People used to eat mummies. |
Last week for the first time, I saw someone else writing about this, but in the spirit of the season, which is Halloween here in the US. Good time for a perennial favorite here at Limbic Signal:
People used to eat mummies. |
For two years straight, Michael Snyder, MD, professor and chair of genetics at Stanford, sported a peculiar accessory — a little gray box strapped to his bicep taking sips of air and recording his exposome cloud.It turns out, at any given time, we are bombarded by a combination of microbes, fungi, chemicals, viruses, particulates and even tiny microscopic animals, a new paper in Cell reported. This whirling plume of particulates is called the human exposome.The long-term goal, Snyder said, is to simplify the device into something that resembles an exposome-monitoring smart watch that can suck up and analyze the atmosphere on its own.
MIT researchers have a new and better way to compress models.It's so simple that they unveiled it in a tweet last month: Train the model, prune its weakest connections, retrain the model at its fast, early training rate, and repeat, until the model is as tiny as you want.
"We study spiking neural networks, which are systems that learn much as living brains do," said Los Alamos National Laboratory computer scientist Yijing Watkins. "We were fascinated by the prospect of training a neuromorphic processor in a manner analogous to how humans and other biological systems learn from their environment during childhood development."Watkins and her research team found that the network simulations became unstable after continuous periods of unsupervised learning. When they exposed the networks to states that are analogous to the waves that living brains experience during sleep, stability was restored. "It was as though we were giving the neural networks the equivalent of a good night's rest," said Watkins.
Global pandemics are real good for motivating exposure scientists to identify threats in the environment. Add to that the threat detection capabilities of chemosensation (smelling), and you've got some ingredients for a burgeoning field of study that overlaps with olfaction-inspired technologies.
Olfaction is for threat detection perhaps above all things, so it is fitting that we see this application become more common. One common use already being implemented by the company Aclima is the distributed air-quality sensor network for pollutants:
Early warning sensor sniffs out cities' harmful gas
May 2020, phys.org
The IGZO thin-film transistor acts as both an electronic component of the device and also as the NO2-sensing layer. The strongly electron-accepting NO2 molecule is drawn to the electrons on the transistor's surface. The more NO2 molecules that adhere to the IGZO, the more electrons are depleted from its surface, altering its electronic output and triggering an NO2 detection alert.
After a detection event, the sensor is reset by reviving the IGZO layer with the light from an integrated blue LED. Similar to a solar cell, the light generates negatively charged electrons and positively charged holes in the IGZO, which neutralizes the adsorbed NO2 and releases it from the surface. "This is the first study to achieve sensing and revival of a semiconducting metal oxide-based thin-film transistor sensor at room temperature," says Surya.
*Nitrous oxides (NO2) are a by-product of burning fuel, just like carbon monoxide, carbon dioxide, and sulfur oxides, and all of these are harmful to human health.
And here's another related report:
Aerosol-printed graphene unveiled as low cost, faster food toxin sensor
June 2020, phys.org
Researchers in the USA have developed a graphene-based electrochemical sensor capable of detecting histamines (allergens) and toxins in food much faster than standard laboratory tests.
The team created high-resolution interdigitated electrodes (IDEs) on flexible substrates, which they converted into histamine sensors by covalently linking monoclonal antibodies to oxygen moieties created on the graphene surface by a CO2 thermal annealing process.
As an additive manufacturing method that only deposits material where it is needed and therefore minimizes waste, aerosol-jet-printed sensors are low-cost, straightforward to make, and portable. This could potentially enable their use in places where continuous on-site monitoring of food samples is needed to determine and maintain the quality of products, as well as other applications.
-Aerosol-jet-printed graphene electrochemical histamine sensors for food safety monitoring, 2-D Materials, DOI: 10.1088/2053-1583/ab8919
And still further sensorific developments:
Paper-based device provides low-power, long-term method for analyzing sweat
June 2020, phys.org
Using a process known as capillary action, akin to water transport in plants, the device uses evaporation to wick fluid that mimics the features of human sweat to a sensor for up to 10 days or longer.
"We expected that the flow of the model sweat will be suppressed by the deposition of a salt layer inside the drying pad," Velev said. "By following the flow of model sweat, we found, quite surprisingly, that such a simple paper construct can achieve continuous sweat pumping and disposal for very long periods."
"The biological markers or drug metabolites that seep in the patient's sweat over a long period will be captured on the paper pad and preserved in a time-stamped manner to be analyzed later, similar to tree rings preserving the record of tree development," Dickey said.
-Principles of long-term fluids handling in paper-based wearables with capillary-evaporative transport, Biomicrofluidics (2020). aip.scitation.org/doi/10.1063/5.0010417
Post Script:
The exposome - When our environment drives health and disease
May 2020, phys.org
From this press article: The exposome is the sum of all the environmental drivers of health and diseases: a combination of external factors such as chemicals contained in the air, water or food, and of internal components produced by our organism in response to various stress factors.
Notes:
Aclima delivers hyperlocal air pollution and climate emissions intelligence at unprecedented block-by-block resolution.
Once in a while, I end up with a whole bunch of headlines and not much inspiration. Here’s to clearing out the queue –
Oldest material on Earth discovered
Jan 2020, BBC News
Dust grains within a space rock that crashed on Earth are found to be really old -- older than the Earth itself in fact. But I only came here to post this:
In order to analyze the rock, it has to be prepared... "Once all the pieces are segregated, it's a kind of paste, and it has a pungent characteristic – it smells like rotten peanut butter."
Asking yourself what rotten peanut butter smells like? Go find a tree-of-heaven, snap off a leaf, and smell it. It has to be a slightly older tree, not one just shooting out of the ground, or it will smell too mild and too much like not-rotten peanut butter.
Watch that smell! Scents can regulate fat storage
Apr 2020, phys.org
Honestly I can't even follow this, but it is a story that features the indispensable C. Elegans.
Ayse Sena Mutlu et al, Olfactory specificity regulates lipid metabolism through neuroendocrine signaling in Caenorhabditis elegans, Nature Communications (2020). DOI: 10.1038/s41467-020-15296-8
http://dx.doi.org/10.1038/s41467-020-15296-8
New sleep method strengthens brain's ability to retain memories
Mar 2020, phys.org
"By triggering consolidation processes in only one side of the brain during sleep, we were able to compare the activity between the hemispheres and isolate the specific activity that corresponds to memory reactivation," -Prof. Yuval Nir of TAU's Sackler Faculty of Medicine and Sagol School of Neuroscience
While exposed to the scent of a rose, research participants were asked to remember the location of words presented on either the left or right side of a computer screen. Participants were then tested on their memory of the word locations, then proceeded to nap at the lab. As the participants were napping, the scent of roses was administered again, but this time to only one nostril.
With this "one-sided" odor delivery, the researchers were able to reactivate and boost specific memories that were stored in a specific brain hemisphere.
"Our findings emphasize that the memory consolidation process can be amplified by external cues such as scents," she concludes. "By using the special organization of the olfactory pathways, memories can be manipulated in a local manner on one side of the brain. Our finding demonstrates that memory consolidation likely involves a nocturnal 'dialogue' between the hippocampus and specific regions in the cerebral cortex." -Ella Bar, Ph.D. student at TAU and the Weizmann Institute of Science
Local Targeted Memory Reactivation in Human Sleep, Current Biology (2020). DOI: 10.1016/j.cub.2020.01.091
http://dx.doi.org/10.1016/j.cub.2020.01.091
Study shows major gender differences in the human social brain
Mar 2020, phys.org
I bring this one up because it’s a general fact that women “smell better” than men, meaning they have a better sense of smell. Personally I think it’s because women tend to be better at communication and language, and smell has such a poor affinity for language. If women can use language better, then it will seem like they’re better at identifying and detecting smells, when really they’re just better at talking about something that most people never talk about in the first place.
The Data:
· U.K. Biobank database, background data and MRI scans of the brains of 10,129 male and female participants.
· 36 parts of the brain involved in processing social cues and behavior.
· Lifestyle factors such as how many people were in a household, whether a person was married, how much they enjoyed their relationships and degree of social support.
The Results:
· Neuroanatomical associations in the amygdala that were predominant in socially stimulated women, but barely present in most of the males.
· Differences in volume of the ventromedial prefrontal cortex of men who lived alone versus those who were socially stimulated—variations not generally seen in the brains of the women under study.
Hannah Kiesow et al. 10,000 social brains: Sex differentiation in human brain anatomy, Science Advances (2020). DOI: 10.1126/sciadv.aaz1170
http://dx.doi.org/10.1126/sciadv.aaz1170
Smelling a rat - How rodents sniff out fake beggars
Mar 2020, phys.org
· Lead author is Karin Schneeberger of the University of Potsdam in Germany.
· They took rats that were either hungry from fasting overnight, or well-fed, and placed them in a room separate from the "focal" rat whose generosity they wanted to test.
· Air from the rooms of the hungry or well-fed rats was pumped into the chamber of the focal rat.
· They found that the focal rats were much quicker to provide help -- by pulling a food tray within reaching distance of another rat -- when the air was pumped from a hungry rat's room.
· The authors then analyzed the air around the rats and found seven different organic compounds that differed significantly in their abundance between hungry and satiated rats.
· These might result from recently ingested food sources, the metabolic processes involved in digestion, or possibly even a pheromone that indicates hunger.
· Taken together, these signals form a "smell of hunger" for rats that serves as a reliable cue of need, said Schneeberger.
Schneeberger K, Röder G, Taborsky M (2020) The smell of hunger: Norway rats provision social partners based on odour cues of need. PLoS Biol 18(3): e3000628. https://doi.org/10.1371/journal.pbio.3000628
Sweat sensor detects stress levels; May find use in space exploration
Mar 2020, phys.og
It detects cortisol in sweat. Another similar device measures uric acid in the blood.
Rebeca M. Torrente-Rodríguez et al, Investigation of Cortisol Dynamics in Human Sweat Using a Graphene-Based Wireless mHealth System, Matter (2020). DOI: 10.1016/j.matt.2020.01.021
http://dx.doi.org/10.1016/j.matt.2020.01.021
Scientists discover a new class of taste receptors
Apr 2020, phys.org
Our bodies, all bodies will be perpetually a source of wonder. Here we see how receptors meant for detecting light are used also to detect very small amounts of a bitter-tasting chemical: Much like rhodopsins turned on by very dim light, the chemically-activated opsins then initiated a molecular cascade that amplified the small signals. This enabled the flies to detect concentrations of the compound that would otherwise be insufficient to trigger a response in their sensory neurons.
Could you imagine if every pore on your body was an eyeball? Because it kind of already is.
Nicole Y. Leung et al, Functions of Opsins in Drosophila Taste, Current Biology (2020). DOI: 10.1016/j.cub.2020.01.068
http://dx.doi.org/10.1016/j.cub.2020.01.068