Sound could replace lasers in surgery
Moving from HOT to HAT, a dazzling new acoustic technology.
- Scientists announce the ability to simultaneously manipulate individual levitated objects.
- Using high-frequency sound waves may provide a safer alternative to laser microsurgery.
- Video of the research looks like a cartoon, but it's all real.
For a while now, scientists have presented demonstrations of sound's ability to levitate and move suspended particles. It's pretty cool stuff, and you can find lots of amazing videos showing intriguing patterns made with acoustic waves. Now, though, mechanical engineers Asier Marzo of Spain's Universidad Publica De Navarra and Bruce Drinkwater of the UK's University of Bristol have published research in which they demonstrate, for the first time, the ability to independently move particles in 3D space using ultrasonic sound waves. This technology has the potential to one day offer a less-invasive and destructive alternative to the lasers current employed in surgery suites. As Drinkwater tells University of Bristol News, "Optical tweezers are a fantastic technology, but always dangerously close to killing the cells being moved. With acoustics we're applying the same sort of forces but with way less energy associated. There's lots of applications that require cellular manipulation and acoustic systems are perfect for them."
HAT, not HOT
Marzo and Drinkwater call their invention "Holographic Acoustic Tweezers" (HOT), or simply "acoustic tweezers" in conversation. The HOT acronym differentiates the method from Holographic Optical Tweezers (HAT), the laser-based technology it hopes to supplant. The technique's medical applications do seem plausible: The scientists have already shown that they can connect polystyrene spheres with thread and use HAT to sew fabric.
Since moving polystyrene balls in the air is hardly the same as manipulating tiny objects in the body, the current breakthrough is seen as just a first step. Marzo and Drinkwater hope to demonstrate the system working in water in about a year, and from there move on to getting it going in biological tissue. Marzo says, "The flexibility of ultrasonic sound waves will allow us to operate at micrometre scales to position cells within 3D printed assemblies or living tissue. Or on a larger scale, to levitate tangible pixels that form a physical hologram in mid-air."
Working in the HAT array
Sergio Larripa, Asier Marzo, Bruce Drinkwater
How HAT works
Even in its current form, the HAT technology is impressive, to say the least.
"We applied a novel algorithm that controls an array of 256 small loudspeakers," says Marzo, "and that is what allows us to create the intricate, tweezer-like, acoustic fields." The speakers emit very high-frequency sound waves, in the 40 kHz range — human hearing is said to top out at just above 20 kHz, though there's some debate about its upper limits.
The HAT demonstration takes place inside a box-like array with the 256 single-centimeter speakers arranged on walls opposite each other over a reflective base. The "particles" they're moving are styrofoam balls from 1-3 millimeters in diameter, and HAT is currently capable of moving up to 25 of them at a time.
The future of HAT
Marzo describes his vision for HAT's future, saying, "The flexibility of ultrasonic sound waves will allow us to operate at micrometer scales to position cells within 3D printed assemblies or living tissue. Or on a larger scale, to levitate tangible pixels that form a physical hologram in mid-air." He describes another tantalizing use to Agencia Sync: "At micrometric scales," "Marzo says, it could allow "the manipulation of 3D cells to create structures beyond a simple culture in a two-dimensional Petri dish."
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
- Women tend to associate more masculine faces with physical strength, social assertiveness, and formidability.
- Women who display higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, are more likely to prefer hairy faces.
Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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