A relaxed approach for curve matching with elastic metrics

In this paper we study a class of Riemannian metrics on the space of unparametrized curves and develop a method to compute geodesics with given boundary conditions. It extends previous works on this topic in several important ways. The model and resulting matching algorithm integrate within one common setting both the family of $H^2$-metrics with constant coefficients and scale-invariant $H^2$-metrics on both open and closed immersed curves. These families include as particular cases the class of first-order elastic metrics. An essential difference with prior approaches is the way that boundary constraints are dealt with. By leveraging varifold-based similarity metrics we propose a relaxed variational formulation for the matching problem that avoids the necessity of optimizing over the reparametrization group. Furthermore, we show that we can also quotient out finite-dimensional similarity groups such as translation, rotation and scaling groups. The different properties and advantages are illustrated through numerical examples in which we also provide a comparison with related diffeomorphic methods used in shape registration.Comment: 27 page

Joint 3D Shape and Motion Estimation from Rolling Shutter Light-Field Images

In this paper, we propose an approach to address the problem of 3D reconstruction of scenes from a single image captured by a light-field camera equipped with a rolling shutter sensor. Our method leverages the 3D information cues present in the light-field and the motion information provided by the rolling shutter effect. We present a generic model for the imaging process of this sensor and a two-stage algorithm that minimizes the re-projection error while considering the position and motion of the camera in a motion-shape bundle adjustment estimation strategy. Thereby, we provide an instantaneous 3D shape-and-pose-and-velocity sensing paradigm. To the best of our knowledge, this is the first study to leverage this type of sensor for this purpose. We also present a new benchmark dataset composed of different light-fields showing rolling shutter effects, which can be used as a common base to improve the evaluation and tracking the progress in the field. We demonstrate the effectiveness and advantages of our approach through several experiments conducted for different scenes and types of motions. The source code and dataset are publicly available at: https://github.com/ICB-Vision-AI/RSL

A hybrid transport-diffusion model for radiative transfer in absorbing and scattering media

International audienceA new multi-scale hybrid transport-diffusion model for radiative transfer calculations is proposed. In this model, the radiative intensity is decomposed into a macroscopic component calculated by the diffusion equation, and a mesoscopic component. The transport equation for the mesoscopic component allows to correct the estimation of the diffusion equation, and then to obtain the solution of the linear radiative transfer equation. In this work, results are presented for stationary and transient radiative transfer cases, in examples which concern solar concentrated and optical tomography applications. The Monte Carlo and the discrete-ordinate methods are used to solve the mesoscopic equation. It is shown that the multi-scale model allows to improve the efficiency of the calculations when the medium is close to the diffusive regime. Moreover, the development of methods for coupling the radiative transfer equation with the diffusion equation becomes easier with this model than with the usual domain decomposition methods

Para lá das aparelhagens: perceções de jovens do ensino profissional em relação à homossexualidade em contexto escolar

As questões das sexualidades, em particular no que respeita à homossexualidade,continuam alicerçadas em estruturas de fragilidade em termos de produção deconhecimento. De facto, os estudos no campo educativo são ainda parcos. Tem-se,contudo, tentado pensar as sexulidades para além de uma visão que as situa apenas emcontexto escolar e num paradigma heteronormativo, onde o poder controla os discursossobre sexualidade e influencia as formas de conhecimento e de desconhecimento,promovendo assim ausências no que à homossexualidade diz respeito ou, caso contrário,criando presenças tímidas e confinadas ao discurso do combate ao bullying homofóbico,numa lógica reprodutiva das fragilidades e da dialética das sexualidades, onde a um pólodominante se subordinam as margens que se querem silenciosas. Este estudo, que envolvemetodologias quantitativas e qualitativas, nomeadamente recorrendo à etnografia, a uminquérito por questionário e a sessões de grupo de discussão focalizada, procurou darconta da visão dos/as jovens sobre os lugares/ausências efetivos/as da homossexualidadena escola, do poder da escola na construção e reprodução de [pre] conceitos, questionandoo seu papel na promoção de cidadanias a todos/as e refletindo sobre uma [possível]educação para as sexualidades, numa rutura pedagógica que procure dar voz e ser a vozde todos/as, à luz das teorias queer e da pedagogia crítica, para uma educação a e sobretodos/as. Os resultados apontam para uma visão dos/as jovens que destaca os vazios noque às sexualidades e à homossexualidade em contexto(s) escolar(es)diz respeito, numaabordagem às sexualidades, quando existente, sobretudo preventiva, bem como para umforte questionamento do papel da escola na abordagem destas temáticas, por um ladoporque do domínio da privacidade, por outro por um questionamento das própriasaprendizagens escolares

Estudo do metabolismo do 7-nitroindazol: uma abordagem in silico

TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Farmácia.A sepse é um problema mundial de saúde que afeta cerca de 30 milhões de pessoas anualmente. É definida como uma resposta desregulada do hospedeiro frente a um processo infeccioso associado à disfunção orgânica. Muitos trabalhos relatam o envolvimento do óxido nítrico (NO) no desenvolvimento da sepse, por meio de evidências do aumento dos níveis plasmáticos de nitrito e nitrato em pacientes sépticos e no choque séptico. Embora o NO ou peroxinitrito apresentem ação bactericida, níveis plasmáticos excessivos são contraprodutivos, como já evidenciado pelo seu envolvimento na hipotensão e hiporresponsividade à vasoconstritores e na redução da perfusão tecidual. O 7-nitroindazol (7-NI) é uma substância conhecida por sua capacidade de inibir seletivamente a enzima óxido nítrico sintase neuronal (NOS-1), ao se ligar reversivelmente ao grupo heme desta enzima, impedindo a ligação do cofator BH4 e competindo com a L-arginina. Estudo in vivo mostraram que o 7-NI foi eficaz em melhorar a resposta aos vasoconstritores na fase tardia da sepse, além de reduzir a mortalidade dos animais em modelo de CLP e pneumosepse. Apesar de ser promissor para o tratamento da sepse, estudos farmacocinéticos do 7-NI são escassos e não há relatos de estudos de metabolismo na literatura. Assim, este trabalho teve como objetivo por meio de estudo in silico, investigar as vias de metabolização e os prováveis metabólitos do 7-NI. Os possíveis sítios de metabolismo (SoMs) do 7-NI foram avaliados pelos softwares SMARTCyp e Rs-WebPredictor. Para a identificação dos prováveis metabólitos os softwares BioTransformer e MetaUltra foram empregados. Os resultados obtidos com o emprego dos softwares SMARTCyp e Rs-WebPredictor demonstraram que os principais SoMs estão localizados nas posições orto, meta e para em relação ao grupamento nitro do anel aromático. O software Rs-WebPredictor também indicou os nitrogênios do anel de cinco membros e o próprio grupo nitro como possíveis SoMs. Os metabólitos preditos pelos softwares Biotransformer e MetaUltra envolvem principalmente reações oxidação. Além disso, reações de conjugação também foram preditas pelo software MetaUltra. Os resultados obtidos no presente estudo poderão ser utilizados para orientar investigações futuras sobre as propriedades farmacocinétics e toxicológicas do 7-NI.Sepsis is a global health issue that affects more than 30 million people worldwide every year. Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Several studies have reported the involvement of the nitric oxide (NO) in the sepsis, by the elevated circulating nitrite/nitrate, the stable byproducts of NO, observed in septic patients and septic shock. Although NO or peroxynitrite has bactericidal action, excessive plasma levels are counterproductive, as already evidenced by its involvement in hypotension and hyporesponsiveness to vasoconstrictors and in the reduction of tissue perfusion. The 7-nitroindazole (7-NI) is a substance known for its ability to selectively inhibit the enzyme neuronal nitric oxide synthase (NOS-1) by reversibly binding to the heme group of this enzyme, preventing the binding of the BH4 cofactor and competing with L-arginine. In vivo studies have demonstrated that 7-NI was able to improve the response to vasoconstrictors in the late stage of sepsis, in addition to reducing animal mortality in the CLP and pneumosepsis models. Despite being promising for the treatment of sepsis, pharmacokinetic studies are scarce and there are no reports of metabolism studies for 7-NI in the literature. Thus, in this study in silico metabolism studies were carried out to predict the metabolism pathways and probable metabolites of 7-NI. The possible sites of metabolism (SoMs) of the 7-NI were evaluated using the softwares SMARTCyp e Rs-WebPredictor. To identify the probable metabolites of 7-NI, the softwares BioTransformer e MetaUltra were employed. The results obtained by using both SMARTCyp and Rs-WebPredictor softwares demonstrated that the main SoMs for 7-NI are located in the ortho, meta or para positions of the aromatic ring, in relation to the nitro groups. Rs-WebPredictor software also predicted the nitrogens of the five-membered ring and the nitro group as possible SoMs. The metabolites identified were originated from oxidation reactions as predicted by BioTransformer and MetaUltra softwares. Besides, conjugation reactions were predicted by using MetaUltra software. The results obtained in the present study can be used to guide future investigations on the pharmacokinetic and toxicological properties of 7-NI

Magnetic ordering in doped coupled frustrated quantum spin-1/2 chains with 4-spin exchange

The role of various magnetic inter-chain couplings has been investigated recently by numerical methods in doped frustrated quantum spin chains. A non-magnetic dopant introduced in a gapped spin chain releases a free spin-1/2 soliton. The formation of a local magnetic moment has been analyzed in term of soliton confinement. A four-spin coupling which might originate from cyclic exchange is shown to produce such a confinement. Dopants on different chains experience an effective space-extended non-frustrating pairwise spin interaction. This effective interaction between impurity-spins is long-ranged and therefore is expected to play a crucial role in the mecanism of antiferromagnetic (AF) long-range ordering (LRO) observed in spin-Peierls (SP) compounds such as CuGeO$_3$ doped with non-magnetic impurities.Comment: 4 pages, 5 figures. Proc. of the 7th International Symposium of Research in High Magnetic Fields in Toulouse, France (July 2003

Traveling/non-traveling phase transition and non-ergodic properties in the random transverse-field Ising model on the Cayley tree

We study the random transverse field Ising model on a finite Cayley tree. This enables us to probe key questions arising in other important disordered quantum systems, in particular the Anderson transition and the problem of dirty bosons on the Cayley tree, or the emergence of non-ergodic properties in such systems. We numerically investigate this problem building on the cavity mean-field method complemented by state-of-the art finite-size scaling analysis. Our numerics agree very well with analytical results based on an analogy with the traveling wave problem of a branching random walk in the presence of an absorbing wall. Critical properties and finite-size corrections for the zero-temperature paramagnetic-ferromagnetic transition are studied both for constant and algebraically vanishing boundary conditions. In the later case, we reveal a regime which is reminiscent of the non-ergodic delocalized phase observed in other systems, thus shedding some light on critical issues in the context of disordered quantum systems, such as Anderson transitions, the many-body localization or disordered bosons in infinite dimensions

Anti-polyethylene glycol antibodies alter the protein corona deposited on nanoparticles and the physiological pathways regulating their fate in vivo

Multiple studies highlight the strong prevalence of anti-poly(ethylene glycol) (anti-PEG) antibodies in the general human population. As we develop therapeutic modalities using this polymer, it is increasingly relevant to assess the importance of anti-PEG antibodies on biological performances. Here, we show that the anti-PEG Immunoglobulin M (IgM) raised in mice following the injection of polymeric nanoparticles could have significant neutralizing effects on subsequent doses of PEGylated nanosystems in vivo. The circulation times of PEGylated nanoparticles and liposomes were strongly reduced in animals with circulating anti-PEG IgMs, irrespective of the PEG density or the surface properties of the system. In comparison, despite that anti-PEG IgMs could bind free methoxy-terminated PEG and PEGylated bovine serum albumin, the circulation kinetics of these systems remained unaltered in the presence of antibodies. The binding of IgMs to the PEGylated surface of nanoparticles alters the nature of the proteins adsorbed in the surrounding corona, notably due to the activation of the complement cascade. These changes are responsible for the observed differences in circulation times. In comparison, the PEG-BSA is unable to activate complement, even in the presence of anti-PEG IgMs. These results inform on how anti-PEG antibodies can affect the fate of PEGylated nanomaterials and highlight how the architecture of nanoparticles impacts the deposition of the protein corona