| 1. |
- Fredenberg, Erik, 1979-
(författare)
-
Spectral Mammography with X-Ray Optics and a Photon-Counting Detector
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Early detection is vital to successfully treating breast cancer, and mammography screening is the most efficient and wide-spread method to reach this goal. Imaging low-contrast targets, while minimizing the radiation exposure to a large population is, however, a major challenge. Optimizing the image quality per unit radiation dose is therefore essential. In this thesis, two optimization schemes with respect to x-ray photon energy have been investigated: filtering the incident spectrum with refractive x-ray optics (spectral shaping), and utilizing the transmitted spectrum with energy-resolved photon-counting detectors (spectral imaging). Two types of x-ray lenses were experimentally characterized, and modeled using ray tracing, field propagation, and geometrical optics. Spectral shaping reduced dose approximately 20% compared to an absorption-filtered reference system with the same signal-to-noise ratio, scan time, and spatial resolution. In addition, a focusing pre-object collimator based on the same type of optics reduced divergence of the radiation and improved photon economy by about 50%. A photon-counting silicon detector was investigated in terms of energy resolution and its feasibility for spectral imaging. Contrast-enhanced tumor imaging with a system based on the detector was characterized and optimized with a model that took anatomical noise into account. Improvement in an ideal-observer detectability index by a factor of 2 to 8 over that obtained by conventional absorption imaging was found for different levels of anatomical noise and breast density. Increased conspicuity was confirmed by experiment. Further, the model was extended to include imaging of unenhanced lesions. Detectability of microcalcifications increased no more than a few percent, whereas the ability to detect large tumors might improve on the order of 50% despite the low attenuation difference between glandular and cancerous tissue. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.
|
|
| 2. |
- Amundin, Mats, et al.
(författare)
-
A proposal to use distributional models to analyse dolphin vocalisation
- 2017
-
Ingår i: Proceedings of the 1st International Workshop on Vocal Interactivity in-and-between Humans, Animals and Robots, VIHAR 2017. - 9782956202905 ; , s. 31-32
-
Konferensbidrag (refereegranskat)abstract
- This paper gives a brief introduction to the starting points of an experimental project to study dolphin communicative behaviour using distributional semantics, with methods implemented for the large scale study of human language.
|
|
| 3. |
- Fredenberg, Erik, PhD, 1979-, et al.
(författare)
-
A low-absorption x-ray energy filter for small-scale applications
- 2009
-
Ingår i: Optics Express. - : The Optical Society. - 1094-4087. ; 17:14, s. 11388-11398
-
Tidskriftsartikel (refereegranskat)abstract
- We present an experimental and theoretical evaluation of an x-ray energy filter based on the chromatic properties of a prism-array lens (PAL). It is intended for small-scale applications such as medical imaging. The PAL approximates a Fresnel lens and allows for high efficiency compared to filters based on ordinary refractive lenses, however at the cost of a lower energy resolution. Geometrical optics was found to provide a good approximation for the performance of a flawless lens, but a field-propagation model was used for quantitative predictions. The model predicted a 0.29 ΔE/E energy resolution and an intensity gain of 6.5 for a silicon PAL at 23.5 keV. Measurements with an x-ray tube showed good agreement with the model in energy resolution and peak energy, but a blurred focal line contributed to a 29% gain reduction. We believe the blurring to be caused mainly by lens imperfections, in particular at the periphery of the lens.
|
|
| 4. |
- Abbaspour, S., et al.
(författare)
-
Real-Time and Offline Evaluation of Myoelectric Pattern Recognition for the Decoding of Hand Movements
- 2021
-
Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 21:16
-
Tidskriftsartikel (refereegranskat)abstract
- Pattern recognition algorithms have been widely used to map surface electromyographic signals to target movements as a source for prosthetic control. However, most investigations have been conducted offline by performing the analysis on pre-recorded datasets. While real-time data analysis (i.e., classification when new data becomes available, with limits on latency under 200-300 milliseconds) plays an important role in the control of prosthetics, less knowledge has been gained with respect to real-time performance. Recent literature has underscored the differences between offline classification accuracy, the most common performance metric, and the usability of upper limb prostheses. Therefore, a comparative offline and real-time performance analysis between common algorithms had yet to be performed. In this study, we investigated the offline and real-time performance of nine different classification algorithms, decoding ten individual hand and wrist movements. Surface myoelectric signals were recorded from fifteen able-bodied subjects while performing the ten movements. The offline decoding demonstrated that linear discriminant analysis (LDA) and maximum likelihood estimation (MLE) significantly (p < 0.05) outperformed other classifiers, with an average classification accuracy of above 97%. On the other hand, the real-time investigation revealed that, in addition to the LDA and MLE, multilayer perceptron also outperformed the other algorithms and achieved a classification accuracy and completion rate of above 68% and 69%, respectively.
|
|
| 5. |
- Ranisch, Robert, et al.
(författare)
-
Ethics of digital contact tracing apps for the Covid-19 pandemic response
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- There is a growing interest in contact tracing apps (CT apps) for pandemic man- agement. These apps raise significant moral concerns. It is therefore crucial to consider ethical requirements before and while implementing such apps. Public trust is of major importance for population uptake of contact tracing apps. Hasty, ill-prepared or badly communicated implementations of CT apps will likely under- mine public trust, and as such, risk impeding general effectiveness. In response to these demands, to meet ethical requirements and find a basis for justified trust, this background introduces an ethical framework for a responsible design and implementation of CT apps. However, even prudently chosen measures of digital contact tracing carry moral costs, which makes it necessary address different trade-offs. This background paper aims to inform developers, researchers and decision-makers be- fore and throughout the process of implementing contact tracing apps.
|
|
| 6. |
|
|
| 7. |
- Schötz, Susanne, et al.
(författare)
-
Phonetic Characteristics of Domestic Cat Vocalisations
- 2017
-
Ingår i: Proceedings of the 1st International Workshop on Vocal Interactivity in-and-between Humans, Animals and Robots, VIHAR 2017. - 9782956202905 ; , s. 5-6
-
Konferensbidrag (refereegranskat)abstract
- The cat (Felis catus, Linneaus 1758) has lived around or with humans for at least 10,000 years, and is now one of the most popular pets of the world with more than 600 millionindividuals. Domestic cats have developed a more extensive, variable and complex vocal repertoire than most other members of the Carnivora, which may be explained by their social organisation, their nocturnal activity and the long period of association between mother and young. Still, we know surprisingly little about the phonetic characteristics of these sounds, and about the interaction between cats and humans.Members of the research project Melody in human–cat communication (Meowsic) investigate the prosodic characteristics of cat vocalisations as well as the communication between human and cat. The first step includes a categorisation of cat vocalisations. In the next step it will be investigated how humans perceive the vocal signals of domestic cats. This paper presents an outline of the project which has only recently started.
|
|
| 8. |
- Liu, Yuanhua, 1971, et al.
(författare)
-
Considering the importance of user profiles in interface design
- 2009
-
Ingår i: User Interfaces. ; , s. 23-
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- User profile is a popular term widely employed during product design processes by industrial companies. Such a profile is normally intended to represent real users of a product. The ultimate purpose of a user profile is actually to help designers to recognize or learn about the real user by presenting them with a description of a real user’s attributes, for instance; the user’s gender, age, educational level, attitude, technical needs and skill level. The aim of this chapter is to provide information on the current knowledge and research about user profile issues, as well as to emphasize the importance of considering these issues in interface design. In this chapter, we mainly focus on how users’ difference in expertise affects their performance or activity in various interaction contexts. Considering the complex interaction situations in practice, novice and expert users’ interactions with medical user interfaces of different technical complexity will be analyzed as examples: one focuses on novice and expert users’ difference when interacting with simple medical interfaces, and the other focuses on differences when interacting with complex medical interfaces. Four issues will be analyzed and discussed: (1) how novice and expert users differ in terms of performance during the interaction; (2) how novice and expert users differ in the perspective of cognitive mental models during the interaction; (3) how novice and expert users should be defined in practice; and (4) what are the main differences between novice and expert users’ implications for interface design. Besides describing the effect of users’ expertise difference during the interface design process, we will also pinpoint some potential problems for the research on interface design, as well as some future challenges that academic researchers and industrial engineers should face in practice.
|
|
| 9. |
- Pardon, Gaspard, 1983-
(författare)
-
From Macro to Nano : Electrokinetic Transport and Surface Control
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today, the growing and aging population, and the rise of new global threats on human health puts an increasing demand on the healthcare system and calls for preventive actions. To make existing medical treatments more efficient and widely accessible and to prevent the emergence of new threats such as drug-resistant bacteria, improved diagnostic technologies are needed. Potential solutions to address these medical challenges could come from the development of novel lab-on-chip (LoC) for point-of-care (PoC) diagnostics.At the same time, the increasing demand for sustainable energy calls for the development of novel approaches for energy conversion and storage systems (ECS), to which micro- and nanotechnologies could also contribute.This thesis has for objective to contribute to these developments and presents the results of interdisciplinary research at the crossing of three disciplines of physics and engineering: electrokinetic transport in fluids, manufacturing of micro- and nanofluidic systems, and surface control and modification. By combining knowledge from each of these disciplines, novel solutions and functionalities were developed at the macro-, micro- and nanoscale, towards applications in PoC diagnostics and ECS systems.At the macroscale, electrokinetic transport was applied to the development of a novel PoC sampler for the efficient capture of exhaled breath aerosol onto a microfluidic platform.At the microscale, several methods for polymer micromanufacturing and surface modification were developed. Using direct photolithography in off-stoichiometry thiol-ene (OSTE) polymers, a novel manufacturing method for mold-free rapid prototyping of microfluidic devices was developed. An investigation of the photolithography of OSTE polymers revealed that a novel photopatterning mechanism arises from the off-stoichiometric polymer formulation. Using photografting on OSTE surfaces, a novel surface modification method was developed for the photopatterning of the surface energy. Finally, a novel method was developed for single-step microstructuring and micropatterning of surface energy, using a molecular self-alignment process resulting in spontaneous mimicking, in the replica, of the surface energy of the mold.At the nanoscale, several solutions for the study of electrokinetic transport toward selective biofiltration and energy conversion were developed. A novel, comprehensive model was developed for electrostatic gating of the electrokinetic transport in nanofluidics. A novel method for the manufacturing of electrostatically-gated nanofluidic membranes was developed, using atomic layer deposition (ALD) in deep anodic alumina oxide (AAO) nanopores. Finally, a preliminary investigation of the nanopatterning of OSTE polymers was performed for the manufacturing of polymer nanofluidic devices.
|
|
| 10. |
- Petersson, Jesper, 1974, et al.
(författare)
-
Off the record: The invisibility work of doctors in a patient-accessible electronic health record information service.
- 2021
-
Ingår i: Sociology of health & illness. - : Wiley. - 1467-9566 .- 0141-9889. ; 43:5, s. 1270-1285
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we draw on Michael Lipsky's work on street-level bureaucrats and discretion to analyse a real case setting comprising an interview study of 30 Swedish doctors regarding their experiences of changes in clinical work following patients being given access to medical records information online. We introduce the notion of invisibility work to capture how doctors exercise discretion to preserve the invisibility of their work, in contrast to the well-established notion of invisible work, which denotes work made invisible by parties other than those performing it. We discuss three main forms of invisibility work in relation to records: omitting information, cryptic writing and parallel note writing. We argue that invisibility work is a way for doctors to resolve professional tensions arising from the political decision to provide patients with online access to record information. Although invisibility work is understood by doctors as a solution to government-initiated visibility, we highlight how it can create difficulties for doctors concerning accountability towards patients, peers and authorities.
|
|
