Application of discriminant function analysis and change-point problem in dating volcanic ashes

The application of Discriminant function analysis (DFA) is not a new idea in the studyof tephrochrology. In this paper, DFA is applied to compositional datasets of twodifferent types of tephras from Mountain Ruapehu in New Zealand and MountainRainier in USA. The canonical variables from the analysis are further investigated witha statistical methodology of change-point problems in order to gain a betterunderstanding of the change in compositional pattern over time. Finally, a special caseof segmented regression has been proposed to model both the time of change and thechange in pattern. This model can be used to estimate the age for the unknown tephrasusing Bayesian statistical calibration

Positioning an underwater vehicle through image mosaicking

Mosaics have been commonly used as visual maps for undersea exploration and navigation. The position and orientation of an underwater vehicle can be calculated by integrating the apparent motion of the images which form the mosaic. A feature-based mosaicking method is proposed in this paper. The creation of the mosaic is accomplished in four stages: feature selection and matching, detection of points describing the dominant motion, homography computation and mosaic construction. In this work we demonstrate that the use of color and textures as discriminative properties of the image can improve, to a large extent, the accuracy of the constructed mosaic. The system is able to provide 3D metric information concerning the vehicle motion using the knowledge of the intrinsic parameters of the camera while integrating the measurements of an ultrasonic sensor. The experimental results of real images have been tested on the GARBI underwater vehicle

Evaluation of two HbA1c point-of-care analyzers.

BACKGROUND Measurement of HbA1c is the most important parameter to assess glycemic control in diabetic patients. Different point-of-care devices for HbA1c are available. The aim of this study was to evaluate two point-of-care testing (POCT) analyzers (DCA Vantage from Siemens and Afinion from Axis-Shield). We studied the bias and precision as well as interference from carbamylated hemoglobin. METHODS Bias of the POCT analyzers was obtained by measuring 53 blood samples from diabetic patients with a wide range of HbA1c, 4%-14% (20-130 mmol/mol), and comparing the results with those obtained by the laboratory method: HPLC HA 8160 Menarini. Precision was performed by 20 successive determinations of two samples with low 4.2% (22 mmol/mol) and high 9.5% (80 mmol/mol) HbA1c values. The possible interference from carbamylated hemoglobin was studied using 25 samples from patients with chronic renal failure. RESULTS The means of the differences between measurements performed by each POCT analyzer and the laboratory method (95% confidence interval) were: 0.28% (p<0.005) (0.10-0.44) for DCA and 0.27% (p<0.001) (0.19-0.35) for Afinion. Correlation coefficients were: r=0.973 for DCA, and r=0.991 for Afinion. The mean bias observed by using samples from chronic renal failure patients were 0.2 (range -0.4, 0.4) for DCA and 0.2 (-0.2, 0.5) for Afinion. Imprecision results were: CV=3.1% (high HbA1c) and 2.97% (low HbA1c) for DCA, CV=1.95% (high HbA1c) and 2.66% (low HbA1c) for Afinion. CONCLUSIONS Both POCT analyzers for HbA1c show good correlation with the laboratory method and acceptable precision.

Tibial component positioning in total knee arthroplasty: bone coverage and extensor apparatus alignment.

Correct positioning of the tibial component in total knee arthroplasty (TKA) must take into account both an optimal bone coverage (defined by a maximal cortical bearing with posteromedial and anterolateral support) and satisfactory patellofemoral tracking. Consequently, a compromise position must be found by the surgeon during the operation to simultaneously meet these two requirements. Moreover, tibial tray positioning depends upon the tibial torsion, which has been shown to act mainly in the proximal quarter of the tibia. Therefore, the correct application of the tibial tray is also theoretically related to the level of bone resection. In this study, we first quantified the torsional profile given by an optimal bone coverage for a symmetrical tibial tray design and for an asymmetrical one. Then, for the two types of tibial trays, we measured the angle difference between optimal bone coverage and an alignment on the middle of the tibial tubercule. Results showed that the values of the torsional profile given by the symmetrical tray were more scattered than those from the asymmetrical one. However, determination of the mean differential angle between the position providing optimal bone coverage and the one providing the best patellofemoral tracking indicated that the symmetrical prosthetic tray offered the best compromise between these two requirements. Although the tibiofemoral joint is known to be asymmetric in both shape and dimension, the asymmetrical tray chosen in this study was found to fulfill this compromise with more difficulty.

Posicionamento estratégico em resposta às restrições regulatórias de emissões de gases do efeito estufa

No trabalho relatado, analisa-se a estratégia de redução das emissões dos gases do efeito estufa (GEE) em uma empresa de distribuição de energia elétrica. A pesquisa foi conduzida por meio de entrevistas semiestruturadas com a presidência da empresa e com os gestores das áreas de planejamento e controle, marketing, regulação, meio ambiente, responsabilidade social, e pesquisa e desenvolvimento. Tendo-se como ponto de partida o resultado do inventário de emissões de GEE, os gestores foram questionados sobre as iniciativas e os benefícios dos projetos de mitigação das emissões de GEE, as pressões dos stakeholders e o papel da regulamentação na remediação e na prevenção dos impactos decorrentes da mudança climática. Os resultados indicam que os gestores não reconhecem oportunidades de investimentos em projetos de redução das emissões de gases do efeito estufa. A empresa adota uma estratégia instrumental e atua em um ambiente de negócios com restrições regulatórias incipientes de controle das emissões de GEE. No estudo, revela-se que a empresa adota uma estratégia climática evasiva e explora a ausência de prioridade do setor elétrico brasileiro na redução do impacto ambiental ou da vulnerabilidade à mudança climática.

Phylogenetic approach reveals that virus genotype largely determines HIV set-point viral load.

HIV virulence, i.e. the time of progression to AIDS, varies greatly among patients. As for other rapidly evolving pathogens of humans, it is difficult to know if this variance is controlled by the genotype of the host or that of the virus because the transmission chain is usually unknown. We apply the phylogenetic comparative approach (PCA) to estimate the heritability of a trait from one infection to the next, which indicates the control of the virus genotype over this trait. The idea is to use viral RNA sequences obtained from patients infected by HIV-1 subtype B to build a phylogeny, which approximately reflects the transmission chain. Heritability is measured statistically as the propensity for patients close in the phylogeny to exhibit similar infection trait values. The approach reveals that up to half of the variance in set-point viral load, a trait associated with virulence, can be heritable. Our estimate is significant and robust to noise in the phylogeny. We also check for the consistency of our approach by showing that a trait related to drug resistance is almost entirely heritable. Finally, we show the importance of taking into account the transmission chain when estimating correlations between infection traits. The fact that HIV virulence is, at least partially, heritable from one infection to the next has clinical and epidemiological implications. The difference between earlier studies and ours comes from the quality of our dataset and from the power of the PCA, which can be applied to large datasets and accounts for within-host evolution. The PCA opens new perspectives for approaches linking clinical data and evolutionary biology because it can be extended to study other traits or other infectious diseases.

A New Imaging Software To Evaluate The Centration Of Capsulorhexis And Intraocular Lens (IOL) After Cataract Surgery

Purpose: IOL centration and stability after cataract surgery is of high interest for cataract surgeons and IOL-producing companies. We present a new imaging software to evaluate the centration of the rhexis and the centration of the IOL after cataract surgery.Methods: We developed, in collaboration with the Biomedical Imaging Group (BIG), EPFL, Lausanne, a new working tool in order to assess precisely outcomes after IOL-implantation, such as ideal capsulorhexis and IOL-centration. The software is a plug-in of ImageJ, a general-purpose image processing and image-analysis package. The specifications of this software are: evaluation of the rhexis-centration and evaluation the position of the IOL in the posterior chamber. The end points are to analyze the quality of the centration of a rhexis after cataract surgery, the deformation of the rhexis with capsular bag retraction and the centration of the IOL after implantation.Results: This software delivers tools to interactively measure the distances between limbus, IOL and capsulorhexis and its changes over time. The user is invited to adjust nodes of three radial curves for the limbus, rhexis and the optic of the IOL. The radial distances of the curves are computed to evaluate the IOL implantation. The user is also able to define patterns for ideal capsulorhexis and optimal IOL-centration. We are going to present examples of calculations after cataract surgery.Conclusions: Evaluation of the centration of the rhexis and of the IOL after cataract surgery is an important end point for optimal IOL implantation after cataract surgery. Especially multifocal or accommodative lenses need a precise position in the bag with a good stability over time. This software is able to evaluate these parameters just after the surgery but also its changes over time. The results of these evaluations can lead to an optimizing of surgical procedures and materials.

Structure-function analyses point to a polynucleotide-accommodating groove essential for APOBEC3A restriction activities.

Members of the human APOBEC3 family of editing enzymes can inhibit various mobile genetic elements. APOBEC3A (A3A) can block the retrotransposon LINE-1 and the parvovirus adeno-associated virus type 2 (AAV-2) but does not inhibit retroviruses. In contrast, APOBEC3G (A3G) can block retroviruses but has only limited effects on AAV-2 or LINE-1. What dictates this differential target specificity remains largely undefined. Here, we modeled the structure of A3A based on its homology with the C-terminal domain of A3G and further compared the sequence of human A3A to those of 11 nonhuman primate orthologues. We then used these data to perform a mutational analysis of A3A, examining its ability to restrict LINE-1, AAV-2, and foreign plasmid DNA and to edit a single-stranded DNA substrate. The results revealed an essential functional role for the predicted single-stranded DNA-docking groove located around the A3A catalytic site. Within this region, amino acid differences between A3A and A3G are predicted to affect the shape of the polynucleotide-binding groove. Correspondingly, transferring some of these A3A residues to A3G endows the latter protein with the ability to block LINE-1 and AAV-2. These results suggest that the target specificity of APOBEC3 family members is partly defined by structural features influencing their interaction with polynucleotide substrates.

Devenir charrùa dans l'Uruguay de l'après dictature Entre mémoires fragmentées et « sens du collectif ». Une ethnographie audiovisuelle en collaboration.

Dans cette recherche, je me suis intéressée à la genèse des rapports sociaux construisant un collectif, dans l'articulation être nommé et se nommer. En Uruguay, pays construit sur un imaginaire social dit "sans indiens", mon travail a consisté à essayer de comprendre les conditions historiques, sociales et politiques d'émergence de collectifs de personnes réclamant l'appartenance à une identité autochtone précise, l'identité charrùa. J'ai démontré qu'il s'agit d'un processus en cours, individuel et collectif, qui a des temporalités diverses, qui a néanmoins émergé depuis une vingtaine d'années, dans le contexte de la post-dictature et celui géopolitique de l'autochtonie, dans une articulation local/global. L'analyse dévoile que l'identité charrùa est l'enjeu du rapport social qui est la lutte politique contre l'exclusion. Cette identité accompagne l'état-nation depuis sa fondation. Figure duelle, cette identité contient les traces des violences internes dans un continuum de mémoires fragmentées et entrelacées. Elle est aussi promesse de devenir en tant que modèle identitaire parvenu à l'autonomie et conservant le « sens du collectif ». Anthropologue engagée, me situant dans une perspective décoloniale, j'ai proposé aux personnes avec qui j'ai effectué cette recherche, d'élaborer une ethnographie collaborative, la caméra et les films se situant au coeur du terrain, compris comme espace relationnel de construction d'une connaissance partagée. -- My research is based on the genesis of social relations which build up a collective, structured on being named and be named. My work in Uruguay, country built on a social construct called "without Indians", was to try to understand the historical, social and political conditions of emerging collectives. These claim the belonging of a precise indigenous identity, the charrua identity. I showed that the current process, which is individual and collective, with different temporalities, emerged twenty years ago, in the post-dictatorship context as well as the geopolitical context of indigeneity, in a local/global structure. The analysis reveals that the charrua identity is the stake of the social relation which is political fight against exclusion. This identity accompanies the nation state since its foundation. Dategory dual, this identity keeps the traces of the internal in the continuum of the fragmented and intertwined memories. This is also the becoming promise of an identity model, which reaches autonomy and keeps the "sense of collective". As an involved anthropologist, I worked from a decolonization point of view. I suggested that the people who went through the research with me, should work out a collaborative ethnography, the video camera and the movies being set in the middle of the fieldwork. This one is conceived as a relational space of construction of a shared knowledge.

Localització i control en temps real de PDA's basades en Windows Mobile mitjançant el sistema GPS

Desenvolupament d'un sistema consistent en un software per la recopilació de dades GPS per a Windows Mobile, un servidor de comunicacions, un server web i una plana web de consulta de les posicions en temps real de les PDA's.

City of Center Point, June 30, 2002

City Audit Report