Virtual vibration measurement using KLT motion tracking algorithm

This paper presents a practical framework and its applications of motion tracking algorithms applied to structural dynamics. Tracking points (“features”) across multiple images is a fundamental operation in many computer vision applications. The aim of this work is to show the capability of computer vision (CV) for estimating the dynamic characteristics of two mechanical systems using a non contact, marker less and simultaneous Single Input Multiple Output (SIMO) analysis. KLT (Kanade-Lucas-Tomasi) trackers are used as virtual sensors on mechanical systems video from high speed camera. First we introduce the paradigm of virtual sensors in the field of modal analysis using video processing. To validate our method, a simple experiment is proposed: an Oberst beam test with harmonic excitation (mode 1). Then with the example of helicopter blade, Frequency Response Functions (FRFs) reconstruction is carried out by introducing several signal processing enhancements (filtering, smoothing). The CV experimental results (frequencies, mode shapes) are compared with classical modal approach and FEM model showing high correlation. The main interest of this method is that displacements are simply measured using only video at FPS (Frame Per Second) respecting the Nyquist frequency

Targeted Destruction of Photosensitive Retinal Ganglion Cells with a Saporin Conjugate Alters the Effects of Light on Mouse Circadian Rhythms

Non-image related responses to light, such as the synchronization of circadian rhythms to the day/night cycle, are mediated by classical rod/cone photoreceptors and by a small subset of retinal ganglion cells that are intrinsically photosensitive, expressing the photopigment, melanopsin. This raises the possibility that the melanopsin cells may be serving as a conduit for photic information detected by the rods and/or cones. To test this idea, we developed a specific immunotoxin consisting of an anti-melanopsin antibody conjugated to the ribosome-inactivating protein, saporin. Intravitreal injection of this immunotoxin results in targeted destruction of melanopsin cells. We find that the specific loss of these cells in the adult mouse retina alters the effects of light on circadian rhythms. In particular, the photosensitivity of the circadian system is significantly attenuated. A subset of animals becomes non-responsive to the light/dark cycle, a characteristic previously observed in mice lacking rods, cones, and functional melanopsin cells. Mice lacking melanopsin cells are also unable to show light induced negative masking, a phenomenon known to be mediated by such cells, but both visual cliff and light/dark preference responses are normal. These data suggest that cells containing melanopsin do indeed function as a conduit for rod and/or cone information for certain non-image forming visual responses. Furthermore, we have developed a technique to specifically ablate melanopsin cells in the fully developed adult retina. This approach can be applied to any species subject to the existence of appropriate anti-melanopsin antibodies

Post-intervention Status in Patients With Refractory Myasthenia Gravis Treated With Eculizumab During REGAIN and Its Open-Label Extension

OBJECTIVE: To evaluate whether eculizumab helps patients with anti-acetylcholine receptor-positive (AChR+) refractory generalized myasthenia gravis (gMG) achieve the Myasthenia Gravis Foundation of America (MGFA) post-intervention status of minimal manifestations (MM), we assessed patients' status throughout REGAIN (Safety and Efficacy of Eculizumab in AChR+ Refractory Generalized Myasthenia Gravis) and its open-label extension. METHODS: Patients who completed the REGAIN randomized controlled trial and continued into the open-label extension were included in this tertiary endpoint analysis. Patients were assessed for the MGFA post-intervention status of improved, unchanged, worse, MM, and pharmacologic remission at defined time points during REGAIN and through week 130 of the open-label study. RESULTS: A total of 117 patients completed REGAIN and continued into the open-label study (eculizumab/eculizumab: 56; placebo/eculizumab: 61). At week 26 of REGAIN, more eculizumab-treated patients than placebo-treated patients achieved a status of improved (60.7% vs 41.7%) or MM (25.0% vs 13.3%; common OR: 2.3; 95% CI: 1.1-4.5). After 130 weeks of eculizumab treatment, 88.0% of patients achieved improved status and 57.3% of patients achieved MM status. The safety profile of eculizumab was consistent with its known profile and no new safety signals were detected. CONCLUSION: Eculizumab led to rapid and sustained achievement of MM in patients with AChR+ refractory gMG. These findings support the use of eculizumab in this previously difficult-to-treat patient population. CLINICALTRIALSGOV IDENTIFIER: REGAIN, NCT01997229; REGAIN open-label extension, NCT02301624. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that, after 26 weeks of eculizumab treatment, 25.0% of adults with AChR+ refractory gMG achieved MM, compared with 13.3% who received placebo

Minimal Symptom Expression' in Patients With Acetylcholine Receptor Antibody-Positive Refractory Generalized Myasthenia Gravis Treated With Eculizumab

The efficacy and tolerability of eculizumab were assessed in REGAIN, a 26-week, phase 3, randomized, double-blind, placebo-controlled study in anti-acetylcholine receptor antibody-positive (AChR+) refractory generalized myasthenia gravis (gMG), and its open-label extension

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe

Effect of the drying rate on the complex viscosity of wheat flour dough transforming into crust and crumb during baking

This study aimed at characterizing the effect of hydrothermal dynamics on the dough rheology, in order to develop a complete dough viscosity model valid at different locations during baking. The dough rheology was characterised using dynamic mechanical thermal analysis (DMTA). Temperature and water content (WC) were monitored during DMTA. At high heating rates (15-30 degrees C/min), relevant to the top crust, viscosity behaved as if WC was kept constant, in spite of dehydration (37%); such similarity was valid up to 80 degrees C (stage A). Beyond, the viscosity decrease observed in the samples at constant WC was replaced by a long-lasting plateau (stage B, 3-4 x 10(6) Pa.s), attributed to WC reduction below similar to 37%. Above the boiling water temperature, the logarithm of viscosity increased linearly with decreasing WC (stage C). At lower heating rates (5 degrees C/min), relevant to the bottom crust, viscosity was two-fold higher than that at higher heating rates, suggesting lower oven-rise. The viscosity decrease, observed at high temperatures (>80 degrees C) for samples at constant WC, was not observed if drying occurred late (case of crumb beneath the crust); instead, viscosity increased up to levels close to that of the top crust (2-3 x 10(7) Pa.s at WC similar to 20%). Despite these deviations, viscosity as a WC function was modelled with a unique equation set. (C) 2013 Published by Elsevier Ltd

Simulating the formation of bread crust in a DMTA rheometer

Water evaporates very fast from the surface layers of dough, enhanced by high heating rates at the beginning of baking. The rheological properties of the surface layers play an important role during the baking process, especially in local and overall expansion and water loss. The aim of this study was to determine the rheological properties of bread dough in the heat-moisture dynamics of the baking process, especially in surface drying and delayed drying conditions. The DMTA method was used in tensile mode in order to expose the samples to fast dehydration to simulate real bread crust. The degree of starch gelatinization was demonstrated by the disappearance of the ‘‘Maltese cross’’ (polarized light microscopy). Temperature and water content were monitored during baking. The modulus evolution depended on both the heat and moisture evolution (i.e. immediate or delayed in the present study). In contrast to reports in the literature, starch gelatinization was observed even under drying conditions. Nevertheless, comparison between samples under drying and under delayed drying conditions suggested that water content prevailed in the rheological changes

Biaxial extensional viscosity in wheat flour dough during baking

International audienceLubricated squeezing flow (LSF) experiments on wheat flour dough were conducted at a constant biaxial extensional rate followed by relaxation experiments. The effect of temperature on the rheology of the dough was studied in the range 25'95 °C under small and large strain to characterize changes in the dough through a possible pathway to simulate the dough-crumb transition during the first step of the baking process. A strain hardening effect was shown over the whole temperature range. Like extensional viscosity measured at 0.1 and 0.65 biaxial strain, the consistency index (K) decreased from 25 °C to 45 °C and increased at temperatures above 50 °C. Two levels of the behaviour index (n) were found: 0.35'0.40 below 45 °C, and 0.1'0.2 above 45 °C. The relaxation degree also changed dramatically but only at higher temperatures (56'60 °C), below which it remained almost constant (98-99%), once the dough became a viscoelastic liquid, above this temperature the main physical-chemical reactions (starch and protein) started to occur, leading to more solid properties. These results complement those of LSF. LSF experiments at large biaxial strain (0.75), combined with a relaxation experiment, were successfully used for dough/crumb characterisation at a temperatures ranging from 25 °C to 74 °C. Alpha values estimated from Launay's model were incorporated in the flow behaviour index, underwent the same type of changes as a function of temperature as n but with a less marked transition; n was divided by two and K increased by about one decade. © 2018 Elsevier Lt

The 1965 Mahavel Landslide (Réunion Island, Indian Ocean): Morphology, Volumes, Flow Dynamics, and Causes of a Rock Avalanche in Tropical Setting

International audienceIn May 1965, a main landslide occurred in a deeply incised valley of Piton de la Fournaise volcano, in Réunion Island. This event occurred one day after heavy rainfalls and was consequently interpreted as a mud/debris flow. We take advantage of several sets of historical photographs to reappraise this event. They show that the collapse of a large part of the valley headwall produced a rock flow that dropped 1,740 m and traveled 5,050 m. The surface morphology suggests that the landslide produced a main flow that evolved in a secondary flow in the distal part. The main flow deposit is composed of a matrix-rich fragmented facies and a jigsaw-fracturated facies. The matrix presents a gravely-to-silty granulometry and fractal dimensions ranging between 2.472 and 2.865. Volumes of the collapsed material (59.7 ± 3.1 Mm3) and the deposit (46 ± 13 Mm3) were determined from a photogrammetric approach. We estimated velocities ranging between 86 and 44 m s−1 along the flow path. Our simulations with SHALTOP reveal that the landslide geometry and velocities are well reproduced with frictional Coulomb rheology. We thus interpret the 1965 Mahavel landslide as a main rock avalanche rather than a mud/debris flow. We propose that the trigger of the 1965 avalanche, and of the smaller events in 1995 and 2001, is the water infiltration related to the intense rainfalls, which systematically preceded by one day each collapse. Finally, the succession of dry and wet years before each collapse event could promote favorable conditions to failure

Identification of broad-spectrum viscoelastic parameters: Influence of experimental bias on their accuracy and application to semihard-type cheese

This paper sets out a method to extract Maxwell model parameters from experimental compression-relaxation tests and investigates common experimental sources of bias when dealing with viscoelastic materials. Particular attention was given to viscoelastic materials that relax stress quickly. The proposed method differs from the methods usually used in that it takes into account the stress that can relax when a material is submitted to compression before proper relaxation. Among the experimental biases that can affect the tests, this study investigated the impact of the geometry defects of the samples, of the sensitivity of the rheometer used and of the compression speed on the characterization of the material. The uncertainties caused by these biases were then propagated in the proposed method. The proposed method was used to study the evolution of the viscoelastic properties of semihard cheese during ripening. Variability between cheeses proved to be greater than the uncertainty of the proposed method, and no tendency could be established, meaning that the viscoelastic parameters were considered constant during ripening