Notice bibliographique
Résumé
It's been known for some time that cuttlefish have contractile veins, but only from dissections; nobody had ever seen them contract in a live,free-swimming cuttlefish. To investigate this remarkable feature, Alison King and her colleagues at Dalhousie University and the Scripps Institution of Oceanography developed an ingenious set-up to see cuttlefish circulatory systems in action (p. 2071).King wanted to know how blood returns to the cuttlefish heart. Most of our veins are conveniently located in muscles, and their contractions squeeze blood back to our heart. But the large cuttlefish veins aren't surrounded by muscle. Instead, they sit in a body cavity enclosed by the mantle - a big,muscular body wall that ventilates the cuttlefish's gills. It's generally assumed that the large veins are compressed by increased pressure in the cavity caused by the mantle's contractions, and that this pushes blood back to the cuttlefish's heart. But is this really what happens? Radiologist Matthias Schmidt astutely suggested that King could try using ultrasound to find out.King and Schmidt began experimenting, but soon hit a snag; they found that the cuttlebone in cuttlefish backs is opaque to ultrasound. Realising that she'd have to go underneath the cuttlefish to see anything, King designed a plastic cylinder propped up with struts. To get ultrasound images of the insides of the cuttlefish happily resting in the cylinder, King pressed an ultrasound transducer against the bottom of the cylinder and hoped the creature would sit still long enough for her to get 30-second video clips. It worked; King could finally take a peek inside cuttlefish. But she had to make sense of the seething mass of cuttlefish insides. Poring over an atlas of cuttlefish body parts, she struggled to decipher her upside-down moving images. It was worth it. `For the first time, we could see blood vessels changing shape in live cuttlefish,' King says. `It was magical seeing physiology in action.'So, does increasing mantle cavity pressure compress the veins, pushing blood to the heart? If it does, the contractions of the anterior and lateral venae cavae (two of the major veins that deliver oxygen-depleted blood to the heart) should be in sync with the mantle's contractions. But King saw that the lateral venae cavae and the mantle contract at different rates. Since they are out of sync, the mantle can't be compressing the lateral venae cavae. Taking a closer look at her real-time images, King saw peristaltic waves moving along the anterior and lateral venae cavae; the veins contract on their own! So it's unlikely that pressures created by the mantle compress the veins, because then`we'd expect the veins to collapse as a unit, rather than progressively along their length,' King says. She suggests that `actively contracting veins aid the return of blood to the cuttlefish heart.'But King also noticed that the anterior and lateral venae cavae contract at different rates, which could spell disaster. The two veins are connected, so if one relaxes and expands while the other contracts, blood could flow in the wrong direction. Cuttlefish solve this potential problem in the same way we do; King discovered a new valve (which she has dubbed the Wells valve) sitting between the venae cavae, which ensures that blood always flows towards the heart.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,010 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,004 | 0,002 |
| Communication savante | 0,003 | 0,004 |
| Science ouverte | 0,001 | 0,006 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,127 | 0,022 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».