Thursday, February 29, 2024

Chromatic Classification of Odor Identities


Scientists are smart - the way they figured this out is really clever, because they literally "blinded" the participants to the study; they're not asking you to tell them what color comes to mind, they ask you to just choose the neutral gray. This is how they figure out racial bias too:

Our sense of smell alters the colors we see, show scientists
Oct 2023, phys.org

"In a previous study, we had shown that the odor of caramel commonly constitutes a crossmodal association with dark brown and yellow, just like coffee with dark brown and red, cherry with pink, red, and purple, peppermint with green and blue, and lemon with yellow, green, and pink," explained Ward.

Ward and colleagues tested 24 adult women and men between 20 and 57 years of age with one of six odors chosen at random from caramel, cherry, coffee, lemon, and peppermint, plus odorless water as a control, and asked to manually adjust two sliders - one for yellow to blue, and another for green to red - to change its color to neutral gray. 

Participants had a weak but significant tendency to adjust one or both of the sliders too far away from neutral gray. For example, when presented with the odor of coffee, they wrongly perceived 'gray' to be more of a red-brown color than true neutral gray. 

An exception was when the odor of peppermint was presented: here, the participants' choice of hue was different from the typical crossmodal association demonstrated for the other odors. As expected, the participants' selection likewise corresponded to true gray when presented with the neutral scent of water. 

via John Moores University in Liverpool: Ryan J. Ward et al, Odors modulate color appearance, Frontiers in Psychology (2023). DOI: 10.3389/fpsyg.2023.1175703



Thursday, February 22, 2024

How Robots Will Learn to Smell


Parenting a 3-year-old robot
Aug 2023, phys.org

RoboAgent, an artificial intelligence agent that leverages passive observations and active learning to enable a robot to acquire manipulation abilities on par with a toddler. The team's agent learns through a combination of self-experiences and passive observations contained in internet data. As a parent would guide their child, researchers teleoperated the robot through tasks to provide it with useful self-experiences.

Our novel policy architecture allows our agents to reason even with limited experiences, using temporal chunks of movements instead of commonly used per-timestep actions, and learning from videos on the internet, akin to how babies acquire knowledge and behaviors by passively observing their surroundings.

via Carnegie Mellon University and Facebook: RoboAgent and RoboSet Project - Towards Sample Efficient Robot Manipulation with Semantic Augmentations and Action Chunking. Homanga Bharadhwaj et. al. 

Post Script: Partnership between Carnegie Mellon University and Meta, which is exactly how you wanted this to happen.


Thursday, February 15, 2024

Calling All Chemosignals


Chemical communication between female rats exists and is complex
Jun 2023, phys.org

I'm just here because today I learned that mice urine and rat urine are very different:

At this point, MUP (major urinary proteins) enter into play. MUPs are key in the transmission of odors through marks, yet function differently in mice (found in the urine with which they mark) as opposed to rats (whose marks contains sebaceous secretions, in addition to urine).

But the research found that a variety of these scent marking proteins came from the clitoral glands of the females, and we didn't know that before. ... the combination of urine and the secretion from the clitoral glands is necessary for the marks of the females to arouse interest in other females.

via University of Córdoba, University of Liverpool: Guadalupe Gómez-Baena et al, Unraveling female communication through scent marks in the Norway rat, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2300794120

Post Script: Scent marking in rats has been studied in depth when it comes to males, but, in the case of females,  there's a knowledge gap.



Hand odor can reveal a person's sex, study shows
Jul 2023, phys.org
https://phys.org/news/2023-07-odor-reveal-person-sex.html

Statistical analysis and mass spectrometry analyze the volatile scent compounds present on the palms of 60 individuals - half male and half female predicted a person's sex with a 96.67% accuracy rate.
via Florida International University: Multivariate regression modelling for gender prediction using volatile organic compounds from hand odor profiles via HS-SPME-GC-MS, PLoS ONE (2023). DOI: 10.1371/journal.pone.0286452

Post Script: On Handshakes and Animal Behavior, 2021


Thursday, February 8, 2024

Flood the Dataspace


A new approach to warding off mice eating wheat seed using camouflage scents
May 2023, phys.org

Spraying wheat fields with wheat germ oil after seeding deters mice that feed on seeds.

Mice consume approximately 70 million tons of maize, rice and wheat grains each year around the globe

Colleagues in New Zealand had tried smearing the scents of endangered birds over areas where the birds would never visit. This led to predators growing suspicious of such scents, because when followed, there was no payoff. That led them to ignore the smell of the birds even when they were present.

To see if the approach might work with mice, the team treated 60 10x10 plots with wheat germ oil, which contains the scent of the wheat germ - the part of the wheat the mice want to eat. To gauge its effectiveness, the team sprayed it on plots before planting seeds and others after seeding. They also left a few plots untreated.

They were surprised to find that the oil did not serve as a false signal; the mice still ate the seeds where the plots had been pretreated. But they also found that the mice largely left alone the plots where treatment had occurred after planting. This, the researchers suggest, was likely because an overabundance of aroma had confused the mice, making it nearly impossible for them to find the seeds.

via University of Sydney: Finn C. G. Parker et al, Olfactory misinformation reduces wheat seed loss caused by rodent pests, Nature Sustainability (2023). DOI: 10.1038/s41893-023-01127-3

Post Script: In the modern world where we scavenge for data more than we do food, and in an effort to protect our own personal data, quite valuable in this modern world, we would call this "data poisoning," where you might use a different name every time you register for a webservice or purchase an e-ticket, filling the spreadsheet with similar but not the same names, confusing the predictive analytics machine with dirty data. On this note, one bonus we can expect from the deluge of artificially-generated digital detritus coming our way, is that it will fill the entire internet with fake people, which will fill the entire data-bundle of your favorite data broker with fake people, all with fake addresses and fake phone numbers and fake preferences for consumer products, and this will collapse the surveillance advertising industry.  


Thursday, February 1, 2024

Interpersonal Olfactory Intelligence


One of the few people who really understands the intersection of language and smell, and what they mean for the truly scientific pursuit of knowledge in a field of study that refuses to submit to objective observation --

Meditations on Scent With Andreas Keller, the Socrates of Smell
Mar 2023, High Snobiety

"It’s very difficult to find a middle ground in talking about smell that conveys what's interesting and fascinating to you in a way that other people can understand,” Keller notes. “The limited vocabulary, the differences in perception between people, the emotional connection to smells… One way is to describe what a smell does to you, how it makes you feel – but that probably tells us more about yourself than about the smell.”

Unrelated image credit: This is not a picture of Andreas Keller, and it's not even a real person, because it's artificially generated. It's a "Rave Party for Jesus Birthday." Also pay artists for their work. 


Thursday, January 25, 2024

The Smell of Regular Things


We don't know why some things smell the way they do. What do you mean we don't know what a walnut smells like? You heat it up, run it through a gas chromatograph, and look for the spikes. Right? Not so fast. For some things, like walnuts, we didn't know how to recreate its odor without an actual walnut. Cannabis too; we all know the most easily identifiable characteristic of cannabis is it's stinky skunky odor, and yet we don't know where it comes from, down to the single molecule. 

The problem is that some odors that we identify as distinctive, indivisible, or unique are actually more than one molecule; the secret is in the ratio. In other words, the secret ingredient in the secret sauce is the recipe itself, not the ingredient:

Researchers isolate key compounds in the aroma of walnuts
Jun 2023, phys.org

As the team shows for the first time, the typical walnut aroma is created by the combination of two odorants that are present in the nuts in roughly a one-to-one ratio. The first substance is sotolon, which smells like Maggi Seasoning sauce and which, as a single component, characterizes the aroma of lovage, for example. The second compound is called (2E,4E,6Z)-nona-2,4,6-trienal. It is known from oat flakes and is responsible for the typical odor there.

British scientists had already olfactorily characterized numerous volatiles from walnuts about 50 years ago. However, none of the compounds they found had a specific walnut note. Thus, the researchers concluded that the characteristic walnut aroma is based on a combination of odorants. Despite this finding and further experiments, however, it had still not been clarified which odor-active compounds are decisive for the aroma of walnuts.

Not the components but the ratios of components -- "In our sensory tests, the walnut note intensified even further when we increased the natural concentrations of both odorants up to tenfold," reports Christine Stübner, a doctoral student who worked on the study. "However, it was important to maintain the one-to-one ratio," she continues.

(By the way, what's the purpose of all this -- based on these findings, new breeding strategies can now be developed to improve walnut aroma.) 

Finally, Instant Walnuts: Put a tablespoon of oatmeal in a glass, add a few drops of the well-known Maggi Seasoning seasoning sauce, shake it a bit and smell the mixture. (Maggi Seasoning smells like sotolon, fenugreek, hot transmission fluid.)

via Leibniz-Institut für Lebensmittel-Systembiologie (Inst for Food Systems Biology) -- Christine A. Stübner et al, Sotolon and (2E,4E,6Z)-Nona-2,4,6-trienal Are the Key Compounds in the Aroma of Walnuts, Journal of Agricultural and Food Chemistry (2023). DOI: 10.1021/acs.jafc.3c01002


A closer look at the compounds and molecules involved in giving cannabis its unique scent
Nov 2023, phys.org

(I was looking at the authors for Avery Gilbert, but no. I think some rec ognition is in order; he was the first to conduct smell research on cannabis.)

Using mass spectrometry, gas chromatography and flame ionization detection, researchers found that a molecule called 3-methyl-2-butene-1-thiol (321MBT), along with other volatile sulfur compounds (VSCs), appeared to play a prominent role in odor production. 321MBT is the same molecule that gives warm beer and skunk spray their distinctive smells. 

via terpene distributor Abstrax Tech: Iain W. H. Oswald et al, Minor, Nonterpenoid Volatile Compounds Drive the Aroma Differences of Exotic Cannabis, ACS Omega (2023). DOI: 10.1021/acsomega.3c04496


Research team identifies human odorant receptor for 'horse stable' odor, with implications for food testing
Aug 2023, phys.org

Para-cresol (4-methylphenol) is an aromatic compound with a strong horse stable-like odor, it is formed during the microbial degradation of certain amino acids, but also during thermal degradation processes, it's also a characteristic odorant in whiskey and tobacco.

  • The OR9Q2 receptor was the only one that responded to physiologically relevant concentrations of the substance.
  • Conversely, 4-ethylphenol was the only one of 176 aromas able to significantly activate the receptor. (and that's called being highly selective).
  • "The receptor fills a gap in the recognition spectrum of the phylogenetically older human odorant receptor OR2W1, which detects a wide range of structurally different odorants, but not para-cresol."

via Leibniz-Institut für Lebensmittel-Systembiologie aka Leibniz Institute of Food Systems Biology at the Technical University of Munich: Franziska Haag et al, The multi-faceted food odorant 4-methylphenol selectively activates evolutionary conserved receptor OR9Q2, Food Chemistry (2023). DOI: 10.1016/j.foodchem.2023.136492


Thursday, January 18, 2024

Electronic Hedonics


Electronic noses sniff out volatile organic compounds
May 2023, phys.org

Many e-noses generate different signals toward VOCs of the same concentration when the sensor is located in different parts of the "nose" chamber:

"To counteract this problem, the fluidic behavior of the gas flow needs to be well controlled," said author Weiwei Wu. "This ensures a uniform fluidic field and concentration of VOCs in the chamber and avoids generating any fake sensing characteristics."

A vertical chamber that looks much like a showerhead promotes vertical flow so gas spreads through holes at the bottom of the device and around to evenly distributed sensors.

via Interdisciplinary Research Center of Smart Sensors, School of Advanced Materials and Nanotechnology, Xidian University; Intelligent Perception Research Institute, Zhejiang Lab, Hangzhou: Controlling fluidic behavior for ultrasensitive volatile sensing, Applied Physics Reviews (2023). DOI: 10.1063/5.0141840

Note: This problem has come up in two other papers where they talk about how the two different nostrils cancel each other out because they can't rely on evenly distributed air; it messes up the statistics, so at least with two different nostrils, you can have some error correction. See "Domestic cat nose functions as a highly efficient coiled parallel gas chromatograph", We et al. PLoS Computational Biology (2023). DOI: 10.1371/journal.pcbi.1011 https://pubmed.ncbi.nlm.nih.gov/37384594/ and "Odor representations from the two nostrils are temporally segregated in human piriform cortex", Dikeçligil et al, Current Biology (2023). DOI: 10.1016/j.cub.2023.10.021 https://dx.doi.org/10.1016/j.cub.2023.10.021



Perceiving the smell of lemon, geranium or eucalyptus: A study on the electrical signals behind human olfaction
Jul 2023, phys.org

Somewhat related to electronic noses, real-live odor receptors obtained from nasal biopsies:

"Until now, nobody had measured in intact human tissue the electrical activity of cells, neurons and epithelial cells that form the olfactory epithelium of our nose in which odorant molecules are captured."

via International School of Advanced Studies, Aldo Moro University of Bari, University of Trieste, and the Otorhinolaryngology Clinic of Azienda Sanitaria Universitaria Giuliano Isontina: Andres Hernandez-Clavijo et al, Shedding light on human olfaction: electrophysiological recordings from sensory neurons in acute slices of olfactory epithelium, iScience (2023). DOI: 10.1016/j.isci.2023.107186


'Electronic tongue' holds promise as possible first step to artificial emotional intelligence
Oct 2023, phys.org

It sounds to me a bit of a stretch right now to call this emotional intelligence; it sounds like basic chemical detection to me, but with the addition of a memristor.

The memristor is the new part, and one day we will have gustatory chips, and olfactory chips, vision chips, etc.; chips for everything; everything will have its own chip. Christmas chips and new mother chips and traffic chips for cars and ambient energy harvesting chips for sneakers and even organic chemistry chips for med students so they don't have to study. Everything will have its own chip. There won't be categories of chips, instead every single thing will have its own chip. Just not today. 

Continuing:

The artificial tastebuds comprise tiny, graphene-based electronic sensors called chemitransistors that can detect gas or chemical molecules. The other part of the circuit uses memtransistors, which is a transistor that remembers past signals, made with molybdenum disulfide. This allowed the researchers to design an "electronic gustatory cortex" that connect a physiology-drive "hunger neuron," psychology-driven "appetite neuron" and a "feeding circuit."

"When detecting salt the device senses sodium ions. This means the device can 'taste' salt."

"We are trying to make arrays of graphene devices to mimic the 10,000 or so taste receptors we have on our tongue."

via Penn State: Subir Ghosh et al, An all 2D bio-inspired gustatory circuit for mimicking physiology and psychology of feeding behavior, Nature Communications (2023). DOI: 10.1038/s41467-023-41046-7