Comment

Comment by Dr. Krishna Kumari Challa on November 3, 2020 at 6:07am

Bats can predict the future, researchers discover

Bats are quite skilled at predicting one thing: where to find dinner ( in the future). 

Bats calculate where their prey is headed by building on-the-fly predictive models of target motion from echoes researchers find. The models are so robust, bats can continue to track prey even when it temporarily vanishes behind echo-blocking obstacles like trees.

Although predicting object motion paths through vision has been extensively studied, these findings, published today in the journal PNAS, are the first to examine the comparable process in hearing. The work enhances the understanding of auditory-guided behaviours in animals and humans, including sight-impaired people who use listen to sounds to track objects in their surroundings.

Just the way a tennis player needs to find out when and where they will hit the ball, a bat needs to anticipate when and where it will make contact with the insect it's hunting. The insect is flying. The bat is also flying. In this very rapidly changing environment, if the bat were to just rely on the information it got from the most recent echo, it would miss the insect.

The bat uses the time delay between each echolocation call and the resulting echoes to determine how far away prey is. They tilt their heads to catch the changing intensity of echoes to figure out where the prey is in the horizontal plane. Bats must put together echo information about object distance and direction to successfully track an erratic moving insect.

But because bats are such good hunters, the research team thought that in addition, the bats must also be somehow using this information to predict where they prey is headed.

Researchers hypothesized that bats use both the velocity information from the timing of the echoes and further adjust their head aim. When they tested this model with their data, they saw it fit very well.

The question of prediction is important because an animal must plan ahead to decide what it's going to do next. A visual animal or a human has a stream of information coming in, but for bats it's remarkable because they're doing this with only brief acoustic snapshots.

Although bats are studied here, the findings apply to any animals that track moving sounds, and even to people, like the blind, who use clicks and cane taps to help them navigate while avoiding obstacles.

Angeles Salles el al., "Echolocating bats accumulate information from acoustic snapshots to predict auditory object motion," PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2011719117

https://phys.org/news/2020-11-future.html?utm_source=nwletter&u...

Comment by Dr. Krishna Kumari Challa on November 3, 2020 at 5:53am

New insight into how brain neurons influence choices

When you are faced with a choice—say, whether to have ice cream or chocolate cake for dessert—sets of brain cells just above your eyes fire as you weigh your options. Animal studies have shown that each option activates a distinct set of neurons in the brain. The more enticing the offer, the faster the corresponding neurons fire.

Now, a study in monkeys by researchers has shown that the activity of these neurons encodes the value of the options and determines the final decision. In the experiments, researchers let animals choose between different juice flavours. By changing the neurons' activity, the researchers changed how appealing the monkeys found each option, leading the animals to make different choices.

A detailed understanding of how options are valued and choices are made in the brain will help us understand how decision-making goes wrong in people with conditions such as addiction, eating disorders, depression and schizophrenia.

Values encoded in orbitofrontal cortex are causally related to economic choices, Nature (2020). DOI: 10.1038/s41586-020-2880-x , www.nature.com/articles/s41586-020-2880-x

https://medicalxpress.com/news/2020-11-insight-brain-neurons-choice...

Comment by Dr. Krishna Kumari Challa on November 3, 2020 at 5:50am

**Nylon finally takes its place as a piezoelectric textile

Saleem Anwar et al. Piezoelectric Nylon‐11 Fibers for Electronic Textiles, Energy Harvesting and Sensing, Advanced Functional Materials (2020). DOI: 10.1002/adfm.202004326

https://phys.org/news/2020-10-nylon-piezoelectric-textile.html?utm_...

Comment by Dr. Krishna Kumari Challa on November 2, 2020 at 6:19am

Doubts over a ‘possible sign of life’ on Venus show how science works

Further searches for reported hints of phosphine have been turning up empty

It was one of those “big, if true” stories. In September, scientists reported that Venus’ atmosphere seems to be laced with phosphine, a possible sign of life.

Now there’s increasing emphasis on the “if.” As scientists take fresh looks at the data behind the Venus announcement, and add other datasets to the mix, the original claim of inexplicable amounts of phosphine is being called into doubt. And that’s a good thing, many scientists say.

It’s exactly how science should work.

On September 14, astronomer Jane Greaves of Cardiff University in Wales and colleagues reported that they had seen signs of phosphine in Venus’ clouds using two different telescopes (SN: 9/14/20). The phosphine seemed to be too abundant to exist without some kind of source replenishing it. That source could be strange microbes living in the clouds, or some weird unknown Venusian chemistry, the team said.

Greaves and colleagues first spotted phosphine with the James Clerk Maxwell Telescope in Hawaii and followed up with the powerful ALMA telescope array in Chile. But those ALMA data, and particularly the way they were handled, are now being called into question.

The key Venus observations were spectra, or plots of the light coming from the planet in a range of wavelengths. Different molecules block or absorb light at specific wavelengths, so searching for dips in a spectrum can reveal the chemicals in a planet’s atmosphere.

Phosphine showed up as a dip in Venus’ spectrum at about 1.12 millimeters, a wavelength of light that the molecule was thought to be absorbing. If Venus’ spectrum could be drawn as a straight line across all wavelengths of light, phosphine would make a deep valley at that wavelength.

But real data are never that easy to read. In real life, other sources — from Earth’s atmosphere to the inner workings of the telescope itself — introduce wiggles, or “noise,” into that nice straight line. The bigger the wiggles, the less scientists believe that the dips represent interesting molecules. Any particular dip might instead be just a random, extra-large wiggle.

That problem gets even worse when looking at a bright object such as Venus with a powerful telescope like ALMA

“The reason those bumps and wiggles are here at all is because of the intrinsic brightness of Venus, which makes it difficult to get a reliable measurement,” Cordiner says. “You could think of it as being dazzled by a bright light: If there’s a bright light in your vision, then your ability to pick out fainter details becomes diminished.”

So astronomers do a few different things to smooth out the data and let real signals shine through.

https://www.sciencenews.org/article/venus-phosphine-possible-sign-l...

I.A.G. Snellen et al. Re-analysis of the 267-GHz ALMA observations of Venus: No statistic.... arXiv:2010.09761. Posted October 19, 2020.

T. Encrenaz et al. A stringent upper limit on the PH₃ abundance at the cloud top of Venus. Astronomy & Astrophysics, in press, 2020. doi:10.1051/0004-6361/202039559.

Comment by Dr. Krishna Kumari Challa on November 2, 2020 at 6:02am

The Mystery of The Platypus Deepens With The Discovery of Its Biofluorescent Fur

Scientists are seeing the  platypus in a whole new light. Under an ultraviolet lamp, this bizarre-looking creature appears even more peculiar than normal, glowing a soft, greenish-blue hue instead of the typical brown we're used to seeing.

https://www.sciencealert.com/the-australian-platypus-is-the-latest-...

Comment by Dr. Krishna Kumari Challa on November 2, 2020 at 5:49am

Researchers Decipher The Secret Ingredients of Ancient Egyptian Ink

An analysis of 12 ancient papyrus fragments has revealed some surprising details about how the Egyptians mixed their red and black ink – findings which could give us a lot more insight into how the earliest writers managed to get their words down on the page.

Ancient Egyptians were using inks to write at least as far back as 3200 BCE. However, the samples studied in this case were dated to 100-200 CE and originally collected from the famous Tebtunis temple library – the only large-scale institutional library known to have survived from the period.

Using a variety of synchrotron radiation techniques, including the use of high-powered X-rays to analyse microscopic samples, the researchers revealed the elemental, molecular, and structural composition of the inks in unprecedented detail.

The red inks, typically used to highlight headings, instructions, or keywords, were most likely coloured by the natural pigment ochre, the researchers say – traces of iron, aluminium, and hematite point to this being the case.

More intriguing was the discovery of lead-based compounds in both the black and the red inks, without any of the traditional lead-based pigments used for colouring. This suggests the lead was added for technical purposes. Lead-based driers prevent the binder from spreading too much, when ink or paint is applied on the surface of paper or papyrus.

As well as explaining how the ancient Egyptians kept their papyrus smudge-free, it also suggests some pretty specialised ink manufacturing techniques. The fact that the lead was not added as a pigment but as a drier infers that the ink had quite a complex recipe and could not be made by just anyone.

Insights into the composition of ancient Egyptian red and black inks on papyri achieved by synchrotron-based microanalyses

https://www.pnas.org/content/early/2020/10/22/2004534117

https://www.sciencealert.com/chemical-analysis-has-revealed-the-adv...

Comment by Dr. Krishna Kumari Challa on November 1, 2020 at 11:14am

**How to figure out what you don't know

Increasingly, biologists are turning to computational modeling to make sense of complex systems. In neuroscience, researchers are adapting the kinds of algorithms used to forecast the weather or filter spam from your email to seek insight into how the brain's neural networks process information.

Testing various computational models of the nervous system, researchers have found that just because a model can make good predictions about data does not mean it reflects the underlying logic of the biological system it represents. Relying on such models without carefully evaluating their validity could lead to wrong conclusions about how the actual system works.

By building and comparing several models of neural signaling, Engel and Genkin found that good predictive power does not necessarily indicate that a model is a good representation of real neural networks. They found that the best models were instead those that were most consistent across multiple datasets. This approach won't necessarily work for all situations, however, and biologists may need alternative methods of evaluating their models. Most importantly, Genkin said, "We shouldn't take anything for granted. We should check every assumption we have."

Genkin, M., Engel, T.A. Moving beyond generalization to accurate interpretation of flexible models. Nat Mach Intell (2020). doi.org/10.1038/s42256-020-00242-6

https://techxplore.com/news/2020-10-figure-dont.html?utm_source=nwl...

Comment by Dr. Krishna Kumari Challa on November 1, 2020 at 11:02am

Microplastics in groundwater (and our drinking water) present unknown risk

Microplastics (plastics <5mm) and their negative health impacts have been studied in oceans, rivers, and even soils, and scientists are beginning to grapple with the myriad human health impacts their presence might have. One understudied, but critical, link in the cycle is groundwater, which is often a source of drinking water.
While microplastics in groundwater likely affect human health, only a handful of studies have examined the abundance and movement of microplastics in groundwater. This gap means the potential for adverse health effects remains largely unknown.
Microplastics pose multiple physical and chemical risks to the ecosystems where they're present, and those risks are exacerbated by plastics' longevity in natural environments. Since they're plastic, they're very durable which is why plastic is great. But it doesn't degrade easily. Microplastics' ability to linger in their environments for decades or longer likely has cumulative detrimental effects on both the organisms and quality of the ecosystem. Their chemical threat stems largely from their ability to transport harmful compounds on their surfaces; when organisms at the base of the food chain ingest microplastics, they ingest the toxins, too. As larger organisms consume the smaller ones, the toxins can build up (a process called bioaccumulation), eventually resulting in responses like organ dysfunction, genetic mutation, or death. Cave ecosystems are known for being super fragile to begin with. All the cave organisms—salamanders, blind fish—are sensitive, so any contaminants that are introduced could damage those ecosystems.
Groundwater can stay in the same aquifer for tens to hundreds of years, or even longer. Combining that long residence time with plastics' resistance to degradation means that those chemical effects could effectively build up in the water and in any organisms within it, increasing the likelihood of toxic bioaccumulation. Together, these could result in long-term contamination of water sources with poorly-understood health effects and ecosystem damage.
Researchers found that while microplastics do increase in groundwater during a flood event, there's also a second peak in microplastics after the flooding has begun to wane. Their explanation is that there are two sources of microplastics for groundwater: those that are already in the subsurface, and those that are newly delivered from the surface. Finding so much plastic later on in the flood, thinking that it could be coming from the surface... is important to understand the sourcing of microplastics in the groundwater. Knowing where the plastic is coming from could help mitigate future contamination.

Paper 23-1: Quantifying microplastic debris sourcing and transport for a karst aquifer
Abstract Link: gsa.confex.com/gsa/2020AM/meet … app.cgi/Paper/355066

https://phys.org/news/2020-10-microplastics-groundwater-unknown.htm...

Comment by Dr. Krishna Kumari Challa on November 1, 2020 at 10:58am

Mythbusting: Five common misperceptions surrounding the environmental impacts of single-use plastics

Five misperceptions surrounding the environmental impacts of single-use plastic.

• Plastic packaging is the largest contributor to a product's environmental impact. In reality, the product inside the package usually has a much greater environmental impact.
• The environmental impacts of plastics are greater than any other packaging material. Actually, plastic generally has lower overall environmental impacts than single-use glass or metal in most impact categories.
• Reusable products are always better than single-use plastics. Actually, reusable products have lower environmental impacts only when they are reused enough times to offset the materials and energy used to make them.
• Recycling and composting should be the highest priority. Truth be told, the environmental benefits associated with recycling and composting tend to be small when compared with efforts to reduce overall consumption.
• "Zero waste" efforts that eliminate single-use plastics minimize the environmental impacts of an event. In reality, the benefits of diverting waste from the landfill are small. Waste reduction and mindful consumption, including a careful consideration of the types and quantities of products consumed, are far larger factors dictating the environmental impact of an event.

https://phys.org/news/2020-10-mythbusting-common-misperceptions-env...

Five misperceptions surrounding the environmental impacts of single-use plastic, Environmental Science & Technology (2020). pubs.acs.org/doi/10.1021/acs.est.0c05295

Comment by Dr. Krishna Kumari Challa on November 1, 2020 at 10:51am

Estimating risk of airborne COVID-19 with mask usage, social distancing

The continued increase in COVID-19 infection around the world has led scientists from many different fields, including biomedicine, epidemiology, virology, fluid dynamics, aerosol physics, and public policy, to study the dynamics of airborne transmission.

Employing basic concepts of fluid dynamics and the known factors in airborne transmission of diseases, the researchers propose the Contagion Airborne Transmission (CAT) inequality model. While not all factors in the CAT inequality model may be known, it can still be used to assess relative risks, since situational risk is proportional to exposure time.

Using the model, the researchers determined protection from transmission increases with physical distancing in an approximately linear proportion.

If you double your distance, you generally double your protection. This kind of scaling or rule can help inform policy."

The scientists also found even simple cloth masks provide significant protection and could reduce the spread of COVID-19.

 Any physical activity that increases the breathing rate and volume of people will increase the risk of transmission. These findings have important implications for the reopening of schools, gyms, or malls.

Rajat Mittal et al, A mathematical framework for estimating risk of airborne transmission of COVID-19 with application to face mask use and social distancing, Physics of Fluids (2020). DOI: 10.1063/5.0025476

https://phys.org/news/2020-10-airborne-covid-mask-usage-social.html...

• ‹ Previous
• 1
• …
• 759
• 760
• 761
• 762
• 763
• …
• 1110
• Next ›
• Page