Cartes de photons et visibilité

Les méthodes de simulation d'éclairage par tracé de photons sont souvent utilisées pour leur simplicité et leur versatilité. Les deux étapes classiques de ces approches sont : (i) les calculs d'inter-réflexions lumineuses, indépendantes du point de vue, correspondant à des suivis de chemins lumineux dont les impacts sur les surfaces de la scène sont stockés sous forme de cartes de photons ; (ii) l'exploitation des cartes de photons pour produire une ou plusieurs images de l'environnement virtuel. La première phase repose exclusivement sur des méthodes de Monte-Carlo ; la seconde requiert au moins une estimation de densité pour le calcul d'éclairement. Malheureusement, le tracé de photons est également connu pour les différents biais produits lors de l'estimation de densité des photons pour le calcul de l'éclairement en un point. Ce rapport montre pourquoi la visibilité est un élément fondamental lors de l'estimation de densité ; nous proposons de la prendre en compte de manière précise pour réduire ou supprimer certains biais. Nos résultats mettent en évidence l'importance de la visibilité dans la qualité des images produites

Handheld In Vivo Reflectance Confocal Microscopy for the Diagnosis of Eyelid Margin and Conjunctival Tumors

OBJECTIVE To assess the diagnostic accuracy of handheld in vivo reflectance confocal microscopy (IVCM) for the diagnosis of eyelid margin and conjunctival tumors. DESIGN A prospective observational study was conducted at University Hospital of Saint-Etienne from January 2, 2011, to December 31, 2016 (inclusion of patients until December 31, 2015, and follow-up until December 31, 2016). A total of 278 consecutive patients with eyelid margin or conjunctival lesions were included. Conjunctival lesions were diagnosed with a conventional clinical examination using a slitlamp and by handheld IVCM. Final diagnoses were established by histopathologic examination for 155 neoformations suspicious for being malignant through clinical and/or IVCM examination that were excised and on follow-up of 12 months or longer for the remaining 140 lesions. MAIN OUTCOMES AND MEASURES Sensitivity, specificity, and positive and negative predictive values for malignant tumors of the conjunctiva and eyelid margin were calculated using clinical examination with slitlamp and handheld IVCM. RESULTS In the 278 patients (136 [48.9%] females; mean [SD] age, 59 [21] years), a total of 166 eyelid margin and 129 conjunctival lesions were included in the analysis. Of the 155 excised neoformations with a histopathologic diagnosis, IVCM showed higher sensitivity compared with clinical examination conducted with the slitlamp for malignant tumors of the eyelid margin (98%vs 92%) and conjunctiva (100% vs 88%). The specificity for malignant eyelid margin tumors was higher for IVCMthan for slitlamp examination (74%vs 46%), but slightly less for malignant conjunctival tumors (78%vs 88%). Analysis of all neoformations (155 excised and 140 in follow-up) confirmed these differences in the diagnostic accuracy of the clinical examination and IVCM. The presence of hyperreflective Langerhans cells mimicking malignant melanocytes was the main cause for misdiagnosis of malignant conjunctival tumors with IVCM. CONCLUSIONS AND RELEVANCE Handheld IVCM could be a useful tool for the identification of malignant conjunctival tumors. Further studies are required to confirm the usefulness of this device and identify possible features that can differentiate Langerhans cells from malignant melanocytes to prevent the misdiagnosis of melanoma using IVCM

Quantitative pulsatility measurements using 3D dynamic ultrasound localization microscopy

ABSTRACT: A rise in blood flow velocity variations (i.e. pulsatility) in the brain, caused by the stiffening of upstream arteries, is associated with cognitive impairment and neurodegenerative diseases. The study of this phenomenon requires brain-wide pulsatility measurements, with large penetration depth and high spatiotemporal resolution. The development of dynamic ultrasound localization microscopy (DULM), based on ULM, has enabled pulsatility measurements in the rodent brain in 2D. However, 2D imaging accesses only one slice of the brain and measures only 2D-projected and hence biased velocities . Herein, we present 3D DULM: using a single ultrasound scanner at high frame rate (1000–2000 Hz), this method can produce dynamic maps of microbubbles flowing in the bloodstream and extract quantitative pulsatility measurements in the cat brain with craniotomy and in the mouse brain through the skull, showing a wide range of flow hemodynamics in both large and small vessels. We highlighted a decrease in pulsatility along the vascular tree in the cat brain, which could be mapped with ultrasound down to a few tens of micrometers for the first time. We also performed an intra-animal validation of the method by showing consistent measurements between the two sides of the Willis circle in the mouse brain. Our study provides the first step towards a new biomarker that would allow the detection of dynamic abnormalities in microvessels in the brain, which could be linked to early signs of neurodegenerative diseases

The quasi-universality of nestedness in the structure of quantitative plant-parasite interactions

Understanding the relationships between host range and pathogenicity for parasites, and between the efficiency and scope of immunity for hosts are essential to implement efficient disease control strategies. In the case of plant parasites, most studies have focused on describing qualitative interactions and a variety of genetic and evolutionary models has been proposed in this context. Although plant quantitative resistance benefits from advantages in terms of durability, we presently lack models that account for quantitative interactions between plants and their parasites and the evolution of these interactions. Nestedness and modularity are important features to unravel the overall structure of host-parasite interaction matrices. Here, we analysed these two features on 32 matrices of quantitative pathogenicity trait data gathered from 15 plant-parasite pathosystems consisting of either annual or perennial plants along with fungi or oomycetes, bacteria, nematodes, insects and viruses. The performance of several nestedness and modularity algorithms was evaluated through a simulation approach, which helped interpretation of the results. We observed significant modularity in only six of the 32 matrices, with two or three modules detected. For three of these matrices, modules could be related to resistance quantitative trait loci present in the host. In contrast, we found high and significant nestedness in 30 of the 32 matrices. Nestedness was linked to other properties of plant-parasite interactions. First, pathogenicity trait values were explained in majority by a parasite strain effect and a plant accession effect, with no parasite-plant interaction term. Second, correlations between the efficiency and scope of the resistance of plant genotypes, and between the host range breadth and pathogenicity level of parasite strains were overall positive. This latter result questions the efficiency of strategies based on the deployment of several genetically-differentiated cultivars of a given crop species in the case of quantitative plant immunity

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Safety Concern between Autologous Fat Graft, Mesenchymal Stem Cell and Osteosarcoma Recurrence

Background: Osteosarcoma is the most common malignant primary bone tumour in young adult treated by neo adjuvant chemotherapy, surgical tumor removal and adjuvant multidrug chemotherapy. For correction of soft tissue defect consecutive to surgery and/or tumor treatment, autologous fat graft has been proposed in plastic and reconstructive surgery. Principal Findings: We report here a case of a late local recurrence of osteosarcoma which occurred 13 years after the initial pathology and 18 months after a lipofilling procedure. Because such recurrence was highly unexpected, we investigated the possible relationship of tumor growth with fat injections and with mesenchymal stem/stromal cell like cells which are largely found in fatty tissue. Results obtained in osteosarcoma pre-clinical models show that fat grafts or progenitor cells promoted tumor growth. Significance: These observations and results raise the question of whether autologous fat grafting is a safe reconstructive procedure in a known post neoplasic context

Pratos e mais pratos: louças domésticas, divisões culturais e limites sociais no Rio de Janeiro, século XIX

Reply to ten comments on a paper published in the last issue of this journal. The discussion follows along six main lines: History museums, identity, ideology and the category of nation; the need of material collections and their modalities: patrimonial, operational, virtual; theater versus laboratory; visitors and their ambiguities; Public History: the museum and the academy.Resposta aos comentários de dez especialistas que contribuíram no debate de texto publicado no último número desta revista. A discussão orientou-se segundo seis tópicos principais: museus históricos, identidade, ideologia e a categoria de nação; a necessidade de acervos materiais e suas modalidades: acervo patrimonial, operacional, virtual; teatro versus laboratório; o público e suas ambigüidades; História Pública: o museu e a Academia

Etude spectroscopique des isotopes 51,52,53^{51, 52, 53}Ca par décroissance β\beta des noyaux riches en neutrons 51,52,52^{51, 52, 52}K et interaction effective dans la couche fp

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