Button

Summary

A button is a fastener that joins two pieces of fabric together by slipping through a loop or by sliding through a buttonhole. In modern clothing and fashion design, buttons are commonly made of plastic but also may be made of metal, wood, or seashell. Buttons can also be used on containers such as wallets and bags. Buttons may be sewn onto garments and similar items exclusively for purposes of ornamentation. In the applied arts and craft, a button can be an example of folk art, studio craft, or even a miniature work of art. In archaeology, a button can be a significant artifact. History Buttons and button-like objects used as ornaments or seals rather than fasteners have been discovered in the Indus Valley civilization during its Kot Diji phase (c. 2800–2600 BC), at the Tomb of the Eagles, Scotland (2200-1800 BC), and at Bronze Age sites in China (c. 2000–1500 BC) and Ancient Rome. Buttons made from seashell were used in the Indus Valley Civilization for ornamental pu

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The research presented in this thesis is motivated by the aim to employ microfluidic devices for high-throughput analysis. Two applications, in particular, have been explored: diagnostics and environmental sensing. Miniaturization and multiplexing of laboratory procedures leads to a decrease of the cost and response time of the test. Moreover miniaturization allows the system to become portable, enabling use in the field without bulky external equipment. This need is paving the way for innovative approaches and microfluidics can be a suitable substitute for standard bench top techniques. In order to be appealing, these new technologies should have the same or even better performances over the standard techniques, not only in terms of time and cost, but also quality of results. First, we developed a multilayer microfluidic platform for high-throughput immunoassay analysis. The device is composed of 384 units, each of them containing 4 mechanically induced trapping of molecular interactions (MITOMI) buttons, where the interaction of antibodies and antigens occurs. Therefore, the platform allows us to perform 1'536 tests, and we show that it can be useful for large scale screening in order to identify functional antibody pairs. However this system has two limitations: the experimental time (~10 hours) and the sensitivity (pM). In the second part, we presented another device modified in order to overcome the aforementioned drawbacks and to become more suitable for point of care applications. This new version of the device has 16 independent units, and the MITOMI buttons are patterned with femtoliter wells for digital analysis. We show how digital ELISA improves the sensitivity and allows us to detect down to fM concentrations in human serum. We also show how the combination of both digital and analog detection can broaden the dynamic range. A portable automatic controller has also been built to control the valves and the flow throughout the chip and a USB microscope has been exploited in order to measure the fluorescent signal. In the last part we present a different application for high-throughput microfluidic-based devices. A microfluidic device composed of 769 units has been developed for bacterial cell culture and environmental monitoring. Each unit can be considered as a pixel and the entire device as a biodisplay. Each unit contains a specific bacterial strain, which is deposited using microspotting techniques. We show how different bacterial strains can be cultured over time without contamination between pixels and how they can be monitored after induction. Cells can be spotted according to a specific pattern on the chip and express fluorescent protein reporters in the presence of specific molecules allowing an easy to interpret result of the test. For example, the image of a âskull and crossbonesâ appears if the analyzed sample is contaminated with arsenic. Overall, the presented work provides several microfluidic platforms for high-throughput analysis of clinical or environmental samples; these devices are useful tools for the study of a large number of proteins and molecular diagnostic applications and to characterize bacterial strains and environmental monitoring.

EPFL2017

Evaluation of Proportional and Discrete Shared Control Paradigms for Low Resolution User Inputs

Tom Edward Carlson, Robert Leeb, Guillaume Monnard

For people with severe physical disabilities, low resolution input devices, such as buttons, sip and puff switches and brain–computer interfaces provide an opportunity to interact with the world. However, it can be difficult to control assistive technology, such as wheelchairs, tele–presence robots and robotic arms, when you have only a limited number of commands available and/or a lack of temporal precision in issuing such commands. These limitations can be overcome by employing shared control techniques, whereby the system assists the user in performing the desired task. In this study we compare the use of a simple discrete shared control policy with a more dynamic proportional shared control policy. We evaluate both approaches on a wheelchair that is only operated by two temporally– constrained discrete buttons. The experiments were performed in two different realistic indoor scenarios: an open–plan, spacious environment and a smaller, more cluttered ofﬁce environment. A total of 10 healthy participants took part in this study.

IEEE2011

Monitoring our actions is a key function of the brain for adaptive and successful behavior. Actions can be discrete such as when pressing a button, or continuous, such as driving a car. Moreover, we evaluate our actions as correct or erroneous (performance monitoring) and this appraisal of performance comes with various levels of confidence (metacognition). However, studies of performance monitoring have focused on discrete actions and are mostly agnostic to metacognitive judgments. The objective of this thesis was to extend the study of performance monitoring to more ecological conditions, in which monitoring occurs during continuous motor tasks under various degrees of error and confidence level. We first investigated the role of actions in performance monitoring together with metacognitive judgments, using simultaneous EEG and fMRI recordings. To dissociate the role of motor actions, we designed an experimental paradigm in which subjects had to rate their confidence level about an action that they had either performed themselves (a button press) based on a decision or passively observed (a virtual hand displayed). We found correlates of confidence in both condition, in the EEG and in the supplementary motor area (SMA). Furthermore, we found that subject showed better metacognitive performances when they were the agents of the action. This difference was further emphasized for subjects that showed higher activations of a network previously linked to motor inhibition and comprising the pre-SMA and inferior frontal gyrus (IFG). Our results imply that the SMA plays a primary role in the monitoring of performance, irrespectively of a commitment to a decision and the resulting action. Our findings also suggest that the additional neural processes leading to decisions and actions can inform the metacognitive judgments. In the following chapters, we ask whether electrophysiological correlates of performance monitoring can be found in less experimentally constrained paradigms for which motor output continuous unfolds and visual feedback is not segregated into discrete events. By decomposing the unfolding hand kinematics during a visuo-motor tracking task into periodic acceleration pulses âhenceforth referred to as sub-movements, we found three electrophysiological markers that could possibly be linked to performance monitoring. Firstly, we found an ERP in the SMA, time-locked to sub-movements which encoded the deviation of the hand, 110 ms before. Secondly, we found high-gamma activity in the ACC and SMA of epileptic patients, that was phase-locked to sub-movements. Thirdly, we found a transient modulation of mu oscillations over the ipsilateral sensorimotor cortices that depended on sub-movement amplitude. Altogether, these results provide a strong contribution in the understanding of the neurophysiological processes underlying performance monitoring. Our work proposes a methodological framework to study electrophysiological correlates of performance monitoring in less controlled paradigms during which continuous visual feedback has to be constantly integrated into motor corrections. In the conclusion chapter, we propose a way of extending current models of performance monitoring and decision making to explain the findings of this thesis by considering continuous motor tasks as a succession of decision making processes under time pressure and uncertainty.

EPFL2018