Totally implantable robot to treat chronic atrial fibrillation

Chronic atrial fibrillation affects millions of people worldwide. Its surgical treatment often fails to restore the transport function of the atrium. This study first introduces the concept of an atrial assist device (AAD) to restore the pump function of the atrium. The AAD is developed to be totally implantable in the human body with a transcutaneous energy transfer system to recharge the implanted battery. The ADD consists of a motorless pump based on artificial muscle technology, positioned on the external surface of the atrium to compress it and restore its muscular activity. A bench model reproduces the function of a fibrillating atrium to assess the circulatory support that this pump can provide. Atripump (Nanopowers SA, Switzerland) is a dome-shaped silicone-coated nitinol actuator 5 mm high, sutured on the external surface of the atrium. A pacemaker-like control unit drives the actuator that compresses the atrium, providing the mechanical support to the blood circulation. Electrical characteristics: the system is composed of one actuator that needs a minimal tension of 15 V and has a maximum current of 1.5 A with a 50% duty cycle. The implantable rechargeable battery is made of a cell having the following specifications: nominal tension of a cell: 4.1 V, tension after 90% of discharge: 3.5 V, nominal capacity of a cell: 163 mA h. The bench model consists of an open circuit made of latex bladder 60 mm in diameter filled with water. The bladder is connected to a vertically positioned tube that is filled to different levels, reproducing changes in cardiac preload. The Atripump is placed on the outer surface of the bladder. Pressure, volume and temperature changes were recorded. The contraction rate was 1 Hz with a power supply of 12 V, 400 mA for 200 ms. Preload ranged from 15 to 21 cm H(2)O. Maximal silicone membrane temperature was 55 degrees C and maximal temperature of the liquid environment was 35 degrees C. The pump produced a maximal work of 16 x 10(-3) J. Maximal volume pumped was 492 ml min(-1). This artificial muscle pump is compact, follows the Starling law and reproduces the hemodynamic performances of a normal atrium. It could represent a new tool to restore the atrial kick in persistent atrial fibrillation.

Étude des sédiments quaternaires, de la molasse et sa tectonique, dans le Grand Lac (Léman) à partir de données sismiques 2D et 3D

RESUME L'Institut de Géophysique de l'Université de Lausanne a développé au cours de ces dernières années un système d'acquisition de sismique réflexion multitrace à haute résolution 2D et 3D. L'objectif de cette thèse était de poursuivre ce développement tout améliorant les connaissances de la géologie sous le lac Léman, en étudiant en particulier la configuration des grands accidents sous-lacustres dans la Molasse (Tertiaire) qui forme l'essentiel du substratum des formations quaternaires. En configuration 2D, notre système permet d'acquérir des profils sismiques avec une distance inter-CDP de 1,25 m. La couverture varie entre 6 et 18 selon le nombre de traces et la distance inter-tir. Le canon à air (15/15 eu. in.), offre une résolution verticale de 1,25 ni et une pénétration maximale de 300 m sous le fond de l'eau. Nous avons acquis au total plus de 400 km de sections 2D dans le Grand Lac et le Haut Lac entre octobre 2000 et juillet 2004. Une campagne de sismique 3D a fourni des données au large d'Evian sur une surface de 442,5 m sur 1450 m, soit 0,64 km2. La navigation ainsi que le positionnement des hydrophones et de la source ont été réalisés avec des GPS différentiels. Nous avons utilisé un traitement sismique conventionnel, sans appliquer d'AGC et en utilisant une migration post-stack. L'interprétation du substratum antéquaternaire est basée sur l'identification des sismofaciès, sur leurs relations avec les unités géologiques adjacentes au lac, ainsi que sur quelques données de forages. Nous obtenons ainsi une carte des unités géologiques dans le Grand Lac. Nous précisons la position du chevauchement subalpin entre la ville de Lausanne, sur la rive nord, et le bassin de Sciez, sur la rive sud. Dans la Molasse de Plateau, nous avons identifié les décrochements de Pontarlier et de St. Cergue ainsi que plusieurs failles non reconnues jusqu'ici. Nous avons cartographié les accidents qui affectent la Molasse subalpine ainsi que le plan de chevauchement du flysch sur la Molasse près de la rive sud du lac. Une nouvelle carte tectonique de la région lémanique a ainsi pu être dressée. L'analyse du substratum ne montre pas de failles suggérant une origine tectonique de la cuvette lémanique. Par contre, nous suggérons que la forme du creusement glaciaire, donc de la forme du lac Léman, a été influencée par la présence de failles dans le substratum antéquaternaire. L'analyse des sédiments quaternaires nous a permis de tracer des cartes des différentes interfaces ou unités qui les composent. La carte du toit du substratum antéquaternaire montre la présence de chenaux d'origine glaciaire dont la profondeur maximale atteint la cote -200 ni. Leur pente est dirigée vers le nord-est, à l'inverse du sens d'écoulement actuel des eaux. Nous expliquons cette observation par l'existence de circulations sous-glaciaires d'eau artésienne. Les sédiments glaciaires dont l'épaisseur maximale atteint 150 ni au centre du lac ont enregistré les différentes récurrences glaciaires. Dans la zone d'Evian, nous mettons en évidence la présence de lentilles de sédiments glaciolacustres perchées sur le flanc de la cuvette lémanique. Nous avons corrélé ces unités avec des données de forage et concluons qu'il s'agit du complexe inférieur de la pile sédimentaire d'Evian. Celui-ci, âgé de plus de 30 000 ans, serait un dépôt de Kame associé à un lac périglaciaire. La sismique réflexion 3D permet de préciser l'orientation de l'alimentation en matériel détritique de l'unité. La finesse des images obtenues nous permet également d'établir quels types d'érosion ont affecté certaines unités. Les sédiments lacustres, dont l'épaisseur maximale imagée atteint plus de 225 m et sans doute 400 ni sous le delta du Rhône, indiquent plusieurs mécanismes de dépôts. A la base, une mégaturbidite, épaisse d'une trentaine de mètres en moyenne, s'étend entre l'embouchure de la Dranse et le delta du Rhône. Au-dessus, la décantation des particules en suspension d'origine biologique et détritique fournit l'essentiel des sédiments. Dans la partie orientale du lac, les apports détritiques du Rhône forment un delta qui prograde vers l'ouest en s'imbriquant avec les sédiments déposés par décantation. La structure superficielle du delta a brutalement évolué, probablement à la suite de l'évènement catastrophique du Tauredunum (563 A.D.). Sa trace probable se marque par la présence d'une surface érosive que nous avons cartographiée. Le delta a ensuite changé de géométrie, avec notamment un déplacement des chenaux sous-lacustres. Sur l'ensemble de nos sections sismiques, nous n'observons aucune faille dans les sédiments quaternaires qui attesterait d'une tectonique postglaciaire du substratum. ABSTRACT During the last few years the institute of Geophysics of the University of Lausanne cleveloped a 2D and 3D high-resolution multichannel seismic reflection acquisition system. The objective of the present work was to carry on this development white improving our knowledge of the geology under Lake Geneva, in particular by studying the configuration of the large accidents affecting the Tertiary Molasse that makes up the basement of most Quaternary deposits. In its 2D configuration, our system makes it possible to acquire seismic profiles with a CDP interval of 1.25 m. The fold varies from 6 to 18 depending on the number of traces and the shooting interval. Our air gun (15/15 cu. in.) provides a vertical resolution of 1.25 m and a maximum penetration depth of approximately 300 m under water bottom. We acquired more than 400 km of 2D sections in the Grand Lac and the Haut Lac between October 2000 and July 2004. A 3D seismic survey off the city of Evian provided data on a surface of 442.5 m x 1450 m (0.64 km2). Ship's navigation as well as hydrophone- and source positioning were carried out with differential GPS. The seismic data were processed following a conventional sequence without .applying AGC and using post-stack migration. The interpretation of the pre-Quaternary substratum is based on sismofacies, on their relationships with terrestrial geological units and on some borehole data. We thus obtained a map of the geological units in the Grand Lac. We defined the location of the subalpine thrust from Lausanne, on the north shore, to the Sciez Basin, on the south shore. Within the Molasse de Plateau, we identified the already know Pontarlier and St Cergue transforms Fault as well as faults. We mapped faults that affect subalpine Molasse as well as the thrust fault plane between alpine flysch and Molasse near the lake's south shore. A new tectonic map of the Lake Geneva region could thus be drawn up. The substratum does not show faults indicating a tectonic origin for the Lake Geneva Basin. However, we suggest that the orientation of glacial erosion, and thus the shape of Lake Geneva, vas influenced by the presence of faults in the pre-Quaternary basement. The analysis of Quaternary sediments enabled us to draw up maps of various discontinuities or internal units. The top pre-Quaternary basement map shows channels of glacial origin, the deepest of them reaching an altitude of 200 m a.s.l. The channel's slopes are directed to the North-East, in opposite direction of the present water flow. We explain this observation by the presence of artesian subglacial water circulation. Glacial sediments, the maximum thickness of which reaches 150 m in the central part of the lake, record several glacial recurrences. In the Evian area, we found lenses of glacio-lacustrine sediments set high up on the flank of the Lake Geneva Bassin. We correlated these units with on-land borehole data and concluded that they represent the lower complex of the Evian sedimentary pile. The lower complex is aider than 30 000 years, and it could be a Kame deposit associated with a periglacial lake. Our 3D seismic reflexion survey enables us to specify the supply direction of detrital material in this unit. With detailed seismic images we established how some units were affected by different erosion types. The lacustrine sediments we imaged in Lake Geneva are thicker than 225 m and 400 m or more Linder the Rhone Delta. They indicate several depositional mechanisms. Their base is a major turbidite, thirty meters thick on average, that spreads between the Dranse mouth and the Rhone delta. Above this unit, settling of suspended biological and detrital particles provides most of the sediments. In the eastern part of the lake, detrital contribution from the Rhone builds a delta that progrades to the west and imbricates with the settling sediments. The shallow structure of the Rhone delta abruptly evolved, probably after the catastrophic Tauredunum event (563 A.D.). It probably coincides with an erosive surface that we mapped. As a result, the delta geometry changed, in particular associated with a displacement of water bottom channels. In all our seismic sections, we do not observe fault in the Quaternary sediments that would attest postglacial tectonic activity in the basement.

Estimation of a maximum Lu diffusion rate in a natural eclogite garnet

Lutetium zoning in garnet within eclogites from the Zermatt-Saas Fee zone, Western Alps, reveal sharp, exponentially decreasing central peaks. They can be used to constrain maximum Lu volume diffusion in garnets. A prograde garnet growth temperature interval of 450-600 A degrees C has been estimated based on pseudosection calculations and garnet-clinopyroxene thermometry. The maximum pre-exponential diffusion coefficient which fits the measured central peak is in the order of D-0= 5.7*10(-6) m(2)/s, taking an estimated activation energy of 270 kJ/mol based on diffusion experiments for other rare earth elements in garnet. This corresponds to a maximum diffusion rate of D (600 A degrees C) = 4.0*10(-22) m(2)/s. The diffusion estimate of Lu can be used to estimate the minimum closure temperature, T-c, for Sm-Nd and Lu-Hf age data that have been obtained in eclogites of the Western Alps, postulating, based on a literature review, that D (Hf) < D (Nd) < D (Sm) a parts per thousand currency sign D (Lu). T-c calculations, using the Dodson equation, yielded minimum closure temperatures of about 630 A degrees C, assuming a rapid initial exhumation rate of 50A degrees/m.y., and an average crystal size of garnets (r = 1 mm). This suggests that Sm/Nd and Lu/Hf isochron age differences in eclogites from the Western Alps, where peak temperatures did rarely exceed 600 A degrees C must be interpreted in terms of prograde metamorphism.

Double incretin receptor knock-out (DIRKO) mice present with alterations of trabecular and cortical micromorphology and bone strength.

A role for gut hormone in bone physiology has been suspected. We evidenced alterations of microstructural morphology (trabecular and cortical) and bone strength (both at the whole-bone - and tissue-level) in double incretin receptor knock-out (DIRKO) mice as compared to wild-type littermates. These results support a role for gut hormones in bone physiology. INTRODUCTION: The two incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), have been shown to control bone remodeling and strength. However, lessons from single incretin receptor knock-out mice highlighted a compensatory mechanism induced by elevated sensitivity to the other gut hormone. As such, it is unclear whether the bone alterations observed in GIP or GLP-1 receptor deficient animals resulted from the lack of a functional gut hormone receptor, or by higher sensitivity for the other gut hormone. The aims of the present study were to investigate the bone microstructural morphology, as well as bone tissue properties, in double incretin receptor knock-out (DIRKO) mice. METHODS: Twenty-six-week-old DIRKO mice were age- and sex-matched with wild-type (WT) littermates. Bone microstructural morphology was assessed at the femur by microCT and quantitative X-ray imaging, while tissue properties were investigated by quantitative backscattered electron imaging and Fourier-transformed infrared microscopy. Bone mechanical response was assessed at the whole-bone- and tissue-level by 3-point bending and nanoindentation, respectively. RESULTS: As compared to WT animals, DIRKO mice presented significant augmentations in trabecular bone mass and trabecular number whereas bone outer diameter, cortical thickness, and cortical area were reduced. At the whole-bone-level, yield stress, ultimate stress, and post-yield work to fracture were significantly reduced in DIRKO animals. At the tissue-level, only collagen maturity was reduced by 9 % in DIRKO mice leading to reductions in maximum load, hardness, and dissipated energy. CONCLUSIONS: This study demonstrated the critical role of gut hormones in controlling bone microstructural morphology and tissue properties.

New prognostic factors and calculators for outcome prediction in patients with recurrent glioblastoma: A pooled analysis of EORTC Brain Tumour Group phase I and II clinical trials.

BACKGROUND: Prognostic models have been developed to predict survival of patients with newly diagnosed glioblastoma (GBM). To improve predictions, models should be updated with information at the recurrence. We performed a pooled analysis of European Organization for Research and Treatment of Cancer (EORTC) trials on recurrent glioblastoma to validate existing clinical prognostic factors, identify new markers, and derive new predictions for overall survival (OS) and progression free survival (PFS).¦METHODS: Data from 300 patients with recurrent GBM recruited in eight phase I or II trials conducted by the EORTC Brain Tumour Group were used to evaluate patient's age, sex, World Health Organisation (WHO) performance status (PS), presence of neurological deficits, disease history, use of steroids or anti-epileptics and disease characteristics to predict PFS and OS. Prognostic calculators were developed in patients initially treated by chemoradiation with temozolomide.¦RESULTS: Poor PS and more than one target lesion had a significant negative prognostic impact for both PFS and OS. Patients with large tumours measured by the maximum diameter of the largest lesion (⩾42mm) and treated with steroids at baseline had shorter OS. Tumours with predominant frontal location had better survival. Age and sex did not show independent prognostic values for PFS or OS.¦CONCLUSIONS: This analysis confirms performance status but not age as a major prognostic factor for PFS and OS in recurrent GBM. Patients with multiple and large lesions have an increased risk of death. With these data prognostic calculators with confidence intervals for both medians and fixed time probabilities of survival were derived.

Application des méthodes géophysiques à l'étude de deux sites (Kappelen et Grenchen) de l'aquifère poreux complexe du Seeland

L'aquifère du Seeland représente une richesse en ressources hydriques qu'il est impératif de préserver contre tout risque de détérioration. Cet aquifère prolifique est constitué principalement de sédiments alluviaux post-glaciaires (graviers, sables et limons). Il est soumis aux contraintes environnementales des pratiques d'agriculture intensive, du réseau routier, des villes et de leurs activités industrielles. La connaissance optimale de ces ressources est donc primordiale pour leur protection. Dans cette optique, deux sites Kappelen et Grenchen représentatifs de l'aquifère du Seeland ont été étudiés. L'objectif de ce travail est de caractériser d'un point de vue hydrogéophysique l'aquifère au niveau de ces deux sites, c'est-à-dire, comprendre la dynamique des écoulements souterrains par l'application des méthodes électriques de surface associées aux diagraphies en intégrant des méthodes hydrogéologiques. Pour le site de Kappelen, les méthodes électriques de surface ont permis d'identifier les différents faciès géoélectriques en présence et de mettre en évidence leur disposition en une structure tabulaire et horizontale. Il s'agit d'un aquifère libre constitué d'une série de graviers allant jusqu'à 15 m de profondeur reposant sur de la moraine argileuse. Les diagraphies électriques, nucléaires et du fluide ont servis à la détermination des caractéristiques pétrophysiques et hydrauliques de l'aquifère qui contrôlent son comportement hydrodynamique. Les graviers aquifères de Kappelen présentent deux minéraux dominants: quartz et calcite. Les analyses minéralogiques indiquent que ces deux éléments constituent 65 à 75% de la matrice. La porosité totale obtenue par les diagraphies nucléaires varie de 20 à 30 %, et de 22 à 29 % par diagraphies électrique. Avec les faibles valeurs de Gamma Ray ces résultats indiquent que l'aquifère des graviers de Kappelen est dépourvu d'argile minéralogique. La perméabilité obtenue par diagraphies du fluide varie de 3.10-4 à 5.10-2 m/s, et par essais de pompage de 10-4 à 10-2 m/s. Les résultats des analyses granulométriques indiquent une hétérogénéité granulométrique au niveau des graviers aquifères. La fraction de sables, sables très fins, silts et limons constitue de 10 à 40 %. Ces éléments jouent un rôle important dans le comportement hydraulique de l'aquifère. La porosité efficace de 11 à 25% estimée à partir des résultats des analyses granulométriques suppose que les zones les plus perméables correspondent aux zones les plus graveleuses du site. Etablie sur le site de Kappelen, cette méthodologie a été utilisée sur le site de Grenchen. Les méthodes électriques de surface indiquent que l'aquifère captif de Grenchen est constitué des sables silteux comprenant des passages sableux, encadrés par des silts argileux imperméables. L'aquifère de Grenchen est disposé dans une structure relativement tabulaire et horizontale. Son épaisseur totale peut atteindre les 25 m vers le sud et le sud ouest ou les passages sableux sont les plus importants. La détermination des caractéristiques pétrophysiques et hydrauliques s'est faite à l'aide des diagraphies. Les intensités Gamma Ray varient de 30 à 100 cps, les plus fortes valeurs n'indiquent qu'une présence d'éléments argileux mais pas de bancs d'argile. Les porosités totales de 15 à 25% et les densités globales de 2.25 à 2.45 g/cm3 indiquent que la phase minérale (matrice) est composée essentiellement de quartz et de calcaire. Les densités de matrice varient entre 2.65 et 2.75 g/cm3. La perméabilité varie de 2 10-6 à 5 10-4 m/s. La surestimation des porosités totales à partir des diagraphies électriques de 25 à 42% est due à la présence d'argiles. -- The vast alluvial Seeland aquifer system in northwestern Switzerland is subjected to environmental challenges due to intensive agriculture, roads, cities and industrial activities. Optimal knowledge of the hydrological resources of this aquifer system is therefore important for their protection. Two representative sites, Kappelen and Grenchen, of the Seeland aquifer were investigated using surface-based geoelectric methods and geophysical borehole logging methods. By integrating of hydrogeological and hydrogeophysical methods, a reliable characterization of the aquifer system at these two sites can be performed in order to better understand the governing flow and transport process. At the Kappelen site, surface-based geoelectric methods allowed to identify various geoelectric facies and highlighted their tabular and horizontal structure. It is an unconfined aquifer made up of 15 m thick gravels with an important sandy fraction and bounded by a shaly glacial aquitard. Electrical and nuclear logging measurements allow for constraining the petrophysical and hydrological parameters of saturated gravels. Results indicate that in agreement with mineralogical analyses, matrix of the probed formations is dominated by quartz and calcite with densities of 2.65 and 2.71 g/cc, respectively. These two minerals constitute approximately 65 to 75 % of the mineral matrix. Matrix density values vary from 2.60 to 2.75 g/cc. Total porosity values obtained from nuclear logs range from 20 to 30 % and are consistent with those obtained from electrical logs ranging from 22 to 29 %. Together with the inherently low natural gamma radiation and the matrix density values obtained from other nuclear logging measurements, this indicates that at Kappelen site the aquifer is essentially devoid of clay. Hydraulic conductivity values obtained by the Dilution Technique vary between 3.10-4 and 5.10-2 m/s, while pumping tests give values ranging from 10-4 to 10-2 m/s. Grain size analysis of gravel samples collected from boreholes cores reveal significant granulometric heterogeneity of these deposits. Calculations based on these granulometric data have shown that the sand-, silt- and shale-sized fractions constitute between 10 and 40 % of the sample mass. The presence of these fine elements in general and their spatial distribution in particular are important as they largely control the distribution of the total and effective porosity as well as the hydraulic conductivity. Effective porosity values ranging from 11 to 25% estimated from grain size analyses indicate that the zones of higher hydraulic conductivity values correspond to the zones dominated by gravels. The methodology established at the Kappelen site was then applied to the Grenchen site. Results from surface-based geoelectric measurements indicate that it is a confined aquifer made up predominantly of shaly sands with intercalated sand lenses confined impermeable shally clay. The Grenchen confined aquifer has a relatively tabular and horizontal structure with a maximum thickness of 25 m in the south and the southwest with important sand passages. Petrophysical and hydrological characteristics were performed using electrical and nuclear logging. Natural gamma radiation values ranging from 30 to 100 cps indicate presence of a clay fraction but not of pure clay layers. Total porosity values obtained from electrical logs vary form 25 to 42%, whereas those obtained from nuclear logs values vary from 15 to 25%. This over-estimation confirms presences of clays. Density values obtained from nuclear logs varying from 2.25 to 2.45 g/cc in conjunction with the total porosity values indicate that the dominating matrix minerals are quartz and calcite. Matrix density values vary between 2.65 and 2.75 g/cc. Hydraulic conductivity values obtained by the Dilution Technique vary from 2 10-6 to 5 10-4 m/s.

Sagittal abdominal diameter is a better predictor than body mass index for duration of laparoscopic left colectomy.

BACKGROUND: Visceral obesity (VO) increases technical difficulty in laparoscopic surgery. The body mass index (BMI) does not always correlate to intra-abdominal fat distribution. Our hypothesis was that simple anthropometric measures that reflect VO, could predict technical difficulty in laparoscopic colorectal surgery, as reflected by the operative time, more accurately than the BMI. METHODS: Charts of all consecutive patients who underwent laparoscopic left colon resection in our institution between 2007 and 2010 were reviewed retrospectively. On a preoperative CT scan, anthropometric measures were taken on an axial plane at the L4-L5 level. Demographic, operative and anthropometric CT measures were correlated with the operative time. Logistic regression analysis was performed to assess the value of anthropometric CT measures or BMI to predict the duration of the colectomy. RESULTS: 121 patients with elective left colon resection for benign (56%) or malignant disease (44%) were included. There were 74 sigmoid resections (61%), 21 left hemicolectomies (17%) and 26 low anterior resections (22%). A longer sagittal abdominal diameter (≥24.8 cm) was significantly associated with longer corrected operative time (248 vs. 228 min, p = 0.043). In multivariate analysis, greater sagittal abdominal diameter, sagittal internal diameter and abdominal perimeter were significantly associated with longer operative time. No significant association was found for the BMI neither in univariate nor in multivariate analysis. CONCLUSIONS: This study suggests that simple linear measures taken on a CT scan, such as sagittal abdominal diameter, sagittal internal diameter and abdominal perimeter, may predict longer operative time in laparoscopic left colonic resections more accurately than BMI.