Fumure minérale sur cocoteraie âgée en Côte d'Ivoire

L'étude de la nutrition minérale des cocoteraies de basse Côte d'Ivoire a été entreprise il y a onze ans avec la réalisation d'une expérience factorielle étudiant l'action de la potasse à quatre niveaux, en présence ou en l'absence d'azote, de phosphore et de magnésium. L'effet de chaque engrais minéral sur les teneurs des éléments minéraux dans les feuilles, sur le nombre de noix, le coprah par noix et le coprah total par arbre est examiné. La carence potassique est le principal facteur limitant. La loi de Mitscherlich rend compte de l'action de doses croissantes de KCl sur les teneurs en K et sur la production de coprah. Les effets de doses supérieures à celles qui sont étudiées expérimentalement sont calculés et discutés. On ne peut prévoir d'accroissement de production rentable au-delà de 2, 5 kg/arbre/an. Le sulfate d'ammoniaque n'a pas d'action positive sur les rendements. Il n'y a pas de déficience en magnésium. L'apparition d'une légère déficience en P est probabl

Opening-closing dynamics of the mitochondrial transcription pre-initiation complex

Promoter recognition and local melting of DNA are key steps of transcription initiation catalyzed by RNA polymerase and initiation factors. From single molecule fluorescence resonance energy transfer studies of the yeast (Saccharomyces cerevisiae) mitochondrial RNA polymerase Rpo41 and its transcription factor Mtf1, we show that the pre-initiation complex is highly dynamic and undergoes repetitive opening-closing transitions that are modulated by Mtf1 and ATP. We found that Rpo41 alone has the intrinsic ability to bend the promoter but only very briefly. Mtf1 enhances bending/opening transition and suppresses closing transition, indicating its dual roles of nucleating promoter opening and stabilizing the open state. The cognate initiating ATP prolongs the lifetime of the open state, plausibly explaining the 'ATP sensing mechanism' suggested for the system. We discovered short-lived opening trials upon initial binding of Rpo41-Mtf1 before the establishment of the opening/closing equilibrium, which may aid in promoter selection before the formation of stable pre-initiation complex. The dynamics of open complex formation provides unique insights into the interplay between RNA polymerase and transcription factors in regulating initiation.open4

Artificial Intelligence in the Pediatric Echocardiography Laboratory: Automation, Physiology, and Outcomes

Artificial intelligence (AI) is frequently used in non-medical fields to assist with automation and decision-making. The potential for AI in pediatric cardiology, especially in the echocardiography laboratory, is very high. There are multiple tasks AI is designed to do that could improve the quality, interpretation, and clinical application of echocardiographic data at the level of the sonographer, echocardiographer, and clinician. In this state-of-the-art review, we highlight the pertinent literature on machine learning in echocardiography and discuss its applications in the pediatric echocardiography lab with a focus on automation of the pediatric echocardiogram and the use of echo data to better understand physiology and outcomes in pediatric cardiology. We also discuss next steps in utilizing AI in pediatric echocardiography

Histoire de Grégoire VII

Copia digital. España : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, d2024Rústica.Marca tip. em port.Antep.Registro de la Propiedad Intelectual, Ley de 1847: [sin número];n. de solicitud de ingreso: "6845"; fecha y datos del ingreso: "abril ?/73

Imaging the dynamics of cardiac fiber orientation in vivo using 3D Ultrasound Backscatter Tensor Imaging

The assessment of myocardial fiber disarray is of major interest for the study of the progression of myocardial disease. However, time-resolved imaging of the myocardial structure remains unavailable in clinical practice. In this study, we introduce 3D Backscatter Tensor Imaging (3D-BTI), an entirely novel ultrasound-based imaging technique that can map the myocardial fibers orientation and its dynamics with a temporal resolution of 10 ms during a single cardiac cycle, non-invasively and in vivo in entire volumes. 3D-BTI is based on ultrafast volumetric ultrasound acquisitions, which are used to quantify the spatial coherence of backscattered echoes at each point of the volume. The capability of 3D-BTI to map the fibers orientation was evaluated in vitro in 5 myocardial samples. The helicoidal transmural variation of fiber angles was in good agreement with the one obtained by histological analysis. 3D-BTI was then performed to map the fiber orientation dynamics in vivo in the beating heart of an open-chest sheep at a volume rate of 90 volumes/s. Finally, the clinical feasibility of 3D-BTI was shown on a healthy volunteer. These initial results indicate that 3D-BTI could become a fully non-invasive technique to assess myocardial disarray at the bedside of patients

Biotransformation of anthracene and fluoranthene by Absidia fusca Linnemann

A strain of Absidia fusca was isolated from a pesticide-contaminated soil (Annaba, Algeria). The biotransformation capability of this strain towards two polycyclic aromatic hydrocarbons (PAHs): anthracene and fluoranthene was compared to that exhibited by another strain of A. fusca isolated from a non-contaminated milieu and considered as a control. The results obtained were statistically analyzed and showed that the strain isolated from the contaminated soil was more efficient than the control to remove anthracene from the medium, during all the kinetics (90% removed versus 45% after 24 hrs). Concerning fluoranthene, the amount removed by both strains was very high during the first 24 hrs however the control strain was slightly more efficient (94% versus 89%) while the results were similar for the two strains during the rest of the kinetics. This study reveals for the first time the potential interest of the species A. fusca for the bioremediation of PAHs

Algorithme de contour actif appliqué à la poursuite d'avalanche

Le traitement d'image est un outil de plus en plus utilisé dans l'étude des avalanches de neige, ceci dans le but de les prévenir. On présente ici un algorithme de contour actif spécifique à notre application : l'analyse du front des avalanches. Le but de cette étude consiste en l'extraction de paramètres dynamiques de l'avalanche à partir d'un simple film vidéo. La principale difficulté réside dans le manque évident de contraste de nos images, puisque nous avons à poursuivre un objet blanc sur un fond blanc. L'algorithme présenté repose sur le principe des contours actifs, où on recherche à minimiser une forme énergétique modélisant le contour de l'avalanche. Le résultat obtenu est une séquence de contour d'avalanche

Imaging the dynamics of cardiac fiber orientation in vivo using 3D Ultrasound Backscatter Tensor Imaging

ABSTRACT: The assessment of myocardial fiber disarray is of major interest for the study of the progression of myocardial disease. However, time-resolved imaging of the myocardial structure remains unavailable in clinical practice. In this study, we introduce 3D Backscatter Tensor Imaging (3D-BTI), an entirely novel ultrasound-based imaging technique that can map the myocardial fibers orientation and its dynamics with a temporal resolution of 10 ms during a single cardiac cycle, non-invasively and in vivo in entire volumes. 3D-BTI is based on ultrafast volumetric ultrasound acquisitions, which are used to quantify the spatial coherence of backscattered echoes at each point of the volume. The capability of 3D-BTI to map the fibers orientation was evaluated in vitro in 5 myocardial samples. The helicoidal transmural variation of fiber angles was in good agreement with the one obtained by histological analysis. 3D-BTI was then performed to map the fiber orientation dynamics in vivo in the beating heart of an open-chest sheep at a volume rate of 90 volumes/s. Finally, the clinical feasibility of 3D-BTI was shown on a healthy volunteer. These initial results indicate that 3D-BTI could become a fully non-invasive technique to assess myocardial disarray at the bedside of patients