Probabilistic sonar scan matching for an AUV

This paper proposes MSISpIC, a probabilistic sonar scan matching algorithm for the localization of an autonomous underwater vehicle (AUV). The technique uses range scans gathered with a Mechanical Scanning Imaging Sonar (MSIS), the robot displacement estimated through dead-reckoning using a Doppler velocity log (DVL) and a motion reference unit (MRU). The proposed method is an extension of the pIC algorithm. An extended Kalman filter (EKF) is used to estimate the robot-path during the scan in order to reference all the range and bearing measurements as well as their uncertainty to a scan fixed frame before registering. The major contribution consists of experimentally proving that probabilistic sonar scan matching techniques have the potential to improve the DVL-based navigation. The algorithm has been tested on an AUV guided along a 600 m path within an abandoned marina underwater environment with satisfactory results

Using 3D surface datasets to understand landslide evolution: From analogue models to real case study

Early detection of landslide surface deformation with 3D remote sensing techniques, as TLS, has become a great challenge during last decade. To improve our understanding of landslide deformation, a series of analogue simulation have been carried out on non-rigid bodies coupled with 3D digitizer. All these experiments have been carried out under controlled conditions, as water level and slope angle inclination. We were able to follow 3D surface deformation suffered by complex landslide bodies from precursory deformation still larger failures. These experiments were the basis for the development of a new algorithm for the quantification of surface deformation using automatic tracking method on discrete points of the slope surface. To validate the algorithm, comparisons were made between manually obtained results and algorithm surface displacement results. Outputs will help in understanding 3D deformation during pre-failure stages and failure mechanisms, which are fundamental aspects for future implementation of 3D remote sensing techniques in early warning systems.

Bodyweight and migration-related differences in motor abilities in preschool children "Ballabeina"

Introduction: Motor abilities in schoolchildren have been decreasing in the last two decades (Bös, 2003, Tomkinson et al., 2003). This may be related to the dramatic increase in overweight and adiposity during the same time period. Children of migrant background are especially affected (Lasserre et al., 2007). But little is known about the relationship between BMI and migration background and motor abilities in preschool children. Methods/Design We carried out a cross-sectional analysis with 665 children (age 5.1 ± 0.6 years; 49.8 % female) of 40 randomly selected kindergarten classes from German and French speaking regions in Switzerland with a high migrant background. We investigated BMI, cardiorespiratory fitness (20 m shuttle run), static (displacement of center of pressure (COP)) and dynamic (balancing forward on a beam) postural control and overall fitness (obstacle course). Results: Of the children, 9.6 % were overweight, 10.5 % were obese (Swiss national percentiles) and 72.8 % were of migrant background (at least one parent born outside of Switzerland). Mean BMI from children of non-migrant background was 15.5 ± 1.1 kg/m2, while migrant children had a mean BMI of 15.8 ± 1.7 kg/m2 (p=0.08). Normal-weight children performed better in cardiorespiratory fitness (3.1 ± 1.4 vs. 2.6 ± 1.1 stages, p<0.001), overall fitness (18.9 ± 4.4 vs. 20.8 ± 4.6 sec, p<0.001) and in dynamic balance (4.9 ± 3.5 vs. 3.8 ± 2.5 steps, p<0.001) compared to overweight and obese children, while the latter had less postural sway (COP: 956 ± 302 vs. 1021 ± 212 mm, p=0.008). There was a clear inverse dose-response relationship between weight status and dynamic motor abilities. There were no significant differences in most tested motor abilities between non-migrant and migrant. The latter performed less well in only one motor test (overall fitness: 20.2 ± 5.2 vs. 18.3 ± 3.5 sec, p<0.001). These findings persisted after adjustment for BMI. Conclusion In preschool children, differences in motor abilities are already present between normal weight and overweight/obese children. However, migrant children demonstrate similar motor abilities compared to non-migrant children for almost all tests, despite their slightly higher BMI.

El lavado de manos: ¿una recomendación atendida?

Objective: to determine the incidence of hand washing in parents as a preventive factor in the spread of viral respiratory infections in children under two years assigned to an urban pediatric basic health area affected by catarrhal symptoms during the influenza vaccination campaign. Material and methods: from 230 children under two years included in the basic health area attending the Well Child program, 51 consulted during the influenza vaccination campaign (October 2011) by catarrhal symptoms. Results: fifty-one children were included, 23 male and 28 female. From the clinical point of view, 33 cases were afebrile and only 18 had fever, runny nose 100%. The clinic diagnosis in 44 cases was nasopharyngitis, acute bronchitis in 5 cases and obstructive bronchiolitis in 2 cases. No family history in 19, however 32 cases had a family member with catarrhal symptoms. As for the performance of hand washing as a preventive measure, 34 cases said they did not comply with this measure, only 17 cases did, despite the recommendations. Conclusions: while recognizing the importance of hand washing as a preventive measure for respiratory infections and being included among the recommendations offered in the well child program, only 33% of the population of our study reported washing hands. This recommendation should also be included in consultations on demand during the influenza season to encourage compliance.

Risks of endemicity, morbidity and perspectives regarding the control of Chagas disease in the Amazon Region

Chagas disease, in the Amazon Region as elsewhere, can be considered an enzootic disease of wild animals or an anthropozoonosis, an accidental disease of humans that is acquired when humans penetrate a wild ecosystem or when wild triatomines invade human dwellings attracted by light or searching for human blood. The risk of endemic Chagas disease in the Amazon Region is associated with the following phenomena: (i) extensive deforestation associated with the displacement of wild mammals, which are the normal sources of blood for triatomines, (ii) adaptation of wild triatomines to human dwellings due to the need for a new source of blood for feeding and (iii) uncontrolled migration of human populations and domestic animals that are already infected with Trypanosoma cruzi from areas endemic for Chagas disease to the Amazon Region. Several outbreaks of severe acute cases of Chagas disease, as well as chronic cases, have been described in the Amazon Region. Control measures targeted to avoiding endemic Chagas disease in the Amazon Region should be the following: improving health education in communities, training public health officials and communities for vector and Chagas disease surveillance and training local physicians to recognise and treat acute and chronic cases of Chagas diseases as soon as possible.

Cuestiones de pintura y miniatura en Cerdeña: modelos, intercambios y relaciones internacionales en la segunda mitad del siglo XV

Durante el siglo XV Cerdeña desempeña, gracias a su posicionamiento geográfico en el centro del Mediterráneo, un papel muy importante en la red de comercio internacional. Este movimiento económico-cultural fomenta una extensa producción artística que está caracterizada por depender fuertemente de la presencia en la isla de talleres y artistas catalanes. Al día de hoy se conoce muy poco la presencia y las características de la pintura del gótico tardío en la Cerdeña. Las dificultades encontradas por los investigadores en la reconstrucción de la historia del arte sarda de esta época son numerosas y difíciles de solucionar. El problema depende de la falta de fuentes documentales (directas e indirectas), de la gran dispersión de muchísimas obras, de la inaccesibilidad de unas de las obras más interesantes; del desplazamiento casi total de las obras de su sitio original, y del total anonimato de la mayoría de los artistas. En estas condiciones la única solución para alcanzar nuevos elementos científicos es: integrar los conocimientos procedente de las fuentes documentales; ampliar la practica metodológica (multidisciplinariedad), conectar el tejido sardo (pintura, miniatura, grabados) con el ámbito internacional. El objetivo final es introducir la pintura sarda en un contexto más amplio, para poder descubrir el sistema de modelos y de relaciones artísticas, que la conectan con el mundo artístico mediterráneo. El trabajo de este primer año ha sido particularmente intenso y complicado por las dificultades encontradas en ponerse en un tema tan vasto como lo de la pintura y los modelos figurativos de la segunda mitad del siglo XV. Principales objetivos: averiguar toda la bibliografía conocida sobre el tema e intentar ampliar los estudios cada vez que se encontraban indicios sobre posibles autores y obras sardas; empezar el trabajo de catalogación de las obras pictóricas (conocidas o recien descubiertas.)

Magnetic pill tracking : a novel non-invasive tool for investigation of human digestive motility

RESUME Les améliorations méthodologiques des dernières décennies ont permis une meilleure compréhension de la motilité gastro-intestinale. Il manque toutefois une méthode qui permette de suivre la progression du chyme le long du tube gastro-intestinal. Pour permettre l'étude de la motilité de tout le tractus digestif humain, une nouvelle technique, peu invasive, a été élaborée au Département de Physiologie, en collaboration avec l'EPFL. Appelée "Magnet Tracking", la technique est basée sur la détection du champ magnétique généré par des matériaux ferromagnétiques avalés. A cet usage, une pilule magnétique, une matrice de capteurs et un logiciel ont été développés. L'objet de ce travail est de démontrer la faisabilité d'un examen de la motilité gastro-intestinale chez l'Homme par cette méthode. L'aimant est un cylindre (ø 6x7 mm, 0.2 cm3) protégé par une gaine de silicone. Le système de mesure est constitué d'une matrice de 4x4 capteurs et d'un ordinateur portable. Les capteurs fonctionnent sur l'effet Hall. Grâce à l'interface informatique, l'évolution de la position de l'aimant est suivie en temps réel à travers tout le tractus digestif. Sa position est exprimée en fonction du temps ou reproduite en 3-D sous forme d'une trajectoire. Différents programmes ont été crées pour analyser la dynamique des mouvements de l'aimant et caractériser la motilité digestive. Dix jeunes volontaires en bonne santé ont participé à l'étude. L'aimant a été avalé après une nuit de jeûne et son séjour intra digestif suivi pendant 2 jours consécutifs. Le temps moyen de mesure était de 34 heures. Chaque sujet a été examiné une fois sauf un qui a répété sept fois l'expérience. Les sujets restaient en décubitus dorsal, tranquilles et pouvaient interrompre la mesure s'ils le désiraient. Ils sont restés à jeûne le premier jour. L'évacuation de l'aimant a été contrôlée chez tous les sujets. Tous les sujets ont bien supporté l'examen. Le marqueur a pu être détecté de l'oesophage au rectum. La trajectoire ainsi constituée représente une conformation de l'anatomie digestive : une bonne superposition de celle-ci à l'anatomie est obtenue à partir des images de radiologie conventionnelle (CT-scan, lavement à la gastrografine). Les mouvements de l'aimant ont été caractérisés selon leur périodicité, leur amplitude ou leur vitesse pour chaque segment du tractus digestif. Ces informations physiologiques sont bien corrélées à celles obtenues par des méthodes établies d'étude de la motilité gastro-intestinale. Ce travail démontre la faisabilité d'un examen de la motilité gastro-intestinal chez l'Homme par la méthode de Magnet Tracking. La technique fournit les données anatomiques et permet d'analyser en temps réel la dynamique des mouvements du tube digestif. Cette méthode peu invasive ouvre d'intéressantes perspectives pour l'étude de motilité dans des conditions physiologiques et pathologiques. Des expériences visant à valider cette approche en tant que méthode clinique sont en voie de réalisation dans plusieurs centres en Suisse et à l'étranger. SUMMARY Methodological improvements realised over the last decades have permitted a better understanding of gastrointestinal motility. Nevertheless, a method allowing a continuous following of lumina' contents is still lacking. In order to study the human digestive tract motility, a new minimally invasive technique was developed at the Department of Physiology in collaboration with Swiss Federal Institute of Technology. The method is based on the detection of magnetic field generated by swallowed ferromagnetic materials. The aim of our work was to demonstrate the feasibility of this new approach to study the human gastrointestinal motility. The magnet used was a cylinder (ø6x7mm, 0.2 cm3) coated with silicon. The magnet tracking system consisted of a 4x4 matrix of sensors based on the Hall effect Signals from the sensors were digitised and sent to a laptop computer for processing and storage. Specific software was conceived to analyse in real time the progression of the magnet through the gastrointestinal tube. Ten young and healthy volunteers were enrolled in the study. After a fasting period of 12 hours, they swallowed the magnet. The pill was then tracked for two consecutive days for 34 hours on average. Each subject was studied once except one who was studied seven times. Every subject laid on his back for the entire experiment but could interrupt it at anytime. Evacuation of the magnet was controlled in all subjects. The examination was well tolerated. The pill could be followed from the esophagus to the rectum. The trajectory of the magnet represented a "mould" of the anatomy of the digestive tube: a good superimposition with radiological anatomy (gastrografin contrast and CT) was obtained. Movements of the magnet were characterized by periodicity, velocity, and amplitude of displacements for every segment of the digestive tract. The physiological information corresponded well to data from current methods of studying gastrointestinal motility. This work demonstrates the feasibility of the new approach in studies of human gastrointestinal motility. The technique allows to correlate in real time the dynamics of digestive movements with the anatomical data. This minimally invasive method is ready for studies of human gastrointestinal motility under physiological as well as pathological conditions. Studies aiming at validation of this new approach as a clinically relevant tool are being realised in several centres in Switzerland and abroad. Abstract: A new minimally invasive technique allowing for anatomical mapping and motility studies along the entire human digestive system is presented. The technique is based on continuous tracking of a small magnet progressing through the digestive tract. The coordinates of the magnet are calculated from signals recorded by 16 magnetic field sensors located over the abdomen. The magnet position, orientation and trajectory are displayed in real time. Ten young healthy volunteers were followed during 34 h. The technique was well tolerated and no complication was encountered, The information obtained was 3-D con-figuration of the digestive tract and dynamics of the magnet displacement (velocity, transit time, length estimation, rhythms). In the same individual, repea-ted examination gave very reproducible results. The anatomical and physiological information obtained corresponded well to data from current methods and imaging. This simple, minimally invasive technique permits examination of the entire digestive tract and is suitable for both research and clinical studies. In combination with other methods, it may represent a useful tool for studies of Cl motility with respect to normal and pathological conditions.

Long time behaviour of diffusing particles in constrained geometries; application to chromatin motion

Inspired by experiments that use single-particle tracking to measure the regions of confinement of selected chromosomal regions within cell nuclei, we have developed an analytical approach that takes into account various possible positions and shapes of the confinement regions. We show, in particular, that confinement of a particle into a subregion that is entirely enclosed within a spherical volume can lead to a higher limit of the mean radial square displacement value than the one associated with a particle that can explore the entire spherical volume. Finally, we apply the theory to analyse the motion of extrachromosomal chromatin rings within nuclei of living yeast.

First published record of urban malaria in Puerto Gaitan, Meta, Colombia

Patterns of malaria cases were compared between the department of Meta and the municipality of Puerto Gaitán, Colombia, to examine temporal change in malaria from 2005-2010. During this time frame in Meta the mean ratio was 2.53; in contrast, in Puerto Gaitán it was 1.41, meaning that a surprisingly high proportion of Plasmodium falciparum cases were reported from this municipality. A detailed analysis of data from Puerto Gaitán for 2009 and 2010 detected a significant difference (χ2, p < 0.001) in the distribution of plasmodia, with Plasmodium vivax more prevalent in 2009 and P. falciparum in 2010. Males had the highest number of cases but there was no difference in the distribution of cases between sexes and years. In both years, for both sexes, people 16-40 accounted for the majority of cases (58.9% in 2009; 60.4% in 2010). There were significant differences in the distribution of both P. vivax (χ2, p < 0.01) and P. falciparum cases (χ2, p < 0.05) by geographic setting (urban vs. non-urban) between years. Urban cases of both P. vivax and P. falciparum are recorded in this study for the first time in Puerto Gaitán, possibly the result of area wide displacement and migration due to armed conflict.

Mapping complex tissue architecture with diffusion spectrum magnetic resonance imaging.

Methods are presented to map complex fiber architectures in tissues by imaging the 3D spectra of tissue water diffusion with MR. First, theoretical considerations show why and under what conditions diffusion contrast is positive. Using this result, spin displacement spectra that are conventionally phase-encoded can be accurately reconstructed by a Fourier transform of the measured signal's modulus. Second, studies of in vitro and in vivo samples demonstrate correspondence between the orientational maxima of the diffusion spectrum and those of the fiber orientation density at each location. In specimens with complex muscular tissue, such as the tongue, diffusion spectrum images show characteristic local heterogeneities of fiber architectures, including angular dispersion and intersection. Cerebral diffusion spectra acquired in normal human subjects resolve known white matter tracts and tract intersections. Finally, the relation between the presented model-free imaging technique and other available diffusion MRI schemes is discussed.

Assisted reproductive technology and obstetric outcome in couples when the male partner has a chronic viral disease.

BACKGROUND Assisted reproductive technology (ART) with washed semen can achieve pregnancy with minimal risk of horizontal and vertical transmission of chronic viral diseases (CVD) such as human immunodeficiency virus (HIV), hepati- tis C virus (HCV) and hepatitis B virus (HBV) among serodiscordant couples. How- ever, few studies have been made of the use made by these couples of ARTs or of the obstetric results achieved. MATERIALS AND METHODS In this retrospective study, 93 men who were seropositive for HIV, HCV or HBV and who underwent assisted reproduction treatment at our centre (Hospital Universitario Virgen de las Nieves, Granada, Spain) were included. Washed semen was tested to detect viral particles. Non-infected women were tested before and after each treatment, as were the neonates at birth and after three months. RESULTS A total of 62 sperm samples were washed, and none were positive for the detec- tion of viral molecules. Semen samples from 34 HBV positive males were not washed since the female partner had immunity to hepatitis B. In total, 38 clinical pregnancies were achieved (22% per cycle and 40.9% per couple) out of 173 cycles initiated, and 28 births were achieved (16.2% per cycle and 30.1% per couple), producing 34 live births. The rate of multiple pregnancies was 21.4%. Obstetric and neonatal results were similar in the groups of couples studied. At follow-up, no seroconversion was detected in the women or neonates. CONCLUSION Sperm washing and intracytoplasmic sperm injection are shown to be a safe and effective option for reducing the risk of transmission or super infection in serodiscordant or concordant couples who wish to have a child. Pregnancies ob- tained by ART in couples when the male is CVD infected achieve good obstetric and neonatal results.

Forecasting changes in population genetic structure of alpine plants in response to global warming.

Species range shifts in response to climate and land use change are commonly forecasted with species distribution models based on species occurrence or abundance data. Although appealing, these models ignore the genetic structure of species, and the fact that different populations might respond in different ways because of adaptation to their environment. Here, we introduced ancestry distribution models, that is, statistical models of the spatial distribution of ancestry proportions, for forecasting intra-specific changes based on genetic admixture instead of species occurrence data. Using multi-locus genotypes and extensive geographic coverage of distribution data across the European Alps, we applied this approach to 20 alpine plant species considering a global increase in temperature from 0.25 to 4 °C. We forecasted the magnitudes of displacement of contact zones between plant populations potentially adapted to warmer environments and other populations. While a global trend of movement in a north-east direction was predicted, the magnitude of displacement was species-specific. For a temperature increase of 2 °C, contact zones were predicted to move by 92 km on average (minimum of 5 km, maximum of 212 km) and by 188 km for an increase of 4 °C (minimum of 11 km, maximum of 393 km). Intra-specific turnover-measuring the extent of change in global population genetic structure-was generally found to be moderate for 2 °C of temperature warming. For 4 °C of warming, however, the models indicated substantial intra-specific turnover for ten species. These results illustrate that, in spite of unavoidable simplifications, ancestry distribution models open new perspectives to forecast population genetic changes within species and complement more traditional distribution-based approaches.

Decreased well-being after job loss : testing omitted causes

Job loss is widely known to lead to a substantial decrease in workers' subjective well-being. Functionalist theories explain this fact by arguing that the fundamental needs that work fulfills are absent during unemployment. Recent evidence from longitudinal studies however contradicts this approach, showing that workers who find a new job do not fully regain their former level of well-being upon reemployment. Therefore other mechanisms must be at work. We suggest that changes in social or economic domains of workers' lives - triggered by job displacement - lead to the observed changes in well-being. Drawing on a unique data set from a survey of workers displaced by plant closure in Switzerland after the financial crisis of 2008, our analysis confirms the previous result that finding a job after displacement does not completely restore workers' pre-displacement level of well-being. The factors that best explain this outcome are changes in social domains, notably changes in workers' job - related social status and their relationships to friends. This result provides valuable insights about the long lasting scars job displacement leaves on workers' lives.

Dorsal fractures of the triquetrum: MRI findings with an emphasis on dorsal carpal ligament injuries.

OBJECTIVE: The objective of our study was to report the MRI findings in dorsal fractures of the triquetrum, with an emphasis on dorsal carpal ligament injuries. MATERIALS AND METHODS: A total of 21 patients (16 men, five women; mean age, 41.9 years) with acute or subacute (≤ 6 weeks) dorsal triquetral fractures on radiography and MRI were included in this two-center retrospective study. MRI of the wrist was performed on 3-T units with transverse T1-weighted, coronal or transverse (or both) fat-suppressed T2weighted, transverse gadolinium-enhanced fat-suppressed T1-weighted turbo spin-echo, and 3D gadolinium-enhanced fat-suppressed T1-weighted gradient-recalled echo sequences. Three musculoskeletal radiologists evaluated the ulnar styloid process index (USPI) on radiographs and the following MRI features: fracture pattern (types 1-6), bone fragment size and displacement, bone marrow edema distribution, and dorsal carpal ligament tears. RESULTS: Eight type 1, one type 2, six type 3, five type 4, and one type 5 fractures were identified. These fractures were associated with 14 (66.7%), 17 (81.0%), and 16 (76.2%) tears of the dorsal radiocarpal, ulnotriquetral, and intercarpal ligaments, respectively. There was no correlation between bone marrow edema distribution and dorsal carpal ligament injuries (all p > 0.05). The mean (± SD) bone fragment volume and displacement were 205 ± 157 mm(3) and 1.0 ± 1.1 mm, respectively. The mean USPI was 0.21 ± 0.10. CONCLUSION: Dorsal fractures of the triquetrum are frequently associated with dorsal carpal ligament injuries. Bone marrow edema distribution is not correlated with these ligament tears.

Sex differences in the computation of traveling distance

Path integration is known to provide information to keep track of spatial location. Surprisingly, few investigations concerning sex differences in computation of the traveling distance have been done. This work was aimed at analyzing the reproduction of both passive and active linear displacements in women and men. To this end, the displacement of blindfolded subjects was done in a wheelchair, then on foot, three times in each condition for a fixed distance. Copies of passive and active traveling distance, distance estimations and pointing responses towards the starting point were analyzed. In passive condition and comparatively to men, women error was larger. Whereas traveling distance was generally underestimated in women, it was overestimated in men. In active condition, no sex differences were observed. When blindfolded subjects have to estimate the traveling distance, the female error was larger than the male one. But, when subjects were asked to indicate the visual cue corresponding to the traveling distance, the male error was larger than the female one. Finally, pointing to the starting point (0°) after a whole-body rotation showed a larger deviation from 0° in men than in women. These results suggest that sex of the subjects influence brain computation of path integration information.