Scientists recently discovered that Emperor Penguins-one of Antarctica’s most celebrated species-employ a particularly unusual technique for surviving the daily chill. As detailed in an article published today in the journal Biology Letters, the birds minimize heat loss by keeping the outer surface of their plumage below the temperature of the surrounding air. At the same time, the penguins’ thick plumage insulates their body and keeps it toasty$\dots$
The researchers analyzed thermographic images $\dots$ taken over roughly a month during June $2008$. During that period, the average air temperature was $0.32$ degrees Fahrenheit. At the same time, the majority of the plumage covering the penguin’s bodies was even colder: the surface of their warmest body part, their feet, was an average $1.76$ degrees Fahrenheit, but the plumage on their heads, chests and backs were$-1.84,-7.24$ and $-9.76$ degrees Fahrenheit respectively. Overall, nearly the entire outer surface of the penguin’s bodies was below freezing at all times, except for their eyes and beaks. The scientists also used a computer simulation to determine how much heat was lost or gained from each part of the body-and discovered that by keeping their outer surface below air temperature, the birds might paradoxically be able to draw very slight amounts of heat from the air around them. The key to their trick is the difference between two different types of heat transfer: radiation and convection.
The penguins do lose internal body heat to the surrounding air through thermal radiation, just as our bodies do on a cold day. Because their bodies(but not surface plumage) are warmer than the surrounding air, heat gradually radiates outward over time, moving from warmer material to a colder one. To maintain body temperature while losing heat, penguins, like all warm-blooded animals, rely on the metabolism of food. The penguins, though, have an additional strategy. Since their outer plumage is even colder than the air, the simulation showed that they might gain back a little of this heat through thermal convection-the transfer of heat via the movement of a fluid (in this case, the air). As the cold Antarctic air cycles around their bodies slightly warmer air comes into contact with the plumage and donates minute amounts of heat back to the penguins, then cycles away at a slightly colder temperature.
Most of this heat, the researches note, probably doesn't make it all the way through the plumage and back to the penguin’s bodies, but it could make a slight difference. At the very least, the method by which a penguin's plumage wicks heat from the bitterly cold air that surrounds it helps to cancel out some of the heat that's radiating from its interior. And given the Emperor's unusually demanding breeding cycle, every bit of warmth counts$\dots$ Since [penguins trek as far as $75$ miles to the coast to breed and male penguins] don't eat anything during[the incubation period of $64$ days], conserving calories by giving up as little heat as possible is absolutely crucial.
The passage given below is followed by four alternate summaries. Choose the option that best captures the essence of the passage. Vance Packard’s The Hidden Persuaders alerted the public to the psychoanalytical techniques used by the advertising industry. Its premise was that advertising agencies were using depth interviews to identify hidden consumer motivations, which were then used to entice consumers to buy goods. Critics and reporters often wrongly assumed that Packard was writing mainly about subliminal advertising. Packard never mentioned the word subliminal, however, and devoted very little space to discussions of “subthreshold” effects. Instead, his views largely aligned with the notion that individuals do not always have access to their conscious thoughts and can be persuaded by supraliminal messages without their knowledge.
- Packard argued that advertising as a ‘hidden persuasion’ understands the hidden motivations of consumers and works at the subliminal level, on the subconscious level of the awareness of the people targeted
- Packard argued that advertising as a ‘hidden persuasion’ works at the supraliminal level, wherein the people targeted are aware of being persuaded, after understanding the hidden motivations of consumers and works
- Packard held that advertising as a ‘hidden persuasion’ builds on peoples’ conscious thoughts and awareness, by understanding the hidden motivations of consumers and works at the subliminal level
- Packard held that advertising as a ‘hidden persuasion’ understands the hidden motivations of consumers and works at the supraliminal level, though the people targeted have no awareness of being persuaded