| 180291. |
- Morahan, Ashley J., et al.
(författare)
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Impact of DOI in a Clinical SPECT/MRI System : A Simulation Study
- 2020
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Ingår i: 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2020. - 9781728176932
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Konferensbidrag (refereegranskat)abstract
- A novel SPECT/MRI scanner has been modelled and tested here using Monte Carlo simulation software, SIMIND. The INSERT SPECT/MRI system faces challenges with event reconstruction due to photon depth of interaction. The novel SPECT system is subject to parallax errors due to its crystal size and slit aperture collimator. We present a simple measure of the DOI errors through SIMIND experiments; by modelling the DOI layers we are able to improve the reconstruction of projection data in the INSERT scanner. A set of capillary phantoms are simulated to explore the impact of DOI on the resolution of the scanner and establish corrections in the system's reconstruction.
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| 180292. |
- Morain-Nicolier, Frédéric, et al.
(författare)
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Binary pattern matching from a local dissimilarity measure
- 2010
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Ingår i: 2010 2nd International Conference on Image Processing Theory, Tools and Applications, IPTA 2010. - : IEEE. - 9781424472482 ; , s. 417-420
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Konferensbidrag (refereegranskat)abstract
- This communication deals with finding the position of a reference shape in a given image. The proposed matcher is constructed from local dissimilarity maps. These maps allow to efficiently and robustly measure the differences between two images. It is shown an example that the matcher potentially returns less false-positives than a reference method (chamfer matching). This is possible as the local dissimilarity measure is symmetric, which makes it more robust to noise.We show that the proposed matcher is a generalization of the chamfer matching. It also allows fast computation times. A good robustness to noise is confirmed from presented simulations.
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| 180293. |
- Morain-Nicolier, Frédéric, et al.
(författare)
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Gray level local dissimilarity map and global dissimilarity index for quality of medical images
- 2009
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Ingår i: 7th IFAC Symposium on Modelling and Control in Biomedical Systems (including Biological Systems) MCBMS’09. - : Elsevier. - 9783902661494 ; , s. 281-286
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Konferensbidrag (refereegranskat)abstract
- In order to evaluate performance quality of coding techniques, it is needed to have a good global index and a local index allowing the localisation of the distortions. In this study, a local dissimilarity map is presented for gray-level images. Its application to the comparison of a compressed image and its reference allows an excellent visual detection of the distortions. A global dissimilarity index is computed from the local dissimilarity map. These new measures are compared to the structural similarity index (SSIM). The results of the global measure are as good as the SSIM. The results of the local measure are quite superior to the SSIM computed in a local window. We claim these good results come from the consistency of the proposed index. It is more consistent to compute a global measure from a local one, than a local measure from a global one.
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| 180294. |
- Morais, António P., et al.
(författare)
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Multi-peaked signatures of primordial gravitational waves from multi-step electroweak phase transition
- 2019
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Ingår i: European Physical Society Conference on High Energy Physics (EPS-HEP2019). - Trieste, Italy : Sissa Medialab. - 1824-8039. ; 364
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Konferensbidrag (refereegranskat)abstract
- The first-order electroweak phase transition in the early universe could occur in multiple steps leading to specific multi-peaked signatures in the primordial gravitational wave (GW) spectrum. We argue that these signatures are generic phenomena in multi-scalar extensions of the Standard Model. In a simple example of such an extension, we have studied the emergence of reoccuring and nested vacuum bubble configurations and their role in the formation of multiple peaks in the GW spectrum. The conditions for potential detectability of these features by the forthcoming generation of interferometers have been studied.
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| 180295. |
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| 180296. |
- Moraiti, Kalliopi, 1992
(författare)
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Critically exploring teachers’ work activities in relation to LMS through an “LMS go-along” method.
- 2021
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Ingår i: Paper for Swedish Educational Research Association (SWERA), PhD Council, spring seminar 2021, online - 26 Maj. - PhD council spring seminar 2021, online - 26 Maj : Swedish Educational Research Association (SWERA). - 1401-6788 .- 2001-3345.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- I will present a pilot for the first study out of the three studies that will be conducted as part of my dissertation work. The focus of my dissertation is to critically explore Swedish upper secondary school teachers’ use and approach to Learning Management Systems (LMSs) as part of their professional work. More specifically, this first study aims to explore how the LMS shapes and how is it shaped by teachers’ work activities by focusing on the negotiations between different professional work tasks. A pilot study was performed between January and February of 2021 to gather data on university teachers’ experiences of using a specific learning management system namely Canvas in higher education and to test a go-along methodology for the thesis project. An “LMS go-along” method aims for data production through a ‘virtual tour’ in LMSs between a researcher and a participant. It enables the researcher to follow individual participants in their natural environment and ask questions, listen and observe the participant´s practices. The results showed that the main tasks that the teachers accomplished through Canvas and brought up in the go-along method sessions are the course design, communication with students, assessment, grading, and adding events in the calendar. However, their possibility of action was constrained by three factors; the technical limitations of LMS, the fulfillment of the demands of ‘market’, and the fulfillment of the demands of ‘bureaucracy’.
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| 180297. |
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| 180298. |
- Moraitis, Michail, et al.
(författare)
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A side-channel resistant implementation of AES combining clock randomization with duplication
- 2023
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Ingår i: ISCAS 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Deep learning transformed side-channel analysis and made many conventional countermeasures obsolete. This brings the need for more effective, deep learning-resistant defense mechanisms. We propose a method for protecting hardware implementations of cryptographic algorithms that combines clock randomization with duplication. The presented method ensures that the duplicated block generates algorithmic noise that is dependent on the input of the primary block and has a similar power profile. In addition, the duplicated block does not create any secret key-related leakage. We evaluate the presented method on the example of the Advanced Encryption Standard (AES) algorithm implemented in FPGA. Our experimental results show that the protected AES implementation is resistant to deep learning-based power analysis.
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| 180299. |
- Moraitis, Michail, et al.
(författare)
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Bitstream Modification Attack on SNOW 3G
- 2020
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Ingår i: Proceedings of the 2020 design, automation & test in europe conference & exhibition (date 2020). - : IEEE. ; , s. 1275-1278
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Konferensbidrag (refereegranskat)abstract
- SNOW 3G is one of the core algorithms for confidentiality and integrity in several 3GPP wireless communication standards, including the new Next Generation (NG) 5G. It is believed to be resistant to classical cryptanalysis. In this paper, we show that SNOW 3G can be broken by a fault attack based on bitstream modification. By changing the content of some look-up tables in the bitstream, we reduce the non-linear state updating function of SNOW 3G to a linear one. As a result, it becomes possible to recover the key from a known plaintext-ciphertext pair. To our best knowledge, this is the first successful bitstream modification attack on SNOW 3G.
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| 180300. |
- Moraitis, Michail, et al.
(författare)
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Breaking ACORN at Bitstream Level
- 2020
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Ingår i: 2020 IFIP/IEEE 28TH INTERNATIONAL CONFERENCE ON VERY LARGE SCALE INTEGRATION (VLSI-SOC). - : IEEE. ; , s. 117-122
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Konferensbidrag (refereegranskat)abstract
- Assuring the security of the Internet of Things (IoT) is much more challenging than assuring the security of centralized environments, like the cloud. A reason for this is that IoT devices are often deployed in domains that are remotely managed and monitored. Thus, they cannot be protected from physical attacks as reliably as data centers. Up till now, implementations of many established, standardized algorithms including AES and SNOW 3G have been broken by physical attacks. In this paper, we show that even the most recently designed algorithms are also vulnerable. We attack an SRAM-based FPGA implementation of ACORN v3 stream cipher, a finalist of CAESAR cryptographic competition for authenticated encryption. By modifying the content of several look-up tables directly in the bitstream, we inject faults which reduce the nonlinear feedback function of ACORN to a linear one. As a result, it becomes possible to extract the full key from 2(15.34) bits of faulty keystream by an algebraic attack using 2(35.46) operations. Our results, once again confirm the necessity to rethink the way cryptographic algorithms are implemented in FPGAs.
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