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Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 10:11am

Night mode on screens—useful or not?

We often hear that the short-wavelength component of light from smartphone and tablet screens affects biological rhythms and sleep. The recommendation is therefore to put your mobile phone away early in the evening or at least use the night shift mode, which reduces the short-wavelength light proportions and looks slightly yellowish.  However, the yellowish color adjustment is a by-product that could be avoided.

Technologically, it is possible to reduce the short-wavelength proportions even without color adjustment of the display; however, this has not yet been implemented in commercial mobile phone displays.

 Effects of calibrated blue–yellow changes in light on the human circadian clock, Nature Human Behaviour (2023). DOI: 10.1038/s41562-023-01791-7

Part 3

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Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 10:09am

To get to the bottom of this, the researchers exposed 16 healthy volunteers to a bluish or yellowish light stimulus for one hour in the late evening, as well as a white light stimulus as a control condition. The light stimuli were designed in such a way that they differentially activated the color-sensitive cones in the retina in a very controlled manner.

However, the stimulation of the light-sensitive ganglion cells was the same in all three conditions. Differences in the effect of the light were therefore directly attributable to the respective stimulation of the cones and ultimately the color of the light.

This method of light stimulation allows us to separate the light properties that may play a role in how light effects humans in a clean experimental way.

In order to understand the effects of the different light stimuli on the body, in the sleep laboratory the researchers determined whether the internal clock of the participants had changed depending on the color of the light. Additionally, they assessed how long it took the volunteers to fall asleep and how deep their sleep was at the beginning of the night. The researchers also enquired about their tiredness and tested their ability to react, which decreases with increasing sleepiness.

The conclusion: The researchers  found no evidence that the variation of light color along a blue-yellow dimension plays a relevant role for the human internal clock or sleep. This contradicts the results of the mouse study mentioned above. Rather, these new results support the findings of many other studies that the light-sensitive ganglion cells are most important for the human internal clock.

These findings show that it is probably most important to take into account the effect of light on the light-sensitive ganglion cells when planning and designing lighting. The cones, and therefore the color, play a very subordinate role.

It remains to be seen whether the color of the light also has no effect on sleep if the parameters change, and—for example—the duration of the light exposure is extended or takes place at a different time. Follow-up studies should answer questions like these.

Part 2

Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 10:06am

Light color is less important for the internal clock than originally thought, new study finds

Vision is a complex process. The visual perception of the environment is created by a combination of different wavelengths of light, which are decoded as colors and brightness in the brain. Photoreceptors in the retina first convert the light into electrical impulses: with sufficient light, the cones enable sharp, detailed, and colored vision. Rods only contribute to vision in low light conditions, allowing for different shades of gray to be distinguished, but leaving vision much less precise.

The electrical nerve impulses are finally transmitted to ganglion cells in the retina and then via the optic nerve to the visual cortex in the brain. This region of the brain processes the neural activity into a coloured image.

Ambient light, however, does not only allow us to see; it also influences our sleep-wake rhythm. Specialized ganglion cells are significantly involved in this process, which—like the cones and rods—are sensitive to light and react particularly strongly to short-wavelength light at a wavelength of around 490 nanometers. If light consists solely of short wavelengths of 440 to 490 nanometers, we perceive it as blue. If short-wavelength light activates the ganglion cells, they signal to the internal clock that it is daytime. The decisive factor here is how intense the light is per wavelength; the perceived color is not relevant. However, the light-sensitive ganglion cells also receive information from the cones. This raises the question of whether the cones, and thereby the light color, also influence the internal clock. After all, the most striking changes in brightness and light color occur at sunrise and sunset, marking the beginning and end of a day.

A study in mice in 2019 suggested that yellowish light has a stronger influence on the internal clock than bluish light. However, there is reason to think that the color of light, which is encoded by the cones, could also be relevant for the internal clock.

Part 1

Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 10:01am

Scientists develop 'flying dragon' robot to fight fires from a distance

Imagine a flying dragon that doesn't spout fire, but instead extinguishes it with blasts of water. Thanks to a team of  researchers, this new kind of beast may soon be recruited to firefighter teams around the world, to help put out fires that are too dangerous for their human teammates to approach.

The blueprint of this novel firefighter robot, called the Dragon Firefighter, has been published in Frontiers in Robotics and AI. And as it has been published as Open Science, roboticists around the world may freely use the plans to build their own Dragon Firefighters, for the benefit of all.

Development of a remotely controllable 4 m long aerial-hose-type firefighting robot, Frontiers in Robotics and AI (2023). DOI: 10.3389/frobt.2023.1273676

Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 9:56am

A sweater made from new aerogel fiber tests warmer than one made from down

A team of chemical engineers and materials scientists has developed a new type of aerogel fiber that has proven to be warmer than down when woven into a sweater. In their paper published in the journal Science, the group describes the inspiration for their fibers, how they were made and how well they worked when tested in a cold environment.

Aerogels are types of gels where the liquid is replaced by air. They were invented in the 1930s and have been used for a variety of applications, including NASA space vehicles. Because of their positive thermal properties, material scientists have been trying to make fibers using them that could be used to create warm textiles. Thus far, such attempts have mostly failed, however, due to a lack of moisture permeability and strength. In this new study, a research team in a has found a way to overcome both problems.

The work by the researchers began as an effort to mimic the thermal properties of polar bear fur. They note that the reason the bears can keep warm in such cold temperatures is that the hairs that make up their fur coat have both a porous core and a dense shell. To recreate such attributes, the group created what they describe as an encapsulated aerogel fiber by starting with a precursor, which they spun as it was frozen. This process led to a sol-gel transition. The material was then freeze-dried and coated with a semi-hard shell.

The result was a thin round fiber that could be produced in desired lengths. The researchers note that no post-processing was needed to produce textiles, suggesting their fibers could be produced more cheaply than those currently in use.

The research team next produced batches of their fibers in long strands that they used to weave a sweater. They then tested the warmth of the sweater by exposing it to temperatures as low as −20°C. They claim the sweater demonstrated thermal protection that was better than similar sweaters made of down, wool, or cotton. They also stretched the sweater 10,000 times and found it suffered little damage. They also note that the fiber can be stretched, dyed, and flexed.

Mingrui Wu et al, Biomimetic, knittable aerogel fiber for thermal insulation textile, Science (2023). DOI: 10.1126/science.adj8013

Zhizhi Sheng et al, Mimicking polar bear hairs in aerogel fibers, Science (2023). DOI: 10.1126/science.adm8388

Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 9:28am

Lungs as Resource for Platelet Production

In particular, the study suggests that researchers who have proposed treating platelet diseases with platelets produced from engineered megakaryocytes should look to the lungs as a resource for platelet production. The study also presents new avenues of research for stem cell biologists to explore how the bone marrow and lung collaborate to produce a healthy blood system through the mutual exchange of stem cells.

These observations alter existing paradigms regarding blood cell formation, lung biology and disease, and transplantation.

The observation that blood stem cells and progenitors seem to travel back and forth freely between the lung and bone marrow lends support to a growing sense among researchers that stem cells may be much more active than previously appreciated

https://www.nature.com/articles/nature21706

https://www.ucsf.edu/news/2017/03/406111/surprising-new-role-lungs-....

Part 3

Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 9:26am

The discovery of megakaryocytes and blood stem cells in the lung raised questions about how these cells move back and forth between the lung and bone marrow. To address these questions, the researchers conducted a clever set of lung transplant studies:

First, the team transplanted lungs from normal donor mice into recipient mice with fluorescent megakaryocytes, and found that fluorescent megakaryocytes from the recipient mice soon began turning up in the lung vasculature. This suggested that the platelet-producing megakaryocytes in the lung originate in the bone marrow.

It’s fascinating that megakaryocytes travel all the way from the bone marrow to the lungs to produce platelets. It’s possible that the lung is an ideal bioreactor for platelet production because of the mechanical force of the blood, or perhaps because of some molecular signaling we don’t yet know about.

In another experiment, the researchers transplanted lungs with fluorescent megakaryocyte progenitor cells into mutant mice with low platelet counts. The transplants produced a large burst of fluorescent platelets that quickly restored normal levels, an effect that persisted over several months of observation — much longer than the lifespan of individual megakaryocytes or platelets. To the researchers, this indicated that resident megakaryocyte progenitor cells in the transplanted lungs had become activated by the recipient mouse’s low platelet counts and had produced healthy new megakaryocyte cells to restore proper platelet production.

Finally, the researchers transplanted healthy lungs in which all cells were fluorescently tagged into mutant mice whose bone marrow lacked normal blood stem cells. Analysis of the bone marrow of recipient mice showed that fluorescent cells originating from the transplanted lungs soon traveled to the damaged bone marrow and contributed to the production not just of platelets, but of a wide variety of blood cells, including immune cells such as neutrophils, B cells and T cells. These experiments suggest that the lungs play host to a wide variety of blood progenitor cells and stem cells capable of restocking damaged bone marrow and restoring production of many components of the blood.

To our knowledge this is the first description of blood progenitors resident in the lung, and it raises a lot of questions with clinical relevance for the millions of people who suffer from thrombocytopenia.

Part 2

Comment by Dr. Krishna Kumari Challa on December 23, 2023 at 9:23am

Surprising New Role for Lungs: Making Blood

Cells in Mouse Lungs Produce Most Blood Platelets and Can Replenish Blood-Making Cells in Bone Marrow, Study Shows

Using video microscopy in the living mouse lung, UC San Francisco scientists have revealed that the lungs play a previously unrecognized role in blood production. As reported online March 22, 2017, in Nature, the researchers found that the lungs produced more than half of the platelets – blood components required for the clotting that stanches bleeding – in the mouse circulation.

In another surprise finding, the scientists also identified a previously unknown pool of blood stem cells capable of restoring blood production when the stem cells of the bone marrow, previously thought to be the principal site of blood production, are depleted.

This finding definitely suggests a more sophisticated view of the lungs – that they’re not just for respiration but also a key partner in formation of crucial aspects of the blood. What scientists  observed  in mice strongly suggests the lung may play a key role in blood formation in humans as well.

The findings could have major implications for understanding human diseases in which patients suffer from low platelet counts, or thrombocytopenia, which afflicts millions of people and increases the risk of dangerous uncontrolled bleeding. The findings also raise questions about how blood stem cells residing in the lungs may affect the recipients of lung transplants.

Lungs Produce More Than 10 Million Platelets Per Hour

The new study was made possible by a refinement of a technique known as two-photon intravital imaging recently . This imaging approach allowed the researchers to perform the extremely delicate task of visualizing the behavior of individual cells within the tiny blood vessels of a living mouse lung.

Researchers were using this technique to examine interactions between the immune system and circulating platelets in the lungs. Using a mouse strain engineered so that platelets emit bright green fluorescence,  they noticed a surprisingly large population of platelet-producing cells called megakaryocytes in the lung vasculature. Though megakaryocytes had been observed in the lung before, they were generally thought to live and produce platelets primarily in the bone marrow.

More detailed imaging sessions soon revealed megakaryocytes in the act of producing more than 10 million platelets per hour within the lung vasculature, suggesting that more than half of a mouse’s total platelet production occurs in the lung, not the bone marrow, as researchers had long presumed. Video microscopy experiments also revealed a wide variety of previously overlooked megakaryocyte progenitor cells and blood stem cells sitting quietly outside the lung vasculature – estimated at 1 million per mouse lung.

Part 1

Comment by Dr. Krishna Kumari Challa on December 22, 2023 at 11:46am

Scientists question nematode cancer tests

Doctors have raised concerns that a commercial cancer test produces higher levels of false negatives ... than published figures suggest. The N-NOSE test, sold by Japanese start-up Hirotsu Bio Science, detects the presence of cancer on the basis of whether microscopic nematode worms move towards a urine sample. Hirotsu Bio Science chief technology officer Eric di Luccio suggests that the criticisms are “100% bullshit”. The company has highlighted that the doctors’ figures have not been subject to peer review. Two Japanese medical societies have launched an investigation, with results expected early next year.

https://www.nature.com/articles/d41586-023-03733-9?utm_source=Live+...

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Why some scientists aren’t using ChatGPT

“Why am I even a researcher if I don’t write my own research?” asks psychologist Ada Kaluzna. She is one of those who have shunned using generative artificial intellige..., because she feels it could disrupt her ability to learn and think creatively. Others are concerned about the tendency of chatbots to make up facts and citations when answering niche questions. Some scientists think that the most cutting-edge AI tools could be useful — especially when writing in a language other than your mother tongue — but are stuck on the waiting list for ChatGPT-4.

https://www.nature.com/articles/d41586-023-04071-6?utm_source=Live+...

Comment by Dr. Krishna Kumari Challa on December 22, 2023 at 11:29am

Baby Survives Incredibly Rare Pregnancy Outside of Mother's Uterus

A 37 year old woman from the French island of Réunion east of Madagascar visited a hospital emergency department, only to discover she was – in fact – pregnant. That was okay.

Scans soon revealed a rather surprising twist. Though there was a 23-week-old baby happily kicking around inside the woman's body, her uterus was completely empty. The fetus had instead set anchor to the membrane lining the abdominal cavity, just above the mother's tailbone.

Identifying the situation as a case of abdominal ectopic pregnancy, the woman's medical care team sent her to a more suitable hospital, where at 29 weeks the baby was delivered surgically and placed into neonatal intensive care. Around 2 months after being delivered, the child was given the all-clear to go home.

Most ectopic pregnancies implant themselves into the lining of one of the two fallopian tubes that channel ova from the ovaries, resulting in a potentially life-threatening situation should the embryo continue to grow. Without suitable medical care, as many as 10 percent of such pregnancies can claim the parent's and child's lives. Yet in less than one percent of ectopic pregnancies, the newly-formed embryo drifts out of the uterus's internal environment altogether and into the abdominal cavity, where it settles against the peritoneal membrane, spleen, or some other tissue or organ, and weaves itself a placenta.

Surprisingly, this arrangement isn't always as disastrous for the embryo as it seems. At least, not at first. Sooner or later, however, the unsupported weight of the growing child and pressure of surrounding organs pose risks to both the child's development and their parent's health.

Maternal death beyond 20 weeks of gestation can occur in as many as nearly one in five cases thanks to shock, hemorrhaging, and multiple organ failure.

For the woman in this case, a timely visit to the emergency department almost certainly saved her life.

https://www.nejm.org/doi/full/10.1056/NEJMicm2120220?

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