1,473 research outputs found
A Bayesian Generative Model for Surface Template Estimation
3D surfaces are important geometric models for many objects of interest in image analysis and Computational Anatomy. In this paper, we describe a Bayesian inference scheme for estimating a template surface from a set of observed surface data. In order to achieve this, we use the geodesic shooting approach to construct a statistical model for the generation and the observations of random surfaces. We develop a mode approximation EM algorithm to infer the maximum a posteriori estimation of initial momentum ÎĽ, which determines the template surface. Experimental results of caudate, thalamus, and hippocampus data are presented
Geodesic Warps by Conformal Mappings
In recent years there has been considerable interest in methods for
diffeomorphic warping of images, with applications e.g.\ in medical imaging and
evolutionary biology. The original work generally cited is that of the
evolutionary biologist D'Arcy Wentworth Thompson, who demonstrated warps to
deform images of one species into another. However, unlike the deformations in
modern methods, which are drawn from the full set of diffeomorphism, he
deliberately chose lower-dimensional sets of transformations, such as planar
conformal mappings.
In this paper we study warps of such conformal mappings. The approach is to
equip the infinite dimensional manifold of conformal embeddings with a
Riemannian metric, and then use the corresponding geodesic equation in order to
obtain diffeomorphic warps. After deriving the geodesic equation, a numerical
discretisation method is developed. Several examples of geodesic warps are then
given. We also show that the equation admits totally geodesic solutions
corresponding to scaling and translation, but not to affine transformations
Synthesis of Fused Heterocyclic Derivatives from 5-Ethyl-3-Hydrazino-5H-1,2,4-Triazino[5,6-b]Indole
5-Ethyl-3-hydrazino-5H-1,2,4-triazino[5,6-b ]indole II was used for the synthesis of various heterocyclic derivatives. This was performed by reaction of its 3-hydrazino group with different reagents such as acid anhydrides, ethylacetate, diethyl oxalate, thioglycolic acid, aroyl esters and acid chlorides. The structure of the products was confirmed by different spectroscopic and analytical methods
Bilateral stellate neuroretinitis revealing a pheochromocytoma
Neuroretinitis (NR) is an inflammatory disorder characterized by optic disc edema and subsequent formation of a macular star. We present a case of a 33 year old woman patient admitted for a progressive bilateral visual loss since two weeks. Fundus examination showed bilateral stellate neuroretinitis. Physical examination revealed a malignant hypertension of 210/150mmHg. Magnetic resonance imaging identified a left suprarenal mass, whereas urinary catecholamine level was abnormally high which supported a diagnosis of pheochromocytoma.The patient underwent a laparoscopic left suprarenal adrenalectomy after successful control of blood pressure. histopathologic examination confirmed the diagnosis of pheochromocytoma. Visual acuity was restored and the retinal alterations disappeared 7 months after surgery
Should We Learn Probabilistic Models for Model Checking? A New Approach and An Empirical Study
Many automated system analysis techniques (e.g., model checking, model-based
testing) rely on first obtaining a model of the system under analysis. System
modeling is often done manually, which is often considered as a hindrance to
adopt model-based system analysis and development techniques. To overcome this
problem, researchers have proposed to automatically "learn" models based on
sample system executions and shown that the learned models can be useful
sometimes. There are however many questions to be answered. For instance, how
much shall we generalize from the observed samples and how fast would learning
converge? Or, would the analysis result based on the learned model be more
accurate than the estimation we could have obtained by sampling many system
executions within the same amount of time? In this work, we investigate
existing algorithms for learning probabilistic models for model checking,
propose an evolution-based approach for better controlling the degree of
generalization and conduct an empirical study in order to answer the questions.
One of our findings is that the effectiveness of learning may sometimes be
limited.Comment: 15 pages, plus 2 reference pages, accepted by FASE 2017 in ETAP
Pyocele du cornet moyen : a propos d’un cas
Introduction : Les mucocèles sont des formations kystiques bénignes mais expansives, tapissées par un épithélium respiratoire, sans connexion avec les cavités sinusiennes ou nasales. Elles se développent le plus souvent dans le complexe ethmoïdofrontal. Le terme pyocèle correspond à une mucocèle dont le contenu est infecté. La localisation turbinale moyenne est exceptionnelle.Observation : Nous rapportons l’observation d’un patient âgé de 75 ans qui se plaignait d’une obstruction nasale chronique gauche. L’examen clinique montrait un cornet moyen élargi obstruant la totalité de la fosse nasale gauche. L’Imagerie (TDM et IRM) a révélée une formation ovalaire d’allure kystique expansive développée aux dépens du cornet moyen, associée à un polype postérieur. Le diagnostic de mucocèle sur concha bullosa a été porté. Le patient a été opéré par voie endonasale avec marsupialisation et polypectomie. Les suites opératoires étaient simples avec amélioration des signes cliniques.Conclusion : Les pyocèles du cornet moyen sont des lésions rares bénignes, toutefois destructrices. Un bilan radiologique est indispensable pour guider le choix du traitement chirurgical. La voie endonasale reste le traitement de référence pour cette pathologie.Mots clés : Concha bullosa, Pyocèle, Obstruction nasaleIntroduction : A mucocele is an epithelium-lined cavity that contains mucus that fills the sinus and is capable of expansion. The majority of mucoceles are situated in the frontal and/or ethmoid sinuses. A pyocele occurs when a mucocele becomes infected. Concha bullosa mucopyocele is a rare entity that presents with persistent nasal symptoms.Case report : This paper presents patient aged 75 who were admitted with persistent nasal complaints. Anterior rhinoscopy showed enlarged middle turbinates obstructing the nasal cavities. MRI and CT Scann revealed expansif cystic lesion in the middle turbinate with a nasal polyp. With the diagnosis of concha bullosa mucocele, lateral part of the affected middle turbinate and the polyp were resected with an endoscopic approach. There were no intraoperative or postoperative complications. Nasal obstruction vanished postoperatively.Conclusion: Mucopyocele of middle turbinate are rare benign lesions. Radiological assessment is essential to guide the choice of surgical treatment. Endonasal approach is the standard treatment for this disease.Key words : Concha bullosa, Pyocele, Nasal obstructio
Influence of nominal composition variation on phase evolution and creep life of Type 316H austenitic stainless steel components
AbstractThe present work aims to understand the influence of variation in chemical composition in the long term evolution of secondary phases. Three samples with nominal composition of Type 316H but different specific composition have been exposed to 505°C during 150, 145 and 300 kh. The percentage of ferrite and M23C6 carbide have been measured using EBSD and compared with Thermo-Calc predictions. In addition, thin foils were prepared and characterized to identify secondary phases in the samples. The discussion is focused on the influence of the secondary phases on creep deformation and failure
Preserving Derivative Information while Transforming Neuronal Curves
The international neuroscience community is building the first comprehensive
atlases of brain cell types to understand how the brain functions from a higher
resolution, and more integrated perspective than ever before. In order to build
these atlases, subsets of neurons (e.g. serotonergic neurons, prefrontal
cortical neurons etc.) are traced in individual brain samples by placing points
along dendrites and axons. Then, the traces are mapped to common coordinate
systems by transforming the positions of their points, which neglects how the
transformation bends the line segments in between. In this work, we apply the
theory of jets to describe how to preserve derivatives of neuron traces up to
any order. We provide a framework to compute possible error introduced by
standard mapping methods, which involves the Jacobian of the mapping
transformation. We show how our first order method improves mapping accuracy in
both simulated and real neuron traces under random diffeomorphisms. Our method
is freely available in our open-source Python package brainlit
Locally recurrent subcutaneous and muscular hydatid cysts of the leg: an unusual case report
We report a rare case of 50-year-old Moroccan woman with local recurrence of a subcutaneous hydatid cyst in proximity to the medial surface of the tibia and another cyst at the tibialis posterior muscle in the absence of liver, lung und spleen involvement. The first surgery was done in another hospital three years ago; no adjuvant treatment was performed after surgery. Recurrence was diagnosed according to the MRI appearance, serological and pathological findings. The patient underwent complete excision of the subcutaneous cyst with two centimeters of the medial gastrocnemius muscle; the tibialis posterior muscle cyst was intraoperatively drained and irrigated with scolicidal agent as it was next to the posterior tibial pedicle. A periopertive anthelmintic chemotherapy was administered. Two years after the patient showed no recurrence. This case report and literature review describe an approach to the diagnosis and management of this pathological entity
Recommended from our members
Proposed 237U Evaluation for the next ENDL Release
We detail the new LLNL evaluation of {sup 237}U for inclusion in both the next release of the ENDL and ENDF/B-VII databases. This evaluation is based on a combination of TALYS calculations, data fits and the earlier JEFF-3.1 evaluation. Our evaluation is in excellent agreement with published surrogate (n, f) data [11, 12, 13, 14, 18] and the unpublished LLNL surrogate (n,2n) data [16]
- …