SANTé/MEDECINE - Fonctionnement de l'oeil humain - Schéma d'une coupe transversale de l'œil

Sur ce schéma d'une coupe transversale de l'œil, on voit le cristallin, qui est la lentille de cet organe sensoriel. Il sépare l'œil en un segment antérieur (à l'avant) et un segment postérieur (à l'arrière).

L'œil comprend des milieux transparents :cristallin ;

humeur aqueuse avant le cristallin ;

humeur vitrée après le cristallin.

La cornée est la partie de la sclérotique (ou sclère) transparente située à l'avant de l'œil.

© Rhcastilhos, DP

FuturaSciences

ASTRONOMY - The Solar Corona Unwrapped

 2024 April 5

The Solar Corona Unwrapped
Image Credit & Copyright: Peter Ward (Barden Ridge Observatory)

Explanation: Changes in the alluring solar corona are detailed in this creative composite image mapping the dynamic outer atmosphere of the Sun during two separate total solar eclipses. Unwrapped from the complete circle of the eclipsed Sun's edge to a rectangle and mirrored, the entire solar corona is shown during the 2017 eclipse (bottom) seen from Jackson Hole, Wyoming, and the 2023 eclipse from Exmouth, Western Australia. While the 2017 eclipse was near a minimum in the Sun's 11 year activity cycle, the 2023 eclipse was closer to solar maximum. The 2023 solar corona hints at the dramatically different character of the active Sun, with many streamers and pinkish prominences arising along the solar limb. Of course, the solar corona is only easily visible to the eye while standing in the shadow of the Moon.

SANTé/MEDECINE - HISTOIRE - 1882 : découverte du bacille de Koch et début de la bactériologie

Robert Koch, un médecin allemand, découvrit en 1882 l'agent responsable de la tuberculose, le bacille de Koch (Mycobacterium tuberculosis), ce qui ouvrit la voie à la bactériologie.

Il obtint le prix Nobel de médecine et de physiologie en 1905. Il découvrit également le bacille du choléra (1883) et formula les postulats de Koch qui permettent de déterminer si une maladie est due à un micro-organisme.

© AJC1, Flickr, CC by-nc 2.0

FuturaSciences

INVENTEURS TUéS PAR LEURS CREATIONS - Alexander Bogdanov

Alexander Bogdanov, médecin russe renommé, philosophe, économiste, écrivain de science-fiction et révolutionnaire, développe un intérêt soudain pour le rajeunissement humain qu'il croit possible par la transfusion sanguine. Dans l'espoir d'accéder à l'éternelle jeunesse et à la régénération des lésions corporelles, il entreprend 11 transfusions sanguines, grâce auxquelles il note, selon lui, une amélioration de la vue et une réduction de la calvitie. On crie au miracle ? Pas tout à fait, Bogdanov est mort en 1928, après s'être transfusé le sang d'un étudiant qui avait la tuberculose et le paludisme. 

© Domaine public. Montuno, Flickr, CC by-sa 2.0

FuturaSciences

ASTRONOMY - Comet Pons-Brooks at Night

 2024 April 4

Comet Pons-Brooks at Night
Image Credit & Copyright: Dan Bartlett`

Explanation: In dark evening skies over June Lake, northern hemisphere, planet Earth, Comet 12P/Pons-Brooks stood just above the western horizon on March 30. Its twisted turbulent ion tail and diffuse greenish coma are captured in this two degree wide telescopic field of view along with bright yellowish star Hamal also known as Alpha Arietis. Now Pons-Brooks has moved out of the northern night though, approaching perihelion on April 21. On April 8 you might still spot the comet in daytime skies. But to do it, you will have to stand in the path of totality and look away from the spectacle of an alluring solar corona and totally eclipsed Sun.

SANTé/MEDECINE - Le fonctionnement de l'oeil humain - Les différents muscles (vus de face)

Différents muscles permettent les mouvements de l'œil :

le muscle droit supérieur ;

le muscle droit inférieur ;

le muscle droit latéral ;

le muscle droit médial ;

le muscle oblique inférieur ;

le muscle oblique supérieur.

Le muscle oblique inférieur permet, par exemple, de déplacer l'œil vers le haut. Ces muscles sont innervés.

© Patrick J. Lynch, CC by 2.5

FuturaSciences

ASTRONOMY - Unusual Nebula Pa 30

 2024 April 3

Unusual Nebula Pa 30
Image Credit: NASA, ESA, USAF, NSF;
Processing: G. Ferrand (U. Manitoba), J. English (U. Manitoba), R. A. Fesen (Dartmouth), C. Treyturik (U. Manitoba);
Text: G. Ferrand & J. English

Explanation: What created this unusual celestial firework? The nebula, dubbed Pa 30, appears in the same sky direction now as a bright "guest star" did in the year 1181. Although Pa 30's filaments look similar to that created by a nova (for example GK Per), and a planetary nebula (for example NGC 6751), some astronomers now propose that it was created by a rare type of supernova: a thermonuclear Type Iax, and so is (also) named SN 1181. In this model, the supernova was not the result of the detonation of a single star, but rather a blast that occurred when two white dwarf stars spiraled together and merged. The blue dot in the center is hypothesized to be a zombie star, the remnant white dwarf that somehow survived this supernova-level explosion. The featured image combines images and data obtained with infrared (WISE), visible (MDM, Pan-STARRS), and X-ray (Chandra, XMM) telescopes. Future observations and analyses may tell us more.

SANTé/MEDECINE - HISTOIRE - 1847 : l'hygiène en médecine avec Semmelweis

Ignace Philippe Semmelweis, un médecin obstétricien austro-hongrois, découvrit que le lavage des mains diminuait le nombre des décès suite aux fièvres puerpérales des femmes après l'accouchement.

FuturaSciences

ASTRONOMY - Detailed View of a Solar Eclipse Corona

 2024 April 2

Detailed View of a Solar Eclipse Corona
Image Credit & Copyright: Phil Hart

Explanation: Only in the fleeting darkness of a total solar eclipse is the light of the solar corona easily visible. Normally overwhelmed by the bright solar disk, the expansive corona, the sun's outer atmosphere, is an alluring sight. But the subtle details and extreme ranges in the corona's brightness, although discernible to the eye, are notoriously difficult to photograph. Pictured here, however, using multiple images and digital processing, is a detailed image of the Sun's corona taken during the April 20, 2023 total solar eclipse from Exmouth, Australia. Clearly visible are intricate layers and glowing caustics of an ever changing mixture of hot gas and magnetic fields. Bright looping prominences appear pink just around the Sun's limb. A similar solar corona might be visible through clear skies in a narrow swath across the North America during the total solar eclipse that occurs just six days from today

ASTRONOMY - Swirling Magnetic Field around Our Galaxy's Central Black Hole

 2024 April 1

Swirling Magnetic Field around Our Galaxy's Central Black Hole
Image Credit: EHT Collaboration

Explanation: What's happening to the big black hole in the center of our galaxy? It is sucking in matter from a swirling disk -- a disk that is magnetized, it has now been confirmed. Specifically, the black hole's accretion disk has recently been seen to emit polarized light, radiation frequently associated with a magnetized source. Pictured here is a close-up of Sgr A*, our Galaxy's central black hole, taken by radio telescopes around the world participating in the Event Horizon Telescope (EHT) Collaboration. Superposed are illustrative curved lines indicating polarized light likely emitted from swirling magnetized gas that will soon fall into the 4+ million mass central black hole. The central part of this image is likely dark because little light-emitting gas is visible between us and the dark event horizon of the black hole. Continued EHT monitoring of this and M87's central black hole may yield new clues about the gravity of black holes and how infalling matter creates disks and jets.