Rationnel : La vitesse d'onde de pouls (VOP) est une méthode non invasive d'estimation de la rigidité artérielle. Les recommandations internationales établissent que la VOP est un marqueur puissant du risque cardiovasculaire (CV). La corrélation entre la pression artérielle périphérique et la VOP et leurs influences respectives sur la mortalité ont été peu étudiés chez les sujets âgés. Notre objectif était d'analyser cette corrélation chez les sujets institutionnalisés de plus de 80 ans. Méthodes : PARTAGE (valeur prédictive de la pression artérielle et de la rigidité artérielle chez institutionnalisé la population très âgée) est une étude de cohorte suivant pendant 2 ans 1130 sujets de plus de 80 ans institutionnalisés dans 72 centres en France et en Italie. La corrélation entre pression artérielle systolique et diastolique (PAS et la PAD) et la VOP (mesuré avec un tonomètre PulsePen ®) a été étudié chez 1071 sujets ayant des données de VOP. Résultats : La corrélation entre la PA et la VOP dans notre étude est significative mais faible. Les coefficients de corrélation sont de 0,24 pour la corrélation PAS clinique-VOP, 0,26 pour la corrélation PP-VOP, et 0,30 pour la corrélation PA automesure-VOP. La corrélation est systématiquement plus élevée chez les femmes mais sans atteindre la significativité. Le niveau de corrélation est inversement proportionnel à l'âge : les corrélations les plus fortes sont retrouvées dans la population la plus jeune. Le traitement antihypertenseur n'a pas d'impact sur la corrélation. Conclusion : La faiblesse de la corrélation montre que la PA et la VOP expriment différents phénomènes physiopathologiques de la rigidité artérielle. L'analyse longitudinale de l'étude PARTAGE, mise en perspective avec ceux trouvés dans nos travaux, pourraient permettre de proposer la VOP comme une méthode complémentaire, voire alternative, à la mesure de la PA dans l'évaluation du risque CV dans la population des sujets très âgés / Background: Carotid-femoral pulse wave velocity (PWV) provides a comprehensive non-invasive assessment of arterial stiffness. PWV is now established as a strong marker of cardiovascular disease. The correlation between peripheral blood pressure and PWV and their respective influences on mortality have been poorly studied in the elderly. Our objective was to analyze this correlation in nursing home residents over 80 years of age. Results could ultimately be helpful in implementing strategies for diagnosis and long-term follow-up of the very elderly population. Methods: The PARTAGE (Predictive value of blood pressure and ARTerial stiffness in institutionalized very AGEd population) study is a 2-year cohort study of 1130 subjects living in 72 nursing homes in France and Italy. The correlation between baseline systolic and diastolic blood pressure (SBP and DBP) and baseline PWV (measured with a PulsePen® tonometer) was studied in 1071 subjects with available PWV measurements. Results: Correlations between peripheral blood pressure and PWV were significant but weak: r=0.24 for self-measured SBP, r=0.30 for casual SBP, r=0.11 for self measured DBP, r=0.14 for casual DBP and r=0.26 for casual pulse pressure (PP). A trend for a weaker correlation was observed in the higher age group for self measured SBP and in the lower ADL group for self measured SBP and DBP. The correlations were systematically higher in women compared to men (but did not reach statistical significance) and lower with advanced age group. The correlation was not impacted by antihypertensive. Conclusion: These findings suggest that SBP, DBP and PWV provide different information in the very elderly. The prospective, longitudinal, long term PARTAGE study results will allow further insight; provide additional in-depth information regarding the respective prognostic value of these two measurement methods. NCT00901355

Evaluations of stress history and the geostatic state of stress of soils are ascertained on the basis of field geophysical measurements that provide paired complementary types of shear waves. It is well-established that multiple types of shear waves occur in the ground due to their directional and polarization properties. The shear wave velocity (Vs) provides the magnitude of small strain stiffness (G0) which depends on effective stress, void ratio, stress history, and other factors (cementation, age, saturation). Herein, this study examines a hierarchy of shear wave modes with different directions of propagation and particle motion from in-situ geophysical tests (HH, VH, and HV) and laboratory bender element data. A special compiled database from well-documented worldwide sites is assembled where full profiles of stress state, stress history, and several paired modes of Vs profiles have been obtained from crosshole tests (CHT), downhole tests (DHT), and rotary crosshole (RCHT). Reference profiles of the lateral stress coefficient (K0) are available from direct in-situ measurements (self-boring pressuremeter, hydrofracture, and push-in spade cells). Stress history is documented in terms of yield stress ratio (YSR) from consolidation testing and careful engineering geology studies. A methodology is developed that relates both the YSR and K0 to stiffness ratios obtained from directional shear wave velocities. In further efforts, means to extract reliable shear wave profiles from continuous downhole testing via a new GT autosource and seismic piezocone testing are outlined and applied to results from three test sites in Windsor/VA, Norfolk/VA, and Richmond/BC. A driving impetus to this research involves the geologic conditions at the US Dept. of Energy's Savannah River Site (SRS) in South Carolina. Here, the overburden soils in the upper 60 m depths consist of very old Miocene and Eocene sediments, primarily layered deposits of sands, clayey sands, silty sands, and interbedded clays which exhibit an apparent and unusual stress history profile. Special geologic conditions include the dissolutioning of old calcareous sediments (Santee Formation) at depths of 40 to 50 m below grade, similar to karstic limestone deposits. As a consequence, caves, voids, and infilled soft soil zones occur within the soil matrix at these elevations, probably resulting in localized collapse of the overlying soil column. Based on conventional laboratory and in-situ test data conducted during geotechnical investigations at SRS, available interpretative relationships for assessing the soil stress history and geostatic stress states show scattered and inconsistent results. Complications abound in the systematic assessments of these geomaterials due to effects of very old ageing, cementation, desiccation, and diagenesis, as evidenced by unusual in-situ shear wave velocity profiles that decrease in magnitude with depth, as measured by CHT and DHT. Based on the findings of this study, it is recommended that a new set of shear wave velocity measurements be made at SRS to obtain HH waves (and complementary VH waves) needed for an independent assessment of YSR in the upper soil column.

The ow of a liquid _lm over a rapidly rotating horizontal disk has numerous industrial applications including pharmaceuticals, chemical engineering, bioengineering, etc. The analysis and control of complex uid ows over a rapidly rotating horizontal disk is an important issue in the experimental uid mechanics. The spinning disk reactor exploits the bene_ts of centrifugal force, which produces thin highly sheared _lms due to radial acceleration. The hydrodynamics of the _lm results in excellent uid mixing and high heat or mass transfer rates. This work focuses on developing a novel approach for uid ow tracking and analysis. Speci_cally, the developed algorithm is able to detect the moving waves and compute controlling _lm ow parameters for the uid owing over a rotating disk. The input to this algorithm is an easily acquired non-invasive video data. It is shown that under single light illumination it is possible to track specular portion of the reected light on the moving wave. Hence, the uid wave motion can be tracked and uid ow parameters can be computed. The uid ow parameters include wave velocities, wave inclination angles, and distances between consecutive waves. Once the parameters are computed, their accuracy is analyzed and compared with the solutions of the mathematical uid dynamics models based on the Navier-Stokes equations for the case of a thin _lm. The uid model predicts wave characteristics based on directly measured controlling parameters, such as disk rotation speed and uid ow rate. It is shown that the calculated parameter values approximately coincide with the predicted ones. The average computed parameters were within 5 � 10% of the predicted values. In addition, given recovered uid characteristics and uid ow controlling parameters, full 3D wave description is obtained. That includes 3D wave location, speed, and distance between waves, as well as approximate wave thickness. Next, the developed approach is generalized to model-based recovery of uid ow controlling parameters: the speed of the spinning disk and the initial uid-ow rate. The search in space for model parameters is performed as to minimize the error between the ow characteristics predicted by the uid dynamics model (e.g. distance between waves, wave inclination angles) and parameters recovered from video data. Results demonstrate that the speed of a disk and the ow rate are recovered with high accuracy. When compared to the ground truth available from direct observation, we noted that the controlling parameters were estimated with less than 10% error.

African Americans have increased risk for cardiovascular and cerebral vascular disease relative to Caucasian Americans. While it is generally accepted that arteries become stiffer at a younger age in African Americans; less is known regarding cerebral vascular function / reactivity (CVMR) to hypercapnia in African Americans. Furthermore, little is known regarding the relationship between arterial stiffness and CVMR, particularly in young healthy adults. We hypothesized that African Americans have stiffer arteries (i.e. arterial stiffness) and reduced CVMR during hypercapnia relative to Caucasian Americans. We also hypothesized that there would be a negative relationship between arterial stiffness and CVMR. Lastly, we hypothesized that these responses would be related to a decrease in Vitamin D status in this population and there would be correlation between Vitamin D status and CVMR. In 11 African American and 19 Caucasian American subjects central arterial stiffness was indexed from carotid-femoral pulse wave velocity (PWV). CVMR was assessed by the cerebral vascular conductance (CVC) response to rebreathing-induced hypercapnia. Vitamin D status was assessed from plasma 25(OH) Vitamin D. PWV was elevated in the African Americans (African American: 581.16 ± 27.7 cm/sec vs. Caucasian American: 502.98 ± 17.6 cm/sec; P < 0.01). CVMR was significantly reduced during hypercapnic rebreathing in the African Americans (African American: 3.05 ± 0.38% of baseline/mmHg vs. Caucasian American: 5.09 ± 0.29% of baseline/mmHg; P < 0.001). When data from all subjects was included there was a trend towards a negative relationship (R = 0.32, P = 0.10) between PWV and CVMR. Vitamin D status was significantly lower in African Americans (African American: 14.96 ± 0.97 ng/ml vs. Caucasian American: 32.73 ± 0.99 ng/ml; P < 0.001); however, there was no significant relationship between Vitamin D status and CVMR (R = 0.23 P = 0.23). In conclusion, these data indicate that African Americans have impaired cerebral vascular responses to hypercapnia, stiffer arteries, and lower Vitamin D status when compared with Caucasian Americans. In addition, there may be a negative relationship between CVMR and PWV; however, no significant correlation between Vitamin D status and vascular function including PWV or CVMR was observed in this study. / text

No description available.

The goal of this research is to investigate the fundamentals of fracturing processes in heterogeneous materials such as concrete using geophysical methods and dynamic micromechanical models. This work describes how different aspects of fracture formation in concrete can be investigated using a combination of Acoustic Emission (AE) techniques, ultrasonic wave velocity imaging, and high resolution Computed Tomography (CT). Fracture formation and evolution were studied during shear failure of large reinforced concrete beams and compressive failure of concrete samples. AE analysis includes studying complex spatial and temporal fracture development that precedes shear failure. Predominant microcrack mechanisms were analyzed at different stages of fracture formation. CT images were used to investigate the influence of concrete microstructure on fracture topography. Combined AE and CT damage evaluation techniques revealed different aspects of fracture development, thus expanding our understanding of AE events and their mechanisms. These images show how aggregate particles influence fracture nucleation and development. An emphasis has been placed on the role of coarse aggregates during the interlocking of fracture surfaces at transferring shear stresses. Ultrasonic wave velocity and AE techniques have been applied to uniaxial compression tests of concrete with various aggregate sizes and strengths similar to that of the concrete beams. AE parameters, p-wave velocities, and stress-strain data have been analyzed concurrently to image damage evolution under compression. Influence of material composition on microcracking and material state changes during loading has been investigated in detail. The results of compressive tests were used as building blocks for developing realistic micromechanical numerical models of concrete. The models were designed using a distinct element code, where material is modelled through the combination of bonded particles. A number of procedures were developed to transfer the exact microstructure of material incorporating its visual representation into the model. The models’ behaviour has been verified against experimental data. It was shown that these models exhibit realistic micromechanical behaviour. The results of the experimental investigation of concrete fracturing were expanded by modelling more cases with aggregate size and strength variations. It was shown that geophysical imaging techniques, along with advanced micromechanical numerical modelling, can help us understand damage formation and evolution.

The goal of this research is to investigate the fundamentals of fracturing processes in heterogeneous materials such as concrete using geophysical methods and dynamic micromechanical models. This work describes how different aspects of fracture formation in concrete can be investigated using a combination of Acoustic Emission (AE) techniques, ultrasonic wave velocity imaging, and high resolution Computed Tomography (CT). Fracture formation and evolution were studied during shear failure of large reinforced concrete beams and compressive failure of concrete samples. AE analysis includes studying complex spatial and temporal fracture development that precedes shear failure. Predominant microcrack mechanisms were analyzed at different stages of fracture formation. CT images were used to investigate the influence of concrete microstructure on fracture topography. Combined AE and CT damage evaluation techniques revealed different aspects of fracture development, thus expanding our understanding of AE events and their mechanisms. These images show how aggregate particles influence fracture nucleation and development. An emphasis has been placed on the role of coarse aggregates during the interlocking of fracture surfaces at transferring shear stresses. Ultrasonic wave velocity and AE techniques have been applied to uniaxial compression tests of concrete with various aggregate sizes and strengths similar to that of the concrete beams. AE parameters, p-wave velocities, and stress-strain data have been analyzed concurrently to image damage evolution under compression. Influence of material composition on microcracking and material state changes during loading has been investigated in detail. The results of compressive tests were used as building blocks for developing realistic micromechanical numerical models of concrete. The models were designed using a distinct element code, where material is modelled through the combination of bonded particles. A number of procedures were developed to transfer the exact microstructure of material incorporating its visual representation into the model. The models’ behaviour has been verified against experimental data. It was shown that these models exhibit realistic micromechanical behaviour. The results of the experimental investigation of concrete fracturing were expanded by modelling more cases with aggregate size and strength variations. It was shown that geophysical imaging techniques, along with advanced micromechanical numerical modelling, can help us understand damage formation and evolution.

Kardiovaskuläre Erkrankungen spielen eine immer dominanter werdende Rolle als Ursachen von Morbidität und Mortalität. Endotheliale Dysfunktion, Arteriosklerose und ischämische Herzerkrankungen sind unangefochten die häufigsten Todesursachen in hochentwickelten Ländern. Die Krankheitslast kardiovaskulärer Erkrankungen wird durch die globale Zunahme von Risikofaktoren wie Übergewicht, metabolischem Syndrom und Diabetes mellitus Typ 2 in Zukunft wohl weiter steigen. Keines der in der heutigen Form existierenden Gesundheitssysteme ist den gesundheitlichen Folgen dieser bedenklichen epidemiologischen Entwicklung gewachsen, ohne dafür beträchtliche Einschnitte in Qualität oder Quantität hinnehmen zu müssen. Präventivmedizinische Strategien haben im Vergleich zur Akutmedizin bisher eine wesentlich geringere Aufmerksamkeit erfahren. Aufgrund der weiterhin steigenden Krankheitslast werden gerade präventivmedizinische Strategien immer wichtiger. Die Ermittlung der individuellen kardiovaskulären Gesundheit beinhalten neben einer Untersuchung wichtiger physiologsicher Kernsysteme, einen besonderen Fokus auf die Stärkung der gesundheitlichen Eigenverantwortung durch Vermittlung entsprechender medizinischer Zusammenhänge. Dies kann durch geeignete und prognostisch wertvolle Untersuchungsmethoden und laienverständliche Interpretationen der komplexen kardiovaskulären Zusammenhänge realisiert werden. Mithilfe eines besseren Verständnisses für die eigene kardiovaskuläre Gesundheit und gezielter konkreter Hilfestellungen von ärztlicher Seite, können grundlegende Strukturen für einen achtsameren Umgang mit der eigenen Gesundheit geschaffen werden. Alltägliche körperliche Aktivität, Körperzusammensetzung, Gefäßsteifigkeit und die maximale Leistungsfähigkeit bilden aktuellen Studien zufolge vier relativ einfach zu erhebend Hauptdeterminanten kardiovaskulärer Gesundheit mit großer prädiktiver Vorhersagekraft für kardiovaskulärer Ereignisse. Die Einordnung der Untersuchungsbefunde unter Berücksichtigung altersentsprechender Referenzdaten bietet zusätzlich die Möglichkeit, chronologisches und biologisches Alter zu differenzieren. Darüber hinaus könnte das hier vorgestellte Untersuchungskonzept ebenso dafür eingesetzt werden, die Effektivität von zuvor eingeleiteten therapeutischen Strategien zu überprüfen und eine Übermedikation zu vermeiden. Ein stärkerer Fokus auf nachhaltige kardiovaskuläre präventivmedizinische Strategien birgt das Potential Morbidität und Mortalität zu Reduzieren und die Lebensqualität und Selbstbestimmung der Klienten zu steigern. / Nowadays endothelial dysfunction, arteriosclerosis and ischaemic heart disease depict major issues in most developed countries. Chronic diseases cause an increasing number of deaths worldwide. Responsible for approximately 30% of all deaths, this number is shocking despite the knowledge that these lives could be saved in a realistic point of view. However, disturbing global tendencies and the increase in epidemic overweight, obesity, glucose intolerance and diabetes mellitus type 2 seem to amplify cardiovascular diseases and deaths. No existing medical care system could ever sufficiently match these emergent burdens of global chronic diseases if these tendencies will continue to grow. Due to fatal epidemiological changes general practitioners will not only have to treat more diseases of elderly people, but also be the first contact person for enquiries about their health concerning the cardiovascular systems of younger and older generations. Strengthening prevention concerning cardiovascular diseases is probably the most efficient and only way to escape the vicious circle of pathophysiological processes. To implement cardiovascular prevention it is essential to focus on cardiovascular health rather than on cardiovascular disease. In order to master this challenge sufficiently a deliberate concept of preventive examinations for cardiovascular health is required to quantify cardiovascular wellness and sharpen the awareness of one’s health. Therefore, it is to establish precise, predictive and cost-efficient examination methods to quantify cardiovascular health and subclinical changes at early stages of a disease. Broader acceptance of the preventive potential and the use of modern technological advances could therefore be a powerful instrument to solve the growing global problem of chronic diseases. In this context the routine evaluation of daily physical activity, body composition, arterial stiffness and the maximum physical performance could be a starting point for a preventive diagnostic approach. They can serve as future parameters reflecting health, detecting subclinical diseases and encouraging people’s responsibility for their own health. Detailed information about the major cardiovascular parameters opens specific and efficient course of action to create multiple strategies for gaining or rehabilitating cardiovascular wellbeing

Le but de ce travail est de comprendre les relations entre la déformation et la diagenèse dans les carbonates. Pour cela, l’échelle du m au dam est adéquate car elle permet de séparer les effets matriciels, des fractures et des failles. Celle-ci est sous la résolution de la sismique, donc peu de données géophysiques et diagénétiques spatiale et quantitatives sont disponibles, le plus souvent limitées aux données 1D de puit.Nous avons choisi 4 affleurements présentant des hétérogénéités et des intensités de déformation et de diagenèse diverses. Un protocole multi-échelle et multidisciplinaire a été développé, comprenant de la géophysique à l’échelle du cm au dam, de la diagenèse structurale et de la géochimie sur les ciments de fracture. Nous montrons un fort effet d’échelle entre les Vp en laboratoire et à l’affleurement dû à des hétérogénéités sédimentaire, d’enfouissement et structurale, qui conduisent à différents motifs géostatistiques.Les fractures ont l’effet le plus fort sur les Vp, modulé par leur cimentation, et qui peut entièrement effacer la signature initiale du faciès. La réactivation des fractures induit une anisotropie directionnelle de 10% due à des changements dans le remplissage des fractures, caractérisés par de multiples phases de cimentation, broyage et dissolution.Dans les zones de faille, l’anisotropie sismique est amplifiée, conduisant à un fort affaiblissement de la roche au cisaillement et à une diminution de Vp autour de la faille. Les données géochimiques tracent plusieurs flux de fluides diagénétiques et soulignent les fortes interactions entre l’évolution de la perméabilité, la diagenèse structurale et la signature géophysique des carbonates. / The aim of this work was to understand the relationships between deformations and diagenesis in carbonates. The relevant scale to study it may be the m to dkm scale which allows individualizing fracture, fault and matrix effects. This scale is under the seismic resolution, so few quantitative diagenetic and geophysical spatial data are available, mainly constrained to 1D borehole.Therefore, we selected 4 dkm scale outcrops displaying various heterogeneities and intensities of deformation and diagenesis. We developed a multidisciplinary/multiscale protocol including geophysics from cm to dkm scale along with structural diagenesis study and geochemical measurements on fractures cements. We found a strong scale effect between laboratory and outcrop Vp due to sedimentary, burial and structural heterogeneities that lead to different geostatistical patterns. Fractures have the strongest effect on Vp, being modulated by their cementation and can erase the initial facies acoustic signature. The fracture reactivation induce a 10% Vp directional anisotropy due to microscale changes in the fractures infillings characterized by multiple cementation, crushing and dissolution phases. In fault-zones the seismic anisotropy magnitude is amplified, leading to a strong directional rock shear weakening and a Vp decrease around the fault, caused by higher discontinuities aperture and brecciation. Geochemical data indicate that the Vp signature evolution is linked to different diagenetic fluids flow origins occurring during each deformation phase. This underlines the strong interplay between permeability evolution, structural diagenesis and geophysical signature in carbonates.

This thesis work focuses mainly on the application of non-destructive testing (NDT) methods on wood-based panels (WBP) in order to estimate the bending properties. To prove the accuracy and applicability of these methods on WBP, their results are correlated with results from a standardized static bending test. The behavior in different climate conditions and the application on panels of larger sizes is also questioned to provide an indication about strong points and boundaries of NDT methods applied on WBP.The bending properties are of major importance, especially for materials suited to bear loads. Bending stiffness, represented by the modulus of elasticity (MOE), is an expression of the deflection rate of a material under load. The bending strength, represented by the modulus of rupture (MOR), is an expression of the maximum load withstood by a material before rupture.Before testing, the material is acclimatized in three climate conditions: dry (20°C, 35% RH), standard (20°C, 65% RH) and wet (20°C, 85% RH), to understand the bending properties variation and how the NDT methods are affected by the variation in moisture content.The materials used are seven types of WBP, in particular four types of particleboards (PB), one type of high-density fiberboard (HDF), one type of dual density PB (with high and low density areas along the production direction) and one type of light-weight panel (Board-on-stiles, a composite panel of HDF, PB and paper honeycomb).To test the bending properties the following NDT methods are considered: transversal resonance vibration and longitudinal resonance vibration with the use of the BING system and the time-of-flight with the use of Fakopp Ultrasonic Timer and Silvatest Trio. The resonance vibration methods, transversal and longitudinal, are based on the relation between resonance vibration properties and bending properties of a material. The relation with bending properties also exists for the stress wave velocity (SWV) through a material, calculated with the time-of-flight method. The dynamic MOE resulting from these tests is then correlated with the static MOE and MOR from the static bending test.The NDT methods resulted to be reliable on WBP, with generally high levels of correlation between dynamic MOE and static MOE and MoR. The highest correlation value for MoE is with the transversal resonance vibration while the highest for MOR is with the longitudinal resonance vibration. The results of the dynamic MOE for all the NDT methods are higher than the static MOE, as confirmed also in the literature; the average ratio between the dynamic and the static MOE is, for example, up to 1,6 for WBP in standard climate condition, tested with Fakopp U.T.. These results are extremely higher than values suggested by previous studies. Moreover, the ratio increases with increasing relative humidity of the climate condition. The results from the tests on larger sizes suggest a possible application in this field. The time-of-flight method is suitable for in-plane uniform materials, like the PB and HDF, while the transversal resonance methods give also a good representation of the properties of the dual density PB and the light-weight panel.