of human-computer dialogue

The Seeheim Model of human-computer interaction partitions an interactive application into a user-interface, a dialogue controller and the application itself. One of the formal techniques of implementing the dialogue controller is based on context-free grammars and automata. In this work, we modify an off-the-shelf compiler generator (YACC) to generate the dialogue controller. The dialogue controller is then integrated into the popular X-window system, to create an interactive-application generator. The actions of the user drive the automaton, which in turn controls the application

Building Bridges and Interfaces: Toward the Next Generation of UIMS

User interface management systems (UIMS) have established themselves in both research and commercial arenas. We present several generations in UIMS evolution and discuss some problems of the early generations. In particular, we discuss the problems of a gap between methods used by behavioral scientists and computer scientists during the process of building interfaces. We present an empirical approach to begin bridging this gap and results of our preliminary observations: a human-computer interface development life cycle and recording techniques for interface development, as well as UIMS needed to support them. We conclude with future directions for the evolution of UIMS

Interactive Tools: Making UIMS Usable

The earliest UIMS provided primarily run-time facilities for interface management and a set of programming tools for the development of application from the implementation requirements with which many tool designers have approached UIMS design, there are also methodological requirements that have been seriously neglected. One reason is that interface design methodology is poorly understood and rarely axiomatic. Nevertheless, it is important that we formulate methodological theories and provide UIMS with tools that support them. This paper proposes a storyboard metaphor for the conceptual design of human-computer interfaces

Ubiquitylation activates a peptidase that promotes cleavage and destabilization of its activating E3 ligases and diverse growth regulatory proteins to limit cell proliferation in Arabidopsis

The characteristic shapes and sizes of organs are established by cell proliferation patterns and final cell sizes, but the underlying molecular mechanisms coordinating these are poorly understood. Here we characterize a ubiquitin-activated peptidase called DA1 that limits the duration of cell proliferation during organ growth in Arabidopsis thaliana. The peptidase is activated by two RING E3 ligases, Big Brother (BB) and DA2, which are subsequently cleaved by the activated peptidase and destabilized. In the case of BB, cleavage leads to destabilization by the RING E3 ligase PROTEOLYSIS 1 (PRT1) of the N-end rule pathway. DA1 peptidase activity also cleaves the deubiquitylase UBP15, which promotes cell proliferation, and the transcription factors TEOSINTE BRANCED 1/ CYCLOIDEA/PCF 15 (TCP15) and TCP22, which promote cell proliferation and repress endoreduplication. We propose that DA1 peptidase activity regulates the duration of cell proliferation and the transition to endoreduplication and differentiation during organ formation in plants by coordinating the destabilization of regulatory proteins