Domain: Healthcare — Pathophysiology
Target concept: Temperature Changes in Limbs with Circulatory Hypoxia

Video generation prompt: Ligation of the femoral artery in the hind limb of rats, followed by continuous observation of changes in skin color and temperature of the hind limb, with temperature differences recorded using an infrared thermometer.

Evaluation guide:
(i) Target concept: Circulatory hypoxia-induced peripheral vasoconstriction and deoxygenation manifesting as unilateral skin pallor/cyanosis and a lower infrared-thermometer reading in the ischemic limb.
Minimum mechanism: Arterial occlusion must precede and cause the observed skin and temperature changes; the contralateral limb must remain normoxic and serve as an internal visual control; the physiological response must be localized to the ligated limb and asymmetric between limbs.
(ii)Storyline: [Phase 1: Baseline] Both hind limbs visible, symmetrically pink/red, no visible skin asymmetry. [Phase 2: Intervention] Ligature applied to the proximal thigh of one limb: visible, deliberate, stationary application. [Phase 3: Response Onset] Pallor/cyanosis emerges progressively in the distal portion of the ligated limb only; the contralateral limb stays unchanged. [Phase 4: Thermal Confirmation] Infrared thermometer aimed at the ligated limb, its digital display showing a numeric reading distinctly lower than a normal skin-surface temperature (a standard infrared spot thermometer shows a number, not a false-color thermal palette); no measurement is required on the contralateral limb. [Perspective constraint: Fixed anatomical viewpoint (e.g., lateral or ventral), no camera repositioning; visibility constraint: All critical regions (ligation site, distal footpad, thermometer lens/display) fully in frame and unoccluded throughout.]

Manual:
Experimental Procedure
1. Secure rat in lateral recumbency; expose left hind limb.
2. Apply sterile ligature tightly around proximal thigh to occlude femoral artery.
3. Position infrared thermometer perpendicular to skin surface of ligated limb.
Observation of Experimental Phenomena
- Ligated limb develops progressive pallor or cyanosis distal to ligation site.
- Contralateral limb retains normal pink/red color.
- Infrared thermometer's digital display shows a numerically low reading on the ligated limb only, consistent with reduced blood flow (a standard infrared spot thermometer, not a color thermal-palette camera).
Summary of Experimental Principles
Femoral artery ligation causes acute ischemia → reduced oxygen delivery → cutaneous vasoconstriction & deoxygenated hemoglobin accumulation → pallor/cyanosis + a lower skin-surface temperature reading.

Prompt Grounding rubric:
level_1: No rat hind limb is visible; there is no identifiable femoral-artery ligation site; no infrared thermometer appears; skin color and temperature are not established as anything being observed.
level_2: A rat hind limb is visible, but there is no identifiable ligature (thread or tie) at the proximal thigh; an infrared thermometer is present but is not pointed at the hind limb; skin color and temperature are not visually framed as the focus of observation.
level_3: A rat hind limb is visible with a clearly placed ligature at the proximal thigh; an infrared thermometer is visibly aimed at the hind limb's skin surface; the limb's skin color and the thermometer's use are framed as the objects of observation, matching the posted_prompt.
level_4: All elements from score 3 are present AND the ligature appears on only one hind limb; the thermometer is shown interacting only with that ligated limb (not the contralateral one); both hind limbs (or the ligated limb across a stable, comparable viewpoint) remain visible enough to support before/after comparison.
level_5: All elements from score 4 are present AND the ligature is applied before any skin change appears; the thermometer reading is taken after the ligature is applied, preserving the correct causal order; the camera keeps the same anatomical plane and orientation between the ligation and the thermometer reading; no extraneous object (gloves, clamp, blood) distracts from the limb, ligature, or thermometer.

Scientific and Causal Correctness rubric:
level_1: Skin color stays uniformly pink/red on both hind limbs; the infrared thermometer's digital readout, when aimed at either limb, shows a normal skin-surface temperature; no pallor, cyanosis, or other sign of circulatory hypoxia appears anywhere.
level_2: A color change appears but does not match the expected pathophysiology: e.g., unilateral redness (hyperemia) instead of pallor/cyanosis, bilateral discoloration on both limbs, or skin color changing before the ligature is applied; alternatively, the skin on the ligated limb looks pale/cyanotic but the thermometer's digital readout still shows a normal (not lowered) numeric value.
level_3: Pallor or cyanosis appears only on the ligated hind limb, while the contralateral limb keeps its normal pink/red color; the infrared thermometer's digital display, aimed at the ligated limb, shows a numeric reading distinctly lower than a normal skin-surface temperature, matching the expected circulatory-hypoxia phenomenon.
level_4: All elements from score 3 are present AND the pallor/cyanosis is confined to the distal portion of the ligated limb rather than the whole limb or body; the lowered thermometer reading is taken from that same distal region; no contradictory sign appears (e.g., no sweating, no flushing, no sudden return of normal color).
level_5: All elements from score 4 are present AND the pallor and the lowered thermometer reading only appear after the ligature is applied, with no pre-existing pallor or abnormal reading beforehand; the pale/cyanotic appearance and lowered reading stay consistent for the entire remaining video; nothing on screen (shadow, lighting gradient, reflection) falsely mimics pallor, cyanosis, or a lowered reading.

Spatiotemporal Consistency rubric:
level_1: The hind limb's position, size, or orientation jumps abruptly between frames rather than moving continuously; the ligature appears or disappears with no tying motion shown; the thermometer's position jumps without any hand or arm motion moving it there; the lighting on the limb shifts abruptly partway through the video.
level_2: Several moderate breaks occur: the ligature is visible in one frame, missing in the next, then visible again; the thermometer's aim jumps erratically (e.g., pointing at the abdomen, then instantly at the limb, with no motion in between); the limb's skin color flickers back and forth between pink and pale/cyanotic within a few frames.
level_3: One minor discontinuity occurs: e.g., a hand briefly blocks the view of the limb, or a single frame shows a brief lighting flicker that doesn't change the apparent color or thermometer reading; aside from that, the limb, ligature, and thermometer keep consistent position, orientation, and surface appearance before, during, and after the ligation and observation.
level_4: There is no abrupt jump in the limb's position or shape, no sudden lighting or shadow shift, and no structural break in the ligature or limb; the thermometer's approach toward the limb is a continuous, plausible hand motion; the ligation motion (if shown) is smooth and anatomically plausible with no floating thread or impossible hand position; the skin's color change unfolds gradually with no flicker or reversal.
level_5: Everything required at the 4-point level holds, and in addition: the ligature's application shows unbroken contact as the thread touches, wraps around, and tightens on the limb; the thermometer's approach is one uninterrupted, steady motion ending in a stable aim at the limb; the skin's pallor/cyanosis develops through continuous, non-flickering change; shadows, highlights, and camera perspective stay physically consistent and stable for the whole video.