Gait analysis of patients with knee osteoarthritis highlights a pathological mechanical pathway and provides a basis for therapeutic interventions

Knee osteoarthritis (OA) is a painful and incapacitating disease affecting a large portion of the elderly population, for which no cure exists. There is a critical need to enhance our understanding of OA pathogenesis, as a means to improve therapeutic options. Knee OA is a complex disease influenced by many factors, including the loading environment. Analysing knee biomechanics during walking - the primary cyclic load-bearing activity - is therefore particularly relevant. There is evidence of meaningful differences in the knee adduction moment, flexion moment and flexion angle during walking between non-OA individuals and patients with medial knee OA. Furthermore, these kinetic and kinematic gait variables have been associated with OA progression. Gait analysis provides the critical information needed to understand the role of ambulatory biomechanics in OA development, and to design therapeutic interventions. Multidisciplinary research is necessary to relate the biomechanical alterations to the structural and biological components of OA. Cite this article: Favre J, Jolles BM. Analysis of gait, knee biomechanics and the physiopathology of knee osteoarthritis in the development of therapeutic interventions. EFORT Open Rev 2016;1:368-374. DOI: 10.1302/2058-5241.1.000051

Four quadrant 120 A, 10 V power converters for LHC

The LHC (Large Hadron Collider) particle accelerator makes extensive use of true bipolar power converters, with a high precision regulated output current requirement. A special design and topology is required to allow high performance within the converter operating area, including quadrant transition. This paper presents the ±120A ±10V power converter, well represented in the LHC power converters (300 units). The design is adapted for a wide range of magnet loads [from 10mH to 4 Henry] (time constant load [0.1s..1050s]) with stringent EMC requirements. A quick-connect system was applied to the converter modules allowing easy installation and maintenance operations. Discussion of 4 quadrant control and practical results are presented

Effect of Calcium-Channel Blockade on the Aldosterone Response to Sodium Depletion and Potassium Loading in Man

Angiotensin II (Ang II) and potassium (K+) increase aldosterone (Aldo) production in vitro via Ca2+-dependent mechanisms. To determine the effects of Ca2+ antagonism in vivo, we examined the influence of nifedipine on the Aldo response to Na+ depletion and K+ loading in 11 healthy subjects. On the fifth day of a low-Na+/high-K+ diet (10 mmol Na+/100 mmol K+) the subjects were randomly given either nifedipine 30 mg po or placebo, and on the sixth day they received the alternative drug. KCl in 5% glucose was infused on days 5 and 6 from 10:00 to 12:00 AM(0.6 mmol/kg over 2 hours). Dexamethasone was given to suppress adrenal corticotrophic hormone. Plasma renin activity (PRA) and plasma Aldo were determined every 20 minutes. Nifedipine induced a rise in heart rate at 60 minutes but did not change blood pressure. During KCl/glucose infusions, plasma glucose increased significantly, but plasma K+ remained stable. PRA, but not baseline plasma Aldo, was stimulated by nifedipine. KCl provoked a significant and similar Aldo rise (P < .01) under placebo and nifedipine. Baseline Aldo/PRA ratio was reduced under nifedipine when compared to placebo (P < .01), whereas during KCl infusions this ratio was similarly elevated under placebo and nifedipine. We conclude that acute inhibition of slow Ca2+ channels does not interfere with K+-induced Aldo secretion in man, suggesting that adaptive mechanisms operate in vivo. Am J Hypertens 1988;1:245-24

Walking with shorter stride length could improve knee kinetics of patients with medial knee osteoarthritis.

Walking with a shorter stride length (SL) was recently proposed for gait retraining in medial knee osteoarthritis; however it was never assessed in this patient population. This study tested the hypothesis that shortening SL while maintaining walking speed reduces knee adduction (KAM) and flexion (KFM) moments in patients with medial knee osteoarthritis. Walking trials with normal SL and SL reduced by 0.10 m and 0.15 m were recorded for 15 patients (10 men, 55.5 ± 8.7 years old, 24.6 ± 3.0 kg/m &lt;sup&gt;2&lt;/sup&gt; ). SL was modified using an augmented reality system displaying target footprints on the floor. Repeated one-way ANOVAs and post-hoc paired t-tests were performed to compare gait measures between normal and reduced SL. The individual effects of SL reduction were analyzed using descriptive statistics. Group analysis indicated significant decreases in KAM impulse with both SL reductions (p &lt; 0.05). No systematic change was observed in the first peaks KAM and KFM when walking with reduced SL (p &gt; 0.05). Individually, 33 % of the patients decreased the peak KAM, whereas 20 % decreased the KAM impulse. Among these patients with a decrease in peak KAM or in KAM impulse, 0 % and 33 % had a simultaneous increase in peak KFM, respectively. In conclusion, this study showed that SL shortening can decrease kinetic measures associated with the progression of medial knee osteoarthritis in some patients, demonstrating the importance of considering SL modifications on an individual basis. While further research is necessary, notably regarding dose-response relationships and long-term effects, these findings are particularly encouraging because SL reductions could be easily integrated into rehabilitation protocols

Evaluating the Usability of Automatically Generated Captions for People who are Deaf or Hard of Hearing

The accuracy of Automated Speech Recognition (ASR) technology has improved, but it is still imperfect in many settings. Researchers who evaluate ASR performance often focus on improving the Word Error Rate (WER) metric, but WER has been found to have little correlation with human-subject performance on many applications. We propose a new captioning-focused evaluation metric that better predicts the impact of ASR recognition errors on the usability of automatically generated captions for people who are Deaf or Hard of Hearing (DHH). Through a user study with 30 DHH users, we compared our new metric with the traditional WER metric on a caption usability evaluation task. In a side-by-side comparison of pairs of ASR text output (with identical WER), the texts preferred by our new metric were preferred by DHH participants. Further, our metric had significantly higher correlation with DHH participants' subjective scores on the usability of a caption, as compared to the correlation between WER metric and participant subjective scores. This new metric could be used to select ASR systems for captioning applications, and it may be a better metric for ASR researchers to consider when optimizing ASR systems.Comment: 10 pages, 8 figures, published in ACM SIGACCESS Conference on Computers and Accessibility (ASSETS '17

The openness conjecture and complex Brunn-Minkowski inequalities

We discuss recent versions of the Brunn-Minkowski inequality in the complex setting, and use it to prove the openness conjecture of Demailly and Koll\'ar.Comment: This is an account of the results in arXiv:1305.5781 together with some background material. It is based on a lecture given at the Abel symposium in Trondheim, June 2013. 13 page