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Comment by Dr. Krishna Kumari Challa on December 23, 2022 at 12:47pm

Are elephants afraid of mice?

Mythbusters explore the myth of whether elephants are afraid of mice.

Comment by Dr. Krishna Kumari Challa on December 23, 2022 at 12:25pm

Microplastics deposited on the seafloor have tripled in 20 years

The total amount of microplastics deposited on the bottom of oceans has tripled in the past two decades with a progression that corresponds to the type and volume of consumption of plastic products by society.

This is the main conclusion of a recent study.

Despite the seafloor being considered the final sink for microplastics floating on the sea surface, the historical evolution of this pollution source in the sediment compartment, and particularly the sequestration and burial rate of smaller microplastics on the ocean floor, is unknown. This new study, published in the journal Environmental Science and Technology, shows that microplastics are retained unaltered in marine sediments, and that the microplastic mass sequestered in the seafloor mimics the global plastic production from 1965 to 2016.

Specifically, the results show that, since 2000, the amount of plastic particles deposited on the seafloor has tripled and that, far from decreasing, the accumulation has not stopped growing mimicking the production and global use of these materials.

Researchers explains that the sediments analyzed have remained unaltered on the seafloor since they were deposited decades ago. This has allowed them to see how, since the 1980s, but especially in the past two decades, the accumulation of polyethylene and polypropylene particles from packaging, bottles and food films has increased, as well as polyester from synthetic fibers in clothing fabrics.

The amount of these three types of particles reaches 1.5mg per kilogram of sediment collected, with polypropylene being the most abundant, followed by polyethylene and polyester. Despite awareness campaigns  on the need to reduce single-use plastic, data from annual marine sediment records show that we are still far from achieving this. Policies at the global level in this regard could contribute to improving this serious problem.

The degradation status of the buried particles was investigated, and it was found that, once trapped in the seafloor, they no longer degrade, either due to lack of erosion, oxygen, or light.

Laura Simon-Sánchez et al, Can a Sediment Core Reveal the Plastic Age? Microplastic Preservation in a Coastal Sedimentary Record, Environmental Science & Technology (2022). DOI: 10.1021/acs.est.2c04264

Comment by Dr. Krishna Kumari Challa on December 23, 2022 at 11:59am

Meta-optics: The disruptive technology you didn't see coming

Robots and autonomous cars will have eyes that see much more than the human eye is capable of, a review of the growing field of meta-optics has found.

Meta-optics is advancing science and technology far beyond the 3,000-year-old optical paradigm that we rely on for the visual human-machine interface, such as through cameras in our mobile phones, the lenses in microscopes, drones, and telescopes. Optical components are the technology bottleneck that meta-optics aims to transform, bringing the stuff of science-fiction stories into everyday devices. The field, which blossomed after the early 2000s thanks to the conceptualization of a material with negative refractive index that could form a perfect lens, has grown rapidly in the last five years and now sees around 3000 publications a year. This accelerating volume of research is impossible for scientists and technologists to navigate, which prompted Nature Photonics to commission a review from leaders in meta-optics research.

They found the field was on the verge of industrial disruption.

The biggest driver for the meta-optics field comes from integrating meta-optical elements and devices into optical systems, offering consumer optoelectronics applications. Importantly, meta-optical systems enable novel applications not conceivable before, adding to so-called Industry 4.0. Such applications include the Internet of Things, autonomous cars, wearable devices, augmented reality and remote sensing. The importance of the technology is shown by the large-scale investment from big industry players such as Apple, Google, and Samsung, who have been hiring graduates and investing in the field, especially to develop vision applications.

But the authors note that beyond vision, the non-traditional characteristics of meta-optics could also be used for light sails, LiFi and thermal management. These characteristics come from meta-optics' use of surfaces patterned with regular nanoscale structures, in contrast with the traditional optics of mirrors and lenses. The result is miniature components that scatter and manipulate light in ways that would have astounded Isaac Newton. The first commercial components using these properties are already on the market, with companies such as Metalenz, NILT technologies and Meta Materials Inc delivering flat metalenses, polarization imaging, microscopy and biosensing. These devices also enable access to properties of light that the human eye cannot detect—polarization and phase, for example, and even can be used to engineer, manipulate and quantum states of light, that could be employed for quantum imaging, sensing and communications.

Dragomir Neshev, Enabling smart vision with metasurfaces, Nature Photonics (2022). DOI: 10.1038/s41566-022-01126-4. www.nature.com/articles/s41566-022-01126-4

https://phys.org/news/2022-12-meta-optics-disruptive-technology-did...

Comment by Dr. Krishna Kumari Challa on December 23, 2022 at 11:20am

Researchers use 3D bioprinting to create eye tissue

Scientists used patient stem cells and 3D bioprinting to produce eye tissue that will advance understanding of the mechanisms of blinding diseases. The research team from the National Eye Institute (NEI), part of the National Institutes of Health, printed a combination of cells that form the outer blood-retina barrier—eye tissue that supports the retina's light-sensing photoreceptors. The technique provides a theoretically unlimited supply of patient-derived tissue to study degenerative retinal diseases such as age-related macular degeneration (AMD).

We know that AMD starts in the outer blood-retina barrier. However, mechanisms of AMD initiation and progression to advanced dry and wet stages remain poorly understood due to the lack of physiologically relevant human models.

The outer blood-retina barrier consists of the retinal pigment epithelium (RPE), separated by Bruch's membrane from the blood-vessel rich choriocapillaris. Bruch's membrane regulates the exchange of nutrients and waste between the choriocapillaris and the RPE. In AMD, lipoprotein deposits called drusen form outside Bruch's membrane, impeding its function. Over time, the RPE break down leading to photoreceptor degeneration and vision loss.

Researchers combined three immature choroidal cell types in a hydrogel: pericytes and endothelial cells, which are key components of capillaries; and fibroblasts, which give tissues structure. The scientists then printed the gel on a biodegradable scaffold. Within days, the cells began to mature into a dense capillary network.

On day nine, the scientists seeded retinal pigment epithelial cells on the flip side of the scaffold. The printed tissue reached full maturity on day 42. Tissue analyses and genetic and functional testing showed that the printed tissue looked and behaved similarly to native outer blood-retina barrier. Under induced stress, printed tissue exhibited patterns of early AMD such as drusen deposits underneath the RPE and progression to late dry stage AMD, where tissue degradation was observed. Low oxygen induced wet AMD-like appearance, with hyperproliferation of choroidal vessels that migrated into the sub-RPE zone. Anti-VEGF drugs, used to treat AMD suppressed this vessel overgrowth and migration and restored tissue morphology.

Researchers  are using printed blood-retina barrier models to study AMD, and they are experimenting with adding additional cell types to the printing process, such as immune cells, to better recapitulate native tissue.

Kapil Bharti, Bioprinted 3D outer retina barrier uncovers RPE-dependent choroidal phenotype in advanced macular degeneration, Nature Methods (2022). DOI: 10.1038/s41592-022-01701-1. www.nature.com/articles/s41592-022-01701-1

Comment by Dr. Krishna Kumari Challa on December 22, 2022 at 12:11pm

The physical intelligence of ant and robot collectives

Researchers took inspiration from ants to design a team of relatively simple robots that can work collectively to perform complex tasks using only a few basic parameters.

https://techxplore.com/news/2022-12-physical-intelligence-ants-robo...

Comment by Dr. Krishna Kumari Challa on December 22, 2022 at 11:35am

Study finds birds build hanging-nests to protect offspring from nest invaders

A new study has found that birds build hanging-nests, particularly those with extended entrance tunnels, to help protect offspring against nest invaders like snakes and parasitic cuckoos.

Researchers examined the relationship between nest design and the length of time offspring spend in the nest before fledging across species of weaverbirds and icterids, two bird families renowned for their complex woven nests. They found that species building the most elaborate nests, particularly those with long entrance tunnels, produce offspring with longer developmental periods.

Nests with longer entrance tunnels are more effective at hindering access by nest invaders than shorter tunnels and thereby limits the exposure of developing offspring to nest invaders.

Researchers suggest that the complex structural features in these nests do indeed play a role in protecting offspring from predators and brood parasites. They find the consistency of these findings "striking" given that highly elaborate nests have evolved independently in the weaverbirds and icterids.

Sally Street et al, Convergent evolution of elaborate nests as structural defences in birds, Proceedings of the Royal Society B: Biological Sciences (2022). DOI: 10.1098/rspb.2022.1734. royalsocietypublishing.org/doi … .1098/rspb.2022.1734

Comment by Dr. Krishna Kumari Challa on December 21, 2022 at 12:41pm

New software based on artificial intelligence helps to interpret co...

More is not always better—sometimes, it's a problem. With highly complex data, which have many dimensions due to their numerous parameters, correlations are often no longer recognizable. Especially since experimentally obtained data are additionally disturbed and noisy due to influences that cannot be controlled.

Comment by Dr. Krishna Kumari Challa on December 21, 2022 at 12:25pm

Human-caused emissions create new cloud-forming particles

Human activity is changing atmospheric chemistry—even in remote places—that could alter how and when clouds form.

That's the conclusion of a new study by scientists, which finds that at a laboratory on a mountaintop in Colorado, new aerosol particles are forming in the air on average every other day and that those particles, likely formed from gases emitted by nearby power plants, can grow until they're big enough for water to condense around, forming clouds.

The study draws an important scientific link, using newly developed statistical methods, that link aerosol growth to measured cloud condensation nuclei—which are the critical ingredients for accurately modeling the role of aerosols and clouds in climate change. 

 To form, clouds need something in the air, such as a speck of dirt or salt, around which to begin condensing water vapor. These somethings, about a tenth of the diameter of spider silk, are particles called "cloud condensation nuclei."

It's known that increased aerosols in the atmosphere lead to more cloud formation, and more reflective clouds. But it's not known whether new aerosol particles, much smaller than cloud condensation nuclei and formed with human-caused emissions, can grow into cloud condensation nuclei. And it's also not known how to incorporate the relationship between aerosols and clouds in climate models. As you might imagine, clouds play a large role in the climate, reflecting solar energy and moving water from one place to another. So being able to realistically model those clouds could help increase the accuracy of the models forecasting changes in our climate.

Noah S. Hirshorn et al, Seasonal significance of new particle formation impacts on cloud condensation nuclei at a mountaintop location, Atmospheric Chemistry and Physics (2022). DOI: 10.5194/acp-22-15909-2022

Comment by Dr. Krishna Kumari Challa on December 21, 2022 at 12:00pm

Three quarters of major observatories affected by light pollution

Researchers  have studied and compared the light pollution levels at major astronomical observatories across the world. The study shows that light is polluting the sky above most observatories and that immediate action is needed to decrease the amount of contamination coming from artificial light. The work was published in Monthly Notices of the Royal Astronomical Society.

The study presents the light pollution levels above almost 50 observatories across the globe, including the world's largest professional observatories, as well as smaller observatories for amateurs. The study utilizes a model of propagation of light in the Earth's atmosphere and applies it to night-time satellite data. Using additional light pollution indicators, beyond examining the traditional brightness directly overhead (i.e. at the zenith), reveals that the night sky at major observatory sites is more polluted than one may assume. The zenith is generally the less polluted, therefore darker, zone of the night sky, and is one of the indicators used to classify the sites in the study. The additional indicators are the average brightness at a 30° altitude above the horizon, the average brightness in the first 10° above the horizon, the overall average brightness across the sky, and the illuminance of the ground given by the artificial light coming from the night sky. These indicators, along with the overhead brightness, help to decipher how artificial light affects the night sky.

The key measure is the comparison with the natural sky brightness caused by airglow in the high atmosphere, and light originating from stars and the Milky Way. The study results show that only 7 of the 28 major astronomical observatory sites (sites that host a telescope with a diameter of 3 meters or more) have a zenith sky brightness with light pollution below the expected threshold of 1% of natural sky brightness, and so could be considered almost uncontaminated in that direction. This leaves the remaining 21 other major sites—three quarters of all the major observatories—all above this level. The lowest pointing direction of ground-based telescopes is around 30° above the horizon. Only one observatory of the 28 major sites has light pollution in that direction below the 1% level. A more relaxed 10% limit was set by the International Astronomical Union in the 1970s as the maximum allowable artificial brightness for major observatories. The new study shows that light pollution at two thirds of the ground based observatories in the study has now crossed this higher threshold.

Fabio Falchi et al, Light pollution indicators for all the major astronomical observatories, Monthly Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac2929

Comment by Dr. Krishna Kumari Challa on December 21, 2022 at 11:49am

One of the really interesting properties of the human brain is how it embodies a rich constellation of networks that are active even when we are at rest. These networks create the biological infrastructure of the mind and are thought to be intrinsic properties of the brain.

These include the frontoparietal network, which enables cognitive control and goal-directed decision-making; the dorsal attention network, which aids in visual and spatial awareness; and the salience network, which directs attention to the most relevant stimuli. Previous studies have shown that the activity of these and other networks when a person is awake but not engaged in a task or paying attention to external events "reliably predicts our cognitive skills and abilities".

With the cognitive tests and fMRI data, the researchers were able to evaluate which theories best predicted how participants performed on the intelligence tests.

We can systematically investigate how well a theory predicts general intelligence based on the connectivity of brain regions or networks that theory entails. This approach allowed the researchers to directly compare evidence for the neuroscience predictions made by current theories.

The researchers found that taking into account the features of the whole brain produced the most accurate predictions of a person's problem-solving aptitude and adaptability. This held true even when accounting for the number of brain regions included in the analysis.

The other theories also were predictive of intelligence, the researchers said, but the network neuroscience theory  outperformed those limited to localized brain regions or networks in a number of respects.

The findings reveal that "global information processing" in the brain is fundamental to how well an individual overcomes cognitive challenges.

Rather than originate from a specific region or network, intelligence appears to emerge from the global architecture of the brain and to reflect the efficiency and flexibility of systemwide network function. 

Investigating cognitive neuroscience theories of human intelligence: A connectome-based predictive modeling approach, Human Brain Mapping (2022). DOI: 10.1002/hbm.26164

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