H. de Ridder

A newly designed ergonomic body support for surgeons.

BackgroundOne of the main ergonomic problems during surgical procedures is the surgeon’s awkward body posture, often accompanied by repetitive movements of the upper extremities, increased muscle activity, and prolonged static head and back postures. In addition, surgeons perform surgery so concentrated that they tend to neglect their posture. These observations suggest the advantage of supporting the surgeon’s body during surgical procedures. This study aimed to design a body support and to test its potential.MethodsThe optimum working condition for a surgeon is a compromise between the spine and arm positions and the level of effort and fatigue experienced performing a procedure. The design vision of the Medisign group has led to the development of an ergonomic body support for surgeons that is suitable for use during both open and minimally invasive procedures. The feasibility of the newly designed ergonomic body support was assessed during seven surgical procedures. Electromyography (EMG) was performed for back and leg muscles using the body support in an experimental setting.ResultsSix of seven participating surgeons indicated that the body support was comfortable, safe, and simple to use. The EMG results show that supporting the body is effective in reducing muscle activity. The average reduction using chest support was 44% for the erector spinae muscle, 20% for the semitendinosus muscle, and 74% for the gastrocnemius muscle. The average muscle reduction using semistanding support was 5% for the erector spinae, 12% for the semitendinosus muscle, and for 50% for the gastrocnemius muscle.ConclusionThe results of this study imply that supporting the body is an effective way to reduce muscle activity, which over the long term may reduce physical problems and discomfort. Additionally, the product supports the surgeon in his natural posture during both open and minimally invasive procedures and can easily be adapted to the current layout of the operating theater.

Image Analysis: Focus on Texture Similarity

Texture is an important visual attribute both for human perception and image analysis systems. We review recently proposed texture similarity metrics and applications that critically depend on such metrics, with emphasis on image and video compression and content-based retrieval. Our focus is on natural textures and structural texture similarity metrics (STSIMs). We examine the relation of STSIMs to existing models of texture perception, texture analysis/synthesis, and texture segmentation. We emphasize the importance of signal characteristics and models of human perception, both for algorithm development and testing/validation.

Development and application of a framework for comparing early design methods for young children

When designing with young children, designers usually select user centred design methods based on the childrens required level of engagement and the inspiration expected to be created according to the designer. User centred design methods should be selected for their suitability for children and for the quality of the output of the design method. To understand the suitability of design methods, a framework was developed to describe design methods in terms of required design skills as identified by the Theory of Multiple Intelligences. The proposed framework could provide the basis for a tool to compare design methods and to generate hypotheses about what design method would work optimally with children in a specific school grade. The initial examination of the viability of the framework is a comparison of design methods by the number of skills involved; earlier work showed that the involvement of more skills (as with, e.g. low-fi prototyping) could result in more options for a design problem than the involvement of fewer skills (as with e.g. brainstorming). Options and Criteria were counted to understand the quality of the method in terms of the amount of design-information. The results of the current paper indicate that 8-to-10-year-old children generate significantly more options in prototyping sessions than when they are involved in sessions applying a Nominal Group Technique. The paper indicates that (a) with the framework we can generate hypotheses to compare design methods with children and (b) that the outcome of various design methods, which might lead to very different representations, can be compared in terms of Options and Criteria. Further usage of the framework is expected to result in empirical support for selecting a design method to be applied with young children.

P-15: Presence as an Experiential Metric for 3-D Display Evaluation

In this paper, we argue that the experience of presence, i.e. the sense of “being there” in a mediated environment, provides us with a useful criterion to assess the global experiential impact of immersive and perceptually realistic display and communication media in general, and 3-D displays in particular. Measuring presence in a reliable, valid and robust manner is a considerable challenge to media research and methodology development. We present an experiment in which we attempt to measure presence both through subjective ratings, and through measuring postural responses, i.e. automatic postural adjustments in response to moving video which are hypothesized to corroborate subjective presence ratings.

Image processing and the problem of quantifying image quality

The problem of quantifying perceived quality of processed images is traditionally solved by associating quality with the deviation from the undistorted original. This paper presents experiments challenging two underlying assumptions, namely (1) the original always possesses the highest quality and (2) quality cannot be determined without a direct comparison between the original and processed image. In doing so, percentage scaling is introduced as a scaling procedure for evaluating multiply impaired images.The problem of quantifying perceived quality of processed images is traditionally solved by associating quality with the deviation from the undistorted original. This paper presents experiments challenging two underlying assumptions, namely (1) the original always possesses the highest quality and (2) quality cannot be determined without a direct comparison between the original and processed image. In doing so, percentage scaling is introduced as a scaling procedure for evaluating multiply impaired images.

A learning environment for sign language

We have developed a prototype for a learning environment for deaf and hard of hearing children. This demonstration consists of hands-on experience with the prototype. In total, there are three exercises: 1) an introduction of all pictures and corresponding signs, 2) multiple choice sign-to-picture and 3) performing the sign that corresponds to the picture shown on the screen. The live recognition from a wide-angle stereo camera provides immediate feedback for the third exercise where the sign must be performed.

Signs in Which Handshape and Hand Orientation Are Either Not Visible or Are Only Partially Visible: What Is the Consequence for Lexical Recognition?

We present the results of an experiment on lexical recognition of human sign language signs in which the available perceptual information about handshape and hand orientation was manipulated. Stimuli were videos of signs from Sign Language of the Netherlands (SLN). The videos were processed to create four conditions: (1) one in which neither handshape nor hand orientation could be observed, (2) one in which hand orientation could be extracted but not handshape, (3) one in which an approximation of the handshape could be seen, and (4) one where the video was unmodified. In general, recognition of the signs was almost impossible in the first two conditions, while condition 3 showed a rise in recognition rate to about 60 percent However, some signs were recognized well even in conditions 1 and 2. Their success rate cannot be linked to a single sign property but seems to be due to a combination of factors. In general, handshape information appears more salient for resolving the lexical meaning of a sign than hand orientation.