>In their natural environment, most bacteria preferentially live as complex surface-attached multicellular colonies called biofilms. Biofilms begin with a few cells adhering to a surface, where they multiply to form a mature colony.
>In Caulobacter crescentus biofilms, extracellular DNA (eDNA) is released upon cell death and prevents newborn cells from joining the established biofilm.
>Thus, eDNA promotes the dispersal of newborn cells and the subsequent colonization of new environments.
>Thus, a programmed cell death mechanism using an O2-regulated TAS stimulates dispersal away from areas of a biofilm with decreased O2 availability and favors colonization of a new, more hospitable environment.
... and from the linked summary released by Université de Montréal:
>”We showed that Caulobacter uses a programmed cell death mechanism that causes some cells to sacrifice themselves when the conditions inside the biofilm deteriorate,” said team member Cécile Berne, the lead author of the study.
>“Known as a toxin-antitoxin system, this mechanism uses a toxin that targets a vital function and its associated antidote, the antitoxin,” she said. “The toxin is more stable than the antitoxin and when programmed cell death is initiated, the amount of antitoxin is reduced, resulting in cell death.’’
>“Using a combination of genetics and microscopy, we showed that the toxin-antitoxin system is activated when oxygen becomes sparse as the biofilm becomes larger and cells compete for the available oxygen,’’ Berne added.
>The resulting death of a subset of cells releases DNA, which promotes the dispersal of their live siblings to potentially more hospitable environments, thereby preventing overcrowding that would further reduce environmental quality in the biofilm.
>“The downside is that the biofilm lifestyle is also a strategy used by pathogenic bacteria to become more resistant to antibiotics,” said Brun.
>The orientations of complexes built between 1100 and 750 BCE, in particular, represent the earliest evidence of the use of the 260-day calendar, centuries earlier than its previously known use in textual records.
... and from the linked content by Brian Handwerk, 6 Jan. 2023:
>Newly uncovered ruins along Mexico’s southern Gulf Coast appear to have been designed in alignment with the ancient timekeeping system.
>Aerial surveys using lidar technology revealed that hundreds of architectural complexes were aligned to facilitate timed observations of the rising and setting sun, moon and other celestial objects in line with this 260-day cycle.
>Scientists had suspected that the calendar, which is tied to cycles of maize agriculture and human reproduction, dated back this far.
>But the earliest documented evidence for its use was a glyph depicting “7 Deer,” one of the days in the calendar, as part of a third-century B.C.E. mural in Guatemala.
>
>Since these cultures didn’t leave written records from earlier periods, scientists have found it exceedingly difficult to establish proof of prior calendar use—until this new large-scale discovery.
>These monumental assemblages of plazas, pyramids and platforms, some stretching more than half a mile, indicate the 260-day cycle was likely of central importance to the Olmec, Maya and other cultures since at least the key period of time around 1000 B.C.E.—when more widespread maize agriculture began to take hold in the region.
>“It is obvious that the orientations reflect a complex worldview in which astronomical knowledge conditioned by practical concerns was intertwined with religious concepts,” says co-author Ivan Šprajc, who studies Mesoamerican archaeology and archaeoastronomy at the Slovenian Academy of Sciences and Arts.
>In giant clusters of hundreds or thousands of galaxies, innumerable stars wander among the galaxies like lost souls, emitting a ghostly haze of light. These stars are not gravitationally tied to any one galaxy in a cluster.
>The nagging question for astronomers has been: how did the stars get so scattered throughout the cluster in the first place?
>A recent infrared survey from NASA's Hubble Space Telescope, which looked for this so-called "intracluster light," sheds new light on the mystery.
>The new Hubble observations suggest that these stars have been wandering around for billions of years, and are not a product of more recent dynamical activity inside a galaxy cluster that would strip them out of normal galaxies.
>The survey included 10 galaxy clusters as far away as nearly 10 billion light-years. These measurements must be made from space because the faint intracluster light is 10,000 times dimmer than the night sky as seen from the ground.
>The survey reveals that the fraction of the intracluster light relative to the total light in the cluster remains constant, looking over billions of years back into time.
>"This means that these stars were already homeless in the early stages of the cluster's formation," said James Jee of Yonsei University in Seoul, South Korea.
>Here's the actual paper, because...Vice, seriously?
Linked content from Motherboard/Vice includes remarks from a call with co-author Daniel Brandenburg.
For example, in my excerpt comment:
>“There's never been any measurement in the past of interference between distinguishable particles,” said Daniel Brandenburg, a physics professor at the Ohio State University who co-authored the new study, in a call with Motherboard. “That's the discovery; the application is that we get to use it to do some nuclear physics.”
>For the first time ever, scientists at Brookhaven have captured interference patterns that are created by the entanglement of two particles with different charges, a breakthrough that has opened up a completely new window into the mysterious innards of atoms that make up visible matter in the universe, according to a study published on Wednesday in Science Advances.
>“There's never been any measurement in the past of interference between distinguishable particles,” said Daniel Brandenburg, a physics professor at the Ohio State University who co-authored the new study, in a call with Motherboard. “That's the discovery; the application is that we get to use it to do some nuclear physics.”
>“I wasn't even, in a sense, trying to find something so fundamental about quantum mechanics,” he continued. “When we realized that there's something really interesting going on here, that was a really big surprise to me.”
>
>Brandenburg and his colleagues achieved this milestone with the help of a sensitive detector called the Solenoidal Tracker at RHIC, or STAR, that captured interactions between gold ions that were boosted to the brink of light speed.
>Clouds of photons, which are particles that carry light, surround the ions and interact with another type of particle, called gluons, that hold atomic nuclei together.
>These encounters between the photons and the gluons set off a chain of events that ultimately created two new particles, called pions, which have opposite charges—one positive and one negative.
>When these pions careened into the STAR detector, the precision instrument measured some of their key properties, such as velocity and angle of impact, which were then used to probe the size, shape, and arrangement of gluons inside the atomic nuclei with a precision that has never been achieved before.
>What’s more, the team is even able to make out the rough positions of key particles in the nucleus, such as protons and neutrons, as well as the distribution of gluons.
>It also offers a new way to unravel persistent mysteries about the behavior of atoms at high energies.
Jennifer Ouellette, 1 January 2023, Ars Technica (Condé Nast)
Excerpt:
>Scientists attached GoPro cameras to six dolphins and captured the sights and sounds of the animals as they hunted and devoured various species of fish—even squealing in victory at the capture of baby sea snakes, according to an August paper published in the journal PLoS ONE.
>While sound and video has previously been recorded for dolphins finding and eating dead fish, per the authors, this is the first footage combining sound and video from the dolphins' point of view as they pursued live prey while freely swimming.
>The audio element enabled the scientists to learn more about how the dolphins communicated while hunting.
Is there a peer-reviewed paper documenting the quote by Fu Pao? The THEMIS webpage was last updated in 2006, and I couldn’t find a primary source that the unnamed author may have cited.
>We have located the observational site around Hàojīng (N34°14′, E108°46′) and dated the event to 977 ± 1 or 957 ± 1 BCE. On this basis, we have computed the equatorward extension of the auroral visibility as ≤39.0° in magnetic latitude and reconstructed the equatorward boundary of the auroral oval as ≤45.5° in invariant latitude.
Jennifer Ouellette, 1 January 2023, Ars Technica (Condé Nast)
Excerpt:
>The Bamboo Annals is a chronicle of ancient China, written on bamboo strips, that begins with the age of the Yellow Emperor and runs through the so-called Warring States period (5th century–221 BCE), when rival states were engaged in intense competition. It ended when the state of Qin unified the states.
>The original text of the Bamboo Annals was buried with King Xiang of Wei, who died in 296 BCE, and wasn't discovered until 281 CE, thus surviving Emperor Qin Shi Huang's burning of the books in 212 BCE (not to mention burying hundreds of Confucian scholars alive).
>Independent researcher Marinus Anthony van der Sluijs and Hisashi Hayakawa of Nagoya University relied on the ancient text [version] for their new analysis.
>This text describes the appearance of a "five-colored light" visible in the northern part of the night sky towards the end of the reign of King Zhao of the Zhou dynasty.
>While this is technically an unconfirmed candidate aurora, "The explicit mention of nighttime observation rules out daytime manifestations of atmospheric optics, which sometimes mimic candidate events," the authors wrote.
>Furthermore, "The occurrence of a multicolored phenomenon in the northern sky during the nighttime is consistent with visual auroral displays in mid-latitude regions."
>
>The authors peg the likely date of the event to either 977 or 957 BCE. The next earliest description of a candidate aurora is found on Assyrian cuneiform tablets dated between 679-655 BCE, three centuries later.
>There are two versions of the Bamboo Annals still in existence. One is known as the "current text," consisting of two scrolls printed in the late 16th century. Many scholars believe this text is a forgery, given the many discrepancies between its text and portions of the original quoted in older books, although some scholars have argued that some parts might be faithful to the original text.
>The other version is known as the "ancient text," and was pieced together by studying the aforementioned quoted portions found in older books, especially two dating back to the early 8th century CE.
>A SpaceX Falcon 9 rocket launched the Israeli Earth-imaging satellite EROS C-3 into orbit from Vandenberg Space Force Base in California late Thursday night (Dec. 29), releasing the payload into orbit about 15 minutes after leaving Earth.
>Liftoff occurred at 11:38 p.m. PST at the launch site (2:38 a.m. EST/0738 GMT), with the Falcon 9's first stage returning to land at a nearby SpaceX pad about 8 minutes into the flight.
>"This is our 61st and final SpaceX launch of 2022," Jesse Anderson, SpaceX's production and engineering manager, said during a live webcast.
>The EROS C-3 launch also marked SpaceX's second launch in as many days.
>On Wednesday (Dec. 28), the company launched its first Gen2 Starlink internet satellites from Cape Canaveral Space Force Base in Florida, delivering 54 of the next-generation Starlinks into orbit.
Elizabeth Howell, 29 December 2022, Space.com (Future plc)
>A team of engineers and neuroscientists has demonstrated for the first time that human brain organoids implanted in mice have established functional connectivity to the animals’ cortex and responded to external sensory stimuli.
>Human cortical organoids are derived from human induced pluripotent stem cells, which are usually derived themselves from skin cells.
>These brain organoids have recently emerged as promising models to study the development of the human brain, as well as a range of neurological conditions.
>The implanted organoids reacted to visual stimuli in the same way as surrounding tissues, an observation that researchers were able to make in real time over several months thanks to an innovative experimental setup that combines transparent graphene microelectrode arrays and two-photon imaging.
>
>“No other study has been able to record optically and electrically at the same time,” said Madison Wilson, the paper’s first author and a Ph.D. student in Kuzum’s [Department of Electrical and Computer Engineering] research group at UC San Diego.
>Graphene recordings showed increases in the power of gamma oscillations and phase locking of spikes from organoids to slow oscillations from mouse visual cortex.
>These findings suggest that the organoids had established synaptic connections with surrounding cortex tissue three weeks after implantation, and received functional input from the mouse brain.
>“We envision that, further along the road, this combination of stem cells and neurorecording technologies will be used for modeling disease under physiological conditions; examining candidate treatments on patient-specific organoids; and evaluating organoids’ potential to restore specific lost, degenerated or damaged brain regions,” Kuzum said.
The work was funded through the National Institutes of Health and the Research Council of Norway, as well as the National Science Foundation.
>During the seminar entitled ‘Components of Scientific Literacy and Insight into the Steps of Research in History of Physics’, the students learned about the historical aspect of physical theories and discussed the importance of scientific literacy in daily life. After the seminar, they were given two assignments.
>Using the pre-test and the post-test, we assessed and statistically estimated the development of the students’ scientific research skills.
>The pre-test (Appendix A) defined a scientific problem and enabled students to think like a scientist.
>The post-test (Appendix B) was followed by an evaluation of the pre-test results and a comprehensive discussion. The evaluation of the pre-test results served as a starting point for the discussion. I selected some examples of the answers in the pre-test, which we analysed together.
>The comprehensive discussion highlighted important factors of procedural knowledge of scientific research in various cases, covering different areas of the disciplines, both natural and social sciences.
>In the post-test, the students were given the same task, but they were asked to find their own problem and tackle it using the steps they had learned.
>
>The results of this study suggest that it is not enough to simply conduct an experiment and focus on the content of the experiment.
>In addition to direct experience with experiments, it is also very important to discuss the research process itself, to articulate and justify a single step in the research process in order to increase awareness of the importance of the research procedure.
marketrent OP t1_j3gv8uk wrote
Reply to When conditions in their bacteria colony deteriorate, use of a ‘programmed cell death mechanism’ causes some bacteria cells to sacrifice themselves, stimulating relocation of the colony to survive by marketrent
Finding in title is quoted from the abstract in the research paper, https://doi.org/10.7554/eLife.80808:
>In their natural environment, most bacteria preferentially live as complex surface-attached multicellular colonies called biofilms. Biofilms begin with a few cells adhering to a surface, where they multiply to form a mature colony.
>In Caulobacter crescentus biofilms, extracellular DNA (eDNA) is released upon cell death and prevents newborn cells from joining the established biofilm.
>Thus, eDNA promotes the dispersal of newborn cells and the subsequent colonization of new environments.
>Thus, a programmed cell death mechanism using an O2-regulated TAS stimulates dispersal away from areas of a biofilm with decreased O2 availability and favors colonization of a new, more hospitable environment.
... and from the linked summary released by Université de Montréal:
>”We showed that Caulobacter uses a programmed cell death mechanism that causes some cells to sacrifice themselves when the conditions inside the biofilm deteriorate,” said team member Cécile Berne, the lead author of the study.
>“Known as a toxin-antitoxin system, this mechanism uses a toxin that targets a vital function and its associated antidote, the antitoxin,” she said. “The toxin is more stable than the antitoxin and when programmed cell death is initiated, the amount of antitoxin is reduced, resulting in cell death.’’
>“Using a combination of genetics and microscopy, we showed that the toxin-antitoxin system is activated when oxygen becomes sparse as the biofilm becomes larger and cells compete for the available oxygen,’’ Berne added.
>The resulting death of a subset of cells releases DNA, which promotes the dispersal of their live siblings to potentially more hospitable environments, thereby preventing overcrowding that would further reduce environmental quality in the biofilm.
>“The downside is that the biofilm lifestyle is also a strategy used by pathogenic bacteria to become more resistant to antibiotics,” said Brun.