400 research outputs found
Notions and relations for RKA-secure permutation and function families
The theory of designing block ciphers is mature, having seen signi¯cant
progress since the early 1990s for over two decades, especially during the AES devel-
opment e®ort. Nevertheless, interesting directions exist, in particular in the study of
the provable security of block ciphers along similar veins as public-key primitives, i.e.
the notion of pseudorandomness (PRP) and indistinguishability (IND). Furthermore,
recent cryptanalytic progress has shown that block ciphers well designed against known
cryptanalysis techniques including related-key attacks (RKA) may turn out to be less
secure against related-key attacks than expected. The notion of provable security of
block ciphers against related-key attacks was initiated by Bellare and Kohno, and sub-
sequently treated by Lucks. Concrete block cipher constructions were proposed therein
with provable security guarantees. In this paper, we are interested in the security no-
tions for RKA-secure block ciphers
Density functional theory of phase coexistence in weakly polydisperse fluids
The recently proposed universal relations between the moments of the
polydispersity distributions of a phase-separated weakly polydisperse system
are analyzed in detail using the numerical results obtained by solving a simple
density functional theory of a polydisperse fluid. It is shown that universal
properties are the exception rather than the rule.Comment: 10 pages, 2 figures, to appear in PR
Variation individuelle des paramètres de marche au long d'une distance de 500m chez des personnes atteintes de sclérose en plaques et chez des volontaires sains
Background: we previously demonstrated the usefulness of the Deceleration Index (DI, the ratio between the last 100m of the Timed 500-Meter Walk test –T500MW – and the walking speed - WS – of the Timed 25-Foot Walk Test with a propelled start – T25FW+) to evaluate motor fatigue over a long walking distance in people with multiple sclerosis (pwMS). We also recently designed and internally validated a new gait analysis tool for pwMS (GAIMS) that can measure other relevant gait characteristics than the sole WS, such as ataxia, asymmetry and perhaps spasticity.
Aims: (i) To compare various gait characteristics between the last and the first 100m of the T500MW in a population of pwMS and healthy volunteers (HV), (ii) to compare the ratio between the last and the first 100m of the T500MW with the DI, and (iii) their relationship with the EDSS.
Methods : Subjects were asked to perform the T25FW+ and the T500MW as part of a multimodal evaluation at the MS Clinic of the CHU of Liège. Their gait characteristics were measured using GAIMS. (i) Paired Student’s t-tests were performed on various gait characteristics extracted during the last and first 100m of the T500MW with .05 as a level of significance, (ii) Spearman correlation coefficient (ρ) was calculated (ii) between these ratio and (iii) subject’s EDSS.
Results: Seventy-one pwMS and 129 were enrolled in our study. (i) Significant differences were observed for speed related gait characteristics between the last and first 100m of the T500MW, but also for gait characteristics related to ataxia and precision of foot placement. (ii) A moderate positive correlation was observed between the WS ratio of the last and first 100m of the T500MW and the DI. (iii) The correlation between the DI and the EDSS was weakly negative, while the one between the last and first 100m of the T500MW ratio and the EDSS was moderatly negative.
Conclusion: (i) As previously demonstrated, we here confirm that alongside to WS, there are other gait features affected by locomotor fatigue over a long walking distance, (ii) the moderate positive correlation between the DI and the last/first 100m of the T500MW indicates that these measures are not the same and that next to a long distance walking test such as the T500MW, a short one such as the T25FW+ remains useful. (iii) The last/first 100m of the T500MW is better correlated to the EDSS and might be a better predictive tool of pwMS’ neurologic state than the DI
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