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Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 1:34pm

New work uses this nanowire system to explore the question of human-like intelligence. Central to the investigation are two features indicative of high-order cognitive function: learning and memory.

This study demonstrates we can selectively strengthen (and weaken) synaptic pathways in nanowire networks. This is similar to "supervised learning" in the brain.

In this process, the output of synapses is compared to a desired result. Then the synapses are strengthened (if their output is close to the desired result) or pruned (if their output is not close to the desired result).

Researchers expanded on this result by showing they could increase the amount of strengthening by "rewarding" or "punishing" the network. This process is inspired by "reinforcement learning" in the brain.

Part 2

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 1:31pm

Networks of Silver Nanowires Appear to Learn And Remember Like The Human Brain

New research explores non-biological systems that are more like human brains. In a new study published in Science Advances, researchers found self-organizing networks of tiny silver wires appear to learn and remember in much the same way as the thinking hardware in our heads.

This is a part of a field of research called neuromorphics, which aims to replicate the structure and functionality of biological neurons and synapses in non-biological systems.

The work focuses on a system that uses a network of "nanowires" to mimic the neurons and synapses in the brain.

These nanowires are tiny wires about one thousandth the width of a human hair. They are made of a highly conductive metal, such as silver, typically coated in an insulating material like plastic.

Nanowires self-assemble to form a network structure similar to a biological neural network. Like neurons, which have an insulating membrane, each metal nanowire is coated with a thin insulating layer.

When we stimulate nanowires with electrical signals, ions migrate across the insulating layer and into a neighboring nanowire (much like neurotransmitters across synapses). As a result, we observe synapse-like electrical signaling in nanowire networks.

Part 1

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 1:17pm

HOW Does Carbon Dioxide Trap Heat?

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 11:36am

Why do transversions not expand and accumulate with age? And why do transversion and transition mutations behave differently?

Despite using a duplex sequencing approach, it is possible that the transversions they detect might have been potentially generated in vitro from real in vivo DNA damage.

The researchers built a model to understand this: there are two broad classes of mtDNA molecules (Figure 1): a ‘stem subpopulation’ of actively replicating mtDNAs which are responsible for renewing the mtDNA pool, and a ‘worker subpopulation’ which are located in actively respiring mitochondria. ‘Stem’ mtDNAs reside in mitochondria that respire less and are therefore protected from reactive oxygen species. Consequently, transversions primarily occur on ‘worker’ mtDNA molecules which rarely replicate, which prevents these mutations from being able to clonally expand and accumulate with age. 

https://elifesciences.org/articles/87194?utm_source=content_alert&a...

Part 3

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 11:33am

The team studied eight different tissues – ranging from the kidney, to the brain and the heart – in young and old mice which were 4.5 and 26 months old. This resulted in an unprecedently large dataset consisting of around 80,000 somatic mtDNA mutations, showing that the rate of accumulation and the composition of mutations vary between different tissues. The highest accumulation rate was in the kidney, where mutations reached the level of one in five mtDNA molecules.

In agreement with previous studies, Sanchez-Contreras et al. observed a high proportion of transition mutations, in which purine (adenine and guanine) and pyrimidine (thymine and cytosine) nucleotide bases are only exchanged for other purines or pyrimidines, respectively. An unusually high proportion of transversion mutations – where a purine changes to a pyrimidine, or vice versa – were also detected. However, unlike the transition mutations, these transversions did not clonally expand and did not accumulate with age in any of the tissues studied. Because new transversions are constantly being generated (mostly through damage caused by reactive oxygen species), lack of accumulation with age implies that these mutations are excluded from being propogated in somatic cells.

Intriguingly, another study also found a high proportion of transversion mutations in the mtDNA of mouse egg cells , which was surprising given that the proportion of inherited mutations that are transversions is usually very low. This suggests that transversion mutations are excluded from being propagated in germ cells as well.

Part 2

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 11:31am

Mitochondrial DNA: Are some mutations more equal than others?

A large-scale study of mutations in mitochondrial DNA has revealed a subset that do not accumulate with age.

Every cell in our body contains hundreds to hundreds of thousands of mitochondria. These organelles are involved in a myriad of functions, most notably respiration (combining oxygen with food to generate energy) and controlled cell death. Mitochondria are the descendants of prokaryotic cells (similar to bacteria) that became part of primordial eukaryotic cells via a process called endosymbiosis: this means that they have their own double-stranded circular DNA (mtDNA), which is similar to the DNA found in bacteria.

The mitochondria within a cell are constantly proliferating and replicating their mtDNA to compensate for cell growth and division, as well as to offset the removal of damaged mitochondria. Because of their respiration activity, mitochondria produce large amounts of reactive molecules, most notably reactive oxygen species, which damage the mtDNA. If a damaged nucleotide in mtDNA remains unrepaired, this may lead to an incorrect nucleotide being inserted during replication, which is then copied onto the new strand during the next round of replication. This results in permanent double-stranded mutations that accumulate with age as mtDNA molecules are continuously damaged and replicated over the course of a person’s lifespan. Consequently, the mutation rates in mtDNA are about a thousand times higher than in nuclear DNA.

 In addition to accumulating with age, mutant mtDNAs are also subject to ‘clonal expansion’ within a cell . This is mostly a stochastic process in which a random mutated mtDNA molecule multiplies and replaces its peers, resulting in the same mutation appearing in most mtDNA molecules in the cell. Clonal expansions are fundamentally important. If enough mitochondria in a cell contain the same mutation, then this mutation will have a phenotypic effect on the entire cell. Moreover, in the female germline, clonal expansions allow mtDNA mutations to take over the egg cell lineage, potentially resulting in the next generation inheriting the mutation.

Most approaches used to analyze mutations in mtDNA suffer a major drawback as they typically involve in vitro DNA replication, such as PCR. This means that damaged nucleotides – which, in vivo, would have likely been repaired prior to replication or excluded from replication – end up getting erroneously copied and eventually converted into artificial double-stranded mutations that are indistinguishable from genuine ones. Now, in eLife, scientists report how they used a technique called duplex sequencing, which excludes these artificial mutations, to study how mtDNA mutations accumulate with age in mice.

Part 1 

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 10:16am

Study examines the potential of edible cutlery

Plastic waste is an increasing problem the world over, with food packaging and single-use items such as plastic knives and forks representing a significant component of the waste stream. There have been efforts to replace disposable cutlery with implements crafted from wood or bamboo, but work in the International Journal of Mathematical Modelling and Numerical Optimisation has looked at a radical alternative—edible cutlery.

Researchers think that creating edible cutlery from millet is one possibility. However, as they explain the production of such items from this unusual source material requires a lengthy step-by-step process.

the researchers recognized that such step-by-step processes lend themselves to being defined by a scientific queuing model that can be solved using supplementary variable queuing technology. They have thus developed a conceptual approach to queue theory that might be implemented in the creation of edible cutley and is displayed through a numerical and complex visual analysis.

Millet is a nutritious, gluten-free, and easily cultivable crop that is widely grown in many parts of the world, particularly in Africa and Asia. It is a general term for are small-grained, annual, warm-weather cereals in the grass family of crops. These plants are fast-growing and highly drought-tolerant. They could therefore be useful as a sustainable and accessible source material in the developing world.

If such edible cutlery were to become a sustainable alternative to plastic or wooden products, then there is a cradle-to-grave assessment to be made of energy and resource costs as well as a need for health and safety considerations. The team has surveyed potential users and found the concept largely acceptable. All that said, chewing and swallowing a millet knife and fork at the end of one's meal may not be to everyone's taste.

Vignesh Perumal et al, An Investigation on MX/G/1 Queuing Model of Interrupted Services in the Manufacturing of Edible Cutlery Process, International Journal of Mathematical Modelling and Numerical Optimisation (2022). DOI: 10.1504/IJMMNO.2023.10050913

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 9:55am

"Our analysis does not support the widespread belief that increased affluence is the main driver of increased carbon emissions at the global level. It is definitely an important factor, but neglecting population growth leads to a skewed and misleading vision of reality."

"Developed nations with stable or declining populations should hence quit fighting these trends and instead embrace them. Just as a small population growth in rich countries can drive big emission increases, a population decrease in rich countries could have big emission-related benefits going forward," says Giangiacomo Bravo.

More information: Lucia Tamburino et al, An Analysis of Three Decades of Increasing Carbon Emissions: The Weight of the P Factor, Sustainability (2023). DOI: 10.3390/su15043245

Part 3

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Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 9:54am

The World Bank's four income groups

The World Bank has four classifications of income for the world's countries: low, lower-middle, upper-middle and high income. These are based on the respective country's gross national income (GNI) per capita.

The current figures apply to the year 2021, when 28 countries are defined as low-income countries, 54 as lower-middle, 54 as upper-middle and 81 as high-income countries.

Analysis of 30 years of emission data

The basis for Giangiacomo Bravo's statement is the analysis of 30 years of emission data for all the world's countries that he and two research colleagues have carried out. By splitting the countries into four income groups according to the World Bank's standard classification, the researchers were able to confirm that the contribution of low-income countries to emission increase is indeed limited. However, they also found that:

• Population is growing in all four income groups.
• The largest contribution to global carbon emissions comes from the upper-middle group.
• Population growth is the main driver of increased emissions in all income groups except the upper-middle one.
• The successful reduction in per capita emissions that occurred in high-income countries was nullified by the parallel increase in population in the same group.

Part 2

Comment by Dr. Krishna Kumari Challa on April 25, 2023 at 9:54am

Population growth is the main driver of increased carbon emissions, study finds

The richest countries emit more carbon dioxide than the rest of the world combined, while population is only growing in the poorest countries. These are two widespread notions that argue for focusing on reducing emissions per capita in order to mitigate climate change. But this is not entirely true on the light of data from the last 30 years, new research published in the journal Sustainability shows.

A dominant narrative in the climate change debate is that addressing population is not relevant for mitigation. This is because the population is only growing in the poorest countries, whose contribution to global carbon emissions is negligible, the reasoning goes. The largest emissions come instead from rich countries where the population no longer grows.

"This way of reasoning is not correct. Our thorough analysis suggests that climate change mitigation strategies should address population along with per capita consumption and technological innovation. A comprehensive approach to the problem is needed," says Giangiacomo Bravo, professor at Linnaeus University.

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