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Dr. Mulchaey - Pasadena Carnegie Observatories

By Bob Snodgrass
Posted: 11/02/2021
Science Monday- Guest Lecture - November 8, 2021

I hope that you all are well. I Look forward to next Monday when we have a special guest speaker, arranged by Howard. He is Dr. John Mulchaey,Director of the Pasadena Carnegie Observatories. He will talk about space observation by optical (visual and more and more infra-red), and other technologies and ongoing Carnegie Projects. The Carnegie Observatories began in 1904 as the Mt. Wilson Observatory with funding from George Ellery Hale. The Mt. Wilson telescope was used by Dr, Edwin Hubble in his historical work, which established that our Milky Way is only one of millions of galaxies, that our universe is expanding and many other observations. This was superseded by the Mt, Palomar observatory and now by the Las Campanas observatory in Chile, where the giant Magellan telescope will be installed, which will have seven large primary mirrors for observation in the visual and infra-red spectrum. All village members are welcome to join our Zoom talk even if they have no association with our group. It’s free.

We won’t have time for member presentations this month, but science news has continued to sizzle. NASA’s Lucy mission to the so-called Jupiter Trojan asteroids. Launch on 10/16 went well but within 24 hrs. problems with one of its two giant solar panels became apparent. It couldn’t be fully opened. What to do? It’s still not clear but a human space mission as was sent to fix Hubble’s problem, is not in the offing.Other functions such as thruster maneuvering and navigation are intact. “That solar array is generating nearly the expected power when compared to the fully deployed wing,” NASA said. So while engineers review the data to understand what went wrong, they are also making calculations to figure out if Lucy will be able to do all the things it is supposed to do in the darker areas of the solar system.

It’s likely that with or without a fully deployed solar array, Lucy will continue its journey to the swarms of Trojan asteroids. Scientists believe that these asteroids are remnants of the material that formed giant planets and see them as "fossilized space objects" that hold the keys to understanding the solar system's evolution. There are two small Earth trojans, sharing our orbit. I hope that we can talk further about the Trojan asteroids at a future meeting.

The October 28thissue of Science has interesting new studies and reviews on sleep. Over the past few years, studies in worms, jellyfish, and hydra have challenged the long-standing idea that sleep is unique to creatures with brains. Now, “The real frontier is finding an animal that sleeps that doesn’t have neurons at all,” says David Raizen, a neurologist at the University of Pennsylvania (UPenn). Sponges, some of the earliest animals to appear on Earth, fit that description, but haven’t been found so far to fit the expanded definition.

Scientists often define sleep as temporary loss of consciousness, orchestrated by the brain and for the brain’s benefit. That makes studying sleep in brainless creatures controversial. “I do not believe that many of these organisms sleep—at least not the way you and I do,” says John Hogenesch, a genome biologist at Cincinnati Children’s Hospital. Calling the restful, unresponsive state seen in jellyfish and hydra “sleeplike” is more acceptable to him.

Others in the field have a much more inclusive view: that sleep evolved not with modern vertebrates as previously assumed, but perhaps a half-billion years ago when the first animals appeared. “I think if it’s alive, it sleeps,” says Paul Shaw, a neuroscientist from Washington University in St. Louis. The earliest life forms were unresponsive until they evolved ways to react to their environment, he suggests, and sleep is a return to the default state. “I think we didn’t evolve sleep, we evolved wakefulness.”

Sleep in humans, rodents, and other vertebrates is a highly evolved behavior—one adapted to each organism’s needs and lifestyle. Gleaning insights into its basic function from those species could be difficult. Earlier evolving creatures, with fewer cell types, less complicated molecular pathways, and simpler behaviors may reveal sleep in its most fundamental form.

So,some sleep researchers have turned to invertebrates such as flies and roundworms—and most recently to sponges and another early-evolving group, placozoans. Already, this work has produced two key new insights: that sleep’s benefits extend far beyond the brain, and that muscles, the immune system, and the gut can all have a say in when and how sleep occurs.

A new picture of what controls sleep might also lead researchers to new treatments for sleep disorders. Our hope is that what we learn will help us understand why some people can’t sleep and also how disrupted sleep might affect their health and performance.

The earliest studies of sleep defined it by how it changes human behavior.

By the 1950s and ’60s, researchers converged on a definition of sleep based on polysomnography, a combined measure of brain activity, eye movement, and muscle tone that became a gold standard. Scalp electrode studies (EEGs) showed that human sleep has two major stages: rapid eye movement (REM), a more active stage in which dreaming occurs; and non-REM, defined by slow, synchronous waves of electrical firing.

Behavioral and physiological tests have revealed how varied sleep can be in the animal world. Cows and other large grazing mammals sleep standing up. Some marine mammals sleep while swimming and some seabirds catnap while flying, letting one half of the brain doze while the other keeps working. Bats sleep about 20 hours a day; wild elephants as few as two. Most of the animals studied with electrical recording techniques have at least two stages of sleep, though the brain activity characterizing these stages can vary. The color changes of the octopus as it sleeps suggest it, too, has several sleep stages.

The signs of sleep

Most animals, even very simple ones, have a restful state. How well each creature satisfies these criteria is controversial, but the work is expanding our understanding of the role and control of sleep, even in humans.

Some want to shift to molecular criteria such as whether an organism has genes that are part of sleep-promoting pathways in mammals and other species known to sleep. For example, Itoh’s team reported last year that more than 200 genes changed their activity in sleep-deprived hydra.Several of these genes are involved with sleep in fruit flies.

“We are moving from a behavioral or physiological definition to a cellular and molecular definition,” says Stanford neurobiologist Philippe Mourrain. “As we define more and more what sleep is [on those levels], we will have an idea of its function.”

There’s no question that sleep benefits the brain in creatures that have one. It helps the brain consolidate memories and flush out toxic waste. It may also help the brain stay plastic by pruning and strengthening connections between nerve cells.

If animals without brains need sleep, those functions can’t be the whole story. Because sleep is so widely conserved, it likely serves a fundamental function to preserve basic physiological processes

I expect a good talk and hope to see many of you on the 8th.

Bob Snodgrass.
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